駒澤大学repo.komazawa-u.ac.jp/opac/repository/all/16551/kci011-02-shimizu.pdfCompetitive...

Competitive Relationships between Tree Species of Scalesia

(S. pedunculata, S. cordata, S. microcephala) and

Introduced Plants (Cinchona succirubra, Psidium guaiava,

Lantana camara) with Reference to Regeneration

Mechanism of Scalesia Forests inthe Galttpagos lslands

Yoshikazu SHIMIZU*

Synopsis

Regeneration mechanism of Scalesia forests and competitive relationships between tfuee

species of tree &alesia (5. pedunculata, S. cordata, S microcephala) and some introduced

spcies (Cinchona succintbrg Psiilium gaajava, Lantona carnara. etc.) were studied in 80 plots

ofsix siteg in Santa Cruz, Isabela and Floreana. Especially, the oneyear change ofvegetation

after the 1994 fire was survcyed in connection with the regeneration of S. cordan forest and the

invasion of Psidium guajava in Isabela. The ecology of shrubby Scalesia (5. afinis) was also

studied in 8 plots of four sites in the same islands. Two regeneration types were detected: ( 1)

Synchronous Type in moist for*ts with closed canopy: old trees of Scalesia die synchronously

because of much rain at an Bl Niflo event, new seedlings of Scalesia germinate all at once, and

tley make an even-aged population, and (2) Continuous Type in drier for6ts with sparse

canopy: regeneration ofscalesia trees occur turn by turn in canopy gaps continuously, making

a different-aged population. Cinchona succirubm is spreading rapidly to the vast Highland area

in Santa Cruz, but it has not invaded theS. pedunculato for6t with closed canopy yet' because

it needs bright and moist condition for establishnent. It is speculated that Cinchona may invade

the S pedunculara forest rapidly at the next El Nifro event when the canopy collapses all 8t once.

Psidium gttajava is making a vast secondary forest on the windward slope of Sierra Negra'

Isabela. The 1994 fire burned a large area in this region. New shoots (l-2 m hieh) sprouted

from the base of dead stems of Psidium, while no burnt trees of S. cordata hsld such new shoote.

So the fire accelerated replaceme nt of S cordata 1lirth Psidium. S. cotdata saplings (2-3 m high)

were growing near adult trees which had survived the fire at forest margins and fire'break belts.

Small parches of S. cordaU forest may recover in these places. S. micrccephala makes a sparse

foreet on the north-east slope of Alcedo, Isabela. No introduced tree and ehrub species were

found there. Lantana camom covers tlc ground of S pedunculata forests densely in Florcana.

This may prevent establishment of S. pe&nctlata seedlings at the next regeneration event'

resulting in dirappearance of the forests. The distribution of tree Sbalesrd and S, cfinir never

overlap with each other. Low seed dispersibitity.of Scalesia s€ems to be related with this

distribution pattern. Compared with the introduced plant species, the rapid growth rate ofseedlings and eaplings is a great advantage of tee Scalesia, but the low seed dispersibility is the

largeet weak point. If wc hclp tree Scalesia by making an olrcn land and dispereing seeds at the

appropriate time, it would be possible to restore,Scclesia forest in disturbed area.

I. Introduction

1. Location & GeologyThe Galfupagos Islands are located

Pacific Ocean, 960 km west of the South Ameri-can Continent. They form a province of theRepublic of Ecuador, consisting of sixteen mainislands and more than 40 islets with a total land

in the east area of 7882 km2 (Fig. 1). Seven islands have an

* Professor, Department of Natural Sciences, Komazawa University, Tokyo.

一- 23 -―

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Regional Views No. 11 1997

Fig. 1. Geographicel map of the Galipagos Ishndr. Broken lines on the nap show the 200n, 500n and1000 n contours ftom the sea level.

Table 1. Islands of the Galipagos Islands

Isabela

Santa CruzFernandinaSantiagoSan CristobalFloreanaMarchenaEspafiolaPintaBaltraSanta F6Pinz6nGenovesaRabidaWolfDarwin

Name Area (k-') Altitude (m)

area of more than 100 km2 lTable 1). The larg-est, Isabela, has an area of 4588 km', more thanthe total area of all the other islands combined.The islands are dispersed just under the Equator,ranging from approximately 1"40'N to lo25'Slatitude and from 89" 20'W to 92o 00'W longi-tude. The highest peak in the archipelago is 1707m of Volcan Wolf in Isabela.

The islands have been formed by the activity ofthe hot spot which seems to be located at thenorth-western end of the archipelago. The islandsare made up of basaltic lava flows built one uponanother and deposits of volcanic ash, cinders, andscoria thrown out of craters during eruptions(Jackson 1993). Three rows of island chains aredetected running from the northwest to the south-east: (l) Pinta-Marchena-Genovesa-San Cris-tobal, (2) Santiago-Rabida-Pinz6n-Santa Crvz-Santa F6-Espaflola, (3) Fernandina-Isabela-Floreana (Itow 1983). According to the Plate

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739

640

343

206

777

100

259

458

76

367

253

168

一- 24 -一

Competitive Relationships between Tree Species of Scc/esia and Introduced Plants (Shimizu)

Tectonics theory, the present islands formedwithin 2.8-6.3 million years on the Nazca Plate

have been moving from the northwest to thesoutheast at a speed of 3.7 cm per year, so theolder islands with eroded landscapes are locatedat the south-eastern part of the island chains,

while the younger ones with active volcanoes atthe north-western part (Geist 1996). Recently a

10 million-year-old submerged island was dis-

covered east of San Cristobal, so the age of the

archipelago must be older than the present islands(Christie at al. 1991). There are historical re-

cords of volcanic eruptions in Pinta, Santiago,Fernandina and Isabela. As water percolates

rapidly to considerable depths, there are virtuallyno permanently flowing streams with the excep-

tion of a small stream in San Cristobal.

2. ClimateThe climate of the Galiryagos Islands is excep-

tionally cool and dry for equatorial islands due tothe influence of the cool Hunbolt current runningthrough the islands from the south. The annual

average temperature and precipitation is 23.9"C

and 473.8 mm (1965-1994) at CDRS Meteoro-logical Station, Puerto Ayora in Santa Cruz (Fig.2). Two seasons are detected: (1) rainy season

from January to June with sunny sky, hot temper-

ature and occasional squall, and (2) dry (garua)season from July to December with cloudy sky,

cool temperature and little rainfall (Jackson

1 ee3).The south-east trade wind is prevailing and the

Hunbolt current is dominant in the dry season.

As the air cooled by the ocean current makes an

inversion layer at the altitude of 300 m-600 m,

ascending cloud is suppressed at this height and

brings precipitation to the mountain slope (Fig.3a). But the lowland area remains arid. Thewindward side of the islands gets far more precip-itation than the leeward side. The difference inrain fall is a main cause of the difference ofvegetation between the windward and the leeward

sides.

In the rainy season, the south-east trade windbecomes weak and the warm Panama Basin flowcomes closer to the islands. So the sea tempera-ture arises and the inversion layer disappears,bringing the typical tropical weather with sunnyskies and occasional squall. When the sea temper-ature continues to be unusually high once inseveral years, the total rainfall becomes 5 timesand more larger than usual years (Fig. 3b). Thisevent is called "El Nifio". On the contrary, severe

o i;:T .'- i::;

Fig. 2. Monthly mean temperatures and preci-

pitation recorded from 1965 to 1994 at CDRSMeteorological Station, Santa Cruz.

(a)

□ 1969 層調 1970

(b)

目

Fig. 3. Precipitation of the Galipagos Islands(a) Altitudinal change of precipitation on the

southern slope of Santa Cruz in 1969 and 1970.

Drawn from the data of Werfr (1979). (b)

Annual change of precipitation at CDRS

Meteorological Station, Santa Cruz.

drought sometimes hits the Islands. The occa-

sional occurrence of El Nifro and drought has

much influence on the life of plants and animals

in the Galhpagos.

3. HistoryThe Gal6pagos Islands were discovered by

Tom6s de Berlanga accidentally in 1535. Formany years the islands were used chiefly as a base

of pirates, and later as a port of call by whalers

for repairs and capturing tortoises for fresh meat.

Scientific collection was done in the first quarter

of the nineteenth century. Charles Darwin visited

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four islands of the archipelago on the voyage ofHMS Beagle from September 15 to October 20,1835. He collected 209 plant specimens whichwas the primary foundation for subsequent workon the vascular plants of the islands (Wiggins &Porter l97l). It is famous that he got an inspira-tion of evolution theory here which materializedlater in his book "The Origin of Species".

The history of human establishment is as fol-lows: San Cristobal has been occupied continu-ously since 1869, the south-eastern part of Isabelahas been inhabited since 1893, Floreana has beeninhabited intermittently since early the 19th cen-tury and continuously since 1929, and Santa Cruzwas colonized in the middle 1920's (Wiggins &Porter I97I). Some islands were used as settle-ments of prisoners from the mainland until 1959.Many exotic plants and animals were introducedduring those days (Latore 1990).

The four islands in the archipelago are inhabit-ed now. They have a port town on the coast anda few inland villages at a higher elevation withmoist condition good for cultivation and ranch-ing. The entire archipelago except towns andfarm lands was designated as a National Park in1959. Academy Bay at Puerto Ayora, SantaCruz, has been the home of the Charles DarwinResearch Station (CDRS) since 1964, which hasbeen continuing the activities of research andprotection of the Gal6pagos nature. The uniqueeco-tourism of the Galfupagos was founded in thelate 1960s (Itow 1992, Sayama 1995). Thenumber of tourists has been greatly increasingsince 1980s (Jackson 1993). At the same time,the number of immigrants coming from the main-land is increasing rapidly. The total population isabout 17,000 in 1996.

4. Flora and faunaThe modern flora of the Galfupagos Islands was

compiled by Wiggins & Porter's "Flora of theGal6pagos Islands" in 197 L Native plants arederived from ancestors which accomplished along-distance dispersal from other areas in thepast. The 541 species (including subspecies andvarieties) of vascular plants which has probablyarisen from 413 original introductions are nativeto the Galfupagos, and additional 195 species havebeen brought by man since the discovery of theislands (Porter 1984). According to Carlquist(1974), the methods of the long-distance dispersalfor the ancestral plants in the Gal6pagos Islands

:::"1'"1*:"J:',::a

The 229 species (42.3Vo) out of the 541 speciesare endemic to the Galiryagos. Progenitors of94Vo of the non-endemic natives and 87Vo of theendemics might have come from Tropical Amer-ica and the Andean region including pantropicalelements which are distributed in both the Amer-ican and the Old World Tropics (Porter 1984).Of the 7 endemic flowering plant genera, adaptiveradiation resulted following a single original in-troduction occurring in four genera: Darwiniotha-mnus (2 spp., 4 subsp.), Lecocarpus (3 spp.),Scalesia (15 spp. 7 subsp. 4 var. including S.

gordilloi which was described in 1986), and Jas-minocereus (1 sp., 3 var.) (Porter 1984). Some ofthe introduced species such as Psidium guajava,Cinchona succirubra, and Lantana camara havebecome wild and they are invading the nativevegetation and giving much influence on thenative species (Schofield 1989, Lawesson 1990).

There are no native land mammals except a fewsmall bats and mice in the Galfupagos. Gianttortoises and land iguanas occupied the niche ofthe large mammal herbivores. But they are ex-tinct or endangered at present in many places,and instead, introduced mammals such as goats,pigs, cows, donkeys, horses, dogs and cats havespread all over the islands giving serious damageto native plants and animals (Hoeck 1984, Scho-field 1989).

5. VegetationThe vegetation of the Gal6pagos Islands is ba-

sically determined according to the three mainenvironmental factors: ( 1) island age (old-new)which affects land forms (degree of erosion) anddepth of soils, (2) altitude (low-high) whichmakes a gradient of temperature and moisture inpart, and (3) aspect (windward-leeward) whichdetermines the amount of rainfall. Wiggins andPorter (1971) proposed the six altitudinal zona-tion of vegetation according to the dominantspecies groups; littoral, arid, transition, Sca lesia,Miconia, and fern-sed ge zones from the coast tothe mountain summit. Werff ( 1980) added"Brown vegetation" between Scalesia and Mic-onia vegetation in Santa Cruz. Itow (1985) ad-mitted five zones ecologically; coastal, dry low-land, transitiogal, moist mountain, and highlandzones. Hamann (1981) also classified the vegeta-tion into nine formations according to the veg eta-tion structure. Vegetation maps of all islandswere published by INGALA et al. in 1989.

I propose and use six vegetation zones in thispaper as follows: (1) Littoral zone which appears

一- 26 -―

Competitive Relationships between Tree Species of Scalesia and Introduced Plants (Shimrzu)

along the coast and consists of four mangrove

plants such as Rhizophora mangle, Laguncularia

racemosa, Avisennia germinans, and Conocarpus

errectus together with Hibiscus tiliaceus, Hippo-

mane mancinella, and Maytenus octogona on

rocky bay area, and Ipomoea pescaprae, Scaevola

plumeri, Lycium minimum and Sesuvium portula-

castntm on sandy beaches; (2) Arid zone which

covers vast lowland area made of exposed lava

and is composed of arid-tolerant trees and shrubs

such as Opuntia sPP., Jsminocereus sPP., Bursera

graveolens, Parkinsonia aculeata, Scutia pauci-

flora, Cordia lutea, Castera galapageia, Acacia

rotundiana, Prosopis iuhflora and Erithrina vel-

tina; (3) Semi-arid zone which is a transitional

zone between the Arid and the Moist-forest

zones, and is charactetrzed by the disappeatance

of Opuntia spp. and the occurrence of Trema

micranta and Psidium galapageium; (4) Moist-forest zone which is shrouded by cloud frequently

and is covered with Scalesia forests consisting of

tree species of Scalesia and associated species such

as Psychotria rufipes, Tournefortia rufosericea, T.

pubescens, Zanthoxylum fagara, Croton scouleri,

Pisonia flortbunda, chiococca alba and Psidium

galapageium; (5) Moist-scrub zone which is on

the thin-soiled upper part of mountain slopes

comparable to "subalpine zone" and is covered

with scrubs like Miconia robinsoniana scrub in

Santa Cruz and San Cristobal, and (6) Highland

zonewhich is on the uppermost part of mountains

comparable to "alpine zone" and is composed ofPteridium aquilinum thicket, or herb-grass mead-

ows with patches of Pernettya howellii and Cya-

thea weatherbyana near summits. The elevational

range of each zone depends on the age and size

(height) of the islands and aspects of the slopes.

Invasion of introduced plants is a big problem

for conservation of native vegetation in oceanic

islands of the world (see Stone et al. 1992, Cronk

& Fuller 1995). In the Galapagos Islands, some

introduced plants are invading aggressively into

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一- 27 -―


native Scalesia forests taking the place of Scalesiain the Moist-forest zone, thus the sca lesia forestsare disappearing from the Islands. Invasion ofintroduced plants is closely related with regenera-tion mechanism of scalesra forests and character-istics of introduced species. So I studied theregeneration mechanism of Scalesia forests madeof the three species of tree scalesia: s. peduncu-lata in Santa craz and Floreana, and s. cordataand S. microcephala in Isabela (Fig. 4). I alsoinvestigated competitive relationships betweenthe sca lesia species and some introduced plants:Psidium guajava in Santa cruz,Isabela and Flore-ana, Cinchona succirubra in Sant a Cruz, and Lan-tana camara in Floreana, which have been invad-ing the Scalesia forests to much extent.

A large area in the southern part of Isabelaburned from April through June in 1994 (Mar-quez et al. 1994). I surveyed the influence of thefire on the vegetation as a member of JapaneseMission sponsored by JAICA and EnvironmentalAgency in June, 1994 (JICA 1994). It was aboutone year after the fire when I visited the place thistime. so I studied the one-year change of vegeta-tion after the fire in connection with the regener-ation of scalesia cordata forest and the invasionof Psidium guajava.

This study was conducted in the overseas Re-search Program of Komazawa university inI 995.

ff. Methods

I stayed in the Galhpagos Islands from April 6through June 10, 1995. Six study sites werechosen in the three islands as follows:Santa cruz:Site A (Cerro Crocker: 10 plots) and Site B (LosGemelos: 10 plots), Isabela: Site C (Alemania: l5plots), Site D (Velasco: ZA plots) and Site E(Alcedo: 13 plots), and Floreana: Site F (CerroPajas:l2 plots) (Fig. 4). I put 80 plots in rotal inthe six sites which ( 1) represent vegetation struc-ture and composition of an area, (2) show regen-eration mechanism of scalesia forests, or (3)present invading process of introduced species.In addition to them, r surveyed the lowland aridvegetation with a shrubby scalesia (s. affinrs) inthe four sites; Santa Cruz: Site SC (l plot), Isa-bela: Site IBa (2 plots) and IBb (4 plots), andFloreana: Site FL (1 plot).

Recorded were location (latitude and longitudeby GPS: Panasonic KX-G5500), altitude (bVThommen's altimeter), aspect, inclination, condi-tion of basal rock or soil, and amount of epiphytes

on trunks and ground floor for each plot.I put a l0 m X 10 m quadrat in each plot (the

shape and size were changed in some plots). Fourlayers (Tree: T1, Sub-tree: TZ, Shrub: S, Herb:H) were detected in each quadrat according tothe height of trees, shrubs and herb. The numberof layers decreased in shrubby scrubs. coveragepercentage of each layer was estimated. Lightintensity was measured by a handy illuminancemeter (Topcon IM-3) on the forest floor and at aneighboring open place in some plots to calculatethe relative light intensity.

f measured a DBH (diameter at breast height)of all individuals with a height more than Z m,and also measured a diameter at a height of o.z mif necessary. I counted the number of tree sap-lings and shrubs whose height was between 0.5 mand 2 m.

Locations of all woody individuals (0.5 m( inheight) were mapped, and crown projection wasdrawn on the map for all canopy-making trees. Ialso drew a transect figure of the forest along acenter line of the quadrat.

As for herbaceous species and seedlings of treespecies, names were recorded with relative abun-dance within a quadrat which was rated tenta-tively as follows; 4: many and widely distributed,3: many but narrowly distributed, 2: not so many,1: rare.

These measurements and drawings were partlyomitted in some plots due to limited survey timeand other conditions.

The number of individuals and the basal area ofall tree and shrub species, and the relative abun-dance of herbaceous species and seedlings ofwoody species as well as altitude, plot size, crownheight, and coverage of each layer in all surveyedplots are shown in Appendix.

Nomenclature follows Lawesson et al. (1987).

flf. Results

1. Site A( 1) Location

santa cruz is the second largest island in thearchipelago. It has a conical shape with thehighest peak (Alt. 864 m) of Cerro Crocker atthe center of the island (0" 3g ' 57' 'S, 90" I g, 41,

,

W). The island is located in the middle of thegeological chains (see Fig. l ), thus it has noactive volcano, and the mountains are moderatelyeroded. Puerto Ayora, center of eco-tourism, islocated on the south coast. The town is connect-ed to the airport at Baltra on the opposite side of

一- 28 -―

Competitive Relationships between Tree Species of Scales ia and Introduced Plants (Shimizu)

the island with a partly-paved car road. Twovillages, Vella Vista and Santa Rosa, are on the

way. Site A is located to include both north and

south slopes of Cerro Crocker and its main ridgerunning from the east to the west (Fig. 5).

Scalesia pedunculata forests have almost been

destroyed and pasture lands go up to about 450 min altitude on the south (windward) side of the

island. A thin belt of Miconia robinsoniana thrck'et (Moist-scrub zone) is left around Media Luna

between 450 m and 600 m in altitude and above itappears a vast fern & grass meadow (Highlandzone) with Pteridium aquilinum on a plateau

spreading up to the main ridge about 800 m.

Beyond the ridge, Scalesia forest is widely dis-

tributed on the north (leeward) side of the island.

Prevailing wind blows from the south to the

north. The upper part of this atea is frequently

shrouded by fog. On the ridge near the summit ofCerro Crocker, a wind-swept dwarf scrub compa-

rable to "alpine scrub" is formed where Pernettya

howellii and Cyanea wetherbiana appear- Sphag-

num bogs are also found in concave places

around the ridge. An introduced tree: Cinchona

succirubra has been invading the area from the

south up to the ridge. So many trees of Cinchona

afe found in the Moist-scrub and the Highland

zones, and it seems to be about to invade the

Scalesia forest beyond the ridge (Fig. 5).

(2) Scalesia pedunculata forestThe Scalesia forest is very simple in structure

and species composition. Plot A1 and Plot A2show the typical Scalesia forest in Site A. The

crown (T 1) layer is composed of only Scalesia

pedunculata. Tree crowns are almost even in

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Fig. 5. Vegetedon zones and the invasiot ol Cinchona suecirubra in Stte A. Modifled from ltor (1983).

―- 29 -―

Regional Views No。 11 1997

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PLOT Al

6-9 9-12 12-15DBH CLASS (cm)

alive l■ dead□

height. The T2-layer is usually vacant. The DBHhistograms have an uni-modal distribution, anddead trees are concentrated to thin stems (Fig. 6).Almost all individuals of scalesia have one slen-der bole with no sprouts at the base (Fig. 7).These facts suggest that the population started allat once in the near past and dead trees are theresult of recent self-thinning. The coverage of

Fig.6。 DBH hおtograms or Scaras,α μガ““

c“Jara

in Plots Al and A2。

crown layer is nearly tOOVo, but crowns neveroverlap with each other (Fig. 8), so it is not sodark under the canopy. The relative light intensi-ty is 7.6% in Plot A1.

The Shrub layer is also very poor. Psychotriarufipes and Tournefortia rafosericea are ratherabundant among them. The forest floor is verymoist and mossy, and many fern species are found

□

6-9

DBH CLASS

alive

9-12

(cm)

■ dead

-5m

Fig.7. Profle diagam of Scalqia forest in Plot A1. Keyc to abbreviations: Py, Psychdria rufrryi S,scaleda peduncuhtai Tf, Tountefortia rufovrica. underlined symbotc ghow dead treec.

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Competitive Relationships between Tree Species of Sca/esia and Introduced Plants (Shimizu)

10mX10m

Fig.8. Crown projectioi diagran of Scalesia forest in Plot A1. Keys to abbreviationg: S, Scchiapedurcalata.

Invasion ofCi,nehona

Pteridj-um thicket Scalesia forest

SoilFig. 9. Invasion pattern of Cinchona succirubra on a slope near Mt. Puntudo.

here compared with other vegetation types. Espe-cially, big ferns such as Therypteris balbisii and T.

oligocarpa feature the Herb-layer of the forest.Stems and branches of Scalesia trees are coveredthickly with moss and lichen (Photo l). The

forest as a whole takes on an mossy appearance.Some epiphytes such as Peperomia galapagensts

and Asplenium auritum attach to the mossytrunks and branches. No seedlings and saplingsof Scalesia are found in the forest, though adult

x

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Mt. Puntudo

3l

Regional Views

trees seem to produce many seeds in the canopyevery year. Seedlings and saplings of Cinchonasuccirubra are also not found in the Scalesiaforest, even though many Cinchona trees whichproduce a lot of wind-dispersed seeds are dis-tributed just outside of the Scalesia forest.

(3) Invasion of Cinchona succintbraCinchona succintbra appears only at the alti-

tude of 350 m and above in Santa Cruz, because itneeds moist conditions to establish. Cinchona isinvading the Highland zone widely (Photo 2).The density of Cinchona seems to be inverselyrelated with the amount of Pteridium aquilinum.Fig. 9 shows a transect from the peak of Mt.Puntudo (0o 39'05"s, 90o 2o'21"w, Alt. 780 m)to the dense Scalesia forest on the plateau throughthe Pteridium thicket in Site A. Cinchona has

invaded densely the upper part of the slope wherethe density of Pteridium is low because of thinsoils (basal rocks are exposed everywhere). Theheight of Pteridium thicket is 0.7{.8 m and thedensity (No. of petioles) is 1l-23/sq. m ( 18.4/sq. m in average). The relative light intensity is

2.8Vo on the floor of the thicket. Nearly half ofthe fronds of Pteridium were dead when I ob-served them in April. On the contrary, Cinchonais distributed only sparsely in the lower part of theslope where soils are well developed and the Pteri-dium thicket covers the ground densely. Pteri-

(a) plor A4

No. 11 1997

dium attains to 2 m high there, and the density ofpetioles is 32-39lsq. m (35.2/sq. m in average).The relative light intensity is l.|Vo. Almost allfronds were alive and green in the same day.

Plot A3 and Plot A4 show the Cinchona standslocated on the upper part of the slope. The heightclass distribution of Cinchona has a mode be-

tween 4 m and 5 m (Fig. lOa). The DBH class

histogram also shows uni-modal distribution witha mode between 3 cm and 6 cm (Fig. 10b). Eventhe largest tree was 6 m in height and 11.5 cm inDBH, though Cinchona covld become a tall treeby nature. Almost all trees are growing well withno serious damage on their crowns. These factssuggest that these trees are all young and theinvasion occurred relatively recently. Cinchonamatures very fast. Even a young tree of 1.8 mhigh has some flowers. Seeds with a membranouswing are very light and easily blown off by wind.

Almost all trees have already produced flowersand fruits. However, saplings of Cinchona aterarely found in the area except for a few places

where they are growing around mature trees

(Plot A4) (Fig. l1). I could find Cinchonaseedlings less than 0.2 m high nowhere in thisarea. So the invasion of Cinchona seems to beperiodic rather than continuous. This area isfrequently shrouded by fog, but it occasionallybecomes dry because of thin soil (exposed basal

rocks). The occasional aridness and the dense

thicket of Pteridium may prevent Cinchona fromcontinuous regeneration.

Cinchona has the ability to produce sproutsfrom the base of a tree. It usually takes a multi-stemed growth form (Fig. I2). One individualover 1 m high has 3.4 stems in average in andaround Plot A4. Young trees produc e honzontalbranches which results in a cylindrical shape ofthe crown. In addition, it produces verticalshoots from a fallen stem and then each shoot has

adventitious roots at the base (Fig. 13). So we

find small individuals which are connected toparent tree under the ground (Plot A8) (see Fig.1e).

A former plantation of Cinchona is left at thealtitude of 450 m near Media Luna on the wind-ward side of the mountains. It seems to be one ofthe original source places from which Cinchonainvaded into the upper Highland zone. Plot A5has a few tall Cinchona trees over 15 m in heightoccurring sparsely (Fig. l4), and a lot of saplingsmost of which are lower than 4 m high growingunder the canopy (Fig. 15). It is strange thatmedium-sized trees are rare. This may be the

2-3 3-4

HEIGHT CLASS(m)

目 Cinchona

PLOT A4

DBH CLASS(cm)

雲 Cinchona

Fig. 10. Height and DBH histogramschona young forest in Plot A4.

り

∽蜜≦汽Ｚｂ“壁２

of C,■‐

一- 32 -一


丁2:● Sap I ing: x<l m, o lmS 10mX10m

Fig. 11. Crown projection diagram ol Cinclnna yourg forest in Plot A4. All individnrk in the figure areCittchona succirubra.

εl

C

Ci

ミ

Ｆ講

Fig.12. Profile diagram ol Cinchona young forest in Plot A3. Keye to abbreviations: Ci, Cinclnnasuccirubm; Pfr , Ptefidiam aquilinum.

result of eradication efforts in the past (Tuoc1983). The crowns of tall trees are cylindrical,and the amount of leaves are scarce, thus therelative light intensity is not so low on the floor(I4.2Vo under the canopy and 27.8Vo in thecanopy gap). As this place is located on the

windward side, the forest takes on a mossy ap-pearance. The forest floor is also moist andmossy. Many Cinchona seedlings are found onthe floor, especially on the moss mats. The densi-ty of seedlings, whose height is between 0.1 m and1 m, is l4-36/sq. m (Average: 22/sq. m in ten

一- 33 -一

Regional Views No. 1l 1997

Fig. 13. Growth forms of Cinchona succirubra in various developmental stages.

T1 :O T2:e S:x dead:r 10mX10m

Fig;14. Crown projection .lirgran ol Cinchona forect in Plot A5. All individuals erceptrcbhaoniana (Abbr.: M) are Cinctana succirubra.

↑

―

――

―Ｉ

Ｃ

ＩＩＩＩ）

34


Fig. 15. Profle diagram of Cinchona forest in Plot A5. Keys to abbreviations: 6, Cinchona srrccirubmi M,Miania robinsoniana.

T1 :So,Ci a S:x dead:r

I sq. m quadrats). As this place originally belongs

to the Moist-scrub zone, some individuals of Mic-onia robinsoniana are left in the Shrub layer of the

forest. Seedlings of Miconia are also found on the

floor. In addition, I found many seedlings and

saplings of Cinchona growing along a sunny trailoutside the forest.

There is a place where a small patch of Cincho-

na forest is just adjacent to a wide Scalesia foreston a mountain slope. I put a belt transect (Plot A6) through the border of the two forests (Fig.16). It is noteworthy that no saplings and seed-

lings of Cinchona are found in the Sca lesia forest,

even though seeds of Cinchona must have been

Fig. 16. Crown projection diagram of transitional part between Scalesia

Plot A6. Keys to abbreviations: Ci, Cinchona succirubra; Ptr, Pteridium

Zf, Zanthoxylum fagara.

forest arnd Cinchona young forest inaquilinuni S, Scalesia pedunculata;

dispersed into the Sca lesia forest frequently. On

the other hand, only a few Cinchona saptings were

found within the Cinchona forest, probably be-

cause the dense thicket of Pteridium ptevents new

establishment of seedlings. I could not find any

seedlings and saplings of Sca lesia in both the

Cinchona and the Sco lesia forests. Matured trees

of Cinchona are all vigorous, while some of the

Scalesia trees located on the edge of the forest are

damaged or dead.

(4) Relationships between Scalesia and otherintroduced plants

There is a small patch of Scalesia forest on the

35

Fig. 17. Profile diagram of ScalesiaPanicum maximum; Ptr, PtcridiumTournefortia rufosericea.


forest isolated on a slope inaquilinum; Py, Psychotria

Plot 47. Keys to abbreviations: Pan,rufipes; S, Scalesia pedunculata; Tf,

PLOT A7

0-3 3-6 6-9 9-12 12-15 15-18DBH CLASS (cm)

□ alive l■ dead

18-21

north slope of the mountains (Plot A7). Theupper part is bordered by a dense Pteridium aqui-linum thicket , 2 m high, and the lower part is cutoff by a Panicum m&ximum community, 1.5-2 mhigh (Fig. l7). The upper and lower borders areclearly divided, and neither Pteridium nor Pan-icum can invade the forest floor, because they cannot get enough light under the canopy. Thedistribution pattern of DBH histogram is similarto the typical Scalesia forest (Plots Al and A2)(Fig. 18). Most of the thin stems less than 6 cmDBH are dead. Although the average DBH ofliving trees in Plot A7 is larger than those of PlotsAl and A2, these forests seem to have establishedat the same time. When the forest die all at oncenext time, will this forest be able to regeneratesuccessfully ? If the invasion of Pteridium andPanicum into the open place by undergroundstems su{pass the growth of Scalesra seedlings, theScalesia forest may reduce its area or disappear

ヨ賓⊃∩

＞園

‘

δ

縣

国

晨

ブ

Fig. 18. DBH histogram of Scalesia pedunculatain Plot A7.

completely in this place.As seeds of Psidium guajava are dispersed by

birds and feral animals, the spreading speed seems

to be slower than Cinchona which bears wind-dispersed seeds. However, Psidium is invadingthe Site A area slowly but steadily. A vast Psi-dium forest (deserted plantations in privatelands) goes up to about 540 m in the windwardslope near Media Luna. There are many smallpatches of Psidium in the Highland zone and inopen places adjacent to the Scalesia forest, thoughthe number of individuals is far less than that ofCinchona. Similar to the situation of Cinchona,Icould not find any seedlings and saplings of Psi-dium under the closed canopy of Scaleslc forest.

Plot A8 shows one of the small patches ofPsidium trees in the Pteridium thicket (Fig. l9).Psidium has a good sprouting ability and it usual-ly takes a multi-stemmed growth form, but Psi-dium in Plot A8 has no such sprouts (Fig. 2O).

一- 36 -―


A S:x 10mX10m

Fig. 19. Crown Drojection dlagram of Plot A8 showing the invasion oi Cinclwna succirubra (Abbr.: Ci) and

Psiilium guqjava (Abbr.: Pj) in a dense thicket of Rtzrdium aquilinum (Abbr.: Ptr).

Fig.20. Proffle diagram of Plot A8 showing the lnvasion ol Cinchona succirubm (Abbr.: CD tad Psidium

gu4java (Abbr.: Pj) in a dense thicket ofPtzriilium aqailinum (Abbr.: Ftr).

On the contrary, Cinchona trees in the plot have a

multi-stemmed growth form. They have several

sprouts which are connected through under-ground shoots (fallen stems originally).

Large trees ( 15-20 m high) of Persea america-

na (avocado) which were planted for the land-mark of property borders in the past make a linewithin theScalesia forest (Plot A9). There are so

many saplings of Persea growing around a parent

tree except for just under the dense canopy (Fig.2l). The densest place has 14-20 individuals per

sq. m. The number of saplings decreases sharplywith the distance from the parent tree. Thefarthest sapling in Plot A9 was 16.7 m from the

stem of its parent. Seed of Persea is very big(heavy) and it contains much nutrients, so itgerminates easily and the seedling maintains itselfunder the canopy for some time. Once it es-

37

Regional Views No. I I 1997

Fig.21. Profile diagran of Plot A9 rhoring the invasion of pcnea americam (one adult hee and manysapling$ Abbr: P) in t}re Scalaia pdurculata (!tbbt.: S) forest

Fig. 22. Proflle rliagram ol Miconia scrub il Plot A10. AII Miconia shnbc were dead at the tine of curvey.Keyc to abbrevlations: Ci" Cinclnna succintbraT M, Miconia robiwoniana; Ph', heridium aquilinum.

tablishes in the scalesia forest, it grows up to a talltree shading out adjacent scalesia trees. Butfortunately, there seems to be no animal whichcan disperse seeds of Persea in this area, so itsspreading speed is very slow. On the way fromBella Vista to Media Luna, there is a big planta-tion of Persea whose height attains over 20 m. Itis very dark under the dense canopy and noshrubs or herbs are found on the floor.

(5) Miconia robinsoniana scrubMiconia robinsoniana scrub features the Moist-

scrub zone which is located between Moist-forestzone (Scalesia forest) and Highland zon e (pteri-dium thicket) in Santa Cruz. Most of the Mic-onia habitats were destroyed by human activitiesand alien plants. A Miconia scrub, Z m high,covers the \M-facing slope of Media Luna densely.It is left in a natural condition. The slope is steepbut moist probably because it is shaded by themountain in the morning and it is frequentlyshrouded by fog in the afternoon. Only a few

individuals of Miconia are dead. The invasion ofCinchona is not so frequent.

On the contrary, almost all individuals of Mic-onia are dead due to the drought in 1994 on theopposite side of the slope with a small valley (Fig.22). This side of the slope is gentle but drybecause the soil layer is thin and evaporation mustbe greater in the morning. Cinchona is frequentlydistributed here. The concentrated death of Mic-onia is surely accelerating the invasion of cincho-na. I found many saplings of Cinchona togetherwith those of Miconia growing under the deadopen canopy . Pteridium aquilinum is also invad-ing the scrub. It is speculated that Miconia occa-sionally die all at once in especially arid years, butMiconia scrub could recover soon unless a com-petitive species like Cinchona prevented thegrowth of Miconia saplings. Cinchona may takethe place of Miconia here little by little, and theMiconia scrub will disappear in the future as wecan see in Plot A5.

38

Competitive Relationships between Tree Species of Sco/esia and Introduced Plants (Shimizu)

2. Site B (Los Gemelos)( 1) Location

Site B is located at the altitude 560-580 m inthe western part of the central mountains in SantaCraz (see Fig. a). Most of the area is on a gentleslope of the windward side near the ridge, andsome part is on the leeward side beyond the ridge.The area is called Los Gemelos after the twosmall craters (twins craters). A road which con-nects Baltra Airport and Puerto Ayora passes

through the area. A vast Scalesia pedunculataforest spreads in this area (Photo 3). This forestis frequently shrouded by fog. The twins cratersand a part of the Scalesia forest are one of theimportant eco-tour spots in Santa Cruz. Thelower border of the forest is adjacent to privatepasture lands in which small patches of Scalesia

forest are still left. Cinchona succirubra is spread-ing rapidly along the road and has been invadingin part into the Sca lesia forest.

(2) Scalesia pedunculata forestThe species composition is poor, and the forest

structure is simple in the Scalesia forest (Plots B Iand B8), which is as the same as in the Scalesia

forest in Site A. The canopy (Tl-layer) consistsexclusively of Scalesia pedunculata. The treeheight changes from 4 m to l0 m according to thedepth of soils. The DBH histograms show uni-modal distribution patterns (Fig. 23). Dead treesprobably due to self-thinning are concentrated tothin stem classes. Stems of Scalesia trees areusually straight and single (Fig. 24). These fea-tures suggest that the population is composed of

DBH CLASS(cm)

S[コ alive l■ dead

PLOT B8

0-3 3-6 6-9 9-12 12-15DBH CLASS(cm)

SEコ ahve l■ dead

Fig。 23。 DBH histograms oF Scaras,α fOrest in

Plots Bl,B6and B8。 Key to abbre宙 attons:S,

Scα Jgs'α μ″“"c“

Ja如。

ヽノ

　雀

】くヽバ

〓＞

【】Ｚ

〓バ）“コ“ゝ‘⊃Ｚ

Ｄヽ′

〔コく⊇Ｑ＞一Ｑ乙

』υ“国田２つＺ

０・３

　

□

PLOT Bl

DBH CLASS(cm)

S(aliVO I■ S(dead) □

ffs. 24. ProffIe diagram of Scalrr;ia forert in Plot B8. Keys to abbreviations: Pg Ptiilium galapageium, Pv'Psychotria rufrpq, S, Scal,aia @uncalttti 7,1, Zantlnxylum fagarc. Underlined rymbob chor dead trees.

一- 39 -―


Tl:O T2:s S:x dead:r

Fig. 25. Crown projection diagramgalapageium; S, Scalesi a pedunculatai

10mX10m

of Scalesia forest in Plot 88. Keys to abbreviations: Pg, PsidiumTf, Toumefortia pubescensi Zf, Zanthoxylum fagara.

the same-age individuals which established all atonce in the near past.

The canopy has many small gaps amongcrowns (Fig. 25), so the relative light intensity onthe floor is not so low (8.6Vo). The coverage ofthe Shrub layer is small. It is mainly composed ofsome shrubby species such as Chiococca alba,Psychotria rufipes, Sida rhombifolia, Tournefortiarufosericea and Zanthoxylum fagara. The forestfloor and tree trunks are covered with moss andlichen. Fern species are abundant in the Herblayer. No seedlings and saplings of Scalesia arefound under the canopy of the Scalesia forest.

(3) Regeneration of Scalesra forestPlot B4 is located at the border of the Scalesia

forest adjacent to a private pasture land withPennysetum purpureum. Several fallen trees ofScalesia probably caused by human impact makea canopy gap (Fig. 26). Some saplings (max. 2 mhigh) of Scalesia are found in the canopy gap.

Ageratum conyzoides, a tall herb, invaded the gap

densely. Two vines, Passiflora colinvauxii andStictocardia tiliifolia, appear frequently. A youngtree of Cinchona succirubra, 3 m high, is alsofound at the edge of the gap.

There is a small patch of young forest of Scale-sia in a private land (Plot BZ). Stumps cut at theheight of about 0.5 m are scattered in the plot(Fig. 27). The diameter class histogram ofstumps measured at the height of 0.2 m showsthat a typical Scalesia forest was there beforecutting (Fig. 28). Many saplings of Scalesia,3-4 m high, are growing vigorously in the plot.Each sapling has a straight stem, and branchingat the base is rare. They cover about TOVo of theplot area (Fig. 29). The relative light intensity onthe floor is 27.6Vo. These saplings are all derivedfrom seeds. No sprouts from the old stumps arefound. Small clumps of Pennysetum purpureumare scattered uniformly in the plot (probablyplanted by man) which are grazed by cows. Ac-cording to these features, this forest must havebeen cut one or two years ago.

.S

o.sa

40

Competitive Relationships between Tree Species of Scalesia and Introduced Plants (Shimizu)

-

Fig. 26. Profile diagram of Scalesia

Cinchona succirubra; Py; Psychotria

Zanthoxylum fagara.

-10m

forest with a canopy gap in Plot 84. Keys to abbreviations:rufipes; S, Scalesia pedunculata; Tf, Toumefortia rufosericeai

Ｃｉ，■

Fie,.27. Proffle diagram of Scabia young foreet after cutting in Plot 82. Keys to abbreviations: Pqy'

Pennysefrtm parpurcumi S, &alesia pdunculata.

４

５

０

颯

Ｚ

８

饉

目

２

-6 6-9 9-12 12-15 15-18

DIAMETER CLASS (cm)

■ stump □ Sapling

A lot of saplings and seedlings of Scalesia are

growing in an open grassland (Paspahtm, Cy-

pents, Sida) between the road and one of thetwins craters (Plot B9). A path to the craterpasses through the plot. Two small trees ofScalesia which are the supposed seed source ofthis plot occur in the plot (Fig. 30). Most of the

Fig. 28. Diameter histogram of Scalesia young

forest in Plot 82. Diameter of Scalesia peduncu'

lata (Abbr.: S) was measured at the height of 0.2

m.

saplings are less than I m high. The tallest indi-vidual is 1.45 m high. This means they germinat-ed within one year. Some of the small individualsare dead because of self-thinning and drought inpart. Four saplings of Psidium guaiava are also

invading the plot in a clump.

&Иoγ 7へ『―――→

-41-

Reglonal Views No. 11 1997

Fi8. 30. Dlstribufion of Scalrrria ssDlin$ in an open plrce (Plot B9). Keyr to abbreviationr: Pru,, PasqnlumconiugafrtmiPi,PsidiumsaCiava1,Pol,Ploy@iumdiqenamiSrJr,alaliapr/lurlr,uto&;isid,sida rlnmbijotiaiSlD, Scleria ptercta.

x young tree 5mX10m●XX x X

X●

X X X● X

X メ X

XX .

x /＼ ~ ∧ χ

FfS. 29. Clown projection dirgran of Scalsia young forert after cutting in Plot 82. Keye to abbreviations:Pny, Pennysetum purpureumi S, Scalesia pedunculata.

T1 :O Saplirg: p; s; S x (lm.alm3, dead 8mX10m

Ｘ　

　

　

▲　　　‘

　

　

Ｘ

▲▲　】静

≒直

▲　　▲Ｘ

　

Ｘ　Ｘ

χ

I .li

Ｘ

　

　

　

Ｘ

　

　

Ａ一

′′

ノ

′一一

一一

′

′ノ

′

」１ヽく

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Ｉノレ

ノ

♂　ノ／

“′“ル〃

~● /

X

口子

●

=口号

おンロ

10

―- 42 -―


(4) Invasion of Cinchona succirubraPlot B5 shows the invasion of Cinchona succi-

rabra in a Pteridium aquilinum thicket in a desert-ed private land. Clumps of Cinchona,3-5 m high,

are distributed patchily in the plot (Fig. 3l ).Gaps among the clumps are densely covered withPteridium thicket, l-Zm high (Fig. 32). Even

the tallest tree of Cinchona is 5 m high. All trees

丁2:o S: x lomX10m

Fig. 31. Crown Drojection diagram of Plot 85 chowing the invacion ot Cinclnna succirubru (Abbr.: Ci) in adense Ptcri.itium aquilinum (Abbr.: Ptr) thicket. Itackg of cattle Oroken lines) rrc ranning through the plot-

Fie. 32. Proflle diagram of Plot 85 shorirg the invarion of Cinchona in a dense thi*et of Pnridilzr. Keys

to abbreviedonst Ci, Circhona wccirubmi Pg, hiilium galqageiumi Pfi, Ptcridium aquilinum.

引劇

神ヽ印岸威川

―- 43 -―

Regional Views No.11 1997

丁1:0 丁2:o S:x dead:● 10mX10m

Fig.33. Crown projection diagran ol Scalesia forest with a Cinchana tree in Plot 86. Keys toabbrevirtions: 6, Chiuuca alba; Ci, Cinclwna succirubmi Py, hlchotria rufirc, S, Scalesia pcdunculata;Tf , ToarneJofiia rufueicca; 7,f , T,anthoxylum fagara.

with a height of more than 3 m produce fruit.Only three saplings less than I m high and noseedlings are found in the plot. So the regenera-tion of Cinchona is not continuous. This place isa seed source of Cinchona invasion to the adjacentScalesia forest.

Plot 86 was put in a typical Scalesia forest(Fig. 33), 8 m high, located about 50 m from Plot85. As Plot B6 is at the leeward (north) side ofPlot 85, a lot of wind-dispersed seeds of Cinchonamust be blown into the forest. Nevertheless, theinvasion of Cinchona is very rare. No seedlingsand saplings of Cinchona are found under thecanopy of the Scalesia forest. There are, in fact,a few young Cinchona trees growing in the forest,but they are suppressed by the canopy and noneproduce fruit (Fig. 34). The forest floor is mossyand fern species are abundant in the Herb layer.

Plot B7 shows a rare example that Cinchonahas succeeded in invading the Scalesia forest.Three Cinchona trees, 11 m high, put their crownsabove the canopy of Scalesia forest, 9 m high

(Fig. 35). They produce much fruit. There are atleast 4 dead trees of Sca lesia in the T2-layerstanding just around the Cinchona trees. It isclear that they were shaded out by the crowns ofCinchona trees. A big rotten tree trunk is lying onthe ground. It might have made a canopy gapand Cinchona has invaded the gap successfully. Abig trunk of Psidium galapageium is also lying onthe ground from which some vertical shoots growupward. There are no seedlings and saplings ofeither Scalesia or Cinchona in the plot.

(5) Relationships between Scalesia and otherintroduced plants

Several big trees of Persea americana, 15 mhigh, are found in the ^Scalesia forest (Plot B3).Persea has a large conical crown (Fig. 36). Thecrown made of horizontally spreading branches isso dense that it is dark under the canopy. Scalesiatrees near the Persea tree are suppressed by thecrown and some are dead. There are manysaplings of Persea around the parental tree (Fig.

―- 44 -一


Fig.34. Proffle diagram of Scalasia forest with g Cinclnna tree in Plot 86. Keys to abbrevirtionc: C\Chiococca alba; Ci, Cinclnru saccirubra; Py, Pslchotria rufipes, S, Scalrr;ia pdancuhtaT Tl, Tourncfortia

rufoseica. Underlined symbols ehow dead hees.

Fig.35. Protrle diagram ol Scalcsia forect in Ptot 87 showing the invasion ol Cinclntu trees. Keys to

abbreviations: Ci, Cinclnna succirabm3 S, Scalesia pdunculntai Tl, Tournefortia rufoseicea. Underlined

cymbols show de.d trees.

37). Most of the saplings are distributed withinthe distance of 20 m from the parental tree. Theheight class distribution suggests that these sap-

lings are the same-age population (Fig. 38).Rubus sp. characterized by straight leaf veins

and white hairs underneath is making a dense

bush at the sunny forest edge along the road. Itproduces much edible fruit which is dispersed bybirds and animals. Caesalpinia bondoc also formsa large dense thicket in open places. But these

45


Fig. 36. Proftle diagram of Scolesia forest in Plot 83abbreviations: P, Penea arnericana; Py, Psychotria rufipes;

showing the invasion of a Persea hee. Keys toS, Scclesia pedunculata; Zf, Zanthoxylum fagara.

20m

T1 :O T2:s S:x dead:o Sapf ing:rP

Plot 83 showing the invasion of a large tree andPercea amcricana; S, Scalesia pedunculata; Zf,

2.5♀

Fig. 37. Crown projectionmany sapHngs of Perrea.Zanthoxylum fagara.

diagram of Scalesia forest inKeys to abbreviations: P,

10

1-2 2-3

HEIGHT CLASS (m)

introduced species seemingly can not invade theinside of the closed Scalesia forest.

3. Site C (Atemania)( 1) Location

Isabela is the largest island in the archipelago.It is composed of five main volcanoes each ofwhich has a large caldera at the top. Isabela is

Fig. 38. Height histogram of Percea americanasaplings in Plot 83.

divided geographically into two parts: NorthernIsabela (Alcedo, Darwin and Wolf) and SouthernIsabela (Sierra Negra and Cerro Azul) by anarrow strip of young lava flow named PerryIsthmus.

Site C is located on the south-west slope ofSierra Negra (peak: I49O m). There is a placecalled Alemania where people once colonized and

プ

′針

　

た下　ノ

―-46 -一

Competitive Relationships between Tree Species of Scc/es ia and Introduced Plants (Shimizu)

abandoned before World War II. They intro-duced many alien plants and animals at that time.Our camp site was set up on a gentle slope at 0o54'18"s and 91o I l'30"w (Fig. 39). It tookabout five hours by horse from the end of the carroad near the summit of Sierra Negra to the campsite. The altitude of the camp site, ZZO m, belongsto the lower part of Moist-forest zone (scalesiacordata forest) originally, but almost all the areais covered with a secondary forest of psidiumguajava which was introduced by the colonists inthe past. only small patches of scalesia forests(remnant forest) are scattered among the psi-dium forests.

This area suffered from big fires in 1985 and1994. Approximately 35G4500 ha burned inApril-June, 1994 (Marquez et al. 1994), and theforest has been recovering from the fire (photo4). I surveyed the influence of the fire on thevegetation in this area as a member of JapaneseMission in June, 1994 (JICA 1994). So I couldstudy the vegetation about one year after the firethis time.

DrySW

pteridir,rrlVeJ,aseo(Site D)

As the Moist-forest zone is transitional to driervegetation without Scalesia (Semi-arid zone) atthe lower elevation, I put some plots there, too.There is a small experimental forest of Scalesiacordata left isolated in the agricultural area atSanto Tom6s. It is preserved for the future seedsource of reforestation and education of localpeople. I refer to this forest in Site C.

(2) Scalesia cordata forestScalesia cordata must have made a vast forest

on the Moist-forest zone of the Southern Isabela.As all Scalesia forests left in Site C have receivedmore or less direct or indirect human impacts, itis difficult to imagine the original condition of theScalesia forest. However, the studies of remnantScalesia forests in this area show that the struc-ture and the species composition of the forest arenearly the same as those of Scalesia pedunculataforest in Santa Cruz (Site A and Site B).

The canopy is dominated exclusively by Scale-sia cordata in the typical Scalesia forest at theupper elevation (Plot C10: Alt. 330 m). Stems

SSW ヽ wind

Her Grass Meadow 800m

Psidium Scrub

Psi.dit,m Forest(closed canopy)

Thicket

distribution of Scalesia cordata forest and the invasion ofSee the text for frrrther explanations.

47

Sierra Negra

700m W毛

Mo■ st

Lava F].ow

400m・`

―

、、

Lower limit of\

Semi-arid Zone

Fig. 39. Schematic presentation showing thePsidium guajava in Site C and D area, Isabela.

450m′″

″́ ~｀、`Aユハ爾・ 2ュa

● 0｀〈ヽFite c)■994｀、

0｀、

Ccrd∂ 亡∂ ′′

Bヽurned inヽヽ

ヽ

Fig. 40. Profile diagram of Scalesiaabbreviations: Kln, Kalanchoe pinnata;Zf, Zanthoxylum fagara.


forest in Plot C10 showing the invasionPj, Psidium guajava; S, Scclesia cordatal Tf,

of Psidium. Keys toToumefortia pubescens 1

10mX10m

Fig. 41. Crown projectioa dir€ran of Scalsia forest in Plot C10 showing the invasion ol hidium. Keyr toabbrevirtions: Pj, hidium guajava; S, Scalaia ardata3 Tf, Tourmefortia pufuscensT 7,f, Zanthoxylum fagara.

are usually single and straight (Fig. 40). Thoughthe canopy (Tl +T2layers) is nearly closed (Fig.4l), the relative light intensity is not so low(15.2Vo) . No seedlings or saplings of Scalesia are

found in the plot. There is some amount of soilwith a thick humus layer. The forest floor is

moist and mossy. Kalanchoe pinnata, an escaped

horticultural plant, grew densely in the Herb

48


layer. Psidium guajava has established in thisplot, spreading large crowns in the T2-layer.

On the other hand, the species composition ofthe canopy is more diversified in the remnant

forest at the lower elevation (Plots C3 and C4:Alt. 180m). The ratio of Croton scouleri, an

element of the lower and drier zone, becomeshigh (Fig. 42, Fig. 43). Pisonia floribunda, Psi-

T1 : O T2:a S: x dead: o

Fig.42. Crown projection diagram ol Scalesia-Croton mired forest in Plot Cil showing the invasion ofPsidium. Keyo to abbreviations: G, Cmton scoulori; Pt, Pinnia flaribunda;, Pi, Psidiam guqiaw; S, Scafesiaardata3 Tl, Tounefortfu pubescens; Zl, Tnnthoxylum fagam.

Fig. 43. Proffle diagram of Scalaia-Croton nired forest in Plot C3 ehoring the invesion of Psidium. Keyzto abbreviationsz Cr, Ctobn scouler\ W. Pisonia fl.oribunila; P!, hidiam guajava3 S, Soolesia corfutaS Zf,Zantlnxylum fagaru.

49


ない　『をう∩】≧面Ｚ一ＬＯ∝蜃四Σ⊃Ｚ 6-9

DBH CLASS

9-12 12-15

Crothers

12-15 15-18

Pj

others

□圏

＜ｃｍ■硼

●

∽ｄ己冒２【ｂ蚤冒ヲ

PLOT C10

0-3 ９．‐２＜ｃｍ＞

目硼

□■

6-9

DBH CLASSFig. 44. DBH histograms of Plots C4 and C10.Keys to abbreviations: Cr, Croton scoubrti Pj,Psidium guajava; S, Scclesia cordata.

Fig. 45. ProfiIe diagram of the Scalesia experimental forestKeys to abbreviations: Pg, Psidium galapageium; Pi, Psidiumpubescens; Zf, Zanthoxylum fagara.

in Plot C16 showing the invasion of Psidium.guajava; S, Scalesia cordatal Tf, Tournefortia

d ium gal ap ageiu m, Z an thoxy lu m fagara and Tour-nefortia pubescens ate common in the forest. Thesoil layer is very thin. Basal lava rocks areexposed here and there. The surface of the rockyfloor is thinly covered with fallen leaves, moss andlichen. The canopy is loose and the relative lightintensity on the floor is high (33.lVo in Plot Ca).Nevertheless, no seedlings and saplings of Sca lesiaare found in the forest (Fig. 4). The Herb layeris poor in quality and quantity. Psidium guajava

is invading the forest to some extent. It spreadsbranches forming a large crown in the T2-layer.Young trees and saplings of Psidium are alsofound under the canopy in contrast to Scalesia.

The experimental forest (Plot C16) at Corazonverde (0" 5 r'27"s, 9t"01'35 "w, Alt. 310 m),Santo Tom6s, is the only forest of Scalesia cordataleft on the moist south (windward) slope of SierraNegra near the village (Photo 5). The place (42m X 50 m) is enclosed with a fence to keep live-

-50-


stock out. This forest seems to have the originalstructure and species composition of Scalesia for-est, though some Scalesia individuals were plant-ed in the past and the Shrub and Herb-layersare controled by man (Fig. 45). The total of 168

matured individuals of Scalesia are numbered,and the population dynamics has been observed

by the Isabela Branch of CDRS.The canopy is composed exclusively of S. cor-

data. The DBH histogram shows a clear mode atthe class 6-9 cm (Fi g. 46). Dead trees are con-centrated to thin individuals with the DBH less

than 6 cm. I could find some Scalesia saplingsgrowing in a large canopy gap outside the plotarea. This forest is surrounded by Psidium gua-

java forest and Pteridium aquilinum thicket.Alien species have been removed from the exper-

imental forest. This forest is also used as teaching

materials for local school children. CDRS has aplan to enlarge the enclosed area (to buy the

surrounding area) and to do experimental studies

on the regeneration of S. cordata forest.

(3) Psidium guajava forestOnce Psidium guajava has established in a

1

3-6 6-9 9-12

DBH CLASS (cm)

lalivO ■躍

12-15 15-18

S (dead)Zf

place, it makes a pure forest (Plots Cl and C9).The canopy (TlJayer) and T2-layer are exclu-

sively composed of Psidium (Fig. 47). Crownsare usually wider and thicker than those of Scale-

sia and they overlap with each other (Fig. 48).But the relative light intensity on the floor is notso low in Plot Cl (l3.OVo). Most of the canopy

trees have a multi-stemed growth form. Theaverage number of stems per canopy tree is 2.5 inPlot Cl and 2.9 in Plot C9. Most of the stems are

thin, with DBH less than 6 cm in both plots (Fig.49). Many T}-layer individuals (43.3Vo) of Psr-

dium have damaged top of stems in Plot C9.

These features show that the forests are not so

old. As I found thick dead (rotten) stems left at

the center of the present stumps in Plot C 1, thisforest might have burned in 1985 and recovered

by sprouts again.It is characteristic that saplings of Pstdium exist

under the canopy. The Shrub-layer of the forestis very poor. The soil is very thin but the ground

made of exposed lava is mostly covered thinlywith moss and fallen leaves. The Herb-layer isdominated by Ctenitis sloanei in the moist habitatof Plot Cl, while the coverage of the Herb-layer is

Fig. 4,6. DBH histogram of Plot C16. Keys to

abbreviations: Pj, Psi.dium guaiavai S' Scalesia

cordata; Zf, Zanthoxylum fagara.□陶

「

5m

FiS. 47. Proffle rllagnm ot hidium dominrnt forect in PIot Cl. Keys to abbreviations: Cto., Ct nitis sloartalii

Pi, Itlidiun guojava.

-51-


Tl:O T2:@ S: x dead: e 10mX10m

Fig.48. Crown projection diagram of Psidium doninmt foreet in Plot Cl. Keyr to abbreviatione: Pj,hidium guajavai Tf, Tournefonia pubacens.

PLOT Cl

6-9 9-12 12-15,

DBH CLASS (cm)

alive l■ dead

PLOT C9

12-15 Fig。 419. DBH hbtog,ams of Psjご j“

“

g“a」ava in

Plo撻 Cl and C9。

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一- 52 -―


low in the drier habitat of Plot C9. Seedlings ofPsidium are also found on the floor. The seed-

lings have a thick and straight root under theground (Fig. 50). New shoots frequently appearfrom the base when the top of the old shoot isdamaged or the main stem falls down. Seedlingsand saplings of Psidium with shade-tolerant abil-ity can survive for some years under the canopy.

(4) Semi-arid (Transitional) zoneScalesia cordata disappears at the altitude

around 160 m en route from the remnant forest(Plots C3 and C4) down toward Mt. Soritario.There is a natural forest which belongs to theSemi-arid (Transitional) zone at the altitude 150

m (Plot C5). This forest has not burned before.A big tree of Pisonia floribunda makes a largecrown (7-8 m high) in the plot (Fig. 51). Themain trunk is lying from which several verticalstems elongate upward. This kind of growth formis common to Pisonia trees in this region. It wasshedding most leaves at the time of the survey, so

it is bright in the forest. Eight species form thedense coverage of the T2-layer, 4 m high. Pisonia

floribunda and Psidium galapageium are charac-teristic of the Semi-arid zone in this region. Tou-

rnefortia pubescens, T. rufosericea, Cordia leucost-

achys and Zanthoxylum fagara are common inboth the Semi-arid and the Sca lesia forests. Zan-thoxylum is especially dominant in the Shrub-layer of this forest. Psidium guajava is invadinghere, too, but the frequency is low compared withupper elevations. Most of the herbaceous species

are also common to those of Scalesia forest, butthe ratio of fern species is lower because of driercondition.

plot c6 (0'55'25"S, glo l1'33"\M, Alt. 195 m)is located between the remnant Scalesro forest andthe Semi-arid forest (Plot C5) . Pisonia flo-ribunda, Psidium guajava, Acnistus ellipticus andZanthoxylum fagara make a thick closed canopy(Fig. 52). Psidium guajava has become a memberof this forest completely. The largest tree ofPsidium is 7 m high and 9.9 cm DBH. Zanthox-ylum is frequent in the T}-layer. It is relativelydark under the closed canopy. The Shrub-layer isnearly vacant. No Sca lesia trees are found in andaround the plot. The floor is relatively mossy.

Ctenitis sloanei which indicates the moist andstable condition of the habitat is abundant in theHerb-layer.

25cm

Fig. 50. Growth forms of a seedling and saplings of Psidium guajava.

―- 53 -一


(5) Influence of the fires and regeneration ofScalesia

This area was seriously damaged by the bigfires in 1985 and 1994 (There might have beenseveral non-documented fires in the past). Thedegree of damage is variable according to thevarious conditions such as vegetation types, loca-

tion (altitude, aspect), amount of fuels (driedorganic matters) and wind direction, so burnt andunburned parts make mosaic distribution in thisarea. Only a small part of the area was burnedcompletely to ashes. The burnt area was still darkbrownish one year after the L994 fire, when Ilooked down on it from a high place. Main stems

-8m

″み

'`(11:)〕

4m――

ガ

Fig. 51. Proffle diagram of eeni-.rid mixed forest in Plot C5. Keyc to ebbreviationg: Pf, Pisonia floribunda3co, cordia lcuaphlyctls; Pg, hidium gahpageium, p!, hidium guajaw; rJr, urea caracasana; zr,Tantlnxylun fagara.

Fig" 52. Proffle diagram of remi-erid mixed forest tn Plot C6 with the invagion ol 73idiam. Keyr toabbreviations: Ac, Acnistus ellipticusi h, Ctenitis storlneii Pf, Pisonia floribanda; P!, Psidium guajava; Tt,Toarncfortia pahcensi ft, Tantlnxylun Jagam,

-54-

Competitive Relationships between Tree Species of Scclesia and Introduced Plants (Shimizu)

of Psidium guajava were dead, but still standingwith even small branches on the dead crowns(Plots C2 and C8).

Plot CZ is located close to Plot C 1 (the un-burned Psidium guajava forest). As the distribu-

tion pattern of DBH class histogram for dead

stems in Plot C2 is similar to that of living stems

in Plot Cl (Fig. 53), there must have been aPsidium guajava forest similar to Plot Cl before itburned in Plot C2. Only a few trees have survivedthe fire. Though main stems of Psidium are deadcompletely, many new shoots are sprouting fromthe base of burnt trees, not from the dead trunks(Fig. 54). The number of new shoots per individ-ual is between 0 and 6 (1.6 in average) (Fig. 55).If it is calculated excluding the individuals withno shoots, the average is 2.4 shoots per individual.All new shoots are less than 2 m high at the timeof survey (Fig. 56).

There is a large tree of Trema micrantha in theplot which burned to death. Many saplings ofTrema are scattered around the parent tree (Fig.57). The highest Trema sapling was 2.2 m. These

saplings must have germinated from seeds afterthe canopy became open by the fire. There aresome saplings of Psidium guajava, too. Theheight of saplings from seeds is not so differentfrom that of the new shoots from burnt trees

(Fig. 56). The humus layer burned so completelythat basal lava rock is exposed on the floor of theforest. The HerbJayer is dominated by a lightdemanding fern, Pteridium aquilinuffi, in Plot C2instead of Ctenitis sloanei in Plot C 1.

Plot C8 shows the Psidium guajava forestwhich burned severely (Fig. 58). No canopytrees have survived. The present situation is very

＞

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■ dead

DBH CLASS(cm)

国 Pj ■ Tr

0-3 3-6 6-9 9-12

Pj■l dead

12-15

Fig. 53. DBH histograms of burnt Psidiumdominant forests in Plots C2 and C8. Keys toabbreviation$ Pj, Psidium guajavai Tr, Tremamicrantha.

FiS. 54. hofle diagrrn of bunt hidium dominant forest ir Plot C2. Keyr to abbreviadons: Pl, Ptidiumguqiavai Pfr, Pteridium a4uilinam; T4 Ttuna micmncha. Underlined rynbolg ghov dead treer.

―- 55 -―

Regional Vie■ ァs No。 11 1997

理16

目揚

2 3 4NO. OF SH00TS

0 1 2 3 4 5 6 7

Fig.55。 Histograms of the number of newshoots per bllrnt fな jごj“

“ g“aJavα hdi▼idual in

Plo"C2and C8。

(a)PLOT C2

妻86

:|0。 5-1 1-1.5 1.5-2

HEIGHT CLASS(m)

圏 shoot

(b)

:[

言1

C「0.5 0.5-1 1-1.5 1.5-2 2-2.5HEIGHT CLASS(0

■ sh∞t tt sapling

Fig。 56. H[eight histograms of new shoots and

saplintt of Psiご J“″ g“a」aッα in Plo撻 C2and C8。

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めコく⊃∩一＞】∩ＺＦ【】縣用でこ⊃Ｚ

T1 :O T2:o S: x dead: oPj Sapf ing: nTr 10mX10m

●

● .

ロロ

●

● .

ロ

●

. :ロロロロ |・

ロ

. ● ●

_. ロロ

|ロ

ロロロ ° ロロ ● ロ

●

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ロ

●

●

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ロロロ

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X χ .X ・出ロ

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Fi8. 57. Dirtribution of hidium guqjava (Abbr.: Pj) and new stDtinEr ol Ttema micmntlu (Abbr.: Tr) afterthe fre in the burnt.Bidinz flsninrnt forest in Plot C2.

―- 56-―

Competitive Relationships between Tree Species of Scalesia and Introduced Plants (Shimitu)

FiS. 58. Proffle diagren of burnt.kidizm dominrt forecl Keyc to abbrevirrtions: Pi, Psidium guajava3 Pfu,Ptzridium aquilinum. Undertned symbolo shor dead hees.

Fig. 59. Proflle diagram of transitional part betveen burned and unburned forestr choring denre growth ofScalesia saplinss in Plot C7. Keys to abbreviationr:, Pi, hidium guajava3 Pb' Pteidium aqailinumi S,

Scalqia cordata; Tr, Tlvma mbrantlu. Underlined symbolr show derd hees.

ら

一

号

一

similar to that of Plot C2, though there are noTrema saplings in Plot C8. New shoots aresprouting from the base of the dead stems. Thenumber of shoots per individual falls between 0and 7 (3.0 in average) (Fig. 55). The dense

coverage of Pteridium aquilinilffi, 1-1.5 m high,has established in the Herb-layer. This coverageof Pteridium seems to prevent seedlings of treespecies from re-establishing. Many of the newshoots of Psidium, l-2 m high, have already beenabove the thicket of Pteridium. Rugged basallava is exposed on the floor.

Saplings of Scalesia cordata were found only atthe limited places where some adult Scalesia treeshave survived the fire (Plots C7, Cl1, and C14).

Plot C7 is located at the border between burnt(Plot C8) and unburned (Plot C9) area. Amatured tree of Scalesra is left at the periphery ofthe unburned area, which might be the seed

source of the Scalesia saplings in the plot (Fig.59). A tall tree of Trema is also standing justoutside of the plot. Almost all trees of Psidiumguajava died in the fire, but new shoots are sprout-ing from the base of dead trunks as seen in PlotsC2 and C8. The number of stems per individualis between 0 and 7 (2.3 in average) (Fig. 60).The height of the Psidium shoots is less than 2 m(Fie. 61a).

On the other hand, saplings of Sca lesia originat-ed from seeds have been growing very fast in Plot

burned +le-- unburned

s7

PLOT C7

□ S tt Pj

Fig. 60. Histograms of the number of nerr

shoots from a burnt Psidium guajava (Abbr.: Pj)individual and the number of shoots per Scc lesiacordata (Abbr: S) sapling in Plot C7.

C7. The histogram of sapling height shows a

mode between 2.5 m and 3 m (Fie. 61a). Thehighest individual was 3.5 m. This means Scalesia

has an advantage over Psidium in the early stage

of regeneration after fires. Saplings of Scalesiahave usually one stem per individual, and multi-stemmed growth form is not so frequent (Fig.60). Saplings of Scalesia are distributed aroundthe supposed parent tree. The density of saplingsis 1.4 individuals per sq. m. at the center of thedistribution. Small crowns of the saplings make a

continuous canopy together (Fig. 62). But thenumber of saplings decreases sharply with thedistance from the parent tree. Only one sapling ofScalesia is dead, so self-thinning will happen fromnow. Saplings of Trema micrantha are sparselydistributed in the plot (Fig. 62). Pteridium aqui-linum thrives in an open space of the plot, but itcan not grow under the canopy of Scalesiasaplings.

Plot Cll is a belt-transect which was putthrough the border between burnt and unburnedplaces. It is a part of the remnant Scalesia forest(Plots C3 and C4). According to the presentsituation, the plot area is divided into three parts;Part A: burnt, Part B: transitional and Part C:unburned (Fig. 63, Fig. 64). The fire came toPart B in this place. In Part A and Part B, mostof the canopy trees (Psidium guajava and Scalesia

cordata) were burnt, and only a few have survi-ved the fire (Table 2). As Pteridium aquilinumcovers the ground densely, saplings of Scalesia arerare (8 individuals) in Part A.

On the contrary, many saplings ( 145 individ-uals) of Scalesra form a dense thicket in Part B.The height distribution has a mode between 2 mand 2.5 m (Fig. 61b). The maximum hieght is 3.1


0-0.5 0。 5-1 1-1.5 1.5-2 2-2.5 2.5-3 3-3.5 3.5-4

HEIGHT CLASS (m)

□ S

0-0。 5 0.5-1 1-1.5 1.5-2 2-2.5 2.5-3 3-3.5 3.5-4

HEIGHT CLASS (m)

□ S

0-0。 5 0.5-1 1-1.5 1.5-2 2-2.5 2.5-3 3-3.5HEIGHT CLASS (m)

□ S

Fig. 61. Heig[t histograms of new saplingg afterthe fire in Plots C7, Cll, Cl2 and C14. Keys toabbreviations: Pj, Psidium guajavai S, Scalesiacordata; Tr, Trcma micrantlta.

m. Most of the saplings have single stem with acylindrical crown above 1.5 m. Some saplings less

than 0.8 m high are dead, probably because ofself- thinning. None produces flowers. There aresome saplings of Zanthozylum fagara, Tournefor-tia spp., Psidium galapageium and Chiococca alba.Malvastram coromandelianum is growing fre-quently in the Herb-layer in Part B instead ofPteridium aquilinum in Part A. On the otherhand, canopy trees of Part C are all alive except a

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一- 58 -―


T1 :O T2:s S:x dead:opj Sapling: aS,uTr 10mX10m

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Fig.62。 Dお"ibutton(Abbr.:S)and Tramα

of burnt trees of Psidium guaiava

micrantha (Abbr.: Tr) in Plot C7.

(Abbr.: Pj), and new saplings of Scalesia cordata

10 20m2.5♀

2。5丁1:o T2:●

20

Fig.63. Crown projection diagran of transition l pert between buned and unburned forects chowing

distribution ol Scabia gaplingr in Plot C11. Keye to abbrevhtions: P!, Esidium Pqiava; Ptrl Ptefidium

aquilinumi, S, Scafeeia cordabiTf, Tounulortia pabrrirrlnsi Tl, Tnntlnxylum fagam.

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一- 59 -―

Regio■ al Vie■アs No. 11 1997

Port A----+l- pqrt B----rl€-- port C

burned +le- unburned

Fig. 64. Proffle diagran of transitional part between bumed and unburned forectr rhowing denre growth ofScalrsia caplings in Plot C11. Keys to abbreviations: Pj, hidium guajaw; Ptr, pbridium aquilinumT S,Scalesia cordata. Underlined symbols show derd hees.

Table 2. species compooition in burned, hansitional and unbur:ned parts in plot cll

Species NamePart A (burned) Part B (transitional) Part C (unburned)

No BA No BA No BA

T1-layerScalesia cordataPsidium guajavaZanthoxylum fagara

T2-layerScalesia cordataPsidium galapageiumPsidium guajavaTournefortia pub esc ensZanthoxylum fagara

S-layerChiococca albaPsidium galapageiumPsidium guajavaScalesia cordataTournefortia pubescensTrema micranthaZanthoxylum fagara

H-layerAbutilon depauperatumAsplenium formosumCentella asiaticaCommerina diffusaConyza bonarienseCtenitis sloaneiDoryopteris pedataHyptis mutabilisM alv astrum conomande lianumOxalis corniculaPaspalum conjugatumPolypodium dispersumPteridium aquilinumSida rhombifoliavine sp.

(141)

1

2

(11)

(1)1(7)

(1)

1

155

3

1

7

2

1

2

1

4

1

1

2

3

61

59

(393)

(3)7 (37)

(3)

57499

62

3

2

2(1)

2

46

7

80

11

29(47)

Numerals show the number of individuals (No) and bas al arcadominance value ( l-4) in H-layer. Dead individuals are shown in

(BA: cmt) inparentheses.

―- 60 -―

Tl, T2 and S-layers, and relative


tree of Zanthoxylum. No saplings of Scalesia arefound under the canopy of the forest in Part C,even though the place is adjacent to Part B.Ctenitis sloanei is the most dominant fern in PartC.

plot cl4 (o" 52'29"s, g l o

I 2' 53''W) is locatednear another remnant Scalesia forest (Plot C10).A belt-transect was laid through the border be-tween burnt and unburned places. The generalsituation is common to that of Plot Cl I (Fig. 65).The transect area was a Scalesia-Psidium mixedforest before the fire. It can be now divided intothree parts: burnt, transitional and unburned.There are some matured Sca lesia trees left in theunburned part. Scalesra saplings are found in thetransitional part. Most of the saplings have aheight of 1 .5-2 m (Fig. 61d). The tallest one is2.3 m high. Calanchoe pinnata makes a densecoverage, 1-1.5 m high, in the burnt and thetransitional parts, so Scalesla saplings and Calan-choe are in competitive relation here.

I found a small patch of burnt area (about 25O

sq. m) spotted inside the unburned forest in theremnant forest area neighboring to Plot C3 andPlot C4. I put a belt-transect through the patch(Plot Clz). Canopy trees of Scalesia cordata (9individuals), Psidium guajava (3 individuals) andZanthoxylum fagara (2 individuals) burned,making alarge canopy gap in the forest (Fig. 66).Scalesia saplings make a dense coverage in the gap(Fig. 67), The density was 3.0 individuals per sq.

m in the densest part. The height class distribu-tion has a mode between 2.5 m and 3 m (Fig. 61

c). The maximum individual attains to 3.6 m.Saplings of Trema micrantha, Croton scouleri, andPsidium guajava are also found in the Eap, thoughtheir density is very low. Pteridium aquilinuminvaded the gap and made a small thicket, 1.5-2 m high.

Plot C 13 (belt-transect) was put to includeburnt and unburned forests with a fire-break beltbetween them in the Semi-arid zone near Plot C5

T1 : O T2:o S: x dead: o Sapl ing: a (S)

5 l5m

burned unburned

-

Fig.65. Crown projection dirgram of transitional Dart between burned and unburaed pbcec rhowingdistribution of Scalaia caplings in Plot C14. Keyr to abbreviationg: l(rn, Kalanclne pinnata; P!, Psidiumguqjava; P?c, Pteridium aquilinumi S, Scctracic cordata; Zf, Zanthoxylam fagara.

眺　　ム∴

５ａｒムム

T1 :O T2:O S: x dead: o Sapling: a (S)

ハ　バ▲

▲▲

burned

Fig. 66. Distribution of scalesia saplings in a forest gap Ournt part)croton scoulerii Pg, Psidium galapageium; pj, psidium guajava;cordatal Tr, Trema micrantha; Zf, Zanthoxylum fagara.

in Plot Cl2. Keys to abbreviations: Cr,Ptr, Pteridium aquilinum; S, Scalesia

6t


burned

Fig. 67. Profile diagram of Plot 12 showing dense growth of Scalesia

Keys to abbreviations: Pj, Psidium guajavai Ptr, Pteridium aquilinum;

fagara. Underlined symbols show dead trees.

-5m

saplings in a canopy gap (burnt part).

S, Scalesia cordata; Zf, Zanthoxylum

There is no Scalesia cordata. The forest floor is

mossy and has several fern species. On the con-

trary, the burnt area which burned in 1985 iscovered with a dense thicket of Pteridium aqui'linum. Only a few dead trees of Psidium galapa-

%

fire-break belt

t{ Pi

20m

20burned

FIg.6S. Proflle dirgram of transidonrl part betreen buned and unbutled seni-rrid forects in Plot C13

with a flre.breek belt at the center. Keys to abbreviafions: Pl, Pisonia floribunth; Pg, hidium galnpageiumi

Pj, Psidium guojava; P&', Prtoridium aquilinum', Tf, Toarmefortia pubacensi Zf, Tantlnrylam fagara.Underlined synbolc shov d€rd trecs.

(Fig. 68). The unburned forest consists of smalltrees of Psidium galapageium, Psidium guaiava,

Tournefortia pubescens, T. ntfosericea and Zan-thozylum fagara. Pisonia floribunda is sparselydistributed making a large crown in the forest.

62


geium, P. guajava and Tournefortia pubescens atestanding in this area. I saw tall dead trees ofPisonia floribunda and Trema micrantha standinghere and there in this area (not included in thebelt-transect). It is probably because this placewas severely burnt (most trees became ash) andregeneration has been prevented by the densethicket of Pteridium. Basal lava is exposed insome part of the burnt area. The fire-break belt,4 m wide, was built to prevent the fire fromspreading outward in 1985. It was repaired at thetime of the 1994 fire. Saplings ofPsldium guajavaare growing in open places of the belt. Malvast-rum colomanderianum and Cassia tora are fre-

quently distributed.Plot C15 includes four line-transects (Line 1-

4) in the fire-break belt at Alemania which wasbuilt in 1994 (Fig. 69). Fire fighters cut a forestabout l0 m wide and removed roots and rocks(maybe buried seeds, too) from the surface bytractor. We (Japanese Mission) used this "road"when we came here just after the fire in June,1994. There was no coverage of plants in the beltatthat time (Photo 6). The present condition isabout one year after the belt was abandoned. Thevegetation which recovered in the belt is differentfrom place to place (Table 3). Tall herb andgrasses, 1.5 m high, such as Paspalum conjuga-

Q?中彿け

Fig. 69. One-year recoverabbreviations: fpo, IpomoeaZanthoxylum fagara.

of vegetation on bare grounds of the fire-breakalba; Pj, Psidium guajava; S, Scalesia cordata; Tf,

belt in Plot C15. Keys toTournefortia pubescens; Zf,

63


Table 3. Relative abundance (1-,4) of plants in the fire-break belt (Plot C15)

No. of line transects

Species nameNo .l No. 2 No. 3 No4

( 1) Herb & grasses

Abutilon depauperatum

Bidens pilosa

Cassia tora

Centella asiatica

Commerina diffusa

Ctenitis sloanei

Cyperus sp.

Desmodium canum

Diodia radula

Heliotropium angiospermae

Hyptis mutabilis

Ipomoea alba

Malvastrum colomanderianum

Mecardonia dianthea

Oxalis corniculata

Paspalum conjugatum

Salvia occidentalis

Sida rhombifolia

Stachytarpheta cayennensis

Synedrella nodiflora

(2) Seedlings & saplings

Psidium guajava

Scalesia cordata

Tournefortia pub e sc en s

I

4

2

2

3

tttm, Sida rhombifolia and Mecardonia dianthea

cover the whole ground in a flat place with thicksoils (Line 3). Ipomoea alba covers exposed

rocks and forest edges making a fringe vegetation.

On the contrary, the height and the amount ofherb and grasses are less in a thin soiled place on

a ridge (Line 2), though the species compositionis nearly the same as the moist place. Seedlings ofPsidium guajava (max. 22 cm high) are found inopen parts of the belt.

Saplings of Scalesia cordata are found only ifadult Scalesia trees exist near the fire-break belt(Line I and Line 4). The area where Scalesia

saplings occur is very narrow for the total area ofthe fire-break belt. The saplings ate making a

dense thicket, 2.5 m high in average. No othertrees or herbs are comparable to the rapid growth

of Scalesia within one year. Saplings of Psidiumguajava are only 0.4 m in Line 4 and 0.75 m inLine 1 in maximum height. The distribution ofPsidium seedlings is concentrated and the density

is partly high (17-29 per O.25 sq. m), probably

because the seeds were dispersed by feral animals

(donkeys and pigs). I found a dropping of feral

donkey which included many seeds of Psidium inthe fire-break belt just after the fire. As the

64


surface soil was removed at the construction ofthe belt, these saplings must have originated fromseeds which were dispersed after the fire (notderived from buried seeds).

4. Site D (Velasco)( 1) Location

Site D is located on the south-west slope ofsierra Negra. It is in a transitional zone betweenmoist windward (south) side and dry leeward(north) side of Sierra Negra (see Fig. 39). So thegeneral habitat condition is drier than that of siteC. A wide range of Scalesia cordata forest(about. 0.5 km X 0.5 km; SFI) exists in a naturalcondition at the altitude between 730 m and 900m. Our camp site was put near the upper edge ofthe forest (0" 50'33"5, 91' 1l '29"w, Alt. 790 m).The forest changes to a croton scoulerf dominantforest at the altitude around 73o m, thou gh scale-sia trees are sparsely distributed in the forest up toabout 400 m in altitude. Dry-type vegetation(comparable to Arid and Semi-arid zones) coversthe vast lower elevation. On the other hand,above the upper limit of the Scalesia forest app-ears a narrow strip of "subalpine" scrub and awide range of "alpine" meadow. They can beincluded in Moist-scrub and Highland zones ingeneral classification, respectively.

There is a large lava flow which borders thewest edge of this area. A small crater is located atthe altitude of 700 m (0o 50'40" S, 91o l1 ,I6,,w).several lava flows running vertically from high tolow elevations make hilly landscape in this area.There are some ditches (about l0 m wide, 5 mdeep) which were made of fluent lava flows insmall valleys. Two narrow vertical belts of scale-sia remnant forests (SFII and SFIII) are leftalong depressions located to the south of the firstforest: sFI (see Fig. 39). They are isolated fromeach other by grass and herb meadows. psidiumguajava has been invading this area from thesouth, though the density is still low.

(2) Scalesia cordata forestBecause of the dry habitat, high elevation (cool

temperature) and thin immature soil, the treeheight is low (5 m high) and the canopy is notclosed in the sca lesia forest near the camp site(Plots Dl, D3, and D10). The canopy is exclu-sively dominated by scalesia cordata in plot D10(Fig. 70, Fig . 7l). The crowns are usually small,and most of them have damaged branches. Allcanopy trees of scalesra were bearing seeds at thetime of this survey. The histogram of diameter

class shows a peak between 6 cm and 9 cm, butthe dispersion is large (Fig. 72). The largestdiameter measured atO.2 m high is 15.1 cm, whilethe smallest was 1.7 cm in the plot. I also foundsome Scalesia saplings within the plot whoseheight is 0.5-2 m. This means that the populationhas a variety of individuals in different develop-mental stages. The Shrub-layer is very poor(open). The height of herb and grasses are not sotall (0.3 m high in average). So the plot arealooks like a well-kept garden. The scarcity ofshrubs and herbs may owe partly to grazing byferal animals (mainly donkeys).

Plot Dl is situated on a mound of exposed lava(Fig. 73). The existence of Opuntia insularis,Bursera graveolens, and Gossypium barbadensewhich usually appear in the Arid zone of thelowest elevation shows the aridness of this habi-tat. Cordia leucophlyctis, Tournefortia pubescensand Zanthoxylum fagara take a multi-stemmedgrowth form, making a round crown. Especially,Zanthoxylum has a wide procumbent form on theexposed lava. There is little soil and no mosscoverage on the ground. Moss and lichen on thetrunks are also scarce.

On the other hand, Plot D3 is located on agentle slope with a thin soil layer. Canopy treesof scalesia cordata, Bursera glaveolens and rourne-fortia pubescens are only sparsely distributed inthe plot. Many shrubs of Danviniothamnus tenui-folius and Baccharis gnidiifolia both of which areendemic Compositae species grow in open canopygaps (Fig. 74). Some of them make a largetussock which is composed of many thin stems(2f50 stems per individual) (Fig. 75). Scalesiasaplings and young trees are also found in theplot. Herbs are almost the same in the three plots(Plots Dl, D3, and D10). Acalypha partula,Synedrella nodiflora, Blainvillea dichotoma andAnthephora hermaphrodita are frequently dis-tributed in these plots.

A parasitic plant, Phoradendron henslovii(Photo 7), is frequently found on branches ofscalesia trees in Plots Dl and D3. As severalscalesia trees with many individuals of Phoraden-dron on their crowns are nearly dead, this para-sitic plant may cause the death of some trees ofscalesia. Larvae and adults of a kind of beetle(5 cm long) are also found frequently in deadtrunks of Scalesia in this forest (photo 8).According to Mr. Tupiza, this beetle has beenfound only in scalesia cordata and sapindus sap-onaria trees in Isabela.

―- 65 -一

Regional Views

T1 :O T2.e S: x dead: o

No。 11 1997

1 0mX10m

Fig. 70. Crown projection diagren ol &;allr;ia fored in Plot D10. Keys to abbreviationc: Dw,

Darwiniothamn $ trlnaifoliuq, P!, Psidium gudava; S' Scalesia cordab.

Ffg. 71. Proflle dtagran of &jalff,fu forest in Plot D10. Keys to abbrevietions: Dv, Darwiniotlumnus

tenuifoliusi Op, Opantia ircul.aris, P!, hidium guqiavai S, Scatresia cotdtta.

PLOT D10∽司く⊃∩Σ

∩Ｚ】」ｏ“国ｍΣ⊃Ｚ

3-6 6-9 9-12 12-15

DIAMETER CLASS (cm)

□ alive l■ dead

Fig.72. Diameter histogram of Scalesia cordata

in Ptot D10. Diameter was measured at the

height of 0.2 m.

15-18

―- 66 -一


Fig. 73. Proffle diagram ofScalcda forest in Plot Dl. Keyc to abbreviationr: Co, Cotdfu leunphlyctis; Op,

Opuntia ircularisl Pi, f3itlium guajava3 S, Scclesic anhtai TI, Tournelortia pubwensi ZI, Zantlnxylum

fagam.

10mX10m

Fig. 74. Crown projection diagram ol Scalsia forest ir Plot D3. Keyc to abbreviations: Bls,, Boccluris

gnidiifolial C-h, Chiococca alba, G, Crobn scoulrlri; Dv, Darviniothamnas lancifoliusi Pi, hidium guoiavai

S, Scclcria cordatt; Tf, Tourmelortia pubacensT Zf, Zanthoxflum fagara.

Ftg. 75. Proflle diagrem of Scalsia forect in Ptot D3. Xeyr to abbreviafions: R , Baccrlaris gaidiifolia; Dw'Darwiniathamnus hncilolius; P!, Psidium gaajavai S, ScaLasic corilab, Tf' Tourtufortia Pufuaens.

67


(3) Gap regeneration of Scalesra forestI found saplings of Scalesia with various tree

heights growing in a canopy gap around a largematured tree (Plots D5 and Dlz). Plot D5 (0"50'57" S, 9l" 12'I9''W) was put in a mixed forestwith Croton scouleri, Scalesia cordata and Psidiumguajava at the altitude of 550m (Fig. 76). Allcanopy trees are thin in DBH (less than 8 cm)except a large Scalesia tree with the height of 8 mand DBH 18.1 cm (Fig.77). (I found the largestScalesia tree in Site D near Plot D5: 7 m high and29.4 cm DBH). It is characteristic that twothirds of Croton trees in the plot are dead, thoughthe cause is not known. Saplings of Scalesia havea variety of stem height (1.5 m-5 m) and DBH(1.0 cm-7.8 cm). But no seedlings of Scalesia arefound. It is not sure whether they invaded thegap gradually or all at once. Some saplings ofPsidium guajava are invading the gap, increasingtheir dominance in the plot.

Plot Dl2 is located on a thin-soiled ridge in the

remnant Scalesla forest: SFIII. A narrow belt ofexposed lava runs through the plot. There is a bigScalesia tree (5 - high, 20.0 cm DBH) in thecenter of the plot and many saplings and youngtrees surround the parent tree (Fig. 78). Scalesiasaplings and young trees have diversified treeheight (0.8 m-4m) and DBH (2.1cm-8.1cm),but the height class histogram shows a clear uni-modal distribution (Fig. 79). I could not find anyseedlings of Scalesia here, either. Some saplingsmore than 2 m high have already producedflowers. Darwiniothamnus lancifolizs is dominant

:TJ|1. Shrub layer making large patches of

(4) Invasion of Psidium guajavaThe invasion of Psidium guajava has been com-

pleted on the moist windward (south) slope ofSierra Negra (see FiS. 39). On the other hand,Psidium is invading rapidly into drier area on theleeward slope of Sierra Negra. As the canopy of

Fig. 76. Profile diagram of Plot D5abbreviations: Cr, Croton scoulcri; Pi,trees.

showing the regeneration of ScalesiaPsidium guajava; S, Scclesia cordata.

around a parent hee. Keys toUnderlined symbols show dead

８

く⊃∩ゞ兵日こ

」ｏ産回ｍΣ５Ｚ

PLOT D5

6-9 9-12 12-15 15-18 18-21

DBH CLASS (cm)

■ Cr l■ cr(dead)硼 others

□圏

Fig.77。 DBH htttogram of Plot D5. Keys toabbre▼ iations:Cr,Craro■ scO“ Jθ

“;町,Psj″

“″

g“a」ila7a;S,ScaJgstt cardara.

一- 68 -一


10mX10m

Fig. 78. Crown projection diagnm of Plot D12 shoring the regeneration of Scalesia around a parent tree.Keys to abbreviations: Dv, Darwiniothamnus lancifoliur; Pj, hidium guajava;, S, Scclesic andata; Tf,Tourmefortia rufoserbea.

PLOT D12理

‥

ら

言

2-3 3-4

HEIGHT CLASS (cm)

□ sapling

Scalesia forest is not closed in Site D probablybecause of arid conditions, Psidium easily invadescanopy gaps of the forest. Psidium has alreadymade a mixed forest, 4 m high, with Scalesiacordata near the camp site (Plot D2; Alt. 780 m).

Matured trees of Psidium fill vacant spaceamong Scalesia trees (Fig. 80), though they arestill all thin (max. 5.4 cm DBH). Saplings andseedlings of Psidium (0.65 m-2.3 m high) are alsofound in the plot. Blainvillea dichotoma andAnthephora hermaphrodita cover the bright

Fig. 79. Height histogram of Scalesia cordatasaplings in Plot Dl2.

ground . Psidium has a drought-resistant feature,but it prefers rather moist habitats with soils. Itseems that it invades first into a moist place likethe bottom of a gully (Plot D20) (Fig. 81) andthen spreads to drier habitat around the place.Seedlings and saplings of Psidium were foundaround the parent trees in Plot DzO.

Plot D6 is located in a depressed place withsome amount of soil at the lower altitude (Alt.420 m). The canopy, 6 m high, is closed exceptfor a canopy gap which was made by the death of

―- 69 -一

Regional Views No. I | 1997

T1 :6 T2:s S:x 10mX10m

Fig. t0. Crown projection diNgran of Ptot D2 showing the invagion ol hidium in the Scalesia forect. Keysto abbreviations: Ch, Chinuca alba; Co, Cordia leacophlyais; Pi, Psiilium gyajava; S, Scalesia cordata; Tf,Touraefortit rufoscricea.

FfS. El. Profle diagran of Plot D20 rhowing the invasion ol hidium along a gnall vdley in the Scalesioforest- Keyr to abbreviafionr: C-n, Cordia leuaphl@is; Pl, Priiilium Suajavai Pt., hcridium aquilinum; S,Scabia cordatai Tl, Toaraetortia rufucricu.

two big Sca lesia trees (Fig. 82). Psidium guajavais invading the canopy gap. As the gap hasalready been occupied by the crowns of Psidirffi,no seedlings or saplings of Scalesia were found inthe gap. Small trees and shrubs of Zanthoxylumfagara are abundant in the lower layers of theplot. Three species of Tournefortia grow togetherin the T2-layer.

Plot D I I is located in the remnant Scalesia

forest: SFII at the altitude of 730 m. The loosecanopy is composed of large crowns of Psidiumand smaller ones of Scalesia (Fig. 83). Lavarocks are exposed on the ground. There is nomoss coverage over the ground. The crowns ofPsidium guajava overlap with each other. TheDBH class histogram shows that Scalesia has adiversified distribution with a mode of 6-9 cmclass (Fig. 84). Psidium guajava is thin (max. 6.0

-3m

70


Fig.82. Proffle diagram of Plot D6 showing the invarion of hidium in a canopy grp of Scclesia forect.Keye to abbreviations: Cr, Cmton scoalerii Pj, hidium guqjavai S, Scalesin cordatt; Tf, Tournefortiartfonriceal 7,1, Zanthoxylum fagam. Underlined rymbolo show dead hees.

10mX10m

FiS. 83. Crovn proJection dirgnn of Plot Dll chowlng the invasion ol lrlidiam in the Scalesia forecl f,eyrto abbreviatione: PJ, hidium guqiaw; S, Scalecic cordata; Tf, Tourmefofiia rufucrbu.

5m-

*

7l

賀

マ

⊃Ｑ

昼

壼

ｏ

日

冒

２


PLOT Dll

:0 Sapling:05-lmメ ,lm(o

cm DBH) for its large crown. Darutiniothamnuslanceolata is frequently distributed in the Shrub-

layer.

(5) Psidium guajava forestA vast Psidium guaiava forest continues from

Alt. 400 m to Alt. 700 m in the southern part ofSite D (see Fig. 39). This may be the northernend of the Psidium dominant forest which I sur-

veyed in Site C. Canopy trees are not so tall (3-4m high) and stems are all thin. Most of them take

a multi-stemmed growth form. The canopy layer

Fig. 84. DBH histogram of Plot D11. Keys toabbreviations: Pj, Psidium guaiavai S' Scalesia

cordata.

10mX10m

which is composed exclusively of Psidium is usu-

ally closed. Blackish lichen hangs from branches

at the altitude of 500 m.plot D 13 (0' 5 l'2',1" s, 9 1o I I ' 51" \M, Alt. 670

m) is located at the upper limit of this forest. Itseems to be a front of mass invasion of Psidiumguajava. There is only one adult tree (4 m high,6.5 cm DBH: maybe a pioneer in this area) ofPsidium in the plot (Fig. 85). There ate 78

saplings with a height of more than I m, and 75

with the height between 0.5 m and I m, growing

densely in the plot. Many seedlings (less than 0.5

こ_ミ′/

Ъ

.:。。 /) (

亀x/′ 1-‐

ヽヽヽ、一

/ 00x P

000 o

xX O領

。:l 卜↓ ′く

∫ ノ0° /⌒ヽ。

Jノメ.

J° 。ｘ　

　

　

　

Ｏ

ｘ

/10X0

⌒

Fig. 85. Distribution map of Psidium guajavc (Abbr.: Pj) in an open place in Plot D13.

一- 72 -―


PLOT D13

0

m high) are also found in the plot. The heightclass histogram shows an L-shaped distribution,which means the invasion is proceeding (Fig. 86).The largest sapling was 2.4 m high and 4.1 cmDBH. The ratio of the individuals with flowers orfruit is proportional to the tree height (Fig. g6).Even a small sapling of 1. I m in height has fruit,though the number of fruit is small. The distribu-tion of saplings is patchy rather than uniform,because a fruit includes many seeds and they aredispersed by birds and feral animals. There areopen spaces in the plot where paspalum con-jugatum and Abutilon depauperatum cover theground.

Plot D14 is located on the way from the camp

Fig.86. Height hおtogram of Fs″ J“″ g“aJilava

and the ratio of indi▼ iduals with■ owers or n門 dt

in each height cltt in Plot D13.

site to Plot D13. The south wind is prevailing.Some saplings of Psidium guajava appear in aherb land, 0.5-l m high, which consists of Abuti-lon depauperatum, Stachytarpheta cayennensis,Rhynchosia minima, Acalypha pamula, etc. Thelargest individual of Psidium saplings is 1.3 mhigh and has fruit. The distribution of saplings ispatchy (Fig. 87).

Plot D15 shows the invasion of Psidium gua-java in a Pteridium aquilinum thicket at thehigher altitude than Plot Dl4 (Fig. 88). Thereare three established trees of Psidium, 2.3 m, 2.5m, and 2.8 m high, respectively in the plot. Eachtakes a multi-stemmed growth form. Saplings ofPsidium, O.7 m-1.65 m high, are patchily dis-

0-0.5 0.5-1 1-1.5

HEIGHT

圏囲 No.

1.5-2 2-2.5 2.5-3

CLASS (m)

― %

Fig. 87. Distribution map of psi.dium guajaya (Abbr.: pj) in a meadow in plot D14.

10mX10m

Ｘ―′　　

　

　

　

″

ａｒり　　″

″　　　　　　　μ

1′ イ

′″′

ル″

″

ヽヽ０

口′

′

・

′θ′・もヽ　　　イ

ａｒＶ　　　　　　　　　　　　　　ノ

″　

　

　

Ｘ

メ

χ

　

　

　

′ノ

、

　

　

　

　

　

　

　

Ｘ

　

　

　

ｔ

l′ グ

X

―- 73 -―

T2.s S:x


T1 :O 10mX10m

Fig. 88. Crown projection dhgrsm of Plot D15 showing the invagion ol Pridium in a Ptcridium thicket

Keyc to abbreviations: Dv, Darviniahamnus tnncifoliusi Pi, Psidiam guajava; Ptl,, Pbtidium aquilinum.

tributed around the parent trees. Pteridiumgrows well under the extended crowns of Psidiumtrees, probably because of protection from the

strong prevailing wind.There is a large patch of Daruiniothamnus

scrub near Plot D14 at the altitude of 760m.The scrub seems to be a substitute of Miconiarobinsoniana scrub in Santa Cruz which is notfound in Isabela.

(6) Croton dominant forestCroton scouleri becomes dominant on drier

habitats (thin soil and low humidity) in the loweraltitude compared with Scalesia cordata. Plot D17 is a belt-transect which was put on a slope at

an altitude of about 730 m. The plot atea is

divided into three parts: ( 1) upper part (Scalesia

dominant forest) , (2) middle pafi (transitionalforest), and (3) lower part (Croton dominantforest) (Fig. 89). Scalesia trees with a large

crown make a sparse forest, 4-5 m high, on the

flat place of the upper part. Young trees of

Scalesia are also found, but Croton ts tate.Crowns of Scalesia become small, and saplings

of Croton increase abruptly on the gentle slope ofthe middle part. Scalesia disappears and Croton

trees with thin stems and small crowns grow

densely making a loose canopy on the steep slope

of the lower part. Some dead trees of Croton are

found here. A small tree of Psidium guaiava

invades this part. Pteridium aquilinum makes

small patches in the upper and the middle part,

but it disappears in the lower part. Other herbs

such as Blainvillea dichotoftia, Synedrella nodifl-

ora, Sida salvifolia and Rhynchosia minia are

common throughout the plot atea. Croton forest

like this appears on the north (leeward) side of aridge near the remnant Scalesia forest (SFIII).

plot D16 (0o50'40"S, 91o 1l'46"W, Alt. 700

m) is a Croton dominant forest, 3-4 m high' near

the crater (Fig. 90, Fig. 9l). The ground is

mostly composed of exposed lava- Stems ofCroton are all thin (max. 7 .4 cm DBH) and strai-ght (Fig. 92). There are some dead trees, but

74


Fig.89. Ctown projecdon dirgmm of Plot D17 showing the transitiond part betreen Scalsia forest and

Q1p1412 ilsnimant foreet. f,eys to abbreviationgz Bt, Burtcm gmvulensi Co, Cordia leucophlyctis', Cr' Croton

tcoulerii Dv, Darwinbthamnus hncifolius; Pi, Psidium Su4java; Pt' Ptcridium aquilinun; S, Scalzsia

andan3 TI, Tournalofiia rufuericea; Zl, Tanthoxylm fagara.

Fig. 90. Profile diagram ofgraveolens; Cr, Croton scouleriiZf, Zanthoxylm fagara.

CЮlわπ dominant forest in Plot D16。

Phr,Phο rada降ごro■ λttJoッjj;S,SむαJas'α

Keys to abbreviations: Br, Burcera

cordata; T f , Toumefortia rufosericeai

they include various sizes of trees. The canopywhich is made of small crowns is not closed fully.Parasite of Phoradendron henslovii is very fre-quent. This must cause the death of Croton tosome extent. Saplings of Croton are also growingfrequently. Four individuals of Scalesia exist inthe canopy layer, but no saplings or seedlings ofScalesia are found in the plot. The existence ofBursera graveolens shows the arid condition of

this habitat. Herb species are common to theScalesia forest in the upper elevation.

plot D4 (0"50'51"5,91" 1l'56"W, Alt. 650 m)is a Croton-Scalesia mixed forest on a flat place

with some amount of soil. Scalesia trees havelarge crowns in the canopy layer (Fig. 93). Amulti-stemmed Psidium guajava also spreads itslarge crown in the canopy layer. I found a thickdead stem at the center of the clump, so this

―- 75 -―


丁1:o 丁2:e S:λ deadi.

Fig. 91. Crown projection diagram of Croton dominant forest inBurtera graveolensi Co, Cordia leucophlyctis; Cr, Croton scoulerilrufosericeai Zf , Zanthoxylm fagara.

10mX10m

Plot D16. Keys to abbreviations: Br,S, Scalesia cordata; Tf, Tournefortia

＜ａ

４

ｓ

ｅ

パ

ｚ

ｂ

蚤

冒

ヨ

●

∽習８〓２

６国冒ヲ

□囲

DBH CLASS (cm)

■ cr剛 Others

12-15 15-18

■ cr(dead)

□■

6-9

DBH CLASS

(dead)

9-12

(cm)

■剛

12-15

Crothers

Fig。 92. DBI・ I histogralm of CrarO“ dOlmilant

forestt in Plo撻 D4 and D16。 Keys toabbre▼ iations:Cr,Craro■ sca“ルだ;町,PsJ″

“″

g“a」avα ;S,Scaras,α carda".

COO

0

―- 76 -一


10mX10m

FiS.93. Crown projection diagrem of Scalsia-Crotan nixed forest in Plot I)4 showing the invasion ofPsidium. Keys to abbreviationc: Br, Bancra grawlerci 6, Chiococca alba1, Cr, Cmbn scoaler| Pg, hidiumgalnpagciumi Pj, Psidium gu4javai S, Scalasia cordatai Tl, Tourwfottia ruloscrieca, Zl, Tantlnrylm fagam.

individual probably originated from sprouts afterthe predecessor's death. Many small trees ofCroton make small crowns in the canopy (T1)and T2-layers. However,42Vo of Croton individ-uals in these layers are dead maybe because ofheavy parasite of Phoradendron henslovii. It is

strange that this parasitic plant does not attachScalesia here, though it is found on the crowns ofScalesia in the Scalesia forest at the upper eleva-tion (Plots Dl and D3). There are many Crotonsaplings, but no

^Scc lesia ones in the forest. A

feral pig ran through the plot, while I was study-ing.

There is a Scalesia-Croton mixed forest at theedge of new lava flow in Plot D18 (0"51'12"5,91" 12'39"W, Alt. 460 m). Two individuals ofScalesia cordata appear just adjacent to the lava(Fig. 94). This shows a drought resistant featureof S. cordata. Pteridium aquilinum grows at thefringe of the forest. Darwiniothamnus lancifoliaexists on the lava. The lava flow is made ofrugged rocks with a diameter of 2V30 cm. It

seems to be unstable. Only Polypodium tridensgrows within the lava flow apart from the forest.

Plot D19 is a mixed forest on a slope (Inc. 15')in the Semi-arid zone at the lower altitude(Alt. 450 m) (Fig. 95). Scalesia cordata, Pisonia

floribunda, Sapindus saponaria and Burseragraveolens make the Tl-layer: 6-7 m high, andCroton scouleri, Cordia leucophryctis, Zanthoxylum

fagara and Psidium galapageium occupy thelower layers. They are all native species. Thisforest continues to the Arid zone which coversthe vast lowest elevation.

(7) "Subalpine" scrub and "alpine" meadowThe Scalesia forest disappears abruptly at the

altitude of around 800 m. Above the forest limit,occurs an "subalpine" scrub (paramo-like vegeta-tion), though this is not a real subalpine on thecontinent.

plot D7 (0" 50'16"5, 9L" lO'54" , Alt. 840 m)shows an example (Fig. 96, Fig. 97). Cordiascouleri, C. leucophlyctis, Tournefortia pubescens

77


FiS. 94. Profle diagrrn oI Scalaia-Cmton ni*ed forest on the edge of llrva flow in Plot D18. Keys toabbrevirtions: Ca' Codia leuaphlyctisi Cr, Crcton scoulcri; Dw, Dar*iniothamnus lancifoliusi P!, Psidiumgaajawi Ptr' Pteridium aquilinum; S, &alaia cordata,

Fig.95. Proffle diagran of nixed forect in Plot D19 near the Semi-arid zone. Keys to ebbrevirtions: Br,Burseta gravalerc3 Co, Cordia lcaaphlgisi 6, Crctan scouleri; Pl, Pinnia floribunda, Pg, hidiumgalapngeium, S, Scalesia corddai *, fupinilus sapruria; Zl, Tnnthoxylum Jagara.

and T. rufosericea take a multi-stemmed growthform, making large crowns , 2-3 m high, here andthere. Daruiniothamnus tenuifolius, D. lancifoliusand Baccharis gnidiifolia with smaller crowns aredistributed among them. Cassia picta is alsofrequently distributed. A young tree of Scalesia,1.8 m high, exists, isolated, in the plot. TheHerb-layer consists of Blainvillea dichotorna, An-thephora hermaphrod it a, Syned rella nod iflora, Sid aspp., etc. The species composition is nearly com-mon to that of the Scalesia forest below.

plot Dg (0"50'05"s, glo 11'19"w, Alt. g10 m)is located beyond a strip of lava flow whichborders the Scalesia forest at the north end. As itis drier at this north side of the lava flow than onthe opposite south side, "subalpine" scrubs and"alpine" meadows descend to lower elevation in-stead of Sca lesia forests (see Fig. 39). Two

shrubs of Cordia leucophryctis and Tournefortiarufosericea make tussocks 2.5-3 m high, andAltenanthera echinocephara and Darwiniothamnustenuifoliium are dominant in the open space inthis plot (Fig.98). As Altenanthera echino-cephara is a member of the Arid zone on thewindward slope, its existence indicates the aridityof the habitat. It is characteristic that two thirdsof Cassia picta individuals are dead. Herb speciesare common to Plot D7. These scrubs (Plots D7and D9) may be comparable to the Moist-scrubzone in Santa Cruz, but the habitat is dry, thealtitudinal range is narrow and the species com-position is different (no Miconia robinsoniana).

Pteridium aquilinum ("alpine" meadow) makesa vast dense thicket, 1-1.5 m high, at the altitudeabove 840 m (Plot D8). The density (the numberof petioles) of Pteridium was 13-16 per sq. m.

Cr

78

Competitive Relationships between Tree Species of Sca/es ia and Introduced Plants (Shimizu)

T2:o S:r 10mX10m

FiS. 96. Ctown projecdon diagram of "cub-alpine" scrub in Plot D7. Keyc to abbreviatione Ba, fuccharisgnidiifoliai Cn, Cordia buuphlyctis; Dvl, Darviniotlumnus lnrcifoliusi Dvto Dtrviniotlwmnus tenuifoliru;S, Scatrasia cordata; Tl, Tourmelortia rulosericaT Zl, Zanthoxylum fugara.

PLOT D7

Fig.97. Proflle dirgnn of "oub-alpine' scrub in Plot D7 and D9. Keyr to abbrevirtiong: A\ AltenanthemehhtuepharaS Co, Cordia leuaphlyctis; Cp, Cassia pictai Dvl, Darviniothamnus lnrcifolius; M,,Darviniathtmnus tanuitolius; S, Scatrasia cordatai Tl, Tournefortia rufuericca; Zl, Zantlnxylum fagaru,

(a)

PLOT D9

79


Woody species of the scrubs below are sparsely

distributed in the Pteridium thicket, extruding

their crowns 2-3 m high (Fig. 99). The floor ofthe thicket is so dark that no herb is found except

one individual of Eleocharis sp. The Pteridium

thicket goes down to the lower elevation in a

moist valley, while a scrub of Macraea laricifoliagoes up to the upper elevation on a dry rocky

ridge in this area. The Pteridium thicket is com-

parable to the Highland zone in Santa Cruz.There is a permanent quadrat ( 10 m X 10 m) of

10mX10m

Dr. Gjitte de Vries at the upper limit of the

Scalesia forest near the camp site. There were 9

trees of Scalesia inthe quadrat before the El Nifro

event in 1983, but they all died from unusually

much rain at that time (de Vries & Tupiza 1990).

There is no Scalesia now in the quadrat.

(8) Why are the remnant Scalesia forests left ?

Almost all Scc lesia forests were destroyed or

disturbed by humans, feral animals and intro-duced plants in the Site C area, but there are some

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Fig. 98. Crown projection diagran of "sub-alpine" scrub in PlotDg. Keyc to abbrevirtions: At, Altenantlleta

uhinwphara; Ba, Baccharis gnidiifolia; Co, Cordia leucophlyctis; Cp, Cassia pictaT Dv, Darwinbtlumnus

tenuifoliusi Tf' Tourrcfortia rufosericea.

-15m

Fig. 99. proffIe diagram ol Pteridium thlcket ("alpine" meadow) in Plot D8. Keys to abbreviations: Co'

Cordia leacophtyctis; Ptr, Ptefidiam aquilinum; S, Scolesia cordata,Tf,Tournefortia rufosericea'

-80-


Scalesia forests (SFI, II, III) left in natural condi-tion in the Site D area. Why ? One possiblereason is that there have never been disastrousdisturbance like fire and cultivation after cuttingin the past which could accelerate the invasion ofPsidium guajava. The second idea is that theseforests are located far from the inhabited area(source area of introduced plants), so Psidiumarrived here relatively recently. The third is thatthis place is the northern limit of the Scalesiacordata distribution, and Psidium is not good atgrowing in such a dry habitat, even though theycan endure dry conditions. So the invading speedof Psidium is slower here than in the moist wind-ward area. As the canopy of Scalesra forest is notclosed in this area, it is easy for Psidium to invadethe forest. Psidium is, in fact, invading andestablishing in the forest.

On the contrary, I did not find any proof thatthe Sca lesia forest is spreading outward. As theprevailing wind blows from the south, the seeds

cannot be dispersed to the moist direction. Theremnant Scalesia forests (SFI, II, m) are sepa-rated from each other by grass or herb lands,where I did not find any Scalesia seedlings orsaplings. The present habitats of the remnantforests are confined to flat or depressed places,but these forests might have covered the wholearea when moister climate governed this area inthe past.

5. Site E (Alcedo)( I ) Location

Alcedo (Alt. 1128 m) is an active volcanowhich is located at the middle part of Isabela(north of Perry Isthmus). We can see the geyserinside the crater. I studied the vegetation of thenorth-east slope of the volcano from the coast(Playa Negra: O"2l'18"S,91"03'O4"w) to therim of the uater (about 1100 m) (Fig. 100). Thisplace is a transitional zone between the moistwindward (south-east) slope and the dry leeward(north-west) slope of the mountain. The prevail-ing wind from the south is pretty strong, but thecloud coming from the windward direction disap-pears before it reaches here.

As thick pumice and ash layers cover the wholearea from low to high elevations, the thin-soiledground is dry. There is a wide black belt of newlava flow which separates the area from moistereast-facing slope. A ditch (about 5 m wide, 5 mdeep) originated from fluentlava flow runs paral-lel with the lava belt from the ridge to the coast.Strangely, my compass did not work here maybe

because of the interference of magnetic effect oflava rocks. There is a trail from the coast to themountain top. We set our camp site at thealtitude s7o m (0o 23'19"S, gl" 04'51"w) besidethe trail.

Scalesia microcephala, the third tree Scalesia,makes a sparse forest with Bursera graveolens(35f550 m) and with Trema micrantha (55O-700 m), and forms a parkJike vegetation withherbs and grasses (70f850 m) (Fig. 100). It alsomakes a dry scrub on the rim of the crater.Scalesia afinis, a shrubby species, appears at thedrier, lower altitude (below zDm). The twoScalesia species occur separately along the altitud-inal gradient. It is noteworthy that no introducedtrees and shrubs are found throughout the area.

It is reported that feral goats are destroying theScalesia scrub on the moist part of the crater (notincluded in Site E). A major Alcedo Campaignwas initiated in 1995 to eradicate feral goats andmonitor long-term change of vegetation and tor-toise populations (Cayot & Snell 1996). I foundsome feral goats on rocky places around the rimof the crater. Giant tortoises are living in goodcondition at the upper part of the mountain andinside the crater. Recently tourists visit the craterfrequently to look at the giant tortoises.

(2) Scalesia-Trema mixed forest (Middle eleva-tion)

Scalesia microcephala makes a sparse forestwith Trema micrantha at the middle elevation(550-700 m) of this area (Plots El, E2 and E3).The canopy is usually low in height (3-4 m), andthe coverage is small (lV3OVo) (Fig. 101, Fig.lO2). So the sun light penetrates directly into theforest. The forest includes Scalesla individuals ofall developmental stages i.e. seedlings, saplings,young trees, matured trees and dead old trees(Fig. 103). The situation is rather similar to thatof the Scalesia cordata forests in Site D. Thelargest tree of Scalesia is 5 m high and 10.4 cmDBH. Big trees of Trema (5-6 m high) arescattered in the forest. They usually branch intoseveral stems at the base, thus taking a multi-stemmed growth form and making a huge crown(Fig. lO4, Fig. 105). Saplings of Trema are alsofound. Both Scalesia and Trema produced muchfruit at the time of this survey. Large trees ofPisonia floribunda are also distributed sparsely(Fig. 106). Its huge multi-stemmed growth formis common to that found in Site C. It is strangethat few seedlings of Pisonia are found.

The soil layer on a deep pumice accumulation is

-81-

Dry


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very thin, and the surface is arid. There is nomoss coverage on the ground, and lichen ontrunks is also scarce. The Shrub-layer is exclu-sively dominated by Walteria ovata and Macraealaricifolia. Both species have a multi-stemed

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FIg. 100. Schematic precentation of vegetational zonation and disbibution ol tvo Scalaia species in Site E(Ncedo, Isabefl).

_ ゴ児 J“

growth form making alarge tussock in the Shrub-layer (l-Z m high). Cassia picta and Baccharisgnidiifolia are also abundant in the Shrub-layer.The flora of the Herb-layer is basically similar tothat of Site D. Blainvillea dichotoma, Rhynchosia

Mixed Forest

一- 82 -―

Competitive Relationships between Tree Species of Scalesia and Introduced Plants (Shimi"u)

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Fig. 101. Crown projectiongraveolens; Cp, Cassia picta;Waltcria ovata.

diagram of Scalesia forest in PlotM, Macraea laricifolia; S, Scalesia

El. Keys to abbreviations: Br, Brusera

microcephala; Tr, Trema micrantha; W,

Fig. 102. Profile diagram of Scalesia forest in Plot El.Macraea laricifoliai S, Scalesia microcephala; Tr, Tremashow dead trees.

Keys to abbreviations:micranthai \il, Wsltcria

Br, Brusera graveolensi M,ovata. Underlined symbols

minima and Sida spinosa are dominant. Theirreal density is not so high, even though the cover-age percentage is apparently high. In addition tothem, Cenchrus platyacanthus, Aristida repens,

Stylosanthes sympodialii, etc. are frequently dis-tributed. A parasitic plant, Cuscuta gymnocarpa,

covers small shrubs frequently.

(3) Scalesia parkJike forest (Upper elevation)Large trees of Tremc disappear gradually, and

a park-like forest of Scalesia occurs at the altitudeof 700 m and above (Plots E5 and E6). The

―- 83 -一

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2-3 3-4

HEIGHT CLASS (m)

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llEIGHT CLASS(m)

■l s(dead)


4-5 5-6

■ Tr□ s

L-2 2-3 3-4 4-5HEIGHT CLASS (m)

tls Irr

PLOT E3

_躙 _ Fig. 103. Heieht histograms of Scalesia forestsin Plots El, n2 and E3. Keys to abbreviations: S,

Scalesia microcephala; Tr, Trcma micrantha.

2-3 3-4 4-5 5-6

□ s 圏 Tr

20m

Fig. 104. Crown projection diagram of Plot E2 chowing the regeneration of Scal.aia. Keys to abbreviations:Br,, Baccluris Criiliilolbl Co, Cordia anhonii; M, Macraw laricifoli.a; S, kolasia miouephala; Tl,Tourmefortia pubaceu;Tt, Trcna mbmnthqV, WaI.Eria ovata.

T1 :O T2:s S:x

一- 84 -一


PLOT E2

PLOT E3

Fig. 105. Profile diagrams ofCp, Cassia picta; M, Macroea

micranthai \il, Waltcria ovata.

Plot E2 and E3 showing the regenerationlaricifolia; S, Scalesia microcephala; Tf,

of Scalesia. Keys to abbreviations:Tournefortia pubescens; Tr, Trema

Fig. 106. Typical growth form of Pisonia fl.oribunda in Site E.

canopy height decreases to 3.5 m, and each crownbecomes small (Fig. lO7, Fig. 108). The largest

individual of Scalesia is 3.5 m high and 10.9 cm

DBH in Plot E6. All developmental stages ofScalesia are found here, too (Fig. 109). Dense

thickets of Walteria and Macraea which featurethe Shrub-layer of the middle elevation disappear

in this altitude. Instead, Tournefortia pubescens,

T. psylostacya, Cordia leucophlyctis and Zantho-zylum fagara which are common to Site D mainlycompose the Shrub-layer. The Herb-laY€r, 0.8 mhigh, is densely covered with Crotalaria incana,

Balinvillea dichotorrta, Anthephora hermphroditaand so on. Bumble bees visited flowers of Clotara-lia incana frequently. Many seeds of this plant

were dispersed on the ground at the time ofsurvey. Sparse distribution of Scalesia crownsand the dense herb coverage on the ground make

a park-like physiognomy (Photo 9). Giant tor-toises seem to appear in connection with the

occurrence of this type of vegetation.

Plot E4 is located at the foot of the rim ofcrater (o"24'41"S, 91"05'21"\M, Alt. 810 m).As the place is on the south-east facing slope of a

85


Fig. 107. Profile diagram of ..park-like" Scalesia forest in plotincana; Co, Cordia leucophlyctisi S, Scalesia microcephala; Tf,fagara.

E6. Keys to abbreviations: Clt, ClotalariaTournefortia pubescensi Zf, Zanthoxylum

small ridge, it is sometimes shrouded by fog andtherefore moister than the north-west facing slope(Plots E5 and E6) on the opposite side of theridge. Strangely, there are no Scalesia trees onthis side. Large trees of Burcera graveolens atescattered in the dense grass and herb land (Fig.110, Fig. 111). The Bursera tree in the plot was 5

10mX10m

m high and 33 cm DBH. It forms a large crownwhose leaves were mostly shed at the time ofstudy. A large amount of white, hairy lichen(Usnea sp.) hangs from the branches. This showsthe high humidity at this site. Large trees ofTrema micrantha are also distributed sparsely,but there are no saplings in the plot. Some species

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一- 86 -―

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PLOT E5

0-0.5 0.5-1 1-1.5 1.5-2 2-2.5 2.5-3 3-3.5 3.5-411EIGHT CLASS(m)

□ alive l■ dead

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0.5-1 1-1.5 1.5-2 2-2.5 2.5-3 3-3.5 3.5-4

HEIGHT CLASS (cm)

□ alive l■ dead

Fig。 109. Height hお torams of ScaresJα

“Jc“

′λαJa in Plo"E5and E6.

Tl:o 丁2:o S:x 10mX10m

Ftg. 110. Crorn projection dlagram of Plot E4 showing t l*ge Burcat hee and sone oth€r chnrbs ir adence gnsc.herb lanrl Keyr to abbreviation$ Bt, Burw'lra graveolens; Co, Cordia leucophlyctisi Pg Psidiumgalapgeiumi fi, Tournefortia pubacana'S Ttr, Toamefortia rufoseri.ca; zf, Tanthoxylum fagam.

―- 87 -―


Fig. 11l. Proflle diagran of Plot El rhowing t large Butrrlra tree and some other shrubd in a dence

grrsc.herb land. Keys to abbreviations: Elt, Buneru gmveoIensT Co, Cordia leuaphllctis; Pg, Psidiumgalapagcium;Tftg, Tounufortia pubescerc;Tfu, Tourrcloftia rafoseriw3 Zf, Zantlntylum fagam.

Fig. 112. Profile diagram of "sub.dplne" scrub ir Plot 812. Keyr to abbreviation* CJ[, Clotahri4Co, Cordia leuaphlyaisi Dv, Darwiniotlumnus bnuifolius; Pen, PcnnJE&.m paupcrumS Pg,galapageium3TSg, TourmeJortia pubcsrrlrlaiTfr, Tournefortia rufowrim; Zf, Zanthoxylum fagara.

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such as Cordia leucophlyctis, Tournefortia rufoseri-cea, T. psilostachya, Psidium galapageia and Zan-thoxylum fagara make clumps here and there.

The HerbJay€r, 0.8-l m high, is so developedthat it is difficult to pass through the plot. Grasses

and herb are vigorous compared with those in thedrier slope on the opposite side. Blainvillea dichotoma, Chenchras platyacanthus and Anthephorahermaphrodit are dominant, making dense cover-age over the ground. This may prevent Scalesia

seedlings from establishing in this place. Giant

tortoises live in this grass and herb land. Herband grasses are pressed down to the ground tomake an instant path, 5f80 cm wide, when tor-toises walk through this place, so we can pursue

them easily.Scalesia microcephala disappears once at the

foot of the rim of crater. A kind of dry scrub,1.5-2 m high, which is similar to the "subalpine"scrub in Site D occurs on the steep and rockyoutside slope of the rim (Plot Bl2). It consists ofDarviniothamnus tenuifolius, Psidium galapag-

88


eium, Tournefortia rufosericea, T. pubescens,Cordia leucophryctis and Zanthozylum fagara(Fig. ll2). The species composition of the Herb-layer is nearly the same as that of the loweraltitude. Only atall grass, Pennisetum pauperum,is characteristic to this scrub. I saw a herd offeral goats which had brown hairs with whitepatches, grazing in this scrub (Photo 10). Pteri-dium aquilinum makes a dense thicket over thesteep slope of the rim locating to the north of thisplace.

Scalesia microcephala appears again on theridge of the rim of the crater at the altitudearound 1100 m. Plot E7 was put on a west facingslope inside the crater (0" 25'Ol "S, 9l'05 ' 48" W,Alt. 1070 m). Scalesia makes a scrub, 3 m high,together with other shrubby species such as

Cordia leucophrictis, Tournefortia rufosericea, T.pubescens, Psidium galapageium and Zanthox-ylum fagara (Fig. 113). Most of them take amulti-stemmed growth form (Fig. Ll4). Espe-cially, Cordia leucophrictis had 5.8 stems per indi-vidual on average. I found only one seedling of

Scalesia in the plot. The Herb-layer is nearly thesame as that in the lower elevation, but it seems tobe under pressure of grazing by giant tortoisesand feral goats, because the herb is short likemowed lawn except for large tussocks of Pennyse-

tum pauperum. In fact, I found a big gianttortoise grazing grass within the plot (Fig. I 14).

Some naked lands exist on the ridge which wereattributed to grazing and trampling by giant tor-toises and feral goats. Feral goats are not onlycompeting with giant tortoises in food resources,

but also destroying their habitat (Munoz 1993). Isaw a Scalesia dominant forest standing on thesouth pafi of the ridge which received more mois-ture from the south wind, though I could not getthere in this study. It is reported that feral goatsare causing destruction of the forest (Cayot &Snell 1996). A dry-type vegetation of Burseraand Walteria are found on the dry bottom of thecrater where bare lava is exposed widely.

T2:o 10mX10m

Fig 113. Crown projection diagram of Scalaia gcrub in Plot E7. Keyr to abbreviation$ C;o, CordiahucophlyctisS Pen, Pennyvtum Inuperam, Pg hidium galapgeiam; Tfg, Tounufortia pubmns; Ttr,Touruefonia rafuefieai 7'f, Tanthoxylum fagam.

89


qN\(ff3'h

Fig. 114. Profile diagram of Scalesia scrub in PlotPennysetum pauperurni S, Scalesia microcephala; Tf'

(4) Scalesia-Bursera mixed forest (Lower eleva-

tion)The number of Bursera graveolens increases

and Trema micrantha disappears at the loweraltitude (below 550 m), while Scalesia miuo-cephala continues to be canopy trees (Plots E8

and E9) . Bursera attains to 6 m high, making a

large crown (Fig. 115, Fig. 116). It shed leaves

and had fruit on the bare crown at the time of thisstudy. The largest tree of Scalesra is 3.5 m highand 8.5 cm DBH in Plot E8. No lichen hangsfrom branches. As the canopy is not closed, alldevelopmental stages of Scalesia from seedlings tomature trees are found here, too (Fig. ll7).

The Shrub-layer becomes sparse comparedwith the middle elevation. The dominancy ofWalteria ovata and Macraea laricifolia decrease

and instead, Lantana peduncularis, Chamaesyce

viminea and C. punctulata appear . Castela galapa-

geia and Scutia pauciflora which are originally themembers of dry vegetation also occur to some

extent. The ground is covered with volcanicpumice and ashes. There are few fallen leaves andlitters on the dry ground. The coverage value ofthe Herb-layer is seemingly high, but the actualdensity is low. Grasses such as Aristida divulsa,Boutelona disticha, and Paspalum coniugatumwere dead or half-dead and the total amount ofbiomass was not so much at the time of survey.

Plot Ell is a belt transect which was put in atransitional zone between Scalesia-Trema mixedforest and Scalesia-Bursera mixed forest. Theexistence of two large trees of Trema and Bursera

E7. Keys to abbreviations: Co, Cordia leucophlyctis; Pen,

Toumefortia rufosericea; Zf, Zanthoxylum fagara,

growing in the neighborhood is a feature of the

transitional forest (Fig. I 18). Scalesia micro'cephala is also sparsely distributed. The Shrub-layer is dominated by large clumps of Macraea

and Walteria, but it includes a variety of shrub

species such as Cordia leucophlyctis, three species

of Tournefortia, Cassia picta, Chamaecyce vim-inea, Danviniothamnus tenuifolius and Lantanapeduncularis. The Herb-layer is composed ofboth the upper elevation elements (Anthephora

hermaphrodita, Cenchrus platyacanthus, Clotara-lia spp., Bidens riparia, Zornia piurensls) and the

lower elevation elements (z{rustida divulsa, Tephr-

osia decumbens, Boutelona dis(icha, Polygala gal-apagoensis, Chamaesyce punctulata) togetherwith common elements (Sila rhombifolia, Rhync-

hosia minima, Stylosanthes sympodialis, Ipomoea

triloba), which shows the transitional feature ofthis place.

Scalesia microcephala disappears rather abrupt-ly at the altitude around 3N m where the inclina-tion of the slope becomes steeper downward. PlotElO (Alt. 24O m) is located in the altitudinal gap

between the distribution of S. microcephala (Alt.3411100 m) and that of s. affinis (Alt. 0-210m). So there is no Scalesia here, though the

structure and species composition of the forest is

not so different from those of Scalesia-Burseramixed forest above (Fig. 119, Fig. l2O). The

density of Burserc trees increases a little, and theircrowns become larger compared with Plots E8

and E9 (see Fig. 115 and Fig. 116). As the barkcolor of Bursera trees is bright white, the forest

90


T1 :O T2:a 10mX10m

Fig. 115. Crown projection diagram of Scalesia-Burcera forest in PlotBurrera graveolenq Cg, Castera galapageia; Co, Cordia leucophlyctis;

Dart+,iniothamnus tenuifoliusi S, Scafesia micruephala; Y{, Walteria ovata.

E9. Keys to abbreviations: Br,Cv, Chamaesyce vimineai Dw'

Fig. 116. Profile diagram of Scalesia'Burceragraveolens; Co, Cordia leucophlycfis; M' Macraea

forest in Plot E8. Keys to abbreviations: Br, Burceralaricifoliai S, Scalesia tnicrocephala; St' Sczda pnucifl'ora.

looks like a white birch forest in the subalpinezone in Temperate region (Photo l1). The distri-bution of Bursera is clumpy. Al1 developmen-tal stages of Bursera are found in the plot. Thecoverag e of Aristida divulsa is high, though it was

almost dead at the time of this study.I found the first individuals of Scalesia affinis at

the altitude of 240 m along the path when I wentdown the mountain. It becomes frequent at the

altitude of 210 m and below. The results of the

91


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0.5-1 1-1.5 1.5-2 2-2.5 2.5-3 3-3.5 3.5-4

HEIGHT CLASS (m)

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T1:O T2:s S:x

Fig. 118. Clown projection diagram of Ptot Ell which wrs prt in the transitional zone betreenScalai'a-Trcma forect and fualzrlia-Bunem forect. Keys to abbreviationsz Br, Bunem gravalens; Co, CordialeucophlyctisS I)v' Darviniothamnw tenuifolius; M, Macmu hricifolia; S, Scatresia micruepluhi St, Scutiapaucifurai Tl, Tounuefortia pubacens, Tr, Tlema mitrantha3 W, Waltcria owtt.

丁1:0 丁2:● S:x 10mX10m

Fi3. 119. Crown projection diagren of Bunera forest in Ptot E10. Keys to abbreviationc Blr, Burscragravalcwi Co, Cordia leucophlyctis; L, Lantana pcdunculafis; M, Macma larbifoliai, W, Walteria ovata.

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Moist 5Ao^Dry

Scalesia f. Lantana-Crotonthicket

Cerro Pajas PsidLum― Croton f。rro AzuI

330mP二こ口 guajava

コas

ttacraea - Lantana s crul>

ParkinsoniaScal,esia f .

-Prosopis f.

Bu.rsera f .(open)

Post Office Bay

Ihrrsera f .(cloged)

Puerto Velaeco Ibara

Fig. l2l. Schematic presentation of vegetational zonation in Site F (Floreana).

study of ,S. affinis scrubs are described in the laterchapter.

6. Site F (Floreana)( 1) Location

Floreana is much smaller, lower and drier thanSanta Cruz and Isabela. It must be older geologi-cally, too. There is a large plateau with severalmountain tops at the center of the island above

250 m in elevation (Fig. 121). Floreana has been

inhabited by settlers since the early 19th century.Most of the flat area on the plateau has been

exploited for pasture lands or agricultural planta-tions. Scalesia pedunculata forests are left mainlyon the windward (south) slope of the mountaintops. Especially at Cerro Pajas (the highest moun-tain: Alt. &O m), a natural Scalesia forest existsin a small valley (eroded old crater) open to the

Ceno Pajas

―- 93 -―


T1 :O T2:o S:x deadio,T 10mX10m

Fig. 122. Crown projection diagram of Scalesiamollei, Co, Cordia andesonii; Cr, Croton scouleri;Psidium guajava; S, Scclesia pedunculata.

forest in Plot Fl. Keys to abbreviations: A, CbrodendrumDw, Danviniothamnus tonuifolius; L, Lantana catnara; Pi,

s

forest in Plot Fl. Keys to abbreviations: Cr, Croton scoulerii Ct, CitrusL, Lantana catnara; Pi, Psidium guajava; S, Scalesia Trcdunculata.

Fig. 123. Profile diagram of Scalesiasp.; Dw, Darviniothamnus tcnuifolius;

south-west direction from which the prevailingwind frequently carries moisture. Many intro-duced plants have become wild and invaded Sca-lesia forests around Cerro Pajas. For example,Psidium guajava, Citras spp., Lantana camara,and Kalanchoe pinnata are very common on theplateau area. Feral cows, donkeys, goats and pigs

are also having serious negative impact on thenative vegetation.

(2) Scalesia pedunculata forest (Outside thecrater)

Scalesia pedunculata, which is common toSanta Ctuz, makes a dense forest around Cerro

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PLOT F4

Pajas, especially on the windward slope (plotsF1-4). Plot Fl is located on a rough exposed lava(Fig. 122, Fig. 123). The canopy, 5-6 m high, isexclusively dominated by scalesia. Most of thecanopy trees have thin stems and small crowns.Some of the thin stems are dead (Fig. I24a).Though the canopy is nearly closed, it is bright inthe forest because the amount of leaves of scale-srd crowns is not so much. Even so, no saplings or

Fig. 124. DBH histograms of Scalesia forestswith the invasion of Psidium in Plots Fl, F2, F3and F4. Keys to abbreviations: Cr, Crotonscoulerii Pj, Psidium guajava; S, Scc lesia pedun-culata.

seedlings of Scalesia were found in the plot.croton scouleri, cordia leucophlyctis, Zanthoxy-lum fagara and introduced species such as psi-dium guajava and Citrus sp. appear in the T2-layer sparsely. Darwiniothamnus tenuifolius andLantana camara are abundant in the shrub-layer.The Herb-layer is very poor in species composi-tion and coverage. Though the ground seems tobe dry, moss and lichen occur to some extent on

3-6 6-9

DBH cLASS (cm)

□ S tt Pj

―- 95 -―

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Ffg. 125. Crown projection diagran of Plot F2 showing the invasion of hidium in t Sulosia forect. Keys to

abbreviatione Cl, Clerdendrum mollc; Co, Corilia andaoniii Cr, Crotan scoulerii Ca' Citrus slt.i L' Iantarucamam, Pj, hidium guqiavai S, Scalesia peduncuhb, Zl, lanthoxylum fagara.

Fig.126. Profile diagren of Plot F2 rhowing the invasion ol hidium in the ScaLafio foreot. Keys to

abbreviations: A, Cbrorlcnilrtm moll4 Ct, Crotan scouleri; Ct, Citras sp.; Kln, Kalanche pinnataS laLantatu camana, P!, Psidium guqiava; S, Scalesia pduncuhta.

S

the exposed lava rocks. Trachypteris pinnatagrows frequently on the rocks. A patasitic plant,

Phoradendron henslovii (common to Site D), isfound on the branches of Scalesia.

Plot F2 is located on a flat place just below Plot

Fl. Only two Scalesia trees, 6 m high, are left inthe plot, while small trees of Psidium guaiava,3-4 m high, cover the T2-layer densely (Fig. 124b,

96


10mX10m

Fig.127. Crown projection diagran ol Scatesia forest in Plot F3. Keys to abbreviations: C-n, Cordialeucophllctis; Cr, Crctnn scoulcr\ Ct, Citrus sp.; I)w, Darviniothamnus tznuifolius; M, Macraea taficifolia3Pf, Pisonia floribunilai 4, hiilium guajava\ s, scalcsia @uncul.ata; zt, zaihoxytum fagara.

Fig. 125, Fig. 126). Four dead scalesia treesfound in the plot must have been shaded out bythe invasion of Psidium guajava. Kalanchoe pin-nata, 0.5-1 m high, covers the ground so denselythat establishment of tree seedlings should be verydifficult. Kalanchoe produced many flowers at thetime of study (Photo lz). There are severaldonkey-tracks running through the plot. shrubsof Lantana camara and saplings of psidium gua-java are abundant in the Shrub-layer here, too.

plot F3 ( 1" l g'lo" s, g0o 27, ll,,w, Alt 330 m)is located on an exposed lava. The structure andthe species composition of the scalesia forest inPlot F3 are nearly the same as those of plot Fl.But I could find a few young trees, saplings andseedlings of scalesia in the plot (Fig. rz4c). Thisis because the canopy is not fully closed and theinvasion of Psidium and Lantana has not pro-ceeded so much (Fig. 127).

plot 4 (1" 1g'22"5, gO"27'20"'W, Alt. 340 m)is a developed Scalesia forest, 8 m high, on a flatplace (Fig. 128). Lava rocks slightly coveredwith moss are exposed here and there on the

ground among which black soil is thinly dis-tributed. The DBH histogram has a clear modebetween 6 cm and 9 cm (Fig. l}4d). The largesttree of Scalesia is 8 m high and 14.5 cm DBH.Each individual has a straight stem up to 5 m highand spreads branches upward. Most of the thintrees of scalesia are dead due to self-thinning.The canopy is fully closed, though crowns ofScalesia never overlap with each other (Fig. l}g).Crown size is varied from small to large. The TZ-layer is vacant and the shrub-layer is also poor.Psidium guajava and Lantana camara ate not somany in the plot. small trees of croton scouleri,some of which are dead, are found frequently inthe shrub-layer. Macraea laricifolia makes a fewclumps in the plot. The coverage of the Herb-layer is also small.

(3) Scalesia pedunculata forest (Inside thecrater)

There is a small world inside the old crater ofCerro Pajas. Only the SSW part of the roundridge is cut open by a small valley. As the valley

97


Fig. 12t. Proflle diagran ol Scalxia forest in Plot F4. Keys to abbrevirrtiong: Cr, Crobn scoulerii L,Lantana aamam, M, Mauau laricifoliai P!, Psi.ilium guajavaT S, Scalesia pdunculata. Underlined symbols

show derd hees.

10mX10m

Ftg. 129. Crown projectioa dlegrln ol Scalesia forest in Plot F4. Keys to abbrevirtions: Cr, Crcbn scouWii

Co, Cordia teucophllctis; M, Macmu laficifolia; Pi, Psidium guajava3 S, Scalesiu pdunculan. Underlinedgymbolg shor derd hees.

collects moisture from the prevailing south wind,it is moister than other places outside of the

crater. A Scalesia pedunculata forest in a rathernatural condition covers the whole slope and the

valley bottom of this place (Photo 13).

plot F5 ( 1" I 8' 14' '5, 90" 27'28 "'W, Alt. 3 80 m)is located on the lower part of the slope (Aspect:SSW, Inclination: 22" ). The habitat is moist.

The canopy is composed of large trees of Scalesia

(Fig. 130), all of which have a DBH more than 9

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10mX10m

Fig. 130. Crovn projection diagran of Scalsia forect in Plot F5. Keyc to abbrevirtions: Cr, Cmton scouleriT

Co, Cordia leucophlyctisT Pi, Pl;itlium gaajaw; S, Scalesia pcilanculata.

PLOT F5

cm (Fig. 131). The largest individual is 6 m highand 2l cm DBH. Only a few saplings and seed-

lings of Scalesia are found in the plot. Crotonscouleri is rather abundant in the Shrub-layer.Psidium guajava is invading the forest. Smalltrees of Psidium have established in the T2-layer.The soil layer is thin. Moss covers the surface ofexposed lava rocks. Asplenium formosa growsfrequently on the rocks. Ctenitis sloanei is sparse-ly distributed. Psychotria angustata, the endemicshrub in this area, is found in the Shrublayer.There is a big tree of Pisonia floribunda near theplot. Passtflora edulis, a very invasive vine spe-

Fig. 131. DBH histogram of Scalesia forest inPlot F5. Keys to abbreviatiorun Cr, Croton

scoulerii Pj, Psidium guajava; S, Scclesia pedun-culata.

cies, covers its crown. It produced many maturedfruit at the time of this study.

A Scalesrc scrub, 3 m high, mixed with Crotonscouleri appears on the upper part of the slope(Alt. 430 m; Plot Fl2) (Fig. 132). Mauaealaricifolia and Ctenitis sloanei make clumps hereand there in the Shrub-layer and the Herb-layer,respectively. Psidium guajava and Lantanacamara have also been invading the scrub, thoughthe frequency is still low. Juveniles of dark-rumped petrel (Pterodroma phaeopygia: a kind ofsea bird which nests in moist highlands at the timeof reproduction) live in hollows under exposed

□硼 others

6-9 9-r2 r2-r5DBH cLASS (cm)

S ICr

15-18 18-21 21-24

囲 Pj

I dead

―- 99 -―


Fig. 132. Profile diagram of Scalesia-Croton mixed scrub in Plot Fl2. Keys toscoulerii Co, Cordia leucophlyctisi L, Lantana camara; M, Macraea laricifolia;Scalesia pedunculata.

abbreviations: Cr, CrotonPi, Psidium guajavai S,

Fig. 133. Profle diagram ot Scalzr;ia forect in Plot F7 with the invasion ol Citrus. Keyc to abbrevirtionr: CtCitrus litrlcttai S, Scalelri4 pdarcuhtai Tf, Tournefortia pulrscens1 Zl, Tantlnxylum fagara.

basal rocks on this slope. National Park Serviceshas been recording reproduction of the petrelsince 1987 and doing a project to eradicate ratswhich feed on eggs of the bird.

Plot F7 is a Scalesia-Citrus mixed forest with afully-closed canopy (Fig. 133). The canopy layer,9 m high, is composed of large trees of Scalesia,most of which have thick stems more than 10 cm

- 100-


in DBH. The stems are straight up to +-S m high,which is comparable to the height of saplingsfound in Plot F10 mentioned later. Citrus sp.(akind of lemon) , dn introduced tree, makes thedense T}-layer, 4-5 m high. It takes a multi-stemmed growth form. As it is dark on theground, the Herb-layer is nearly vacant. A fewsaplings of Psidium guajava occur in the forest,but they are dead or nearly dead.

(4) Gap regeneration of Scalesra forestLarge trees of Scalesia (9 m high, 20 cm (

DBH) make a forest with closed canopy at theflat bottom of the valley in the crater. There arerelatively new fallen trees of Scalesia, makingcanopy gaps here and there. As the root systemof Scalesla is shallow (weak ?), large trees with aheavy crown seem to collapse easily by occasionalstrong wind. Plot F6 shows the regeneration ofScalesia saplings in a canopy gap (Fig. 134, Fig.135). A large Scalesia tree (21 cm in diameter)islying up-rooted on the ground, though it still hasliving leaves. Many saplings and seedlings of

Scalesia are growing in the canopy gap with thearea of about 30 sq. m. The highest saplingattains to 2.35 m, while most of them remain less

than 0.5 m high (Fig. 136). This means that theregeneration occurred within one year. Psidiumguajava is also invading the gap. The largest one

is 3 .2 m high, but it must be older than Scalesia

saplings. In contrast to the Scalesia saplings,Psidium saplings include individuals with a varie-ty of sizes (Fig. 136). Plumbago scandens spreads

to make large clumps over the ground.Plot F10 is a belt-transect which was put

through an older canopy gap in the same Scalesiaforest. A dead fallen tree of Scalesia (L4.8 cm indiameter) and seven fallen trees of Croton (six ofthem are still alive) are found on the ground inthe canopy gap (Fig. 137). Seven Scalesia sap-

lings, 3-5.8 cm DBH, grow up to 4-5 m high inthe gap. They are all vigorous. Stems are strai-ght. But no saplings and seedlings smaller thanthose are found even though the gap is still open.The gap seems to have been made about two years

ago. Psidium guajava is invading the gap, too.

dead : Sap I i ng:

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Fig. 134. Crown projectionto abbreviations: Cr, CrotonTf, Tournefortia pubescens.

diagram of Plot F6 showing the regenerationscouleri; Pf, Pisonia fl.oribunda; Pj, Psidium

of Scalesia in I canopy gap. Keysguajava; S, Sca lesia pedunculata;

―-101-一

Regional Views No. I I lggT

F19.135. Profle diagrem of Plot F6 ehowing the regeneretion of Scalasia in a canopy glD. tre1,3 toabbrevirtions: 6, Croton scoulcrl Pl, Pisonfu fuiburulal P!, hidium guajoyai Plb, Plambago scandens; S,Scdesia pdurcahtai Tl., Tournefortit pufuccns.

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□ s tt Pj

(5) Invasion of Lantana camaraScalesia forests change to Croton dominant

Fig. 136. Height histogram of seedlings andsaplings in the canopy in Plot F6. Keys toabbreviations: Pj, Psidium guajavai S, Scalesiapedunculata.

scrubs, 3-4 m high, oD the dry upper part of theslope at the outside of the crater. Plot Fl l shows

Ft8. 137. Crowa projecdon diagram of Plot F10 rrhowing the regeneration ol Scalrrifu in a canopy gap. Keysto abbreviadons: Co, Cordia leucophlyctig &, Croton soulefiS Cq Cit'rlts gp.; Pf, Pisonia floribundaT p!,Psidilrm guoiawi S, Scal.aia @unculataT Tl, Tournefortia pubacens.

T1 : o T2:o S: x dead: r

-102-


Ftg. 13E. hoffle diagran of Plot Fll ohowing the hansition l part betreen Scalcsia forest (lower) rndCrobn-I'antana rcrub (upper). Keye to abbrevlations: h, Corilia leucaphbaisi &, Crtun scoulefi; L,Lantana camami M, Macmea l.aricifolia; W, Pisonia floribunda; Pl, hidium guojava3 S, Scalxiapedunculatai TI, Tournefortia puhcens; Zf, Zantlwxylum fagara.

the transitional part between them (Fig. 138).The situation is similar to that found in Site D(Plot D17) though the Croton dominant forest islocated below the Sca lesia forest in Site D. Inaddition to Croton, the scrub is composed ofM acraea laricifolia, Cordia leudophryctis, Cleroden-drum mole, Lantana camara and so on. Macraeaand Lantana continue to appear in the Shrub-layer of the Scalesia forest at the lower part of theslope.

On the arid leeward side of the mountain, smallpatches of Scalesra forest are scattered in a densethicket of Lantana camara (Plot F8)(Photo 14).Scalesia trees, 5 m high, make a loose canopy(Fig. 139, Fig. 140). Four individuals of Scalesiaare dead (Fig. 141) and the amount of leaves ineach crown is not so much even on living trees.No Sca lesia saplings and seedlings are found inthe forest. The T2-layer is almost vacant. Largeclumps of Lantana camara cover the Shrub-layer,2-3 m high, together with some shrubs of Mac-raea laricifolia, Tournefortia pubescens, Cleroden-drum mole and Chiococca alba. They are so densethat it is very difficult to pass through the plot.The relative light intensity is 24.lVo on theground. The Herb-layer is very poor. Seedlingsof Lantana camara are also rare in the forest.

Plot F9 is located near Plot F8. One adult treegrowing just outside of the plot (the supposedoriginal seed source), three young trees (two of

them producing fruit) and ten saplings (0.9-3.3m high) of Scalesia occur in an open space alonga path (Fig. 142). This is a kind of gap regener-ation of Scalesia. The other part of the plot is

covered densely with many large clumps of Lan-tana camara. Each Lantana individual has one ortwo thick dead stems and many thinner livingsprouts and branches (Fig. 143). The histogramof stem diameter class for the thickest branch ineach individual shows a clear peak at the 3-4 cmclass (Fig. 144). There are some small individ-uals of Lantana, but no seedlings of Lantana Lrefound in the plot, even though most of the largeindividuals bear much fruit. Lantana shed almostall leaves at the time of study, maybe because ofthe arid condition in the dry season. However,they would have many leaves in the moist seasonand shade out seedlings of Scalesia and of theirown. It seems that the Lantana thicket estab-lished all at once in the past, and it has beenreproducing by repeated sprouting.

There is a large tree of Geoffraea spinosa nearthe plot. This introduced tree makes a largecrown sporadically in this area. It produces manylarge fruit, which feral donkeys and pigs eat anddisperse seeds here and there. I sometimes founda mass of seeds in droppings of these animals onthe ground.

-103す


T1 :O T2:@ S:x dead:.,7 10mXlom

Fig. 139. Ctrown projection diagrrm of Plot Ft choring the invssion ol Lantana in the Scaferic forest. Keyc

to abbreviations t A, CbroMrum motlq G, Crotan saulerii L, La ntuna can ara; M, Macraoa larbiloliti S,

Scalaia padunculata.

FiS. l{O. Proffle diagram of Plot Ft choving the invasion of Lantuna in the Scalasia forect. Keyc to

abbrevlrtiono: G, Crobn rcoubri la Lantana saman i M, Macraea laricitoliai Pl, Psidium gt4iawT S,

Scalaia pduruulata.

- 104-

Competitive Relationships between Tree Species of Sco/es ia and Introduced Plants (Shimizu)

PLOT F8碧

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Fig. 142. Crown projection diagram of Plot F9Lantana dominant scrub. Keys to abbreviations:camarai S, Scclesia pedunculata.

Fig. l41^. DBH histogram of Plot F8. Keys toabbreviations: Cr, Croton scoulerii S, Scalesiapedunculata.

10mX10m

showing the regeneration of Scalesia along a path in theCl, Clerodendrum molle; Cr, Croton scouleri; L, Lantana

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7. Scalesia afi,nis scrub( 1) Location

A shrubby Scalesia, S. ffinis, occurs in theArid zone in some big islands. I surveyed theecology of S. afinis in the four sites which arelocated on the way from the coasts to the studysites of Scalesia forests; Site SC: from PuertoAyora to Bella Vista (to Site A and B) in SantaCruz, Site IBa: from Puerto Villamil to SantoTom6s (to Site C and D) and Site IBb: from

Black Beach to Alcedo (Site E) in Isabela, andSite FL: from Puerto Velasco Ibarra to CerroPajas (Site F) in Floreana (see Fig. 4).

(2) Santa Cruz: Site SCI observed the Arid zone vegetation of the

windward slope of Santa Cruz: ( 1) aroundCDRS, (2) on the way from Puerto Ayora toTortuga Bay, and (3)along the road from PuertoAyora to Vella Vista. The Arid zone is composed

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-105-


Fig. 143. Profile diagram of Plot F!)dominant scrub. Keys to abbreviations:

showing the regeneration of Scalesia along a path in the LantanaL, Lantana catnara; S, Scalesia pedunculata.

路

５

０

颯

Ｚ

８

日

目

２

1-2 2-3 3-4 4-5 5-6

DIAMETER CLASS (cm)

□ alive l■ dead

of many tree and shrub species adapted to aridconditions such as Bursera glaveolens (palos-anto), Parkinsonia aculeata, Scutia pauciflora,Castera galapageia, Opuntia echios var. echios,Jasminocereus thouarsii var. delicatus, Croton scou-leri, Cordia lutea, Acasia roradiana, A. macra-cantha, Altenanthera filifolia, A. echinocephara,Chiococca alba, Clerodendrum molle, Prosopisjultflora, Gossypium barbadense, Tournefortiarufoserice a, T. pub e sc en s and Z anthoxy lum fagara.No one species becomes dominant, though theratio of the component species changes fromplace to place. The canopy is usually not closed.Bare lava rocks are widely exposed on the ground.

I searched for Scalesia afinis in the three placesmentioned above, but I could find it only in anarid scrub near the road in the suburbs of PuertoAyora (Plot SCl: Alt. 10 m). There is a big treeof Bursera graveolens,5.5 m high, in the Tl-layerof the plot (Fig. 145). A variety of trees andshrubs make the T2- and the Shrub layers (Fig.

Fig. l44.. Diameter histogram of Lantanacamara in Plot tr9. Diameter of the thickest stemin each individual was measured at the height of0.2 m.

146). Bursera has several saplings around theparent tree. Only one individual of S. affinis, 2.5m high, is found in the plot. It has a multi-stemmed growth form (max. 5.2 cm DBH). Noseedlings and saplings of Scalesia are found, eventhough the canopy is not closed. I could barelyfind another individual of S. affinis near the plot,but no more in this area. Both endemic andintroduced species of Lantana (L. peduncularisand L. camara) occur together in the plot. Thiswould be a problem in preserving the endemicspecies if interbreeding is occurring betweenthem. The ground mostly made of exposed lavarocks is rough and dry. The Herb-layer is poor.It is composed of .Blainvillea dichotoma, Rhyncho-sia minima, Boehaavia erecta, Commicarpus tube-rosus, Mentzelia aspera, Porophyllum ruderale andso on.

Scalesia pedunculata appears at the altitude of120 m and above on the way from Puerto Ayorato Bella Vista. I could not find any Scalesia trees

一-106-―


Fig. 145. Profile diagram of Arid-zone vegetation with Scalesia afinisBr, Burxera graveolens; Ch, Chiococca alba; Co, Cordia andesonii;peduncularis; op, opuntia echios v. gigantea; S, Scalesia afinis; St,fagara.

in Plot SCl. Keys to abbreviations:Lc, Lantana camarai Lp, LantanaScutia pauciflora; Zf, Zanthoxylum

T1: O T2:@ 10mX10m

Fig. 14'6. Crown proJection diagran of Arid-mne vegetadon vlth Scalosia afizis in Plot SCl. Keyr to abbrevia.tions: Br' Bursera graveolensl 6, Cordia andaonii; Lc, Lantana camarai I.p, Lantona @uncultrisi Op,Opantia cchiu t. gigantea: S, Scalsria cjizfu; Sl Scuti.a pucifora1 Zl, Zanthoxylum fagtm.

-to7-


(both S. affinrs and S. pedunculata) at the altitudebetween 10 m (Plot SCI) and tZO m (BellaVista). The distribution of the two Scalesia spe-cies does not overlap with each other along thealtitudinal gradient. I could neither find S. affinisin the arid vegetation around CDRS nor on theway to Tortuga Buy, though these places seem tobe good habitats for ,S. affinis (I might haveoverlooked it, but even so it must be very rare).Unknown events in the past rather than presentconditions may be related to the lack (or rare-ness) of S. affinis in these places.

(3) Isabela: Site IBa (San Vicente)A vast lowland area on the windward side of

Sierra Negra, Isabela, is covered with arid vegeta-tion whose component species are nearly commonto those of Santa Cruz. Plot IBal (0'56713"5,90o59'19"W, Alt. 5 m) was put in the arid vege-tation with Scalesia afinis shrubs. The habitat is

completely made of bare lava. Several Burseragraveolens trees, 4-6 m high, make patches ofcanopy (Fig. 147). Croton scoulerf and S. affinisappear in the T2-layer,2-3.5 m high. The Shrub-layer is composed of many clumps of Chamaecyceviminea and some other shrubby species (Fig.148). Two individuals of S. afinis have a multi-stemmed growth form with 7 and 14 stems perindividual, respectively. Only a few herbs such as

Mentzelia aspera, Plumbago scandens and Passi-

flora foetida grow on the dry and hot ground.Plot lBa} is adjacent to Plot IBal. It was put

in a flat place which had once been bulldozedbefore 1980. Plants have invaded the place againfrom surrounding vegetation. No Bzrsera tree isin the plot. Several shrubby species make smallclumps here and there. Six saplings of S. affinis(0.3-1.9 m high) are found and one of them isdead (Fig. 149). It is characteristic that Darutini-othamnus tenuifoius occurs frequently on the barelava. These two species both of which belong toendemic genera of Compositae are pioneers inthis habitat. The Herb-layer is very poor.

According to Mr. Gordillo's observation, S.

affinis occurs up to 50 m in altitude and S. cordatabegins to appear at the altitude of 75 m, so thereis no Sca lesia between the two elevations. Thedistribution of the two Scalesia species do notoverlap here, either.

(4) Isabela: Site IBb (Alcedo)Scalesia affinis appears from the coast to the

altitude of 210 m on the north east slope ofAlcedo (Site E). Plot IBbl shows a dwarf scrub

on a windy, exposed slope at the low altitude (Alt.50m) (Photo 15). The scrub is composed ofAltenathera filiformis, Camaesyce punctulata,Dodonaea viscosa, Macraea laricifolia, Scalesiaaffinis, Sarcostemma angustissima and Walteriaovata. Some of them including Scalesia haveseedlings in the plot (Fig. 150a). Almost allindividuals are less than 1 m high and take awind-shaped growth form because of the strongprevailing wind. Aristida divulsa occurs sparselyon the ground which is made of thick pumiceaccumulation. Most of the individuals were dead

at the time of survey.A small tree of Bursera glaveolens, 3.5 m high,

appears in the arid scrub in Plot IBb2 (Alt. 100

m). It is interesting that eight shrubby species(Scalesia affinis, Scutia pauciflora, Chamaesycepunctulata, Cordia revoluta, Sarcostema angus-tata, Lantana peduncularis, Yallesia galbra andCastera galapageia) make a clump of crownsaround the Bursera tree (Fig. 150b). Two S.

affinis individuals (0.6 m and 0.9 m high) arefound in the plot. Chamaesyce viminea and C.

punctulata are frequently distributed. Aristidadivulsa occurs sparsely on the ground.

Many S. affinis individuals are distributed inPlot IBb3 (Alt. l50m) (Fig. 151). A variety ofdevelopmental stages are included in the plot(Fig. I52a). The regeneration of S. affinis seems

to be successful here. A mature individual of S.

affinis takes a multi-stemmed and procumbentgrowth form. It spreads branches to all direc-tions, forming a semi-spherical crown. But iteasily collapses with the increase of leaves onbranches and dies, so the large crown above theground does not last long. I found many collaps-ing individuals some of which were nearly dead(Photo 16). I also found that a small individual,0.43 m high, had flower buds. It is characteristicthat old dead leaves do not drop for several years,

covering stems densely. The beetle which I foundin the trunk of S. cordata in Site D was found inthe stem of S. affinis here.

Plot IBb4 (Alt. 190 m) is located near theupper limit of the S. affinis distribution. Tenindividuals of S. affinis (one is dead) grow in a

Bursera sparse forest on the sunny and windysouth-facing slope (FiS. 153, Fig. 154). ,S. affinishas individuals with a variety of sizes exceptseedlings in the plot (Fig. l52b). But I did notfind any S. affinrs individuals in the same type offorest around the plot. Many clumps of Macraealaricifolia and Walteria ovata are distributed inthe plot. The situation is similar to the Scalesia

-108-


Fig. lg. Proflle diagran of Arid-zone vegetation vilft-ftalrr;io afinis in Plot lbal. Keys to abbreviations:Bt, Burscra gtaveolens; G, Ctdan scouler\ Ct, Chamesyce vimhuti, Dv, Darwiniotlumnus Enuifoliuq Og,Opuntia uhios t. incrmis; S, Scalasia afinis.

10mX10m

Fig. 148. Crown projection diagran of Arid.zone vegetation with Scclesia afinis ia Plot IBal. Keys toabbreviationc: Bt, Bursera gmveolrzr;S &, Croton scoulcr\ Cr., Chamesyce viminea; Dv, Darwiniathamnusbnuifolius; Op, Opuntia thi.os t. incrmis; S, Scolan:a afrnisi St, Scutia paaciflotu3 Tl, Tounulortiapsilostachya.

-109-


丁2:o S: x 10mX1 0m

aca2--t:a

x.s

tt------

Fig.149. Crora projection diegren of Plot IBa2 showing the regeneration of Arid. zone vegetation on abare bva. Keyr to abbrevirrffonr: C4 Capraria peruvianal Dv, Darviniothamnus tcnuifolius; S, Sca;esiaafinis; Tf, Tournefortia pilostachya.

PLOT IBbl

v(ind*--Do

PLOT IBb2

Fig. 150. Proflle diagrems of Arid-zone yegetation with Scalecia afinis in Plotc IBbl gnd IBb2. Xeyr toabbreviations: Ats' Aristidt tlivalsa; Bt, Bunera gmvulcns; Cr., Chanusyce vimircai Do, Ddonau viscosa;S, Scalrsia a1fllnis; St, Scutia puciflom3 Sr, Satxoshma angustissima; Ya, Vallaia galbm.

- 110-

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ロ

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T2:s S:x 10mX10m

Fig. 151. Crown projection diagran of Arid-zone vegetation with Scalesia afinis in Plot IBb3. Keysabbrevirtions: Br, Burtem graveolens; M, Macraea laricifulia3 s, scalesia afinis7 w, waltpria ovata.

PLOT IBb3

0-0。 2 0.2-0.4 0.4-0.6 0.6-0「百 0.8-1.0 1.o-1.2llEIGHT CLASS(0

□ s.affinis

Fig。 152. Height hお tOgrams of scaJgsjα q"πおin Plots IBb3 and IBb4.

0-0。 2 0.2-0.4 0.4-0.6 0.6-0.8 0.8-「 0 1.o― ゴ両HEIGHT CLASS (m)

□ s.affinis

―-111-―


T2:@ S: x 10mX10m

Fig. 153. Crown Drojectlon diagran of Burrera foregt with Scalqia afinis in Plot IBM. Keys to

abbreviations: Br, Buncm gruveolerti M, Macraea laricifolia; S, Scalesia afrnhi W, llalhtia ovata.

Fig. 154. Profile rtiagram ol Bunem forest with Scatrr;ia afinis in Plot IBlr4. Keys to ebbrevietionc: Br'

Buncra gaveolensiM, Macmu hricifolia; S, Scal.aia afinisl Vl,lfaltzria ovata'

- 112-

Competitive Relationships between Tree Species of Scalesia and Introduced Plants (Shim izu)

microcephala forest (Plot E1-3) at the upper alti-tude. Saplings of Bursera are also growingaround adult trees. Aristida divulsa, less than 0.2m high, covers 4ovo of the ground which is madeof thick pumice accumulation.

As mentioned previously, no Scalesia (neithers. affinrs nor s. microcephala) occurs between 2r0m and 350 m in altitude. The two species neveroverlap with each other in this region, either. Itseems that s. microcephala needs moisture, while,S. ffinis needs wide, open ground made of barelava or pumice accumulation for its establish-ment.

(5) Floreana: Site FLI observed the altitudinal change of vegetation

on two slopes of Floreana: (a) west-facing slopefrom cerro Pajas to the coast of puerto velascoIbarra ( 1" 1 7'm' '5, 90" 29'zg' ') and (b) north_facing slope from cerro Pajas to the coast of postoffice Bay (1" 14'3g"S, 90"27'07',w)) (see Fig.I2l).

The vegetation of the west-facing slope is divid-ed into three zones except a coast al zone. ( 1)Lowland area less than 100 m in altitude is cov-ered with a Bursera forest, 7-8 m high, associatedwith woody species such as clerodendrum mole,scutia pauciflora, Prosopis juliflora, parkinsoniaaculeata, castera galapageia, cordia leucophlyctis,Gossypium barbadense var. danvinii, vallesiagalbra and capraria bffiora. The lower part ofthis zone (up to 50 m in altitude) has been ex-ploited for cattle fields and residence area . (Z)Bursera sparse forest, 5-6 m high, appears at themiddle part of the slope (Alt. l,ZV250 m) withspecies common to the lowland forest and someother species such as Macraea laricifolia, crotonscouleri, Zanthoxylum fagara, Pisonia floribunda,cordia andesonii, Tournefortia leucostachyus andwalteria ovata. (3) scalesia pedunculata forestoccurs at the altitude of 290 m and above, butmost of the area has become a secondary bushwith croton scouleri and Lantana camara. Thesezones (three types of forests) are connected witheach other with a narrow transitional zone ( l0o-l2o m and 25v280 m). It is noteworthy thatintroduced species of Lantana camara, psidiumguajava and Kalanchoe pinnata grow well only atthe altitude above 2so m. I did not find thesespecies below 200 m. Their occurrence must berelated to moisture of the habitat.

The arangement of vegetation on the north-facing slope is more complicated than the west-facing slope (see Fig. l2l). It seems to be related

not only to elevation but also inclination of slopesand edaphic condition. A spinous scrub, 4-6 mhigh, dominated by Parkinsonia aculeata and pro-sopis juliflora continues to occur from the coast tothe altitude of 110 m. It is difficult to pass thr-ough the dense coverage of spinous trees in thiszone. Bursera forest appears at the altitude be-tween 110 m and 26o m. This zone is divided intotwo parts. The lower part ( I 10 m-190 m) is a tallBursera forest, 7-8 m high. The species composi-tion is mostly common to the upper part, but theamount of herb and grass on the ground is less,and lichen hung on the crowns is scarce becauseof the arid condition. On the other hand, theupper part ( 190 m-260 m) is a low Bursera forest,6-7 m high. The Shrub layer is composed ofClerodendrum mole, Prosopis juliflora, Casteragalapageia, Cordia leucophlyctis, Tournefortia psy-lostachya, Pisonia floribunda, Vallesia galbra, andZanthoxylum fagara. Lichen with white color(Usnea sp.) is frequently hanging on the crowns.Blainvillea dichotoma covers the ground densely.

A dry scrub with sparse distribution of Mac-raea laricifolia, Lantana camara, Walteria ovata,and Prosopis juliflora appears on a rocky steepslope at the altitude between 260 m and 330 m.similar scrubs occur on arid rocky slopes at lowerelevations, too. A low forest, 4 m high, dominat-ed by croton scouleri and Psidium guajava dense-ly covers the flat area on the plateau at thealtitude of 330 m. clerodendrum mole, pisonia

floribunda, Cordia leucophlyctis, Zanthoxylumfagara are main component species. Citrus sp.invaded the forest and Geoffraea spinosa makes alarge crown here and there in the forest. Kalan-choe pinnata is dominant on the ground. NoScalesia trees are found in this forest.

Psidium guajava disappears on this slope at thealtitude lower than 300 m. Lantana camara alsooccurs only at the upper par1" of the slope, 200 mand above in altitude, but instead, Lantana ped-unculata (native sp.) appears in the lower part ofthe slope at the altitude lower than 180 m. so thedistribution of the two Lantana species does notoverlap in altitude. This situation is differentfrom that in Santa craz (Plot scl) where bothLantana species are growing together.

It is noteworthy that a kind of endemic Compo-sitae, Lecocafpus pinnatifidus, occurs on a barelava near the coast in both the north-facing andthe west-facing slopes of the island. plot FL Ishows one of the habitats of Lecocarpus on a barelava near the town of Puerto vellasco lbarra. Itis located about 500 m inland from the coast line.

― H3-

10mX10m

Fig. 155. Crorn projection diagram of Bursera forest with Scalesit afinis in Plot FLl. Keye to abbrevla-tions: Br, Bunem gmvalensi Ct, Chamaaycc viminui J\ fasmirmcereus tlnuanii t. tlnaani\ Le,I*cuarpus pinnatifrilusi S, Scclesia afinis7 Tl, Tournefortia psilostachyai W, Waltzria ovata.

Fig. 156. Proffle diagram ol Bursem forest with Scal.aia afinis in Plot FLl. Keyr to rbbreviations: Br'Bunera gaveolenq Jt, lasminucnus tlnuarsii v. tlnuanii; Le, Lamrpus pinnatifidus; Rhy, Rhynchuiaminina; S, Scalesic afinis;Tf, Tournefoftia psilntoahya.

Regional Views No. l l

T1 :9 T2:s S:x

1997

crown in the plot (Fig. 155, Fig. 156). The

canopy is not closed. Saplings of Bursera are also

found. Six individuals (0.45-1.8 m high) of S.

I could find Scalesia afinis only here in Floreana.The plot is at the lower limit of the Bursera forest.One large tree of Bursera, 6 m high, has a large

- 114-


affinis are growing in the plot. The regenerationof S. ffinis seems to be successful. Jasminocereusthouarsii var. thouarsii, Lecocarpus pinnatifidus,Tournefortia leucostacys, Walteria ovata and Cha-maesyce viminea are other associates. Rhynchosiaminima covers the bare lava to some extent.

,S. pedunculata and S. affinis do not overlapwith each other in the altitudinal distribution inFloreana, either.

IV. Discussion

1. Regeneration mechanism of Scalesia forestSuccess of the invasion of introduced plants

into Scalesia forests depends on relationshipsamong environments (location, geology & geog-

raphy, climate, disturbances, etc.) , characteristicsof Scalesia forests (species composition, foreststructure, regeneration mechanism, fauna, etc.),and traits of introduced plants (life form, shade

tolerance, drought resistance, dispersibility ofseeds, growth rate, age at maturity, life span,sprouting ability, pollination mechanism, devices

against animals, etc.). In addition to these,human impacts (destruction, pollution, feral ani-mals. etc.) also play an important role (Fig. 157).Among the various factors, the regeneration mech-anism of Scalesia forests is especially importantfor establishment of introduced species.

I detected two types of regeneration mecha-nisms of Scalesic forests which mainly depend onthe habitat conditions (Fig. 158). Seedlings andsaplings of tree Scalesia usually grow fast, andmake a developed forest with a closed canopy inmoist condition (Sites A, B, C and F). Old trees

die synchronously because of unusually heavyrain fall at El Niflo events. Other factors likeinsects or parasite attack may cause a concentrat-ed death in some cases. New seedlings genninateat the same time in the open forest floor, andgrow rapidly to make the next generation offorest which is composed of even-aged population(Synchronous Type Regeneration).

This type of regeneration is the same mecha-nism as studied in ,S. pedunculata forests byHamann (1979a) and ltow & Mueller-Dombois( 1988) in Los Gemelos, Santa Craz and in S.

cordata forests by de Vries & Tupiza (1990) inSierra Negra, Isabela. Itow & Mueller-Dombois( 1988) explained the phenomena as the conceptof stand-level dieback. The most recent El Niflowhich brought extremely high rainfall to the Ga-l6pagos occurred in 1982-83 (see Fig.3).Hamann (1985) found that Scalesia trees of var-

ious sizes died just after the El Nifio event in hispermanent quadrats in Santa Cruz, though Psi-

dium galapageium, Pisonia floribunda, and Zan-thoxylum fagara were not killed at that time. Hespeculated that the recovery might start after thenext dry season in Los Gemelos, but abundantvines (Stictocardia tilliifolia, Passiflora col-invauxii) covering the tree and shrub layerswould retard the recovery in Caseta. Itow &Mueller-Dombois ( 1988) found a recoveringyoung cohort and some remnant trees left afterthe synchronous collapse at Los Gemelos (Site Bin this study) in 1987. De Vries & Tupiza (1990)recorded a new cohort and some old trees of S.

cordata in Alemania (Site C in this study) afterthe 1982-83 El Nifio event.

On the other hand, tree Scalesia makes a sparse

forest with a broken canopy in dry habitats (SiteD and E). As the canopy is not closed due to theusual arid condition, regeneration of Scalesia

occurs turn by turn in the canopy gaps (vacantspace) continuously (Continuous Type Regenera-tion). Thus the population is heterogeneous inage structure, in contrast to the homogeneous age

structure in the forests of the moist windwardarea. De Vries & Tupiza (1990) recognizedseveral life classes (different cohorts) in a ,S.

cordata forest at Velasco (Site D in this study).They also showed that many old Scc lesia trees

died at the 1982-83 El Nifro event, but synchro-nous regeneration (germination of new seedlings)did not occur after the event in the Sca lesia forestat Velasco. This type of regeneration is true for S.

microcephala forest in the dry habitats of Site E.As the life span of tree Scalesia is short ( 15

years for S. pedunculata estimated by Hamann(1979a) and 2C-4O years for S. cordata estimatedby de Vries & Tupiza (1990)), it is speculatedthat the Continuous Type regeneration couldoccur even in the moist condition as seen in Sites

B and F, if the events to reset the forest regener-ation would be delayed. So which type of regen-eration mechanism occurs is affected greatly bythe impact of trigger events and the durationbetween two successive events.

2. Invasion of introduced plantsInvasion of introduced plants is usually delayed

under closed canopies, but it may progress greatlyand rapidly at the time of synchronous collapse ofthe canopies in case of Synchronous Type Regen-eration. Hamann (1985) also stated that someplants had a higher chance of successful immigra-tion during a Nifro event than during normal

- 115 -


Sca■ esュa Forest

Biological Elaments <-) Environmental Elenents. Species composition . Location

(1ife forrns, population size, (latitude, longitude, attitude)evergreen or deciduous)

. Geology. Forest structure (1and forn, aspects, inclination,

(canopy height, coverage, kinds of rocks, depth of soils,stratification, area, DBH, degree of weathering)dj-stribution pattern,liqht condition) . Climate

(temperature, precipitation,oRegeneration mechanism wind direction & velocity,

(disturbance oriented or frequency of fog)gap dynamics)

o Special events. Fauna and fl-ora (Ef Nino, erruption of volcanoes,

(grazing, pollination, disease, drought, fire, storm, landslide)seed dispersal, germination)

Human lmpactsDirect : developmeot, pollution,

touri smIndirect: feral animals

Introduced Plants. Life form (tree, shrub, herb, vine)' Shade tolerance (pione€r, climax )

. Drought resistance

. Seed dispersibility (abundance,distance, dormancy, dgents )

. Growth rate

. Life span

. Sprouting ability. Age of maturity. Pollination mechanism.Resistance against fire

Fig. 157. Elements concerning the invasion of introduced plants into Scalesia forest.

一 H6-


Dry Condition MOist conditiOn

\v

SapJ-inge

OPen canopy I u1osec canoPy , I

(different-age tr

^ H@J-asepopul:::_, ???.*rffi _.////.ta\- / e+e+e+b+?+g i- I

V ...r.,r4.r-J , ,. Gap regeneration ,,tbli--.tl' tt--

- -- ---a??to?r*f+o \ 't?ff?f?.-

T: ff?ilt??-

_)lEl Ninc J, ,"n.""un." I I

Vn*hlf*h^^^^-lil? scalesia spp.

+ rntroduced plants

?,? Young or old, treeg

?,1 Dead treeg / Introduced plant f.Main-route of

regeneration

regf€neration

Fig.158. Schematic preeentation of the regeneration nechanigms of Sccrssia forect and the invacion ofintroduced plants.

Table 4. Comparison of ecological characteristics among Scalesia spp. and three introduced plants

Scalesia spp. Psidium guajava Cinchona succirubra Lantana camara

Introduced plant

Life form (Max. height)Shade toleranceDrought resistanceEarly growth rateSeed dispersibilitySprouting abilityLife span

2

I2

3

II

ITotal

Numerals show the tentative evaluation (l-3; 3 is highest).

years. On the other hand, it is possible that theinvasion proceeds little by little continuously incanopy gaps in case of Continuous Type Regener-ation (see Fig. 158).

The method of invasion owes to traits of intro-duced species. Table 4 shows the comparison ofseven characteristics among tree Scalesia speciesand three introduced plants studied in this paper.Cinchona succirubra was introduced to SantaCruz in 1946 for the first time, and a few wereestablished at the Moist-scrub (Miconia) zone

and the Highland (Fern-Sedge) zone in 1965.

The first control program (uprooting of the smallplants and digging out of larger individuals withpicks) started in 197l, but it spread to about4,000 ha in 1987. The density was high near thesouth boundary of the National Park area,lowerbetween Media Luna and Mt. Puntudo, and nonewas observed on the western slope of Mt. Cro-cker in 1987 (MacDonald et al. 1988). I found so

many Cinchona trees invading from the southboundary of National Park area to the southern

- 1t7 -


slope of Mt. Crocker through Media Luna andMt. Puntudo in 1995. It seems that its invasionhas stopped just in front of the Scalesia forestswith closed canopies in Site A and Site B, SantaCraz (see Fig. 5).

Cinchona is not a dominant tree in its nativeforest habitats in the Ecuadorian mountainswhere it occurs naturally, but it spread rapidlyinto the native vegetation in the Galiryagos withits advantageous characteristics such as rapidgrowth, early maturity, wide ecological tolerance,a large amount of wind-dispersed seeds, and sp-routing ability (MacDonald et al. 1988). It isgenerally thought that germination and seedlinggrowth of Cinchona occur under a wide range ofconditions including deep shade (MacDonald etal. 1988, Cronk & Fuller 1995). However, Cin-chona seems to need bright conditions for estab-lishment of seedlings judging from the fact that itcan never invade Scalesia forests with a closedcanopy. In addition, small winged seeds dis-persed by wind and its vigorous growth in sunnyplaces along paths suggest that Cinchona is origi-nally a pioneer (light-demanding) species. Sap-lings found in deep shade might have germinatedwhen the canopy was open in the past. Onceseedlings grow up to saplings, they acquire shade-tolerant ability to some extent and they mayendure under the closed canopy for several years.

Cinchona seems to need moist condition as wellas bright condition for establishment, because thedistribution of Cinchona in Santa Cruz coincideswith moist mountainous area. Many small seed-

lings were found on a moist mossy ground nearMedia Luna, while no such seedlings were foundon a dty, thin-soiled ground in the Highland zone.

The coverage of Pteridium aquilinum must berelated to the invasion of Cinchona in the High-land zone. Cinchona can not establish under thedense coverage of Pteridium, so the invasionmight have advanced rapidly and greatly justafter the Pteridium thicket died widely in a se-

verely arid year and before it recovered complete-ly, for example.

MacDonald et al. (1988) suggested that thedominance of Cinchona in the Gal6pagos owed tothe lack of biological controllers. However, Ithink the unique island ecosystem and the com-petitive relationships among plant species aremain causal factors. The characteristics of Cin-chona mentioned above may not be so advanta-geous in the original habitat with many climax(shade-tolerant) species, but they must be effec-tive in invading the ecosystem of the Galfpagos

which lacks real climax species. This situation isvery similar to that of the Bischofia javanica inva-sion in the Bonin Islands (Shimizu 1995). Iworry that Cinchona may invade the Scalesiaforests rapidly at the next El Nifro event whenbright and moist condition is realized after thecanopies of Scalesia forests collapse all at once.

Psidium guajava is rapidly spreading to thesparse Scalesia forests (Site D) or the fragmentalScalesia forests left in the vast Psidium forests(Sites C and D) in Isabela. It is also increasing inthe central part of Santa Cruz (Sites A and B)and Floreana (Site F). Psidium is more shade-tolerant than Cinchona, so it can endure darkcondition under closed canopies. Psidium is in-creasing its total dominance little by little in theseislands. Feral animals (pigs and donkeys) as wellas birds play an important role in dispersing seeds

of Psidium widely. But dispersibility of seeds isless than Cinchona.

Both Cinchona and Psidium ( 1) make large anddense canopy which shade out light-demandingspecies like Scalesia, (2) elongate new shootsfrom the base when main stems are damaged, (3)have longer life span than Scalesia, (4) do not dieeven at El Nifro events. So once they succeed ininvadin g Scalesia forests, they take the place ofScalesia to make a dominant forest of their own.Fragmentation (breakdown of closed canopy) ofnatural forests accelerates invasion of the intro-duced plants.

Lantana camara is a shrub species, which is nota competitor of tree Scalesia in the usual sense.

However, if it covers the ground of Scalesia fore-sts densely as seen in Floreana (Site F), it isdifficult for seedlings ofScalesia to establish them-selves even if the canopy of Scalesia becomes openat El Nif,o events. So Sca/esla forests will gradu-ally change to Lantana scrrub in the end. On theother hand, Lantana is also a light-demandingspecies, thus it will disappear from the forest ifthe forest canopies become fully closed. A herba-ceous species, Calanchoe pinnata, has a similareffect on regeneration of Scalesia forest in Sites Cand F.

There is an opinion that Trema micrantha isnot a native but an introduced species (Wiggins &Porter 1971, Nowak & Lawesson 1988). Howev-€r, it is not strange that a nativ e Trema speciesexists in oceanic islands, because species of thisgenus are usually pioneer trees producing smalledible fruit dispersed by birds (good for long-distance dispersal). In fact, Trema orientalis isdistributed naturally in remote islands such as the

-118-一

Competitive Relationships between Tree Species of Sca/esia and Introduced Plants (Shimi"u)

Hawaii and the Bonin Islands. Judged from thesituation of Trema micrantha in Alcedo (Site E)where no other introduced trees are found, thisspecies must be native to the Galfpagos Islands.

Trema micrantha is a typical pioneer species inthe secondary succession as shown in the burntarea in Site C. Large trees of Trema are dis-tributed on a dry habitat made of pumice and ashaccumulation which is not matured in Site E. Thevegetation of Site E seems to remain in an earlystage of primary succession (a kind of edaphicclimax). Welff (1980) stated that Alcedo was inan intermediate phase, that is, it had passed thestage of colonization of base volcanic substrate,but had not yet reached the florally and structur-ally more complex stage of forest. Trema micr-antha plays an important role in the vegetationalsuccession together with tree Scalesia in the Ga-l6pagos.

Persea americana is invading the Scalesia fore-sts in Sites A, B and C. But it is not so aggressiveprobably because of its large, heavy seeds whichare difficult to be dispersed over a long distance.Saplings are found only around a parent tree. Butit grows up to a tall tree with a large crown, so itshades out native plants around it. Citrus spp.seem to be increasing in Site F. They establishthemselves under the canopies of Scalesra forests,so they would prevent regeneration of the forestsin some places.

3. fnfluence of the 1994 fueThe 1994 fire burned a wide range of forests

(about 35-45 k-') at Alemania (Site C area) inIsabela (Marquezet al. 1994). The altitude of theburnt area ( 150-450 m) is comparable to thelower part of the Moist-forest (Scalesia) zone. Itwas lucky that most of the burnt area was thesecondary forest of Psidium guajava. But smallpatches of Scalesia cordafc forests which had beenleft in the Psidium forests also burned in someplaces. When I saw the burnt forest just after thefire in June, 1994, the burnt stems of Psidiumguajava seemed to be alive, even though crownswere completely damaged (JICA 1994). But, Irecognized in April, 1995, that all the stems weredead about one year after the fire. Instead, newshoots sprouted vigorously from the base of thedead stems. They were l-2 m high at the time ofsurvey. The new shoots of Psidium would growfast to make a new Psidium dominant forest in afew years, which is nearly the same as that beforethe fire.

De Vries & Tupiza (1990) suggested the possi-

bility that thick cover of ferns should not allownew cohorts of Scalesia to emerge in many years.

Pteridium aquilinum began to appear on theground just after the fire. It has covered the openfloor of burnt forests so densely in one year that itmust prevent seedlings of tree species other thanPsidium from establishing. So species composi-tion of the Shrub and the Herb layers wouldremain poor in contrast to the rapid recovery ofcanopies. When the canopy is closed again, thepioneer Pteridiutn would disappear, and instead, ashade tolerant species, Ctenitis sloanei, wouldgrow frequently in the Herb layer.

No Sca lesia trees which died of the fire had newshoots from the base of trunks like Psidium gua-java. So the patchy Scalesia forests disappeared insome places after the fire, and maybe Psidiumwould establish and take over the places. I founddonkey droppings which contained many seeds ofPsidium on an open fire-break belt just after thefire. Feral donkeys and pigs are effective seed

dispersers of Psidium in this area. Nowak et al.(1990) stated that some endemic and rare taxahad very little or no regeneration, whereas intro-duced species showed a high degree of survivaland regeneration after the 1985 fire.

Small patches of Scalesra saplitrgs, 2-3 m high,were found at forest margins or in canopy gaps. Icould find adult trees which survived the fire inthese places. It is clear that these saplings germi-nated after the fire. But it is not sure whetherthey came from buried seeds under the ground ornewly dispersed seeds after the fire. Dr. Mauch-amp in CDRS told me that he studied new Seale-sia saplings in places where no adults were leftaround them. Kastdalen (1982) reported thatextensive damage to the under-brush by pro-longed droughts in 194y',-45 and grazing by cattlein part made an ideal combination of circum-stances for regeneration of Scalesia, and the suc-ceeding garua season showed a fantastic recoveryof the Scalesia forest. These facts suggest that thesaplings were derived from buried seeds.

On the contrary, the saplings growing in thefire-break belt must have originated from newlydispersed seeds, because the soil and maybeburied seeds were removed by bulldozers at thetime of construction of the belt. The patches ofScalesia saplings which had germinated after thefire are all small in Site C. Even a farthest saplingis located within 2O m from the supposed seedsource (adult trees which survived the fire) in thisstudy. If seeds buried under the ground is effec-tive for germination after the fire, the distribution

一-119-一

of saplings should be more wide and prevalentunless the seeds were damaged in burnt area. So

the contribution of buried seeds seems to be littlein this case.

As a general feature of pioneer plants, Scalesiaproduces a lot of small and slender seeds in theend of rainy season. The light seeds are apparent-ly easily dispersed by wind, but in fact, the dis-tance of dispersal may be shorter than we imag-ine. An isolated tree of S. pedunculata on Santi-ago had many seedlings growing around in a

radius of about 20 m (De Vries & Tupiza 1990).The number of S. cordafa seedlings which emerg-ed after the fire decreased sharply with the dis-tance from a parent tree and almost all individu-als were located within 2O m from the supposedparent in Site C. It is thought that the dis-persibility of the ancestral species of Scalesia hasreduced with the process of evolution in the is-

lands (It may be an example of loss of dis-persibility noted by Carlquist 1,974). This lowseed dispersibility is a crucial weak point of Scale-

sia compared with other introduced species (see

Table 4). The direction of prevailing wind has

also an important meaning for seed dispersionOn the other hand, Scalesia surpasses any other

trees in the growth rate of seedlings. It is surpris-ing that Scalesia seedlings grow up to max. 3 mheight within one year after germination. This is

a great advantage of Scalesia over the introducedtrees. EvenPs idium guajava and Pteridium aquilin-um can not establish within the patch of Scalesia

saplings, because the Scalesia saplings grow dense

making a closed canopy together from the begin-ning. If the saplings of Scalesia continue to growfavorably, they would form a small Scalesia

stand. Nowak & Lawesson (1988) studied theregeneration of Scalesia cordata after the 1985 fireat Sierra Negra (nearly the same area as Site C),and found that Scalesia saplings, 3 m high, werekilled in some places by plagues of snails, andbutterfly and beetle larvae. These plagues mayhappen again.

It is said that the 1994 fire was caused by localhunters accidentally (Marquez et al. 1994). Butthere must have been natural fires caused byvolcanic activities in the past. Though Scalesia is

not tolerant to fires, Scalesra forests could recoverfrom new seedlings which had germinated afterthe fires. In fact, Hendrix & Smith (1986) foundthat Scalesia cordata recovered well from seeds

after the 1968 eruption in Fernandina. In thetime before many plants were introduced by man,the regeneration of Scalesia was not interrupted


by other species even if its speed was slow. Firescaused by volcanic eruptions must have been atrigger of regeneration of old Sca lesia forests likeEl Nifro events. However, Psidium guajava in-vaded burnt area faster than Scalesia, if seeds ofScalesia were not dispersed effectively after thefire. Psidium would take over the places in theend. So fires accelerate the invasion of introducedspecies (see Fig. 158) and lead to loss of remnantScalesia forests at present.

4. Comparison of three species of tree ScalesiaThe three species (5. pedunculata, ,S. cordata

and S. microcephala) among fifteen Scalesrc spe-

cies in the Galiryagos take a true "tree" growthform. They form a moist forest at the middlealtitude of severallarge islands (see Fig. a). Theyare taxonomically different species which seems tohave evolved in the different islands, but theyhave almost the same features ecologically. Theyall have the traits of "pioneer plant" such as

production of many light seeds dispersed by wind,light-demanding feature, high growth rate of see-

dlings and saplings, tolerance of aridness, and so

on. The tree height is variable according to thehabitat conditions. They make a dense forestwith a closed canopy in moist habitats, while theyform sparse forest with a broken canopy in dryhabitats. Though S. microcephala is the smallestin height among the three species and it makes a

sparse forest on the dry habitat in Site E, it mustbe larger and the canopy is more closed in themoister habitat of windward slope of Alcedo.

The regeneration mechanism is also commonamong the three species. They take SynchronousType Regeneration in moist and dense forests,

while they have Continuous Type Regeneration indry and sparse forests. So they would get nearlythe same influence from El Nifio events and fires.

The invasion of introduced trees also proceeds inthe same way in the Sca lesia forests. It is aninteresting problem that the evolution from shrubto tree habit occurred only once and then theancestral species diversified to the three species,

or it occurred three times independently in thepast. Genetic analysis will make it clear.

Many trees, shrubs and herbs are associated

with Scalesia forests (Table 5). Most of them are

common irrespective of the canopy species (threespecies of tree Scalesia). Among 61 woody spe-

cies which appeared in the seven sites (includingthe study sites for S. afinis as one site) studied inthis paper, 16 species were found in more thanthree sites. As for herbaceous species, 37 out of

一-120-一


Table 5. Frequency of occurrence of all species which appeared in the plotsFour sites of S. afinis are grouped in Site SA.

No of plots Site A Site B Site C Site D Site E Site F Site SA10 10 16 20 12 12 8

TlJayerAcnistus ellipticusBursera graveolensCinchona succintbraCroton scouleriOpuntia echios v. inermisOpuntia insularisPersea americanaPisonia floribundaPsidium galapageiumPsidium guajavaSapindus saponariaScalesia cordataScalesia microcephalaScalesia pedunculataTournefort i a pub e sc e n s

Trema micranthaZanthoxylum fagara

1 1

2 5

3 3

1

1 14 1

1 4 111 5

1

7 10

4 71 21 3

1 3 3

T2-layerAcnisus elliptictts IBuneragraveolens 3 4 5Chiococca alba 4 |Cinchona succirubra 4 4Citrus lirnetta ICirnrs sp. 3Clerdendntm molle ICordia andesonii ICordialeucophlyctis 2 3 5Cordia lutea ICordia rqolun ICordia scouleri ICrcton scouleri 2 S ll IJasminocereus thouanii v. thouanii IOpuntia echios v. gigantea IOpuntia echios v, inermis IPenea atnertcana IPircidio carthagenensis IPisoniafloribunda I I 3Psidiumgalapageium | 7 Z IPsidium guajava I 14 g 5Psychotria ntfipes IScalesia afinis 2Scalesia ardan 6 lOScalesia micrccephala 7Scalesiapdunculata 4 7 llScutia pauciflom ITournefortia psihsnchya I ITournefortiapubescens I 9 5 3 3 ITournefortiarufosericea 3 2 g

Trema micrantha 4Urea caracasana IWalteria ovata IZanthoxylumfagara4lo4l4l

―-121-―

Regional VievJs No。 11 1997

Table 5。 (Continued)


S-layerAcasia rorudianaAcnistus ellipticusAltenanthera echinocepharaBaccharis gnidiifoliaBursera graveolens

Capraria bifloraCapraria peruvianaCapsicum frutescensCassia pictaCastera galapageia

Chamaesyce vimineaChiococca albaCinchona succirubraCitrus limettaCitnts sp.Clerodendram molleCordia andesoniiCordia leucophlyctisCordia luteaCordia revolutaCordia scouleriCroton scouleriDanv iniothamnus lancifoliusD anv in io thamnu s t enuifo liu sDodonaea viscosa

Gossypium barbadense v. darvtiniiLantana camaraLantana peduncularisL ecoc arpus p innatifidusMacraea lartcifoliaMiconia robinsoniana

Opuntia echios v. inermisOpuntia insularisPersea americanaPisonia floribundaPleuropetalum daruiniiPsidium galapageium

Psidium guajava

Psychotria angustataPsychotrta rufipesRabzs sp.

Sarcostema angustissimaScalesia afinisScalesia cordataScalesia microcephalaScalesia pedunculataScutia paucifloraSida rhombifoliaTournefortia psilostachya

Tournefortia pub esc en s

T o u r n efo r t i a rufo s e rtc e a

Trema micranthaUrea caracasanaYallesia galbra

1 2 2

1

1

1 14 6

1 2

2 3

5371125 1

1

2

6

1 2 1

12 7 51

1

1

2 4 10 17

4 3 2 21

4

8 1

3 41

5 6

3

2

1

1 1 2

1

19432 1 14 11 11

1

4 7 11

4

7

6 88

1 1 5

1 3

1 43 1 3 40663

4 5 3 13 4 24 31

1

一-122-―


Table 5。 (Conttnued)

No of plots Site A Site B Site C Site I) Site E Site F Site SA10 10 16 20 12 12 8

Walteria ovataZanthoxylum fagara 2 4 ll l0 4 8

H-layerAbutilon depaupemtum 9 12 2

Acalypha pamula 1l IAdenostemma lavenia 2

Adianthum matophylum IAdiantum henslovianum 9 7

Ageratumconyzoides | 4 6

Altenanthera fiIifolia 4

Altenantherahalimifolia 2 6 4 2 3

Amaranthus gracilis IAnredem ranosa IAnthephora hermaphrcdita l0 9

Apium leptophyllum IAristida divulsa 3

Asplenium auritum 5 5

Asplenium cfistatum 3

Aspleniurn feei | 2

Aspleniumformosum 2 5 6

lsplenium paraemonturn? |Asplenium serm IBidms pilosa 2

Bidens riparia 12 5

Blainvillea dichotoma 12 8

Blechnum occidentale 3 IBlechnum polypodioides 5 4

Blechum brownei f, pubentlum 3 2 2 |Boehaavia erecta

Boutelona disticha 2 5

Brickellia difusa 5

Capsicttm frutescens ICassia occidennlis 4

Cassia tora 4

Cenchrus platyacanthus 9

Centellaasiatica I 2 2 2

Chamaesyce punctulata 3

Chrysanthellum pusillum 4

Cissampelos pareim I ICissus sicyoides ICloularia incana 2 7

Clotalaria pumila 1 5

Commerinadifisa 3 3 7 3 ICommicarpus tuberosus 7

Conyza bonariensis 5 2

Ctenitissloanei | 7 13 6 4

Cuscuta gJ,mnocarpa 3

Cyperus andesniiCyperus brevi.folius ICyperus anfertus ICyperusspp. I I I I 2

Dennstaedtia glofuldera 2

Desmodium canum I IDesmodium glabrum 6

―-123-―


Table 5。 (Continued)


Desmditm prccumbens IDigitaria adscendens 3 IDigiuria horinnnlis IDiodiamdula 4 5 13 4 | IDiplazium subobtusum 2Doryopterispedan 2 5 11 I 3Drymaria cordata 2 2Elaphoglonm firmum? IEleocharis sp. 1

Epidendrumspicatus 1 I IEuphorbia sp. IEuphorbia tireanii IFleurya aestuans IGalactiastrian I 3 IGalactia tenuiflorz 4Galium galapagense IGraminaespp, I I IHeliottopiumangiospermae I 3 2 2Hyperic,um uliginosum IHypolepis hostilis? IHyptismutabilis 9 2 IHyptis rhomboidea 4 |Ichnanthusnemor.osus 3 2 IIpomoea alba 3

Ipomoea hair IIpomoea nil 2 3

Ipomoeatriloba 3 5 IJusticiagalapagana 3 2 IKalanchoe pinnata 3 ILyapodium clavatutn 2Malvastntm corcmandelianum l0 5 IMuardonia dianthea I 5

Menuelia aspera 2 4Merrcmia aegptica IMomordia charantia INephtolepis cordifolia I IOxaliscorniaian 4 | 4Paspalumconjugatum 5 7 7 4 2Passiflora colinvauxii IPassifura edulis I IPassiflora fetida 2Pennisetum purpureum IPennysetum pauperum 2Peperomiagahpagensis 3 3 2 4Pepercmia petiolan I 3

Phomden&onhenslovii I 5 I IPhysalis pubescens 2 |Pilea baurii 2Pityrcgramma calomelanos IPlumbagoscandens 5 6 2Polygala galapagoensis 3 2Polygonum galapageia 4Polypodiumdispenum I 6 IPolypodium lanceohum IPolypdium phyllitidis 4

―-124-―


Table 5. (Continued)


Polypodium steirolepisPolypodium tridensPorophyllum ruderalePotomorphe peltataPseudolephatopus spicatusPteridium aquilinumPteris quadriauritaRhynchosia minimaSalvia occidentalisScleria pterotaScoparia dulcisSida hederifoliaSida rhombifuliaSida salvifolia ?

Sida spinosa

Solanum nodiflontmSonchus oleraceus

Sporobolus indicusS tachy tarph eta c ay enn e n sis

Stictocardia tiliifoliaStylosanthes sympodialisSynedrella nodifloraTephrosia decumbensThelypteris balbisiiThelypteris oligocarpaThelypteris patensThelypteris tetragonaTillandsia insullarisTrachypteris pinnataUniola pittieriVerbena townsendiivine sp.

Zornia piurensis

1

1 3 1 3

1

1

1 1

719716

14 81 1 2 13 3 3

1

3 3

5 2 31 4 4 3 3

10 18 8

1 1 2

3 2

1 1

4 4 21 5

10

5 15 1

5

4 2 1

1

3 1

10

14O species also occurred in more than three sites. the habitat conditions are quite different fromThe most common species are Zanthozylurn each other. This phenomenon is explained as anfagar4 Chiococca alba, Tournefortia pubescens, example ofecological release ofplants in oceanicand T. rufosericea in woody species, and Diodia islands.radula, Salvia occidentalis, Altenanthera halimi-foliaCommeinadiffusa,Ctenitissloanei,Doryopt- 5. Relationship between tree Scalesia and S.eris pedata, Paspalum conjugatun, heridium aquil- afinisinum, and Sida rhombifolrc in herbaceous spe- I studied four sets of relationships betweencies. Especially,Zanthoxylumfagara occurredin three species of tree Scalesia (5, pedunculata, S.all sites. This species takes a variety of growth cordata, andS. microeephala) and a shrubbyScc-forms from a tree to a procumbent shrub accord- lesia (5. afinis) in Santa Cruz (l set), Isabela (2ing to habitat conditions. Large morphological sets), and Floreana (l set). The,Scclesro treesplasticity of plants is a characteristic of oceanic form a forest at moist mountain slopes in theislands. Hamann (1979b) showed a variety of middle altitude (Moist-forest zone), while ,S.

leaf sizesandshapesof Crolonscouleri indifferent afinis occurs in the arid lowland area (Aridenvironments in the Gal6pagos Islands. It is zone) in all cases. The distribution of the tree andinteresting that Scalesia forests and S. affinis the shrubby species never overlap with eachscrubs have many common species, even though other, though the altitude and range of occur-

―-125-―


SantaCruz IsabeJ.a Floreana

/\/\Sierra Negra Alcedo

400-

,A

8300-v

200-

100-

0-

Fig. 159. Distribution prtterns of three speciec of tree Scalaia and S. ajtzic in the four ctudy cites.

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η「目Ц

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rence is different from each other (Fig. 159).Itow (1995) pointed out that all Scalesia species

are completely allopatric in distribution.Why are they separate from each other ? It is

sure that tree species of Scalesia prefer moisthabitat, and S. affinis is adapted to arid environ-ment. In addition to that, both species need openhabitats when they regenerate. Difference oftemperature along the altitudinal gradient seems

to have little effect on their segregation. Onepossible hypothesis is this: ,S. affinis with theheight of max. 2 m is susceptible to shade byother trees. So, ,S. affinis will disappear from aplace in the long run unless the place suppliesopen habitats one after another around it. It is

suggestive that S. affinis goes up to the highestelevation in Site E where open habitats are dis-

tributed most widely among the four study sites.

It is known that biomass of vegetation increases

at El Niflo events, so the unusual dense coverageoccuring just after the events results in exclusion

of S. affinis.Unusually much rain at El Nifro events may

give more damage to S. affinis at the upper eleva-

tion than at the lower elevation, because theamount of rainfall seems to be proportional to theelevation (see Fig. 3a). On the other hand, treeScalesia may enlarge its distribution toward the

Semi-arid zone in wet years, but they may recede

againin ordinary arid years. The important thingis that dispersibility of seeds is relatively low in allScalesia species. So, once they separate, it is

difficult to merge again. The non-overlappingdistribution may owe to unusual climate condi-tions as well as ordinary ones.

6. Growth forms of tree and shrub species ofScalesia

Tree Scalesia grows up about 2-3 m tall withinone year after germination in moist habitats. Asshown in several sites, main stems elongate strai-ght up to 5-6 m high, then they spread branches

“●■『コυロコ■０ヽ

- 126-


Fig. 160. Branching pattern of a Scalesia tree.

upward. When they reach the height for matura-tion, they produce inflorescens atop the currentshoot, and next branches come out laterally. Thesame pattern of flowering and branching contin-ues year after year, thus the crown becomes largerand heavier exponentially (Fig. 160).

On the other hand, the wood of tree Scalesia issoft and weak, maybe because they have evolvedfrom a herbaceous ancestor. It seems that thestem and root system of tree Scalesia can notsupport the large and heavy crown of itself for along time. So large trees easily collapse by strongwinds as seen in Site F, or by decaying of rootsystems at El Nifro events. The physiologicalmechanism may not be fully adapted to maintainlarge amount of leaves in the crown. This seemsto be related with the fact that many living Scale-sia trees have some dead stems and branches intheir crowns and the crowns never overlap witheach other. Fortun ately, hurricanes never attackthe Gal6pagos Islands. If they hit the islands, thedamage to Scalesic forests would be beyond imag-ination.

I recognized the "yearly node" on the trunkand branches of tree Scalesia. It seems that onenode coincides with one year, because the nodeshows the elongation between one year's and thenext year's flowerings. I could count the nodes oftrees up to I I in Site B (Plot B 1) (Los Gemelos,Santa Cruz). Thus the number of nodes coincides

with the age of the forest estimated from the lastEl Nifro event in 1982-83.

Scalesia affinis has the same branching patternas that of tree Scalesia, but it never becomes atree. Fig. 161 shows a schematic presentation ofdevelopmental stages of S. affinis. It usually takesa multi-stemmed and procumbent growth formwhich must be an adaptation to the arid andthin-soiled environment. It spreads branches toall directions, forming a semi-spherical crown.However, the branch with much leaves at the tipeasily collapses to the ground and dies, so thelarge crown above ground can not be maintainedso long. It is difficult to estimate the age of S.

affinis individual because the counting of nodes isnot so easy as tree Scalesia, but the life span of S.

affinis is probably not so long. It is characteristicthat old dead leaves remain on a stem for severalyears after they withered, densely covering thestems and branches. They may be useful to keepmoisture in the plant body.

7. Effects of feral aninalsIt was a custom of whalers and navigators to

release goats and pigs to remote islands for theirfuture food. This must also have been true for theGalfipagos. In fact, at the time of Darwin's visitin 1935, many goats were observed on Floreana(Koford 1966). In addition, the later settlers tothe Gal6pagos introduced domestic animals such

-127-


Y 'y)(i,0,

as goats, cattle, horses, pigs and donkeys from thelate 19th century to the early z0th century. These

animals have gone wild and given serious damageto the native ecosystem which originally lackedlarge mammal herbivorers (Hoeck 1984, Scho-

field 1989, Jackson 1993).Feral animals affect the ecosystem in various

ways: ( 1) they eat endemic plant species directly,reducing them in numbers or leading them toextinction, (2) they disturb habitats by browsingand trampling, providing open spaces, orchanging nutrient balance, thus letting other alienplants invade more easily, (3) they help the

spread of introduced plants in native vegetation

by eating fruit and dispersing seeds, (4) theyinterfere with regeneration of forests by eliminat-ing seedlings and saplings of canopy trees, thusdestroying the vegetation in the end, (5) theycompete with endemic herbivores such as landiguanas and giant tortoise by eating the same kindof food plants, thus causing the decrease of theirnumber. In this study, I saw pigs, cattle, and

donkeys in Site C, pigs, donkeys, and horses inSite D, goats in Site E, and cattle and donkeys inSite F. I also found many cattle in private pasture

lands near Site A and Site B.Among the four feral animals, goats are the

most harmful, because they eat grass and herb tothe roots, exposing the soil to erosion. Theyadapt to adverse conditions so well and multiplyso quickly that they thrive in many islands in the

Galfupagos and have destroyed their native vege-

Fig. 16l. Life form cycle of Scalesia afi.nis.

tation. Eradication programs were carried outand accomplished in South Plaza, Santa F6, Esp-

afiola, Marchena, Rabida and Pinta so far (Sch-ofield 1989). Feral goats have increased greatlysince the early 1990's in Alcedo, Isabela and have

caused serious destruction of vegetation (Cayot &Snell 1996). The destruction is occurring mainlyon the moist southern rim and slopes of themountain. A new eradication program started in1995. I saw a herd of goats on the eastern rim ofcrater, but I did not detect any serious damage ofgoats on the vegetation with Scalesia micro-

cephala on the eastern slope of the mountain (Site

E). We should keep an eye on the condition ofthis slope, too.

8. A plan to preserve and restore Scalesia for'ests

Preservation of Scalesra forests is classified intothree categories as follows (Fig. 162):

( 1) Keeping natural condition (preventing fur-ther invasion)

Choose a protect area where a Scalesla forest isstill preserved in natural condition and then clas-

sify the area further into Core zone (inside) and

Buffer zone (outside). It is better to surround theCore zone by fences to keep feral animals out (toprevent further dispersal of introduced plants byanimals). Monitor the condition of the protectarea periodically. If you find invasion of an

introduced plant, eradicate it as soon as possible.

- 128-


Core zone should not be used for any humanactivities including eco-tours.

(2) Eliminating introduced plants and animalsEradicate all introduced plants and feral ani-

mals first from Core zone and then from Bufferzone. It is supposed that eradication in Bufferzone takes a long time (many years). It is betterto find usage of introduced plants, for example,wood carvings for tourists, housing materials, firewood or charcoal, and extracting chemicals fromleaves or roots. Prior to the practice of eradica-tion, test carefully the influence of eradication onnative plants and animals. Biological methods(for example, introduction of some host-specificparasites) is attractive, but be prudent in adoptingsuch risky methods in small oceanic islands likethe Gal6pagos, because it might give unexpectedeffects on native creatures. Take care of thespaces after introduced plants are eradicated (forexample, planting of native plants), otherwise the

ScaJ'esj'aIntroduced plants

( f nrras ive )

Introdueed pJ,ants( Non j- rrva s i.re )

same or other introduced plants will establishthere again.

To reduce seed source of introduced plants inprivate lands, ask for cooperation of land ownersto eliminate harmful plants from their farm landsand show them alternative way (for example,agroforestry project being done in Sant a Cruz) .

(3) Restoring Scalesia forest in disturbed area(original habitat)

Scalesia is superior to the introduced plants inthe early growth rate of seedlings (3 m high in ayear in a good condition). Saplings make a densecoverage for the first several years, so even intro-duced species may find it difficult to invade theregenerating place if the coverage is wide andcomplete. On the other hand, Scalesia has lostefficient dispersal ability of seeds while it stillneeds much light for germination as a pioneerplant. Seedlings of Scalesia can enter an openplace only if seed source (matured tree) is close to

？

キ

ー

Fig. 162. A plan to preserve and restore Scalesia forest in an imaginary island.

奸11缶ィ |

啓ふ′‐1 “、下嵩 “

Disturbed area

一-129-―

Regional Views

the place.

So if we help Scalesia by making open land(eliminating competitors by bulldozing the

ground) and dispersing seeds there at the appro-priate time (beginning of rainy season), it is pos-

sible to restore Scalesta forest again We can get

seeds of Scalesia in Core zone of protect area ineach island.

Acknowledgments

I wish to express my thanks to Dr. ChantalBlanton, Director of the Charles Darwin Re-

search Station, and Mr. Michael Bliemsrieder,

Director of Galfupagos National Park Service, forallowing me to carry out my field studies in the

Galfupagos Islands. I extend my sincere thanks toDr. Andre Mauchamp for helpful suggestions inthe course of this study, Mrs. Gayle Merlen forkind advice in library work, and Miss LavtaChellis and the staff of CDRS and GNPS for theirsupport and encouragement in logistics and field-work. I also thank the following persons for theircompany and help in fieldwork: Mr. JacintoGordillo and Mr. Arnaldo Tupiza in Isabela, and

Mr. Anibol Son Miguel and Mr. Angel Naula inFloreana. I also express my gratitude to Mr.Santiago Buitron who assisted me devotedly forthe whole period of my research as assistant

fellow. I cordially acknowledge the valuable

advice by Dr. Shuzo Itow in planning and apply-ing for this study.

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- 131-


Photo 1. Scalesia pedunculata forest taking on amossy appearance (April,1995; Site A)

Photo 3. Canopy of Scalesia pedunculata forestat Los Gemelos (April, 1995; Site B)

Photo 5. Experimental forest of Scalesia cordataat Santo Tomfs (June, 1994; Site C)

Photo 2. Invasion of Cinchona succirubra in aPteridium thicket near Mt. Puntudo

(April, 1995; Aite A)

Photo 4. A view of Psidium guajava dominantforest just after the 1994 fire at Alemania

(June, 1994; Site C)

Photo 6。 Fireabreak belt

1994■re at Alemania

made at the time of the(June, 1994; Site C)

一-132-―

Competitive Relationships between Tree Species of Scalesra and Introduced Plants (Shimizu)

Photo 7. Parasite of Phoradendron henslovii ona branch of Scalesia cordata at Velasco

(April, 1995; Site D)

Photo 8. A kind of beetle (adult and larvae)living in a dead trunk of Scalesia cordata

at Velasco (April, 1995; Site D)

Photo 10. Feral goats on a ridge of the craterof Alcedo (May, 1995; Site E)

Photo 12. Kalanchoe pinnata along a path atCerro Pajas (May, 1995; Site F)

Photo 9. Scalesiaof Alcedo

microcephala forest on a slope(May, 1995; Site E)

Photo 11. Bursera graveolens with bright whitetrunks like white birch at Alcedo

(May, 1995; Site E)

- 133 -


Photo 13.

valleyScalesia pedunculata forest inside the

of Cerro Pajas (May, 1995; Site F)

Photo 14. A remnant forest of Scalesiapedunculata in a Lantana camara thicket

at Cerro Pajas (May, 1995; Site F)

Photo 16. Scalesia afi.nis with a crashed crownon a lava at Alcedo (May, 1995; Site IBb)

Photo 15. Scalesia afi.nis growing

vegetation at Alcedo (May, 1995;

in an aridSite IBb)

- 134-

Competitive Relationships between Tree Species of Scareslic and lntroduced Plants(ShimiZu)

Appendix Species compositton of an the p10ts studied in this paper

Numerals show the number of indi宙 duals(No)and basal area(BA:cm2)in Tl,T2,and S‐ layers,and the

relative abundance(1-4)in H‐ layer and seedlings。

Dead individuals are shown in parenthesese

Symbol(+)iS put to show presence of a sp∝ ies in case that evaluation of quantitiy¬ Ⅳas not done.

Plot Noo Al A2 A3 A4 A5Altitude(m) 660 680 710 700 450Plot sizc(m× m) lo× 10 10× 10 10× 10 10× 10 10× 10

Crown height(m) 5 5 4。 5 4.5 15Coverage(%♭ )Tl‐layer 95 100 - - 30

T2‐layer 0 0 50 40 10

S‐layer 10 5 0 5 60

H‐layer 90 85 95 90 100

No BA No BA No BA No BA No BAT1-layerCinchona succirubra

Persea americana

Scalesia pedunculata

T2-layerCinchona succirabra

Scalesia pecunculata

S-layer

Acnistus ellipticusBursera graveolens

Cinchona succintbraMiconia robinsoniana

Psidium guajava

Psychotia rufipes


7 452 6 461 2 70

(13) (176) (14) (92)

Sida rhombifolia 6

Tournefortia rufosericea 3

Zanthoxylum fagara l(l)

Seedling

Acnistus ellipticusCinchona succintbraPsychotia rufipes

H-layerAgeratum conyzoides

Alt e n an the ra h alim ifo I iaAsplenium auritumAsplenium feeiAspleniurn serraBlechnum occidentale

Blechnum polypodioides

Commerina diffusaCtenitis sloanei

Cyperus sp.

D ennstaedtia globuliferaDiodia radula 3

―-135-―

49 1911 73 2035

49

2 1603

7 490290(17) 325

8 209

Diplazium subobtusum

Doryopteris pedata

Elaphoglosum firmum?Epidendntm spicatum

Galactia striataGraminae sp.

Hypericum uliginosumHypolepis hostilis?Hyptis rhomboidea

Ichnanthus nemonosus

Justicia galapagana

Lycopodium clavatumN ep hro lep is c o rd ifo I iaPaspalum conjugatumPeperomia galapagensis

Pilea baurii?Polygonum galapageia

Polypodium trtdensPothomorphe peltataheridium aquilinumSalvie occidentalis

Sida rhombifoliaSolanum nodiflontmThelypteris balbisiiThelypteris oligocafpaThelypteris patens

Thelypteris tetagona

Plot No.Altitude (m)Plot size (m X m)Crown height (m)Coverage (Vo) Tl-layer

T2-layerS-layer

H-layer

T1-layerCinchona succirubra

Persea americana


T2-layerCinchona succintbraScalesia pecunculata

S-layerAcnistus ellipticusBursera graveolens

Cinchona succirubra

Miconia robinsoniana

Psidium guajava


Al A2 A3 A4 A5No BA No BA No BA No BA No BA

1

A6 A7 A8 A9 A10710 705 640 700 560

6× 35 5× 15 10× 10 1ine line4。5 6 3 20 1。 5

―- 95 -―

40 0 -―

30 5 40

95 100 80

No BA No BA No BA

15 1592

8 65412 781 (8) (165)

十

十

8 337

1

5 80

8 101

十

十

―-136-―

Competitive Relationships between Tree Speciee of *alesia and Introduccd Plants (Shimizu)

A6 A7 A8 A9 AIONo BA No BA No BA

Psychotriarufipes 9 4 70

Scaluia pedunc'ulan 8 330

(4) (loe)Sida rhombifoliaTournefortiarufosericea 3 I 4lZanthoxylumfagara (l) (25)

Seedling

Acnistus ellipticttsCinchona succintbraPsychotria rufipes

H-layerAgeratum conyzoides

Altenan thera halimifoliaAsplenium auritumAsplenium feeiAsplenium serra

Blechnum occidentale


Commerina diffusaCtenitis sloanei

Cyperus sp.

D enn st ae d ti a globulifer a

Diodia radulaDiplazium subobtusum

Doryopteris pedata

Elaphoglosum firmum?Epidendrltm spicatum

Galactia striataGraminae sp.

Hypericum uliginosumHypolepis hostilis?

Hyptis rhomboidea

Ichnanthus nemorosus

Justicia galapagana

Lycopodium clavatumN ephrolep is cord ifoliaPaspalum conjugatum

Peperomia galapagensis

Pilea baurii?Polygonum galapageia

Polypodium tridens

Pothomorphe peltataPteridium aquilinumSalvia occidentalis

Sida rhombifoliaSolanum nodiflontmThelypteris balbisiiThelypteris oligocarpa

Thelypteris patens

Thelypteris tetragona

- 137 -

Plot No.Altitude (m)Plot size (m X m)Crown height (m)Coverage (Vo) TlJayer

T2-layerS-layer

H-layer

T I JayerCinchona succintbraPersea americana

Psidium galapageium

Scalesia pedunculataZanthoxylum fagara

T}-layerChiococca albaCinchona succitabraPercea americanaPsidium galapageium

Psidium guajava

Psychotria rufipesScalesia pedunculata

Tourn efort i a pub e sc e n s

Tournefortia rufoseric e a

Zanthoxylum fagara

S-layer

Acnistus ellipticusChiococca albaCinchona succirubraPersea americanaPsidium galapageium

Psidium guajava

Psychotia rufipesRubus sp.

Scalesia pedunculataSida rhombifoliusTournefort i a p ub e sc en s

Tournrfort ia rufosericeaZanthoxylum fagara

SeedlingPsidium guajava


H-layerAdenostemma laveniaAdianthum macrophylumAgeratum conyzoides

A I t e n an the ra hal i m ifo I i aAsplenium auritumAsplenium cristatumAsplenium feei


Bl B2 B3 B4 B5560 490 580 530 520

10× 10 5× 10 5× 20 5× 20 10× 10

6

100

5

15

80

4

70

0

15

7 10 5100 60 -一

5 5 3030 10 10

80 10o loo

No BA No BA No BA No BA No BA

49 1997

1 547

31 1818 12 1481

3 4 1 7

10 580

4 31

2 171

57 527

(27) (275) (14) (1143) (8) (148) (12) (845)

1 85 1 44(1) 47 (1) (119) 5 176

24

25

26

11 90

1

1

3

5

―-138-―


Bl B2 B3 B4


B5

Asplenium formosumBlechnum occidentale

Blechum brownei f. puberulum

Cissampelos pareiraCommerina diffusaCtenitis sloanei

Cyperus sp.

Diodia radulaDoryopteris pedata

Drymaria cordata

Epidendrum spicatum

Galium galapagense

Ichnanthus nemorosus

Justicia galapagana

N ephrolep is cord ifoliaPaspalum conjugatum

Passiflora colinvauxiiPassiflora edulis

Pennisetum purpureum


Peperomia petiolata

Polypodium dispersum

Polypodium phyllitidisPolypodium steirolepis

Pseudolephatopus spicatus

Pteridium aquilinumPteris quadriaurita

Salvia occidentalis

Scleria pterota

Sida rhombifoliaSolanum nodiflorumS tic toc ard ia t il iifol ia

Thelypteris balbisiiTh elyp t e ri s oligoc arp a

Thelypteris patens

Thelypteris teffagona


T}-layerS-layer

H-layer

T1-layerCinchona succirubra

Percea americana

Psidium galapageium


Zanthoxylum fagara

1

4

15 5

5 5

70 70

B6 B7 B8 B9 B10510 540 570 570 500

10× 10 10× 10 10× 10 8× 10 1ine

8 10 5 380 85 100

15

40

80

No BA No BA No BA No BA

3 492

1 597

27 1988 14 1173 52 1958

1 42

―-139-―

T2-layerChiococca albaCinchona succintbraPersea americanaPsidium galapageium

Psidium guajava

Psychotria rufipesScalesia pedunculata

Tournefortia puiescens

Tou rn efo rt i a rufos e ric e aZanthoxylum fagara


B6 B7 B8 B9 BloNo BA No BA No BA No BA

1 11 79 1 40

1 5

1 9

(14) (387) (6) (131) (14) (205)

1 55

1

4 53

S-layer

Acnistus ellipticusChiococca alba 4Cinchona succirabraPersea americanaPsidium galapageium

Psidium guajava

Psychotria n^tfipes 42Rubus sp.Scalesia pedunculataSida rhombifolius 3Tournefortia pubescens

Tournrfortia rufosericea l0 4Zanthoxylum fagara 2

25

Seedling

Psidium guajaua 4Scalesia pedunculata ngel)

H-layerAdenostemma laveniaAdianthum macrophylumAgeratum conyzoides 2 IAltenantherahalimifolia 2 I 3Asplenium auritum I 3Asplenium cristatum IAsplenium feei zAsplenium formosum 2Blechnum occidentale Z 4Blechum brownei f. pubentlum zCissampelos pareira ICommerina difusa I ICtenitissloanei 4 4 2Cypents sp.

Diodia radula 2Doryopteris pedata 2 3Drymaria cordata IEpidendntm spicatum IGalium galapagense

Ichnanthus nemonosus

Justicia galapagana

N ephrolepis cordifolia

-1“ ―


Paspalum conjugatum

Passiflora colinvauxiiPassiflora edulis

Pennisetum purpureum


Peperomia petiolata


Polypodium phyllitidisPolypodium steirolepis

Pseudolephatopus spicatus

Pteridium aquilinumPteris quadriaurita

Salvia occidentalis

Scleria pterota

Sida rhombifoliaSolanum nodiflontmS tic to c ar d i a t il iifol ia

Thelypteris balbisiiThelypteris oligocorpa

Thelypteris patens

Thelypteris teffagona

B6 B7 B8 B9 B10No BA No BA No BA No BA3 4

Plot No. Cl C2 C3 C4 C5Altitude(m) 220 220 190 180 150

Plot size(m× In) 10× 10 10× 10 10× 10 10× 10 10× 10

Crown height(m) 5 4 9 7 10Coverage(%♭ )Tl‐layer 100 5 90 80 35

T2‐layer 10 0 40 50 80

S‐layer 5 30 5 15 10

H‐layer 85 70 30 20 30

No BA No BA No BA No BA No BAT1-layerAcnistus ellipticusCroton scouleri

Pisonia floribundaPsidium galapageium

Psidium guajava

Scalesia cordata

Tournefortia pubescens


T2-layerAcnistus ellipticusCordia leucophlyctis

Croton scouleri


Psidium guajava

Scalesia cordata

1 165

2 136

8 580 3 77

1 569 1 967

1 82 1 38

30 819 4 47 3 78 1 218 1 108

5 287 9 566

1 88

12 144 13 12

(2) (90) (3)1 11

1 5 5 97

7 183 7 49 1 511 50

(2) (414) (46) (481)

一-141-―

4 82

Regional Yiews No. 1l 1997

Plot No. Cl C2 C3 C4 C5No BA No BA No BA No BA No BA

Touraefortiapubescens | 4 2 9 3 j3(2) lO 158Tournefortia ntfosericu | 4Urea caracasana | 29Zanthoxylumfagam Z 122 2 37(j) lO Z4B

S-layer

Acnistus ellipticusCapsicum fnttescensChiococca alba

Croton scouleri

Pisonia floribundaPleuropetalum daruiniiPsidium galapageium

Psidium guajava

Psychotria rufipes

Scalesia cordata

Tou rneforti a p s ilo s t ac hy a

Tournefortia pub esc e n s

T o u rnefo r t i a rufo s e r ic e aTrema micranthaUrera carocasana

Zanthoxylum fagara

Seedling

Acnistus ellipticusCroton scouleri

Psidium galapageium

Psidium guajava

Psychotria rufipes

Scalesia cordata

Tournefort i a pub e sc en s

Tournefortia rufosericea

Trema micranthaUrera caracasana

Zanthoxylum fagara

H-layerAbutilon depauperatum

Altenanthera halimifoliaAnredera ranosa

Asplenium formosumAsplenium paraemorsum ?

Bidens pilosaBlechnum occidentale


Blechum brcwnei

Capsicum frutescensCassia occidentalisCassia tora

Centella asiatica

Commerina dtffusa

Conyza bonariensis

Ctenitis sloanei

12

2

t2

- 142-

Competitive Relationships between Tree Species of Scc/es ia and Introduced Plants (Shimizu)

Plot No.

Cyperus sp.

Desmodium canum


Drymaria cordata

Epidendrum spicatum

Graminae sp.

H eliotropium angiospermae

Hyptis mutabilisIchnanthus nemorosus

Ipomoea albaIpomoea nilJusticia galapagana

Kalanchoe pinnata

Malvastrum conomandelianum

Mecardonia dianthea

Oxalis corniculataPaspalum conjugatum


Peperomia petiolataPhoradendron henslovii

Physalis pubescens


Polypodium tridens

Polypodum lanceolatum

Pteridium aquilinumSalvia occidentalis

Sida rhombifoliaSolanum nodifloramStachytarpheta cayennensis

S tic toc ard ia t i I iifol ia

Synedrella nodifloraThelypteris balbisiiVerbena townsendii

vine sp.

T 1-layer



Psidium guajava

Plot No. C6 C7 C8 C9 ClOAltitude (m) 185 22O 22O 22O 330Plot size (mxm) 10x l0 lOx l0 10x l0 lOx l0 lOX lOCrownheight(m) 7 3 4 5 9Coverage (/o) Tl-layer 95 100 50

T2-layer 30 20 73

S-layer 5 50 lO 2 l0H-layer 50 30 80 5 80

Cl C2 C3 C4 C5No BA No BA No BA No BA No BA


1 106

1 681

3 244

―-143-一

40 885(25)

Regional VievJs No. 11 1997

Plot Noo C6 C7 C8 C9 C10No BA No BA No BA No BA No BA

Scα Jeslia cOだara 9 925

乃“′“e/orrlia′

“basc`“ s

rre“α ″〕Icra“ ′乃α

Za“′乃oxyル“/agara 2 182(58)

T2¨layer

∠c“お′“sθ′J″′lic“S

Caだlicル

“cψ乃″crお

CrarO“ scο

“ルrli

Piso“ liaノθrlib“

“ごα

PsliJ滋

“garapagθJ“

“ 1 6 (1) (3) 16886(6)

Pslid′

““

g“ aJaッα 30 126

(52)(639)(23)(567) (1) (6)Scα Jeslia cOrdara 3 176

(1) (20) (1) (6)乃

““g/Orrlig′

“bescθ

“s 5 38 (8) (38) 2 22(3)

乃““

g/Orrlic m/Osθ rlic“

じレじα cαracasα P2α

Zα

“働oxyル

“/agara 10 173(47) 1 2 2 363

S-layer


Croton scouleri

Pisonia floribundaPleuropetalum danviniiPsidium galapageium

Psidium guajava

Psychotria rufipes

Scqlesia cordata

T ou rn efor tia p s i lo st achy a


T o u r n efo r t i a rufo s e r ic e a


Zanthoxylum fagara

Seedling


Psidium galapageium

Psidium guajava

Psychotria rafipes

Scalesia cordata




Zanthoxylum fagara


1

51(1)

12

1

10 21

-1名 ―


Plot No.

Altenanthera halimifoliaAnredera ranosa


Bidens pilosaBlechnum occidentale


Blechum brownei

Capsicum frutescensCassia occidentalis

Cassia tora

Centella asiatica

Commerina diffusaConyza bonariensis

Ctenitis sloanei

Cyperas sp.

Desmodium canum


Drymaria cordata

Epidendrltm spicatum

Graminae sp.

Heliotropium angiospermae

Hyptis mutabilisIchnanthus nemorosus

Ipomoea albaIpomoea nilJusticia galapagana

Kalanchoe pinnataMalvastntm coromandelianumMecardonia diantheaOxalis corniculataPaspalum conjugatumPeperomia galapagensis

Peperomia petiolataPhoradendron henslovii

Physalis pubescens


Polypodium tridens

Polypodum lanceolatum

Pteridium aquilinumSalvia occidentalis

Sida rhombifoliaSolanum nodiflontmStachytarpheta cay ennensis

S t ic toc ard i a til iifol iaSynedrella nodifloraThelypteris balbisiiVerbena townsendiivine sp.

C6 c7 C8 C9 C10No BA No BA No BA No BA No BA

1

-145-


T}-layerS-layer

H-layer

Tl-layerAcnistus ellipticusCroton scouleri


Psidium guajava

Scalesia cordata



T2-layerAcnistus ellipticusCordia leucophlyctis

Croton scouleri


Psidium guajava

Scalesia cordata


To u r n efo r t i a rafo s e r i c e a

Urea caracasana

Zanthoxylum fagara

S-layer


Croton scouleri

Pisonia floribundaPleuropetalum daruiniiPsidium galapageium

Psidium guajava

Psychotria rafipes

Scalesia cordata

Tou rn efo rt i a p s ilo s t ac hy a


Tou rn efort i a rufo se ric ea


Zanthoxylum fagara

3 225

1 28

6 316 1 29

7 635 3 108

1 62


CH C12 C13

180 C14180 C15 C16150

5× 30 3204〉〈20 350 3405× 30 4× 15 1ines line

6 5 2.5 730 15

0 4

30 5

30 60

35 70

2 5

40 10

90 90

772

97

59 3 123

2 146 +

7(3)

107

(51) (3)(116)

(5) (147)83(10)

24

413 1 14 +

39

++++十


(1) (3) 2(3)

4 87 3

(12) (160) (3) (29) (4)

(13) (534) (9) (355)2 11 6(3)

2

2(2) 29(50) (2) (36) 13

153 123

2

1

11

1

4

4

9

一-146-―


Plot No.

Seedling

Acnistus ellipticus

Croton scouleri

Psidium galapageium

Psidium guajava

Psychotria rufipes

Scalesia cordata


T ou r n efo r t i a rufo s e r i c e a

Trema micrantha

Urera caracasana

Zanthoxylum fagara


Alt e n anthe ra halim ifo li a

Anredera ranosa


Bidens pilosa

Blechnum occidentale


Blechum brownei

capsicum frutescensCassia occidentalis

Cassia tora

Centella asiatica

Commerina diffusa

Conyza bonariensis

Ctenitis sloanei

Cyperus sp.

Desmodium canum


Drymaria cordata

Epidendrum spicatum

Graminae sp.

H eliotropium angiosPermae

Hyptis mutabilisIchnanthus nemorostts

Ipomoea alba

Ipomoea nilJusticia galapagana

Kalanchoe pinnata

M alv as trum c ono m and e lianum

Mecardonia dianthea

Oxalis corniculataPaspalum coniugatum


Peperomia petiolata

Phoradendron henslovii

Physalis pubescens


Polypodium tridens

CHNo BA

C12No BA

2

1

C13No BA

C14 C15 C16No BA

+++

＋

十

＋

＋

十

十

＋

十

十

十

十

1

-147-

+3+

Plot No. Dl D2 D3 D4 D5Altitude(m) 780 780 780 650 550Plot size(m× m) 10× 10 10× 10 1o× lo lo× lo lo× loCrown height(m) 4 4 4 5 6Coverage(%♭ )Tl‐layer 60 70 1o 70 30

T2‐layer ― 一一 __ 15 60

S‐layer 30 5 30 20 1o

H‐layer 40 75 90 80 70

Plot No.

Porypαr“

“ra“ cω rar“

“PrerlilJJ“ ″7 αg“ lirliP3“

“sar71ic accだθ“ra騰

Sida ttο

“b:ル Jlia

sara“

““ “"´ο″″

SraCりたフ乃θra cりθ““

θ“sお

srlicracaだ lila rJJ′ψ肋

シ“″″JJa“″メοra

動 θりた=お

bαJbお″

降 rbθP3α ′ο″“sθ

“ごlili

vine sp.

T1-layerBursera graveolens

Croton scouleri

Opuntia insulariaPisonia floribundaPsidium galapageium

Psidium guajava

Sapindus saponaria

Scalesia cordata

Tou rnefortia p ub e sc e n s

Zanthoxylum fagara


Chiococca albaCordia leucophlyctis

Cordia scouleri

Croton scouleri


Psidium guajava

Scalesia cordata

Tou rneforti a p silo s t achy a

Tournefort i a pub e sc e n s

To u r n efo r t i a rafo s e r ic e a

Zanthoxylum fagara

S-layer

Altenanthera echinocephara


Cll C12 C13 C14 C15 C16No BA No BA No BA No BA

3233 +2 +3

+2 +

2 +


1 670

6 1121 380

5 181 1 124 1 35

13 998 8 583 4 404 5 584 2 305

2 40

1 28

1 8

(1) (47)

2 27

1 7

8 57 7 70

(10) (126) (14) (168)1 36

1 9 5 52

1 13

9 154

2 8

1 5 4 38

2 9 2 35

一-148-―


Dl D2 D3 D4 D5No BA No BA No BA No BA No BA

1 5

1

1

1 4 121 4(1) 2(1) 1

37(2) 18(3)24

Gossypium barbadense v. danvinii IOpuntia insularisPisonia floribundaPsidium galapageium

Psidium guajava

Scalesia cordata

Tournefortia psilostachya


T o u r n efo r t i a rafo s e r ic e a

Zanthoxylum fagara

Seedling

Baccharis gnidiifoliaCordia leucophlyctis

Croton scouleri

D anv in io th amnu s t e nu ifo liu s

Gossypium barbadense v. darwiniiPsidium guajava

T o u rn efo r t i a rufo s e ri c e a

Zanthoxylum fagara


Acalypha parvulaAdiantum henslovianum

Ageratum conyzoides

Altenanthera filifoliaA I t e n an t he ra h ali m ifo li a

Anthephora hermaphroditaApium leptophyllumBidens ripariaBlainvillea dichotoma

Blechum browneiBoutelona distichaBrickellia diffusaCentella asiaticaChrysanthellum pusillumCissampelos pareiraCisszs sicyoides

Clotalaria incanaClotalaria pumilaCommerina diffusaCommicarpus tuberosus

' Conyza bonariensis

Baccharis gnidiifoliaBursera graveolens

Capsicum fnttescensCassia pictaChiococca albaCordia leucophlyctis

Cordia scouleri

Croton scouleri

Danviniothamnus lancifuliusDanv iniothamnus tenuifulius

2

5

1 lo7 3

5 1(1)2 1

7

3

(1)

3

1

3

12

一-149-―


DlNo BA

D2No BA

1

D3No BA

D4No BA

D5No

l

D10780

10× 10

5

60

5

90

No

BACtenitis sloaneiCyperus brevifoliusCyperus sp.

Desmodium canumDesmodium procumbensDigitalia horizontalisDigitaria adscendens

Diodia radulaDoryopteris pedataEleocharis sp.

Galactia tenuifloraH eliotropium angiospermumHyptis mutabilisIpomoea trilobaM alv astrum coromand erianumMecardonia diantheaOxalis corniculataPaspalum conjugatumPhoradendron hensloviiPityrcgramma calomelanosPlumbago scandens

Polypodium dispersumPolypodium tridensPteridium aquilinumRhynchosia minimaSalvia occidentalisScoparia dulcisSida hederifoliaSida salvifoliaSida spinosa

Sonchus oleraceus

Sporobolus indicusStachytarpheta cayennensis

Synedrella nodifloraTrachypteris pinnataVerbena townsendii


T2-layerS-layer

H-layer


Crcton scouleriOpuntia insulariaPisonia floribundaPsidium galapageiumPsidium guajava

D6420

10× 10

6

75

鵜

5

75

No

2

D8840

10× 10

3

5

100

No

D9810

10× 10

3

3

50

80

No

D7840

10× 10

3

30

20

80

No BABA

74

4 330(7)

-150-

BA BA BA


Sapindus saponarta

Scalesia cordata


Zanthoxylum fagara

TZ-layerBursera graveolens


Cordia scouleri

Croton scouleri


Psidium guajava

Scalesia cordata

Tourn efor tia p s ilo s t achy a


Tournefo rt i a rufo s eric e a

Zanthoxylum fagara

S-layer

Altenanthera echinocephara


Capsicum frutescensCassia pictaChiococca alba

Cordia leucophlyctis

Cordia scouleri

Croton scouleri

D arw in io th amnu s I anc ifol iu s

D arw in io th am nu s t enuift liu s

Gossypium barbadense v. darutiniiOpuntia insularisPisonia floribundaPsidium galapageium

Psidium guajava

Scalesia cordata

Tourn eforti a p s ilo s t a c hy a

Tournefo rt i a pub e sc en s

Tou rnefort i a rufo se rtc e a

Zanthoxylum fagara

Seedling

Baccharis gnidiifoliaCordia leucophlyctisCrcton scouleriD arut in io th amnu s t enuifo liu s

Gossypium barbadense v. darutiniiPsidium guajava

T o u r n efo r t i a rufo s e ric e a

Zanthoxylum fagara

D6 D7 D8 D9 D10No BA No BA No BA No BA No BA

5 569

1 70

1 12

2 17

4 162

(2) (270)1 42 44 2 161

2 21 1 75

10 115 1 65

24 2594

(1) (43)

1 71

31

2

6(12)

2 13

1 20 11

1

1 43

1

3

4(1)

11

11

-151-


Acalypha pamulaAdiantum henslovianum

Ageratum conyzoides

Altenanthera filifoliaA I t e nanthe ra halim ifol iaAnthephora hermaphrod itaApium leptophyllumBidens ripariaBlainvillea dichotoma

Blechum brcwneiBoutelona distichaBrickellia dffisaCentella asiatica

Chrysanthellum pusillumCissampelos pareiraCissus sicyoides

Clotalaria incana

Clotalaria pumilaCommerina difusaCommicarpus tuberosus

Conyza bonariensis

Ctenitis sloanei

Cypents brevifoliusCyperus sp.

Desmodium canum

Desmodium procumbens

Digitalia horizontalisDigitaria adscendens


Eleochafls sp.

Galactia tenuifloraHeliotropium angiospermumHyptis mutabilisIpomoea trilobaM alv astrum coromanderianumMecardonia dianthea



Pityrogramma calomelanos

Plumbago scandens


Polypodium tridens

Pteridium aquilinumRhynchosia minimaSalvia occidentalis

Scoparia dulcisSida hederifoliaSida salvifoliaSida spinosa

Sonchus oleraceus

Sporobolus indicus



2

―-152-―



S t achy t arph e ta c ay e nn e n s is



T2-layerS-layer

H-layer


Croton scouleri


Psidium guajava

Sapindus saponaria

Scalesia cordata

Tournefort i a pub e sc e n s

Zanthoxylum fagara

TZ-layerBurcera graveolens


Cordia scouleri

Croton scouleri


Psidium guajava

Scalesia cordata

Tourn efort i a p silo st achy a


T o ur n efo r t i a rufo s e ric e a

Zanthoxylum fagara

S-layer

Altenanthera echinocepharaBaccharis gnidiifoliaBursera graveolens

Capsicum frutescensCassia pictaChiococca alba


Cordia scoulert

Croton scouleri

5541。 3

60 20 -― 一―

DH D12 D13 D14 D15730 715 670 770 780

10× 10 10× 10 10× 10 10× 10 10× 10

15 40

20 30

70 70

一- 30

1 15

90 90

2.8

3 768


5 107

14 904 7 698

1 19

8 145 9 131

(1)(23)

2 33

1 8

1 33

―-153-―

Darwiniothamnus lancifolius 20

D anv iniothamnus tenuifoliusGossypium barbadense v. darwiniiOpuntia insularisPisonia floribundaPsidium galapageium

Psidium guajava

Scalesia cordata

Tournefortia p silo stachy a

Tournefort ia p u b e sc e n s

Tou r nefor t i a rufo s e ric e a

Zanthoxylum fagara

Seedling

Baccharis gnidiifoliaCordia leucophlyctis

Crcton scouleri

D arut in io th am nu s t enuifo I iu s

Gossypium barbadense v. daruiniiPsidium guajava

Tou rn efo rt i a rufo se ric e a

Zanthoxylum fagara


Acalypha pamulaAdiantum henslovianum

Ageratum conyzoides

Altenanthera filifoliaAltenanthera halimifoliaAnthephora hermaphroditaApium leptophyllumBidens ripariaBlainvillea dichotoma

Blechum brownei

Boutelona disticha

Brickellia diffusaCentella asiatica

Chrysanthellum pusillumCissampelos pareiraCisszs sicyoides

Clotalaria incana

Clotalaria pumilaCommerina diffusaCommicarpus tuberosus

Conyza bonariensis

Ctenitis sloanei

Cyperus brevifoliusCyperus sp.Desmodium canum



Diodia radula


DH D12 D13 D14 D15No BA No BA No BA No BA No BA

3 1 78(2) 1 221 6

1

1

―-154-―


Doryopteris pedata

Eleocharus sp.

Galactia tenuiflora

H eliotropium angiosPermum

Hyptis mutabilisIpomoea trilobaMalvastntm coromanderianumMecardonia dianthea




Plumbago scandens


Polypodium tridens



Sonchus oleraceus

Sporobolus indicusStachytarpheta cayennensis

Synedrella nodifloraTrachypteris pinnata

Verbena townsendii


T2-layerS-layer

H-layer

T I -layerBursera graveolens

Croton scouleri


Psidium guajava

Sapindus saponaria

Scalesia cordata

Tournefortia pub escens

Zanthoxylum fagara

T2‐layer

J“ rsθ ttα grαッθOた■s 5 24 2 35

Chliocοccα αJbα

DH D12 D13 D14 D15No BA No BA No BA No BA No BA

D16 D17 D18 D19 D20700 730 460 450 770

10× 10 5)く 30 1ine line line

4。 5 4。5 3.5 7 3。 5

- 5

80 50

5 20

60 95

No BA No BA

7 926

＋

＋

十

＋

＋

＋

一-155-―


Cordia scouleriCroton scouleri


Psidium guajava

Scalesia cordata

Tou rneforti a p s i lo s t achy aTournefo rti a p ub e sc en s

Tou r nefo rt i a rufo se ric e aZanthoxylum fagara

S-layer

Altenanthera echinocepharaBaccharis gnidiifoliaBursera graveolens

Capsicum frutescensCassia pictaChiococca albaCordia leucophlyctis

Cordia scouleri

Croton scouleriD anv in ioth am nu s I an c ifo I iu s

Dany iniothamnus tenuifoliusGossypium barbadense v. danyiniiOpuntia insularisPisonia floribundaPsidium galapageium

Psidium guajava

Scalesia cordata

Tournefort ia p s i lo stac hy aTourn efort i a pub e sc e n s

Tou r nefort i a rufo s e ric e a

Zanthoxylum fagara


D16 D17 D18 D19 D20No BA No BA

(1) (2)

45 654 29 186 +

(7) (134) (9) (87)

1 5 +4 183 5 95 +

4 97

1 2

＋

＋

1

1

2

43(5)

2

7

37

3

2

1

3

1

3

5

15

1

1

2

1

2

―-156-―

Seedling

Baccharis gnidiifolia ICordia leucophlyctisCroton scouleriDan+tiniothamnus tenuifoliusGossypium barbadense v. danyinii IPsidium guajava

Tournefortia rufoseric e a

Zanthoxylum fagara

H-layerAbutilon depauperatumAcalpha pamulaAdiantum henslovianumAgeratum conyzoides

Altenanthera filifoliaAltenanthera halimifoliaAnthephora hermaphrodita

十

Competitive Relationships between Tree Species of Scalesia and Introduced Plants (Shimbu)

D16 D17 D18 D19 D20No BA No BA

Apium leptophyllumBidens ripariaBlainvillea dichotoma

Blechum browneiBoutelona distichaBrickellia diffusaCentella asiatica

Chrysanthellum pusillumCissampelos pareiraCisszs sicyoides

Clotalaria incana

Clotalaria pumilaCommerina diffusaCommicarpus tuberosus

Conyza bonariensis

Ctenitis sloanei

Cyperus brevifoliusCyperus sp.

Desmodium canum




Eleocharis sp.

Galactia tenuifloraHeliotropium angiospermumHyptis mutabilisIpomoea ffilobaMalvastrum conomanderianum

Mecardonia dianthea




Plumbago scandens


Polypodium tridens



Sonchus oleraceus

Sporobolus indicusStachy t arpheta c ay ennen s is


十

+

十

十

＋

+

―-157-―



T2-layerS-layer

H-layer


Scalesia microcephala

Trema micrantha

T}-layerBursera glabeolens

Cordia lutea

Cordia revoluta

Psidium galapageium


Scutia paucifloraTournefortia pub e sc en s

Trema micranthaWalteria ovata

Zanthoxylum fagara

S-layer

Baccharts gnidiifoliaBursera graveolens

Cassia pictaCastela galapageia

Chamaecyce viminea

Chiococca alba

Cordia andesonii


D anv in io th am nu s t e nuifo liusLantana peduncularisMacraea laricifoliaPsidium galapageium


Scutia paucifloraTourn efort ia p s ilo s t a chy a

Tournefortia pub escen s

Tou r n efo rt i a rufo s e r ic e aTrema micranthaWalteria ovata

Zanthoxylum fagara

Seedling


Psidium galapageium


Tou r nefort i a rufo se rric e a

El

570

10× 10

4

10

60

90

E2

570

10× 20

5

25

20

30

95

E3

610

10× 20

5

20

10

15

100

E4810

10× 10

5

25

10

20

100


1 1280

1 129

1 791 1 630

1 6 1 4

1 505 130 3 174 4 142

(2) (72)

1 111 26 2 51 3 42

2 40

2 111

1

56(1)

3

2

13(3)

1

32(4)

1(3)

2

1

9(6)

21

34

(8)

―-158-一

Colmpetitive Relationships between Tree Species of Scα reslic and lntroduced Plants(ShilniZu)

Plot No. El E2 E3 E4No BA No BA No BA No BA

NQJ′θrlia οッαra l

Zα

“Йoxyル

“/ar“

HerbAcalypha pamulaAdiantum henslovianum

Altenanthera halimifoliaAmaranthus gracilisAnthephora hermaphrodita 2

Aristida divulsa

Aristida repens

Bidens ripariaBlainvillea dichotoma 4

Boutelona disticha 3

Cenchrus platyacanthus 3

Centella asiatica

Chamaecyce punctulata

Commerina diffusaCrotalart pumilaCrotalaria incana 2

Cuscuta gymnocarpa 2

Cyperus confertus

Desmodium glabrum 3

Digitaria adscendens

Diodia radulaEuphorblo sp.

Fleurya aestuans

Heliotropium angiopterinum IHyptis rhomboidea 3

Ipomoea nilIpomoea triloba 2

Mentzelia aspera

Paspalum conjugatum

Pennisetum pauperum


Physalis pubescens

Polygala galapagoensis

Porophyllum ruderale

Pteridium aquilinumRhynchosia minima 4

Salvia occidentalis

Scoparia dulcisSida hederifoliaSida rhombifoliaSida salvifoliaSida spinosa 3

Sonchus oleraceus

Sporobolus indicusStylosanthes sympodialis 2

Synedrella nodifloraTephrosia decumbens 2

Uniola pittieriZornia piurensis I

一-159-―



T2-layerS-layer

H-layer



Trema micrantha

T2-layerBursera glabeolens

Cordia lutea

Cordia revoluta

Psidium galapageium


Scutia paucifloraTourn efortia p ub e sc en s


Zanthoxylum fagara

S-layer

Baccharts gnidiifoliaBursera graveolens

Cassia picta

Castela galapageia

Chamaecyce vimineaChiococca alba

Cordia andesonii


D arw in ioth amnu s t e nuifo I iu s

Lantana peduncularisMacraea lartcifoliaPsidium galapageium


Scutia paucifloraTournefortia p silostachy a

Tournefortia pub e scen s

To u r n efo r t i a rufo s e ric e a


Zanthoxylum fagara

Seedling


Psidium galapageium


Tournefortia rufoserricea

1 93

16 197 42 138

(2) (79) (12) (2)

1

3 24 4 83

1 19

E5

810

10× 10

3。 5

20

100

E6790

10× 10

3.5

2

60

100

E7

1070

10× 10

3

35

20

90

E8

370

10× 10

6

50

15

15

90


5 801

2 89

4 185

(1) (43)1 13

―-160-―

Competitive Relationships betwOen Tree Species of Scaraslic and lntroduced Plants(ShimiZu)

Plot No◆ E5 E6 E7 E8No BA No BA No BA No BA

フИarた rlia。ッαra

Zα"Й

oxyル“

/aga″ 1

HerbAcalypha pamula

Adiantum henslovianum

Alt e n an the ra halimifol i a

Amaranthus gracilisAnth ephora h e r m aphrod it a

Aristida divulsa

Aristida repens

Bidens ripariaBlainvillea dichotoma

Boutelona disticha

C e nchru s p I aty ac anthu s

Centella asiatica


Commerina diffusaCrotalari pumilaCrotalaria incana

Cuscuta gymnocarpa

Cyperus confertus

Desmodium glabram


Diodia radulaEuphorbic sp.

Fleurya aestuans

Heliotropium angiopterinumHyptis rhomboidea

Ipomoea nilIpomoea trilobaMentzelia aspera

Paspalum conjugatum

Pennisetum pauperltm


Physalis pubescens




Scoparia dulcisSida hederifoliaSida rhombifoliaSida salvifoliaSida spinosa

Sonchus oleraceus

Sporobolus indicusStylosanthes sympodialis

Synedrella nodifloraTephrosia decumbens

Uniola pittieriZornia piurensis

-161-

Regional Views No. l1 1997


T2-layerS-layer

H-layer

T1-layerBurcera graveolens


Trema micrantha

T2-layerBursera glabeolens

Cordia lutea

Cordia revoluta

Psidium galapageium


Scutia paucifloraTournefortia pub escens


Zanthoxylum fagara

S-layer


Cassia pictaCastela galapageia

Chamaecyce viminea

Chiococca albaCordia andesonii


Darutiniothamnus tenuifolius ILantana peduncularis 2

Macraea laricifoliaPsidium galapageium


No BA No BA No BA

2 977 3 889 1 832

1 59

10 154 2 69

1 2

3 123 4 82

1 5

1 13

2 19

11 28

1

1

24

2 1

17

7

6

1

4

1

1

35

3

1

1

2

1

2

24

4 1

E9

340

10× 10

6

50

20

30

90

E10

240

10× 10

6

60

15

20

90

Ell

470

5× 20

7

30

5

60

85

E12

990

line 20

2

十

＋

+

Scutia paucifloraTournefo rt i a p s ilo st achy a

Tournefo rti a p ub e sc en IT ou r n efo r t i a rufo s e r ic e a

Trema micranthaWalteriaovata 3 7 20

Zanthoxylum fagara

Seedling


Psidium galapageium

Scalesia micrccephala ITournefortia rufoserricea

十

＋

一-162-―


Ell E12Plot No.

Walteria ovata

Zanthoxylum fagara

HerbAcalypha pamula

Adiantum henslovianum

A I t e n an thera halimifoli a

Amaranthus gracilis

Anthephora hermaphrodita

Aristida divulsa

Artstida repens

Bidens riparia

Blainvillea dichotoma

Boutelona disticha

C e nchru s p laty ac an thu s

Centella asiatica

Chamaecyce PunctulataCommerina diffusa

Crotalari pumilaCrotalaria incana

Cuscuta gymnocarPa

Cyperus confertus

Desmodium glabrum


Diodia radulaEuphorbfa sP.

Fleurya aestuans

H eliotrop iutn angioPterinum

Hyptis rhomboidea

Ipomoea nilIpomoea trilobaMentzelia asPera

Paspalum coniugatum

Pennisetum PouPentmPhoradendron henslovii

Physalis pubescens



Pteridium aquilinum

Rhynchosia rninima

Salvia occidentalis

Scoparia dulcis

Sida hederifoliaSida rhombifolia

Sida salvifoliaSida spinosa

Sonchus oleraceus

Sporobolus indicus

Stylosanthe s sy mPodialis

Synedrella nodiflora

Tephrosia decumbens

Uniola PittieriZornia piurensis

E9

No BA

E10

No BA No BA

一-163-一

RegiOnal Views No。 11 1997


T2-layerS-layer

H-layer

T1-layerCroton scouleri

Pisonia floribundaPsidium guajava


Danviniothamnus tenuifolium 15


1 1314 835 2 251 15 837 29 1618

Fl

310

10× 10

6

75

10

30

1

F2

310

10× 10

6

15

80

410

100

F3

330

10× 10

5

75

20

30

5

F4

3∞

10× 10

8 `

100

0

10

5

T2‐layer

Cli′ ″s″“θ′ra

Cli′″s sp。 1 5 3 39creЮde.ご″

“ “οJra

Caだlia αだ asθ

“″ 1 5 (1) (8) (1) (12)

CaだJα た“cψλryc麻 2 33 (1) (16)

CrOra“ sca“ルrli 6 70 9 179 7 106

(1) (13) (4) (59) (3) (95) (4) (55)Rso"liaメοrlib“

“ごα l 181 (167)

PslilJliz″2g“ aJaッα 1 24 23 375 3 44

(1) (59)scareslilc Pθご

““c“ raた 5 36 2 31

(5) (87) (4) (171) (3) (72) (5) (227)乃

“′“0わ rrlia′

“besce“ s

Zα

“働り ′

““ragara 1 5 7 51 3 61

S‐layer

Capraria bifloraChiococca alba

Citnts limettaCitras sp.

Clerodendntm molleCordia andesonii


Croton scouleri

1

3

2

13(3)

29

6

1

4(1)

24

1

6

17(3)

11(5)

1

4

4

33(3)

4

11

1

11(1)

Lantana camara

Macraea laricifoliaPisonia floribundaPsidium guajava

Psychotria angustata

Scalesia pedunculataTou rn efo rt ia pub e sc e n s


Zanthoxylum fagara

Seedling

Capraria bifloraCitrus limettaClerodendntm molleCroton sbouleri

4 23(1)

7 20(1)

―-164-―

Competitive Relationships between Tree Species of Scclesia and Introduced Plants (Shimi"u)

Plot No.

D arut in ioth am nu s t enuifoliu s

Macraea laricifoliaPsidium guajava


Zanthoxylum fagara


Asplenium formosumBlechun brownei

Centella asiatica

Ctenitis sloanei

Cyperus sp.


Galactia striata

Graminae sp.

H eliotrop ium angio sP ermum

Hyptis mutabilisKalanchoe pinnata

M alv astrum c o ro m and e lianu m

Oxalis corniculataPassiflora edulis



Plumbago scandens

Polypodium trtdens

Pseudelephatopus sPicatus

Salvia occidentalis

Sida hederifoliaSida rhombifoliaStachytarpheta caYennbnsis

Tillandsia insularisTrachypteris pinnata?


T2-layerS-layer

H-layer

T1-layerCrcton scoulert

Pisonia flortbundaPsidium guajava


T2-layerCitrus limetta

F2

BA No BA

F4

BA No BA

BA

3

F8

3∞

10× 10

5

70

2

100

1

No BA

2530

Fl F3

No

4

F5380

10× 10

6

95

20

30

30

No BA No

1

3

F7330

10× 10

9

100

80

2

3

No

No

+

十

十

十

F6370

10× 10

9

70

20

10

50

BA

1624

134714 1850

一-165-一

9(1)513(19)

850


F8F7F5 F6

No BA

Plot No. BA

No BA No BA No

ll

clir″s sp◆

1creraル“ご″

“ “οJル

)“lii (1) (19)Co′ゼJα α“己es(

70Coガ滋ル“c″力″Crぉ 2 2 17

7 127 1 3345rli 5CrOrO“ scο

“ルl

(1) (18)Piso“ lilaノ οrlib“

“ごα

685PslilJJ“

“g“りαッα

(2) (33)(2) (52)8scareslila′ θご

““c“たた 1

(4) (343) (2) (374) (2) (63) (4) (164)2 57 1 24■,“

“

g/orrlig′

“わascθ

“s 12

1Zα

“漏oxyJ“

“/agara

S-layer

Capraria btfloraChiococca alba

Citrus limettaCitrus sp.

Clerodendrum molleCordia andesonii


Croton scouleri

D anv in io th am nu s t e nu ifol iu mLantana camara



Scalesia pedunculataTournefortia pubescens

Tou r n efo r t i a rafo s e r ic e a

Zanthoxylum fagara

Seedling

Capraria brflora

Citrus limettaClerodendntm molleCroton scouleriD anv in io th am nus te nu ifo I iu s

Macraea laricifoliaPsidium guajavo


H-layerAbutilon depauperatumAsplenium formosumBlechun browneiCentella asiaticaCtenitis sloanei

Cyperus sp.


4

35

1

8(1)

1

6

2

2

2

2

4

4(2)

33(3)

6

4

1

21

1

36

1

4

2

―-166-―


Plot No. F5 F6 Yl F8No BA No BA No BA No BA

Galactia striata 2Graminae sp.

Heliotropium angiospermumHyptis mutabilisKalanchoe pinnataMalY^strum corcmandelianum0xalis corniaiau 2 2

Passiflora edulisPepercmia gahpagensis 2Phoradendron hewloviiPlumbagoscandens 2 4 2

Polypodium tridens I IPseudelephatopus spicatus

Salviaoccidennlis | 2 ISida hederifoliaSida rhombi.folia

Suchytarphen cayennbnsis 2

Tillandsia insularisTrachypteris pinnan?


T2-layerS-layer

H-layer

T1-layerCroton scouleri

Pisonia floribundaPsidium guajava


F10370

5× 20

9

50

50

20

20

No BA No BA

Fll F12340 430line line

4 3

F9280

10× 10

5

15

80

2

4 328

1 609

1 191

T2‐layer

Cli′″s″

“θ′ra

Cli′ ]昭s sp. 1 236crer。ル

“ご″

“ “ο′ル

Co′ゼlia α“ご賀ο

“JJ

Coだliaル

“coPカタc′お 1(1) 13(13) +

crOra“ scο

“ルrli 2 26 8 292 +

(4) (187)Piso“ Jα ノοrlib“

“ごα 2 30 +

PsliJJ“″ g“りαッα

Scalesia pedunculata 3 37 7 123 +

Tournefortia pubescens 5( I ) 309(90)Zanthoxylum fagara

一-167-―

Plot No.

S-layer

Capraria bifloraChiococca alba

Citrus limettaCitrus sp.

Clerodendntm molleCordia andesonii


Croton scouleri

D arw inioth amnu s tenuifoliumLantana camara



Scalesia pedunculataTournefortia pub e sc ens


Zanthoxylum fagara

Seedling


F9 F10No BA No BA

Fll F12

十

十4

1

43(4)

1

10

1

＋

＋

＋

十

十

＋

Capraria bifloraCitnts limettaClerodendrum molleCroton scouleri

D any in ioth amnu s t enuifo I iusMacraea laricifoliaPsidium guajava


H-layerAbutilon depauperatum IAsplenium formosumBlechun brownei

Centella asiatica

Ctenitis sloanei

Cyperus sp.


Galactia striata 2

Graminae sp.

H eliotropium angiospermumHyptis mutabilisKalanchoe pinnataMalvastrum conomandelianum 3

Oxalis corniculataPassiflora edulis


Phoradendron henslov iiPlumbago scandens

Polypodium tidens 十

一-168-―

Competitive Relationships between Tree Species of Sbclesia and Introduced Plants (Shimi"u)

Plot No.

Pseudelephatopus spicatus

Salvia occidentalis

Sida hederifoliaSida rhombifuliaS t achy t arph e t a c ay e nn b n sis

Tillandsia insularisTrachypteris pinnata?


T2-layerS-layer

H-layer


Croton scouleri

Jasminocereus thouarsii v. touarsii

Opuntia echios v. gigantea

Opuntia echios v. inermisPiscidia carthagenensis

Scalesia afinisTournefortia psilostachy a


Zanthoxylum fagara

S-layer

Acasia rontdianaBursera glaveolens

Capraria peruvianaCastela galapageia

Chamaesyce viminea


Cordia lutea

Cordia revoluta

Crcton scouleri

D anv in ioth am nu s t enuifoliu s

Dodonaena viscosa

Lantana camara

Lantana peduncularisLecoc arpus p innatifidusOpuntia echios v. inermisOpuntia insularis

F9 F10No BA No BA

Fll F12

SCl10

10× 10

5。 5

15

25

“20

IBal

5

10× 10

6

50

10

鵜

2

IBa2

5

10× 10

3。 5

2

25

5

IBbl

50

1

10× 10

15

20

No BA No BA No BA No BATl‐layer

J“rscra gravωル“s 1 243 6 861

の““

rlia θcλ lios v。 ′“θr“お 1 272

1 24 1 11

4(2) 29(28)

3 623

(1) (177)1 19

1 39 2 461 1

1 17

3 94

1

2

16

1

7(1)

1

―-169-―

Plot No.

Sarcostema angustissima

Scalesia affinisScutia pauciflora

Tournefortia psilostachy a

Vallesia galbra

Walteria ovata

Seedling

Dodonaea viscosa

Macraea laricifoliaScalesia afinisWalteria ovata

H-layerAltenanthera filifoliaArtstida divulsa


Boehaavia erecta


Commicafpus tuberosus

Cyperus andersonii

Euphorbia tircaniiGalactia striata ?Ipomoea hairIpomoea trilobaMentzelia aspera

Merremia aegyptica

Momordia charantiaPasiflora foetidaPlumbago scandens


Porophyllum ntderaleRhynchosia minimaSarcostemma anustissima

S ty los anth e s sy rnpod iale s


T2-layerS-layer

H-layer

Tl-layerBursera graveolens

Opuntia echios v. inermis

T2-layerBurcera graveolens

Crcton scouleri

Regional Views No. I t 1997

SCl IBal

BA No BA

IBb2

100

10× 10

3.5

2

25

30

BA

IBb3

130

10× 10

2。4

1

15

30

No BA

IBb4

190

10× 10

3

30

30

430

BA

IBbl

No BA10

5(1)

4

+十

++

3

4

2

1

FLl

3

10× 10

6

25

3

30

30

No BA

IBa2

No No

5(1)

2

BA

1

―-170-―

No

“

No

262

“

8


IBb2 1Bb3 1Bb4Plot No.

Jasminocereus thouarsii v. touarsii

Opuntia echios v. gigantea

Opuntia echios v. inermisPiscidia carthagenensis

Scalesia ffinisTournefortia p silostachy a

Tournefortia pub escen s

Zanthoxylum fagara

S-layer

Acasia rorudianaBursera glaveolens

Capraria peruviana

Castela galapageia

Chamaesyce viminea


Cordia lutea

Cordia revoluta

Croton scouleri

D arut iniothamnus tenuifoliusDodonaena viscosa

Lantana camara

Lantana peduncularts

L ecoc arpus p innatifidus

Opuntia echios v. inermisOpuntia insularisSarcostema angustissima

Scalesia ffinisScutia pauciflora

T ournefort i a p s ilo stachy a

Vallesia galbra

Walteria ovata

Seedling

Dodonaea viscosa

Macraea laricifoliaScalesia afinisWalteria ovata

H-layerAltenanthera filifoliaAristida divulsa


Boehaavia erecta


Commicafpus tuberosus

Cyperus andersonii

Euphorbia tircaniiGalactia striata?Ipomoea hairIpomoea trilobaMentzelia aspera

Merremia aegyptica

FLl

No BA No BA No BA No BA1 663

11

1

42

2

2(1)

13

1

2

10 9(1)

14

―-171-

Plot No.

Momordia charantiaPasiflora foetidaPlumbago scandens


Porophyllum ruderaleRhynchosia minimaSarcostemma anustissimaStylosanthes sympodiales


1Bb2 1Bb3 1Bb4 FLlNo BA No BA No BA No BA

―-172-―

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