Aquatic Plant Ecology
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Transcript of Aquatic Plant Ecology
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Aquatic Plant Ecology
Jennifer GutscherM.S. student
South Dakota State University
Nov. 2007
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What are Aquatic Plants?
growing in water or on a substrate that is at least periodically deficient in oxygen as a
result of excessive water content (Cowardin et al. 1979).
Evolved from terrestrial plants, invading water in 50-100 separate events
Approximately 60% of aquatic species have ranges on more than one continent
Due to moderate environmental conditions in water habitats
Often on certain latitudes N & S of equator, but not between (waterfowl seed dispersal)
More than of worlds wetlands are in tropical or subtropical areas
Endemics high in geographically isolated areas
Bacopa monnieri
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Wetland Plant Benefits Roots
Stabilize sediments
Can take up metals/pollutants out of sediments
Roots accumulate nutrients from sediments, release into water column
Senescence/decomposition & loss of organic compounds fromtissues
Leaves
Evapotranspiration returns moisture to atmosphere Floating-leaved plants can reduce evaporation off water surface
Reduce wave erosion on shorelines
Habitat & forage for invertebrates
Seed production for waterfowl
MANY OTHERS!!! Rhynchospora corymbosa
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LAKES: Lacustrine
Larger, deeper,
more permanent >2 m deep OR...
>8 ha in size
Classified byproductivity of waterzone, shape of basin
and # times thewater column mixes
WETLANDS:
Palustrine
Smaller, shallow, dry
out occasionally
Only moist soil
Classified by
hydroperiod,
physiognomy (plant
species structure),sediment types
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Littoral Habitat
Emergent
< 2 m deep
Cyperaceae (sedges), Poaceae (grasses), Juncaceae (rushes), Typhaceae (cattails)
Floating-leaved attached
< 4 m deep Nymphaeaceae (water lily), Nelumbonaceae (lotus), Potamogetonaceae (pond weed)
Submerged
< 10 m deep Most rooted, some free float in water column
Elodea(waterweed), Haloragaceae (water milfoil), Potamogetonaceae (pond weed),Ceratophyllaceae (hornwort), Lentibulariaceae (bladderwort)
= Edge to limit of rooted aquatic
plants (hydrophytes)
Merritt & Cummins (1996)
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Habitat
Sublittoral
Small zone b/w littoral and profundal zone
Shade-tolerant plants
Limnetic
Open water from surface to where light does not penetrate
Free-floating Lemnaceae (duckweed), Pistia stratoides(water lettuce), Eichhornia crassipes
(water hyacinth)
Profundal Deep water from limit of light penetration to bottom substrate
Merritt & Cummins (1996)
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Major Aquatic Plant Families
CYPERACEAE = Sedges
Monocot
Inflorescence = spikelets, usually
surrounded by leaf-like bracts Leaves = flat, 3 vertical rows,
alternate, sometimes bladeless
Stem = trigonous, solid
Fruit = achene
Carex(sedge), Cyperus(flatsedge/nutsedge), Schoenoplectus(bulrush), Eleocharis(spikerush)
JUNCACEAE = Rushes Monocot
Inflorescence = terminal
Leaves = flat to rounded with large vein
divisions, 2 vertical rows, often all basal,often reduced or sometimes bladeless
Stem = round, solid
Fruit = 3-valved capsule, many seeded
Juncus(rush)
Eleocharis obtusa
Sedges have edges
Rushes are round
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Major Aquatic Plant Families
ASTERACEAE = Asters/Sunflowers
Dicot
Inflorescence = involucrate head
(many little flowers = ray &/or disk
florets), 1+ series of bracts
Leaves = variable
Fruit = achene with awns/bristles
Achillea(yarrow), Solidago
(goldenrod), Erigeron(daisy fleabane)
POACEAE = Grasses
Monocot
Inflorescence = terminal, either panicle,
spike, or rame
Leaves = flat, 2 vertical rows, alternate
Stem = round, hollow (except at nodes)
Fruit = grain
Agrostis(bentgrass), Urochloa mutica
(California grass), Poa(bluegrass)
Disk
Ray
www.wikipedia.com www.wikipedia.com
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Major Aquatic Plant Families
POLYGONACEAE = Smartweeds Dicot, annual
Inflorescence = raceme, terminal panicle,axillary clusters
Leaves = simple, alternate Stems = swollen nodes with papery
sheath
Fruit = trigonous or biconvex achene
Polygonum(smartweed)
Polygonum punctatum
LEMNACEAE = Duckweed
Inflorescence = rarely seen, tiny
Leaves = elliptic to oblong
Roots = hang into water column Small to tiny plant
Free-floating
Lemna(duckweed), Wolffia
(watermeal)
Lemna aequinoctialis(large) &Wolffia globosa(small)
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Flowering Plants:Monocot vs. Dicot
www.images.encarta.msn
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Nutsedge/Flatsedge
Cyperus polystachos
Spikerush
Eleocharis obtusa
Climbing dayflowerCommelina diffusa
MONOCOTS
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Primrose willowLudwigia octovalvis
Valley redstemAmmania coccinea
Water hyssopBacopa monnieri
DICOTS
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EFFECTS OF MOWING
GROWING POINT
AT TIP
DICOTSMONOCOTS
GROWING POINTAT BASE
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Reproductive Strategies
Annuals
Early-successional species
Colonize disturbed areas devoid of vegetation
Complete life cycle in one year
Reproduce entirely by seed Prolific!
Seeds remain in seed bank for many years
Bidens(beggarstick), Echinochloa(barnyardgrass), Cyperus(flatsedge)
Cyperus difformis
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S
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Reproductive Strategies
Perennials
Survive few - many years
Reproduce by seed, vegetative means, or both
Shorter-lived species may reproduce entirely by seed
Most longer-lived species may reproduce by both seedand vegetative means
Colonize new areas by seed Then, spread extensively by vegetative
reproduction
Many can tolerate extended flooding
Aerenchyma tissues
Adventitious roots
Typha (cattail), Schoenoplectus(bulrush), Boltonia(aster),
Sagittaria(arrowhead), Sparganium(burreed)
Sagittaria latifolia
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Seed Bank
# of spp. in seed bank reflects community diversity better than just whats growing
Older wetlands tend to have more total seeds
BUT!...lots ofvariation b/w wetlands Most seeds are long lived
Polygonaceae (smartweed), Schoenoplectus(bulrush), Typha(cattail),Chenopodium(goosefoot)
Cyclic hydrology (rather than stability) increases seed bank diversity
Wind, water, birds, fish, etc... disperse seeds
Sedimentation buries seeds deeper, some decompose
Seedlings from large seeds can push through soil better than small seeds
All viable seeds and/or propagules present on or in the soil orassociated litter (Simpson et al. 1989).
S d B k
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Seed Bank
Whats in my seed bank?
Take soil cores, allow germination in diff. abiotic conditions
Temp., drawdown rate, etc...
I.D. seeds from samples Good to know for restoration projects
Inaccuracy
Some quickly predated
Microorganism attack
Bacteria Fungi
Dispersal dependants decompose easily
Phragmites australis(common reed)
Many plants depend mostly on rhizomes/other asexual reprod. methods
Si & Di i f W l d S d B k
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Size & Diversity of Wetland Seed Banks
WETLAND
TYPE
DENSITY
(x/m)
RANGE
(m)
SPECIES
RICHNESS LOCATION REFERENCE
FRESH 29,753 10,875 - 36,230 45 IOWA VAN DER VALKAND DAVIS (1978)
FRESH 110,000 42,000 - 255,000 50 IOWA VAN DER VALK
AND DAVIS (1979)
TEMPORARY 17,943 11,455 - 24,430 21 NEW JERSEY MCCARTHY (1987)
BRACKISH 3,577 93 - 8,253 34 MANITOBA PEDERSON (1981)
LAKESHORE 10,089 1,862 - 19,798 41 ONTARIO KEDDY AND
REZNICEK (1982)
RIVERINE
SWAMP
2,576 759 - 4,392 59 SOUTH
CAROLINA
SCHNEIDER AND
SHARITZ (1986)
SALT 191 50 - 430 3 UTAH KADLEC AND
SMITH (1984)
ADAPTED FROM LECK (1989)
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Dispersal Mechanisms of Seeds
Dispersal Agent &Adaptations
Modification Comments
AnimalChemical attractant
Clinging Structures
Hooks, Viscous materialcolored seed coat
Sticks to fur/feathersEaten by birds
Wind
Size reduction
High Surface/Volume
Ratio
Dustlike seeds
Wings, plumes,
Balloons
Up to Millions/plant
Balloons uncommon
Water
Resistance to sinking
Uses surface tension
Low specific gravity
Hairs or slime
Small Size, Unwettable
Air spaces, Cork, Oil
Submerged transport
Float until wetted
Float long distances
Seed Longevity
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Seed Longevity
Species
Age
(years)
Naturally
Preserved
Natural Field
Conditions Location
Lupinus arcticus
(Arctic Lupin) 10,000 +
Yukon Territory
Chenopodium album 1,700 + Scandinavia
Spergula arvensis 1,700 + Manchuria, Tokyo,
Great Britain
Nelumbium nucifera
(Indian lotus)
100 3,000 + Argentina
Canna compacta 550 + Michigan
Rumex crispus
(Curled dock)
80 + Michigan
Oenothera biennis(Evening primrose)
80 + Michigan
Amaranthus retroflexus
Setaria media
Agrostis vulgaris
Grindelia squarrosa
>30
>30
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D h f b i l
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Depth of burial
3 cm deep Can bring up seeds from
inactive depths through
tilling/discing/scraping
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What you see is not alwayswhat you have!
S d B k & St di V S i
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Seed Bank & Standing Veg. Species
Diversity
Wetland
type
Seed
Bank
Veg Total Location Reference
Fresh 45+ 34 48 Iowa Van Der Valk &Davis (1978)
Temporary 21 29 31 New JerseyMcCarthy (1987)
Brackish 29+ 18 35 Manitoba Pederson (1981)
Lakeshore 41 45 50 OntarioKeddy &
Reznicek (1982)
RiverineSwamp
59 49 73 S Carolina Schneider &Sharitz (1986)
Salt 9 14 15 Utah Kadlec & Smith(1984)
U i S d B k Y B fi
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Using Seed Banks to Your Benefit
Seed banks can be exploited to promote desirable vegetation communities
Success depends on:
1. Presence of seeds of preferred species
2. Suitable conditions for germination and establishment of preferred species are
met
3. Absence of seeds of unwanted species, or these seeds are uncommon
4. Conditions for germination and establishment of unwanted species are not met
Hydrologic Germination Requirements
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Hydrologic Germination Requirements
Each species responds to a unique combination of abiotic and biotic factors to break
dormancy and/or germinate
Requirements can be very different from what mature plants can handle
Drawdown Most all emergents
Potamogeton(smartweed), Fimbristylus littoralis(fimbry)
Flooding A few emergents, i.e. Sparganium(burreed)
Most all submergents
Najas guadalupensis(Southern naiad)
Wet meadow hardest to reestablish
Generally poor dispersers
PLUS, cant persist in seed bank
Carex(sedge)
Fimbristylus littoralis
Succession
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SuccessionRock
Weathering &
Erosion
Ferns
Grasses
Forbs
Perennials
Annuals
Lichen & Moss
ShrubsSeedlings
Trees
IF NO DISTURBANCE: Lower Seed Production
More Perennials
More Woody Vegetation
Germination sets in motion apathway of succession
Influences on Aquatic Plant
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Influences on Aquatic PlantCommunities
Position in Landscape
Hydrology Soils
Light
Temperature
Water chemistry
Seed bank
Competition
Other Biota
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RechargeFlow Through
Discharge
Wetlands in the Landscape...
Relationship with Hydrology
RechargeWetland T pes
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g
Flow-through
Discharge
Wetland Types
Hydrologic Disturbances
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Hydrologic Disturbances
Wet conditions
Submerged, floating-leaved, emergent plants, and algae
Dry conditions
Emergents, mud-flat annuals
What makes conditions change?
Yearly/cyclical fluctuations in water quantity
Hydrologic disturbance of nearby river, lake, etc...
Floods
Can bring in new sediment, remove the old change vegetation community
Hurricanes/Tornados
Can create patchy network of vegetation
Water quality
Like pushing reset button on succession
Typical Zone Vegetation
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Typical Zone Vegetation
Aquatic Nearly continuous flooding at low elevations
Potamogeton(pondweed)
Marsh Most flooded for majority of growing season
Fimbristylus(fimbry)
Wet Meadows Occasional flooding kills woody plants
Cyperus(nutsedges/flatsedges)
Shrubs/Forested Wetlands Periodic flooding (part of year multiple years)
Not enough flooding to kill woody vegetation
Salix(willows)
Adapted from Cronk & Fennessy 2001
Aquatic
Marsh
Wet
Meadow
Shrubs
Amplitude oflong-term
water
fluctuations
Fimbristylus littoralis
Wetland Hydrologic Controls
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y g
Stabilizing water levels (2 - 3+ yrs) can reduce plant species and community diversity
Significantly reduce emergent vegetation cover
Increase open water
Increase # & dominance of exotics/aggressive perennials
Typha(cattail) and Urochloa mutica(California grass)
Allow monospecific vegetation stands &/or one structural type
Decrease species richness
Decrease fungal or pollinator mutualistic relationships
Reduce or eliminate wet meadow and/or marsh zone
Adapted from Cronk & Fennessy 2001
Aquatic
Marsh
Wet
Meadow
Shrubs
Amplitude of
long-term
water
fluctuations
Aquatic
Shrubs
Riverine Hydrologic Controls
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Tropical rivers flood during rainy season
Riparian plant community composition dependant on physical disturbance
Intermediate disturbance hypothesis (Cronk & Fennessy 2001)
Too little disturbance competitive exclusion tends to reduce diversity
Too much disturbance only highly tolerant species are able to persist
Plant diversity also dependant on:
River discharge velocity
Stream order
Soils Microtopographic relief
Upstream plant diversity
Riverine Hydrologic Controls
Soils
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Soils
Soil temperature
Affects germination
Soil Color
Can change with redox reactions
Microbes obtain O2 from mineral oxides = reduction
Indicates hydric soils
Soil Texture
Ribbon test
Gritty sand loamy silt soft, tight clay
Soil moisture
Capillary fringe
Rises higher with tighter pores
Found w/in 12 of soil surface = wetland High organic content slippery feel, easily deformed
Soils
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Organic Content
Black, porous, light weight, smelly hydric Methane & sulfide are smelly!!! redox rxn hydric soil
Residual Plant Material
Anoxic conditions slow plant decomposition
Soil Stratigraphy
Cognizant of horizons
Mineral composition helps control hydrology & water chemistry
Clay soils hold water
Sand lenses transmit water laterally Hard Fe (iron) precipitate in HI bogs can cause ponding
Hydric soils get down 45 cm (18) to test
Soils become hypoxic within a few days of flooding anoxic
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Light
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Light
Most important factor for submerged plant distribution
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Light
Suspended solids, dissolved organic and inorganic compounds
Scatter light & absorb heat
Boat traffic, shoreline erosion, bottom feeding fauna, high wind action
Heavy periphyton coating can reduce productivity
Shading by other vegetation
Residual plant material
Time of Year
Day length
Intensity of light
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Temperature
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Water
Fluctuations much less rapid and extreme
Increases cosmopolitan species
Phragmites australis(common reed), Lemna spp.(duckweed), Ceratophyllum demersum(hornwort/coontail)
High specific heat of water thermal stability
Solar radiation only reaches the uppermost few meters & affects...
Aquatic plants, O2, chemicals, aquatic insects, etc...
Plants
Increase ET
Lose more H2O when open pores to intake CO2, exhale O2
Soil
Increase in temp. fluctuations can incite germination
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Water Chemistry
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Water Chemistry
Soil & bedrock composition is huge influence
Higher pH, conductivity higher site fertility more spp. richness pH
Increases during day use CO2 less carbonic acid (H2CO3)
Decreases at night opposite rxn.
Higher in urbanizing areas
Conductivity (S/cm)
Total dissolved salts (TDS) or total dissolved ions
Increases with more evaporation (concentrates salts) Bigger watershed more contact with soil before entering water
more ions
Too many accumulated ions can be toxic
Ca2+
, Mg2+
, SO4-
, CO32-
, HCO3-
, Cl-
, Na+
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Water ChemistryLeptochloa fusca
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Salinity
Brackish = 0.5 ppt (1.4% seawater) Fresh water hard to obtain
Necessary ion uptake more difficult
CO2 uptake difficult (opening stomata incurs water loss)
Reduces plant productivity Toxic to freshwater plants
Can be used to your advantage!
Nutrients Phosphorus tends to be limiting nutrient in oligotrophic systems
[N] = 1.5% (Cronk & Fennessy 2001)
[P] = 0.13%
Nitrates common in fertilizers/runoff
Pollutants
More in human land use areas
Ammonia, orthophosphate, chloride Can change vegetation community
Batis maritima
Biotic Influence
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Trails form open water pathways
Forage
Plant often dies b/c oxygen supply is cut off
Can change plant community Decreases amount of certain species, allowing others to outcompete
Nesting materials
Wider less strands needed
Tougher less likely to break down
More aerenchyma floatation
Droppings increase plant productivity
Can increase open water habitat
USFWS
Plants Compete Too!
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The better competitors:
Make more biomass
Can gather nutrients when theyre at low levels (& still survive!)
However, high nutrient enrichment (eutrophication) decreases spp. richness
Exotics often win this competition
Increasing MICROtopography...
Increases heterogeneity
Increases # individual plants
Increases biomass Reduces competition
Plants Compete Too!
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Light
Floating-leaved plants can shade out submerged spp., esp. if high turbidity
Nymphaea (water lily)
Submerged spp. can form mats to shade out new growth from bottom
Ceratophyllum(hornwort)
Some emergent monocots reproduce vegetatively, shade out
submerged/floating
Carex(sedge), Cyperus(flatsedge/nutsedge), Typha(cattail)
Nutrients
Ability to assimilate nutrients faster is advantage
Nymphaea capensis
Plants Compete Too!Schoenoplectus juncoides
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Space
Dense, monospecific stands produced by vegetative growth
Myriophyllum(water milfoil)
Fire Increases space less aboveground standing stock reduces
competition
Increases nutrient availability through oxidation (from plants to free in soil)
Maintains current stage or resets succession
Was it a part of natural regime?
Deep water
Diffusive O2 flow to roots outcompeted by pressurized O2 ventilation
Pressurized in some spp. ofNymphaea(water lily), Eleocharis
(spikesedge), Schoenoplectus(bulrush), Typha(cattail) Skinny, tall leaves can be better in deep water than short, wide leaves
Biomass storers
Low disturbance
Low productivity/low light/high
Competitors
Low disturbance
High productivity habitat
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p y g gsalinity
High vegetative reproduction Rhizomes/tubers store biomass
and nutrients
Ruderals
High disturbance (not competitive)
High productivity habitat
High reprod. ability, fast growth, short life
Annuals - disperse!
g p y
Low reprod. ability, high growth rate
Capture available resources well
Stress-tolerators
High disturbance
Low productivity habitat
Low reprod. ability, low growth rate
Elodea(waterweed)
Polygonum punctatum(dotted smartweed)
Carex echinata
(star sedge)
Typha(cattail)
Allelopathy
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Secondary metabolic compounds
Root exudates
Leached from leaves or litter
Thought that chemicals are expensive to make, so usually compete usingonly its physiological adaptations (Cronk & Fennessy 2001)
Therefore, chemicals only produced under crowding stress
Cyperus(flatsedge), Eleocharis(spikesedge), Polygonum(smartweed),Nuphar(water lotus)
Nuphar(water lotus)
Why are Exotic Species so Competitive?
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Rapid regeneration through prolific seeds & vegetative reproduction
The vegetative spread of submerged or floating species is most rapid in thetropics and where water levels remain constant (Cronk and Fennessy2001).
Eichhornia crassipes(water hyacinth) can double areal extent in 3.5 days
Pests/herbivores not evolved to attack/consume exotic plant
Little competition from other plants
Native plants evolved to exploit separate niches
Exotics competitors rarely present in new range
Can grow quickly by capturing resources & light
Why are Exotic Species so Competitive?
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Aquatic environment is relatively uniform
Wide ecological tolerances (generalists) Can become dominant most anywhere if given the chance
Many are cosmopolitan (occur across the world) Pistia stratoides(water lettuce)
Some resistant to fire, flood, drought
Pistia stratoides(water lettuce)
Exotic Species...
on Islands
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...on Islands
Proportion of exotics on islands...up to 50% Proportion of exotics on continents...up to 20%
Hawaii
Few plants colonized mostly evolved once they got here
Generally no frost
would eliminate many exotics Transportation stop b/w Asia & N.A.
...on Disturbed areas
Very susceptible to invasion
Natural Fire, flood, drought, biota
Human
Damming/impoundment
Fragmentation
Urbanization
Pipes/irrigation/drains that change salinity
Climate change
Coastal areas
Weather pattern changes
Veg. movement towards poles
Invasive Infestation
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Change community structure Rhizophora mangle(red mangrove) planted on Oahu
Shade out natives
Dense root system altered animal movements & community
Altered soil O2
Hybridize with natives
Can be more adapted, but just as invasive
Reduce seed bank diversity
Draw water level down with high evapotranspiration rates
Surface & ground water
Invasive Infestation
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Thick submergents Provide refuge for fish fry, allowing high survival overpopulation,stunting
Hard for predator fish to hunt
Dense floating mats
Eichhornia crassipes(water hyacinth)
Inhibit O2 diffusion into water kill fish, invertebrates, plants
Accumulate heavy metals & toxic compounds ingestion can killanimal
Hard for chicks to maneuver
Alters fire regimes
Dry leaves ofArundo donax(Spanish reed) catch fire easily
BUT...plant is fire-tolerant
Invasive Plant Growth Requirements
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Species Salinity
Tolerance
pH range Propagated
American
Lotus
None 4.59 7.40 Seed
Common
Reed
Low 4.50 8.0 Sprig
Reed
Canarygrass
Low 5.50 8.0 Seed and Sprig
BroadleafCattail
Low 5.50 7.50 Sprig
Narrowleaf
Cattail
Medium 3.70 8.50 Seed and Sprig
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Biomass of VegetativelyReproducing Perennials
Nupharrhizome
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Reproducing Perennials
Production (lb/acre)
Species Common name Above Below
Phragmites Common reed 9,580 64,060
Typha Cattail 7,580 16,060
Nuphar Water lotus 5,400 10,225
Need to consider below ground biomass more!
Mowing to cut off meristematic tissue is often not enough
Must grub/scrape/dig to disrupt rhizomes/tubers
Adaptations Roots
Adventitious = laterally from main stem base into soil surface
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Adventitious = laterally from main stem base into soil surface
In positions they normally dont occur Replace deep roots that die b/c anoxia
Stabilize & increase O2 to roots
Salix(willow), Rumex(dock)
Shallow rooting
Allows access to NO3- (nitrate), and O2
Prop & drop roots on red mangrove plants
Covered with lenticels for O2/CO2 exchange
Stability
Buttressed trunks
Jurassic Park
Stems
Elongation to access light, O2, CO2
Sagittaria latifolia(arrowhead)
Sagittaria latifolia
Adaptations
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Rhizomes
Larger carbohydrate storage allows more ATP production for cell metabolism
More ATP needed in anoxia
Phragmites australis(common reed), Schoenoplectus(bulrush), Typha(cattail)
Aerenchyma = tissue with large intercellular spaces (lacunae)
O2 to roots, brings CO2 from roots & out stomata
May be 50-60% of root area in flood-tolerant plants
Stem floating to access light, O2, CO2
Swelling at stem base to enhance aeration Some invertebrates tap into this to respire
Coleoptera larvae (Donacia sp. -Chrysomelidae) Diptera larvae (Mansonia sp. Culicidae
& Chrysogaster sp. Syrphidae)
Schoenoplectusjuncoides
AdaptationsLudwigia palustris
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Leaves
Some float off long stems, spread out to access light, O2, CO2
Heterophylly
Emergent leaves ovate/elliptic/rounded
Submerged leaves ribbon-like/dissected
Ludwigia palustris(marsh seedbox), Sagittaria(arrowhead)
Chemical defenses
Herbivory
Nymphaeaceae(water lily), Arundo donax(giant reed), Colocasia
esculenta(taro) Against invertebrates: Ceratophyllum(hornwort), many submergents
Adaptations
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Salinity
Increase internal solutes freshwater comes in
Exclude or secrete salts, leaf shedding, leaf/shoot succulence
Nutrients
Mycorrhizae = symbiotic fungi
Approx. 85% of all aquatic plants
Increases water, P, N, K+ available for plant, takes carbohydrates fromroots
N-fixing bacteria in root nodules Sesbania(legumes), Alnus(alder), grey, white, and red mangrove plants
Move nutrients from aboveground tissues to roots, rhizomes, tubers, bulbs
Energy for start up next growing season
Batis maritima
Submergence Adaptations
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Leaves
Chloroplasts in epidermis
Ribbon-like or highly dissected
More light to chloroplasts
More surface area for gas &nutrient exchange
Shoots can absorb water & nutrients
Less xylem & lignification
Thin cuticle
No stomata
Gas exchange through diffusion
More aerenchyma
Buoyancy for proximity to light, O2, CO2
More gas transport
Dissolved bicarbonate (HCO3-) in photosyn. Myriophyllum spicatum(Eurasian water
milfoil)
Recycle CO2 from respiration into photosyn.
Elodea nuttallii(western waterweed)
Threats
W tl d l
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Wetland loss
50% loss on U.S. mainland
1/3 T&E plant spp. in U.S. depend on wetlands
30 T&E wetland plants in Hawaii alone
Hydrologic alterations
Agriculture
Groundwater drawdown
Flood control
Stabilized water levels
Altered topography
Pollution
ThreatsUrochloa mutica
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Exotic species
20 spp. exotic biota introduced to HI/year
Monocultures less biodiversity
Extirpation of native species
Alter nutrient cycles
More invasives with more ecosystem degradation
Global climate change
Some wetlands will dry up (i.e. seasonal), others will expand
E.P.A. estimates 15-34 cm sea rise in next century (65 cmpossible)
Strategy
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H.Gee
Monitoring
Limit Exotics & Perennials
Multiple Treatments
PATIENCE
HOW???
Set Back Succession
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Set Back Succession
Flooding/Drawdowns
Gradual basin slope ideal
Small drops in water level can expose large areas
Must understand water budget before flood/drawdown Impact on invertebrates, waterfowl, other fauna
Tilling/Discing
Consider high degree of substrate disturbance
Mowing
Consider meristematic tissue (monocots vs. dicots)
Herbicides
Consider impacts on desired species
Get down to mineral soil
THANK YOU!!!
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Literature Cited
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Cronk, J. K., and M. S. Fennessy. 2001. Wetland Plants: Biology and Ecology. Lewis
Publishers. Boca Raton, FL.
Erickson, T. A., and C. F. Puttock. 2006. Hawaii Wetland Field Guide. Bess PressBooks. Honolulu, HI.
Larson, Gary. 2005. Aquatic Plants. South Dakota State University. Brookings, SD.
Merritt, R. W., & K. W. Cummins. 1996. An Introduction to the Aquatic Insects of
North America, 3rd ed. Kendall/Hunt Publishing Company. Dubuque, IA.
Ward, J. V. 1992. Aquatic insect ecology, Vol. 1. John Wiley & Sons, Inc. New York,
NY.
***Thanks to Hugo Gee for many of the vegetation pictures