J, F, ClineD. W. Ureskand

W. H. Rickard

Ecosystems DepartmentBattelle Northwest LaborarotiesRichland, \Tashington 993 5 2

Plants and Soil of a Sagebrush Community on theHanford Reservation'

AbstractT}ls_srudy delioes a sagebrush/rheatgrass commur ty on the Hanford Reservation, Benton C-ounty,lfashingron. Twenry-seven herbacmus species wete observed.

'lhe average understory cover was

38 peccent. Cheatgrass, an_annual grass, was the dominant species and provided 18 percert ofrhe herbaceols cover. Sagebrush was the conspicuous shrub, providing 15 ro 20 pefcent of thetotal cover. Biomass production of the herbaceous species was approximately 40 g/i2. Soil a|.ly-sis and the mineral composition of the vegetation wete measured and evaluated

lntloduction

The Flanford Reservation, Benton Counry, Ifashington, lies q/ithin the boundaries ofthe sagebrush vegeratiori zone (Daubenmire, 1970). Hovever. rhe land on the Han-ford Reservation located west of the Columbia River can be mapped as three differentvegetariorr rypes ( Fig" 1). The sagebrush-bitterbtush/cheatgrass type occupies a trian-gula! shaped area with its apex near the old Hanford townsite and extends southward.o the Horn Rapids bend of the Yakima River. The sagebrush/bluebunch wheatgrassvegetation type is confined to the Rattlesnake Hills at elevatioru of above 900 ft. Thevegetation between these rwo is designated as the sagebrusvcheatgfass vegetation type.This latter rype occupies much of the area of Han{ord Reservation. Ir differs from thesagebrush/bitterbrush by lacking bitterbrush aod the abselce of bluebunch wheatgrassdistinguishes ir from the sagebrush/bluebunch wheatgrass type. This paper describesthe sagebrush/cheatgrass vegetation type that is not regarded in pristine condition byDaubenmire because ir contains large amounts of cheatgrass (Btotnut tectorum), atalien plant characteristic of man-induced disrurbances, such as grazing by domestic cattleand sheep. Nevertheless, this vegetation type is impotant on the Hanfold Reservationbecause nuclear enetgy facilities are a major long-term use of some of the land.

The purpose of this investigation vias to describe the vegetation and the surface soilof a sagebrush/cheatgrass comrnunity located near the chemical separation facilitiesknoqrn as the 200 East aod 200 Vest areas but well inside the boundaries of access con-trol zones. The area has been proteced from grazing livestock since 1943.

Methods Employed

The experimental design consisted of two stands designated as Site I and Site II locaredcentrally in dre sagebrush/cheargtass vegera-rion type ar an elevation of 700 ft abovesea level (Fig. 2). Each sire contained two rqiicates coosisting of four 50-mm tran-

t W-k p..for^.d for the Arlantic Richfield Hanford Company under United States Energy Re-search and Development Administration cont:acr E ( 4t-1) -2110.

60 Northwest Science, Vol. 51. No. 1. 1977

lS-^--\l s ncr e n u s H /cH EATG R AS s

HANFORD TOWNSITE

COLUMBIAR IVER

R ICHLAN D

0 5E-EEE

M I E S

Figure 1 Geogaphic extent of thlee major vegetation types and the locatron of study sites I andII on the Hanford Reservation.

sec6 arranged lmrallel to each orher and systematically sltaced at 30-m intervals.

Sbrub density was estirnated by counting all individuals rooted ilside a 10 x 50 m

(500 m2) smdy plot in each lePlicated area. Each shrub was measured for long and

short diameters and also extrern€ shoot height from ground level. Caoopy cover Pro-vided by herbaceous taxa was measured by readi[g fifty 2 x 5 dm plot frames systema-

tically spaced at otre-mete! intewals on each line transect. In all,400 Plots were read

at each site. Cover for each taxon was oculady estimated using a modified method of

canopy cove! analysis developed by Daubenmire (i959). Modified cla.ssification num-

bers were 1 ( 5 percent, 2 :5-15 perceot. 3 : 15'25 petcent,4:25-50 Percem,5 : 50-75 percent, and 6 : 75-100 percent.

Aboveground biomass was estimated by hand-clipping herbaceous Plants located

within a 0.5 m2 circular plot. Fout plo$ were systematically strtaced aloog each line

tri--E

Eliijjjjji::il

SAGEBRU SH/B LUEB UNCHWHEATGRASS

SAGEBRUSH-B I TTERBRUSH/CHEATGRAS S

II

YAKIMA

Plana and Soil of a Sagebrush Comrnuoity 6l

uansect. Live material representing the currenr year's gro{vth was hand separated fromdead plant material. All material was oven-dried at 60"C and weighed. The plant ma-terial was ground in a S7iley mill to pass through a 1 mm scleen mesh and chemi-cally analyzed for macro- and micronutrient content by the U.S. Testing C-o., Richland,Washington.

Belowground biomass was obtained by drilling a single hole inro the soil profilelocated within the clipped circular plots. A to,tal of 16 holes vrere drilled into the soilprofile at Site I. Each soil increment one decimeter deep was washed in running tapwatet and the roors retained on a fine mesh screen. Roots were floated to eliminarelarge soil particles. All roors were oven-dried, ashed at 500oC over a 24-hour period,and expressed as ash-free weight.

Four soil cores were sampled at landom at each site for textural and chemical analy-ses. AII field sampling was condricted between April 24 ad May 6, 1974.

Results

Boranicdl Metturement: A total of 27 herbaceoLrs species (taxa) were ob,.served on 800plots ( Tables 1 and 2); 20 taxa occurred on each site. Annual grasses and forbs domi-nated the canopy cover while perennial grasses and forbs provided small amounts ofcover. Average caoopy cover was 37 lrrcent {or Site I aod J9 percenr for Site II( Tables l and 2). More than 60 percent of the ground area did nqt support herbsand was either bare or supported a thin crust of algae, moeses, aod lichens. Clea y, themo6t important herb was cheatgrass. It alone provided almost haif of the herbaceouscover. Tansy mustard (Descurainia pinnata) was rhe most important annual forb interms of canopy-cover.

Russian thistle (Salrcla kali) was more imporranr ro canqpy-cove! than shown ioTable 1 because of the season of rhe year in vrhich the observations wefe recorded.Russian thistle can grow throughout the summer and flowers in late sum,rner. It cansometimes attain sizes as large as sagebrush shrubs.

Shrubs are the conspicuou-s plants of the plant community; however, only three spe-cies were present- These were sagebru'sh (Artemitid tridentdrd) and rwo species of rab-bitbrush (Cbrysoth4rn4Tu! taqieorur and C, oitcid,iflarut) . Artenzitia canopy coverraoged between 15 ar'd 26 percent (Table )) and. Chrysothamnzr beween 0 and Jpercenr. The average nlrmber of shrubs was 243 t 98/1000 m2 ( Table 3). Site Isuported 376 and Site II 110 sbrubs. Site I vrith the Sreatest shrub density had theshortest statured plants with small canopy areas. At either site, less canopy cover wasprovided by shrubs than by associated herbs.

The live biomass (net primary production ) of herbs by species is shown ir Table4. The data were obtained only for Site I, but results are no't expected to be much dif-ferent at Site II. The total aboveground biomass, excluding shrubs, was measured at40 g/m' dry weight of which almost half, 18 grarns, was provided by cheatgrass. Noestimates of shrub weight were obtained in this study.

Total root mass, which includes roots from shrubs in the uppe! meter of soil pro-file, was estimated at )68 g/m2. More than half vras located in the upper 3 dm of soilprofi le (Fig. 3).

Mineral Content ol Plantt: The concentrations of macronutrients io the tissues of im-portanr Srass and forb species afe shown in Table 5. On the average, micro- and ma-

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TABLE 3. Avelage shtub measuremenu of canopy cover, height, and area (L x V) and densityfor Sites I and II.

C,^nop'l Co'/etuge (Vo)Site IRep 2 X Rep 1-Iaxa Rep 11

Site IIRep 2 x

SEChtysothamnus

SE

SE

Chrytalbamn*tTOTAL

25.8

0.4-0.4

Height (cm)85

15.3 18.2

1 l-+1 a - fn 7

116 104

258aO 24i50t 2630 f-1760

0

25.4

0.8=0.8

5188

526

21.2

0.t

23100

102

14200-L960

2260

226

9t

Area (L x \F) cmz6720 10450

!360 :L420

Number of Shrubs Per 1000 m2

4376

76 a436 26

t1.2 110

9414

108

I Rep : Replicate

TABLE 4. Aboveground live biomass g/n2 of herbaceous plhnt taxa (meaa ! SE) ot replicatesat Site I on the 200-Atea Plateau, Hanfotd Reservation, 1974,

Taxa. Rep 1r Rep 2

,{nnual gmsse sBtomat tecrontmFettrcd ocrofloo

Total

Perennial grassesAgro|yon r,icartnS;taniot br$ritcPoa sandbergii

Total

Petennial forbsErigeron fililoliatBrodiaea doaglasiiC alo c b ar, /aJ macrc carq/r t

Annual forbsDercrtuinir' P;nnntaMi.toste J ydcil;rCr)t|tantha circsn t cist aPhl.ox lonsilolhCryPtanlb4 Pterccar!4Pbacelia lineatisAntsi .ch;d lr coP r oi d. erSal.tola kaliSisymbtian ahissiman

Total herbs g/mz

27

0.01 L0.94

0.96

2.S i 1 .11.2 L 0.50.76 ! 0.760.05 :t 0.030.30 ::r 0.1t

00.06 L 0.040.20 i 0.02

193.0

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1 4.6

03.6 ! 3.61.3 f 0.5

0.010.01

0.01 :L 0.0100

1 140 + 4.3

101239

22 2 5

1.81.81.0

00.8 :l: 0.4

4.9 3.8

0.01

0.48

0.01

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0

0.49

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1 Rep = Replicate

Plants and SoiJ of a Sagebrush Community o)

cronutrient content was greater in forbs than in grasses. This finding is particulady evi-dent io potassium and calcium contents. Nitrogen contenr was similar in forb and grasstissues.

Iigure 2. Sagebrush,/cheatgrass vegetation type lepresmtative of the study area on the Hanford-6.eservatlolr.

Percent

Tota lBi onass

Fig!re

U - t | - 2 . - J J - +

3. Distributiotr of roots (Iive atrd dead)cheatgrass community at Site I.

4-5 5-6 6-7 7-8 8-9 9- t0

Depth (dm)

in the upper meter of soil plofile in a sagebrush-

55s--------------+ I a- 21% +

l<- 24% ----+1

66 Cline, Ures\ and Rickard

o /Plants and Soil of a Sagebrush Commuruty

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Soil Propertiet: Soil texture is important to plant growth because it determines to alarge extent the water-holding cayrdcitJ of a given volume of soil and also its cationexchange calmcity. Soils were similar in texr.rte, i,e., sandy loams at both sites ( Table6). Sand dominated the three textural classes followed by silt and clay. Clay-sizedparticles were scarce, making up only 1 percent of the texrure size classes. Thesedata imply that the moisture-holding capacity and cation exchange of the soil profileare low. Also, these sandy soils are subject to serious wind erosion vrhen disturbed(ll inds and Sauer, 1974).

The pH values of surface soils are alkaline, and alkaliniry iorreases with profiledepth ( Table 6). Soluble salts are low, indicating that salinity ( excess salts ) is not ahinderance to plant growth, at least in the upper soil. Organic matter is lovr, indicativeof low soil nitrogen levels.

Discussion

The sagebrush/cheatgrass community described is probably very much like the com,trunity that existed prior to 1!41 when rhe Hanford Reservation was established. Themajor vegetational change has been the incorporation of vreeds of European origininto the plaot community. The most successful of these European weeds is cheatgrass,and it has prot'ably been a member of the plant comrnunity for a cenrury. This grasswas an important plaot on Benton Counry raogelands a half cenmry ago (St. John and

Jones, 1928). Cheatgrass is so well adapted to the climatic and soil conditions of theHanford Reservation that it is pruden to consider the species as an integral part ofrhe flora and to make use of its pioneering aggressiveness in revegetating disturbedland.

The number of plant slxcies in the study area was less when compared to otherkinds of naoral plaot communities in eastero I(ashington and the annual productionof dry land matter is also less (Daubenmire, 1970; Rickard, 1975; Cline and Rickard.1971). ^Ihe low species diversity is atributed to the generally level terrain, i,e., habiathomogeneiq' and the lovr annual precipitation which over a 30-year period has averagedonly 6.1 inches. Sandy soils having a low water-holding calmcity and available nu-trients will influence diversity.

Sagebrush, the important shrub community, is not palatable to livestock. The mostimportant livesto& forage species, in terms of palatability and abundance. is Bromus

TABLE 6. Average chemicai and physical properties of soil from Sites I and II.

Soil Depth (dm))-4 ?-4 t-a0-1 1-2 5-6 Aug

Texture

% Si]t% Clay

Organic MatterVo

Elec. Cond.

pH

59 62 61 63 57 t7 6140 i7 32 16 42 42 38

1 1 1 1 1 1 1

0.68

0.257.5

0.45

0.207.6

0 .35

0.247.7

0.41

0.291.9

0.43

0.21.7.9

0 .50

0.108.1

0.47

0.257.8

68 Clioe. Uresk, and Rickard

lecrorl.rrr, lJoarcvet, the gtazitg season is shon If one-half of the herhaceous produc-

tion could be ingested by livestock, an intake of about 200 kg of dty matter per ha

(200 lbs per acre) is lntentially available as livetock forage. The conclusion is that

species diversity and net produativity and livestock gazitg cayacity is inhelently lower

here than other steppe plant comrnunities of eastern Vashington.

In the absence of livestock, the most important mammaliao herbivore on the sudy

site is the black-tailed Harc (Lep/rt cal'ifornicat). A study of the dietary habits of black-

tailed hares on the Hanford Reservation (Uresk er al' 7975) indicates that cheatgrass

was not eaten by hates; shmbs were sparingly eaten, with rabbitbrush being taken in

preference to sagebrush. Perennial forbs, such as yartow (Achillea millefolfuim) atA

turpentine cymoptelus (CJtnoPterur terebinthixut), plants sparsely represented in the

community, were the preferred hare foods.Two kinds of environmental suesses can be expected to b€ imPos€d on this com-

muniry in the future. These are: (1) fire and (2) mechanical soil disturbances Fire

can be oaturally induced by lightning or ignited by man. Burning destroys sagebrush

plants but perennial grasses and fotbs generally survive and send out new shoots. At

least some seeds of annuals survive the burning and provide a crop during the year

irf post-burning. Recolonization of the burned afeas may also be accomplished by seed

imported from sucounding surviving vegetation.

Mechanical disturt'ances, such as im.p,osed in the consuuction activities of this area,

effectively destroy all existing vegetation. Russian thistle is one of the most aggres-

sive of the early invaders and may dominate in the first yeal, but thereafter cheatgrass

assumes dominance and it tesists invasion by native plants and Salsola. Daubenmire

(1975) describes cheatgrass as dominatiog the vegetation of an abandoned agricultural

field for 52 years with little invasioo by native petennials although nearby seed sources

vrere available. Of the shrubby species, rabbitbrush is more aggressive than sagebrush

in terms of invading disturbed soils.

Unlese there arc rrajot changes in land use, such as irrigated agriculture, livestock

grazing, rx new constluction activities associaced wirh Hanford Reservation industrial

activities, the plant community desctibed here is expected to maintain essentially the

same species cornposidon and productivity as described herein in the fo'rseeable furure,

i.e,, 20-30 years. $0ildfire is the most likely disturbarrce to be exlt€rted as it is not in-

duced by man. From a longer-tetm point of view, change in climate, lvhether wetter or

drier, w-ould have a profourrd impct upon plant species cornpo'sition and primary pto-

dr:,ctivity.

Acknowledgment

The authors wish to thank Virginia A. Uresk fot helpful suggestions and technical ad-

vice during this smdy.

Literature CitedCline, J- F., and \7. H. Rickard. 1971. HetbagB yields io relation to soil water and assimilated

nitrogen. J. Range Manage. 26:296'298.Daubennrire. R. 1959. A canopy-coverage method of vegetntion analysis Nonhw Sci. 33l. 4)'64.

. l9-0. Sreppe vegltarion oF !0asbiogr-on. !ash.. A-9r' Exp. Sta. Tech. Bull. 62: 13.t.1975. Plaflt succession olr abandooed trelds ancl tlre lntluences ln a steppe arca ln

southeastetn Ifashington. Northw. Sci. 49: 36-48.Hinds, V. T., and R. H. Sauer. 1975 SoiI erodibility, soil erosioo, and revegetation following

wiidfire in a shtub*teppe community. In: Symposium on Atmosphere-Sutface Exchange of

Planrs and Soil of a Sagebrush Communiry 69

Particulate and Gaseous Pollutants, R. J. Engelmadn add G. A. Sehmel ( coordinators ) . ( Conf--1092 I ). NTIS. Springfield, Virginra.Rickard, \?. H. 1975. Vegeration of knob and kettle topography ir southcentral lqashington.

Nonhw. Sci. 49: 147-152.Sr. John, J., and G. N. Jones. 1928. Ao annotated catalogue of vasclrlar plants o{ Benton County,

\trashingron. \orrhw. Scj. 2: 73-9J.Uresk, D. I0., J. F. Cline, and W. H. Rickard. 1975. Diets of Black-tailed Hares on the Han-

fotd Reservation, BN\VL-193 1, Battelle-Nonhwest, Richland, \Tashingtod.

Kecetued. Ueaembet lU. 1tt / ) .

Accepted. far publication Jane 2!, 1976,

Association NewsPlans for the spriog meeting of the Association are going forward with increased speed.All indications are that president Ken Holmes and his many able helpers at OregonCollege of Education are putting the finishing rouches on a {ine meeting.

There will be separate sessions in Botany, Chemistry-Physics, Geology-Geography, fti-ence Education, Forestry, Zoology, Social Science, and Soil and Water. And don't for-get the featured symposium on "Coasdine Enviroament of the Paci{ic Northwest."

If you haven't sent your dues in, please do so soon.

Please encourage your colleagues and gaduate students to attend the meering.

DATE: March 24.2i-26. 1977

SPONSOR: Oregon College of Education

PLACE: Monmouth, Oregoo

Mihon M Mosher,Secretary

70 Cline. Uresk. and Rickard