Aquatic Plant Ecology

8/3/2019 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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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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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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[email protected]

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

Documents

Aquatic Plant Ecology