Wetland & Estuarine Formation & Development

Wetland & Estuarine Formation & Development

NREM 665

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I. Wetland Formation & Development

A. Favorable climate (PPT > ET), temperature

1 don’t get WTLs in1. don t get WTLs in

B. Favorable geol/substrate

1. high H2O holding capacity &

C. Hydrologic factors & WTL dvpt

1. H2O source effects what types of WTL dvp1. H2O source effects what types of WTL dvp

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General model of hydrologic inputs which control wetland development 3

II. Estuary Formation

A. Estuary Def: semi-enclosed coastal body of H2O which is connected w/ open sea & in which SW dil t d / FW d i d f l d d i (P it h ddiluted w/ FW derived from land drainage (Pritchard 1967)

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B. 2 Main Physical Processes in Estuaries

1. Stratification (Layering): FW lighter than SW

a tides & winds mix layersa. tides & winds mix layers

2. Settling: Rivers bring susp. sediment to estuary

a. Aggregation/flocculation as FW hits SW

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C. Estuary Formation: 5 Main patterns based on geomorphology (Day et al 1989 Mann 2000)geomorphology (Day et al. 1989, Mann 2000)

1. Drowned river valleys (or coastal plain estuaries)

a. SW progressively extends into river valleys w/ SL rise

i. SL rise occ in most places since last glaciationsglaciations

b. Common in temperate climates w/ TSMs

c. Broad vs narrow dep on size of cont shelf

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d. Classic example?

Estuary formation via river valley drowningdrowning

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Drowned river valley or coastal plain estuary

Chesapeake and Delaware bays 9

2. Fjords formed by glacial erosion

a. form in river valley scoured by Pleistocene glaciers

b. U-shaped, typically very deep

i Ex:i. Ex:

c. little sediment, dom by plankton, temperateclimates

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FjordjGulf of St. Lawrence

http://www.erudit.org/revue/gpq/1999/v53/n3/004873ar_fig01.gif

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FjordPuget Sound

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3. Bar Built

a. Form where deposition of sediment kept pace w/ rising SL, creating spits or barrier islands

b. Common in subtrops & trops, dom by TSM & MGs

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Bar built estuary

http://www.athenapub.com/lagterm1.htmLaguna de Terminos, Campeche, Mexico 15

4. Tectonic

a. coastal indentations formed by faulting or subsidence

b Wh i h l i l ??b. What is the classic example??

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Tectonic estuary

San Francisco Bay,San Francisco Bay, California

http://terraweb.wr.usgs.gov/web-cgi/webvista.cgi?the_Region=SFBay&title=&imgType=1993&Map=1&dev=01&dev 0

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5. Deltaic (land deposition)

a. produced by river processes

b. characterized by silty sediments from terrestrial runoff (Day et al. 1989)

c. 3 types: fluvial, tide-dominated, & wave dominated

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Fluvial deltaic estuary

Mississippi River delta, LA 20

Fluvial deltaic estuary

Atchafalaya delta

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Mississippi OuflowMississippi Ouflow22

Tid d i t dTide-dominated deltaic estuary

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Wave-dominated deltaic estuaryWave dominated deltaic estuary

Sao Francisco delta, Brazil,

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Wave-dominated deltaicWave-dominated deltaic estuary

Chilean Coast

http://faculty.gg.uwyo.edu/heller/Sed%20Strat%p y gg y20Class/Sedstrat6/slideshow_6_12.htm

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D. Estuarine Mixing Classification

1. Salt wedge (stratified): minimal mixing bet FW & SW

a moves up & down seasonally Q: Classic ex?a. moves up & down seasonally, Q: Classic ex?

2. Partially-mixed: more vertical mixing & resuspension via winds & tides

3. Well-mixed (Vertically homogeneous/fully-mixed): strong mixing forces break down stratificationstrong mixing forces break down stratification

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III. WTL Dvpt & Succession

A. Auto vs. Allo

1. Autogenic: linear succession from shallow lake to climax forest

2. Allogenic: plant community ∆ing in resp to ∆ing env. no climax, nonlinear

3. WTLs are ecotones bet. aquatic & terr envs., w/ allogenic forcing from both dirs

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Early wetland ysuccession models:Presumed linearPresumed linear trajectory among plant communities i E l din England (Chapman 1960)

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Gulf Coast wetland succession models: linearity & climax (Penfound & Hathaway 1938) 30

More recent wetland successional models

Successional sequence from stratigraphic & paleoecological data in British peatlands (Walker 1970).

Thicker lines = more common transitions.

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IV. Models of Wetland Development

A. Functional Guild

1 describes comm in terms of functional groups1. describes comm. in terms of functional groups defined by specific traits

a enables prediction of g ilds based on ario sa. enables prediction of guilds based on various env. conds. ~ assembly rules

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Functional Guild

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B. Env. Sieve

1. pres & abun of spp ƒ(life history & adaption to env. conds.)

a. env. conds = sieve, as env. ∆s, so does sieve, & spp. presentsieve, & spp. present

b.

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Environmental Sieve

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C. Centrifugal Org.

1. describes plant comms. along gradients of env. constraints

a. gradients radiate outward from single core habitat to periphery where spp. adapted to p p y pp pconstraint(s) outcompete core spp.

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Centrifugal Organization

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V. WTL as hybrids bet young & mature systems

A. Young Systems

1. high prim prod. (as in most immature systems)g p p od (as ost atu e syste s)

2. open mineral cycling

3. short life cycles

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B. Mature Systems

1. High detrital processing (nutrient demand satisfied by recycling even in open TSMs, MG)

2. Spatial heterogeneity

3. Complex life cycles

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Mature: Spatial Heterogeneity

Aerial view of Everglades tree islands & Cladium (sawgrass) 40

Mature: Spatial Heterogeneity

Ground view of tree islands and slough in the Everglades 41

Mature: Complex Food Webs

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VI. Pulse Stability Concept

A. Ecosys pulse even after reaching carrying cap (Odum et al. 95)

1. paradigm of repeating oscillation poised on edge of chaos

2. TSMs, MGs resist short-term env. ∆s via spp. div, nutr. storage, recyclingnutr. storage, recycling

B. Physical energy pulses ↑ circ of inputs & waste removal ↑ prodremoval, ↑ prod

C. WTLs org. to receive pulses from & impose pulses

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on environment

Pulsed Stability

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VII. Ecosystem Engineers

A. Organisms can have strong autogenic effect on WTLs

1. Plant Example: Mangroves: roots trap debris, sediments

2. Wildlife Examples: Beaver, Muskrat: dam, burrow → spp comp, hydrolBeaver, Muskrat: dam, burrow → spp comp, hydrolCanada Geese, Nutria: herbivory, eat outs → prod, structureManatee Dugong: herbivory → prod flow pathsManatee, Dugong: herbivory → prod, flow paths Alligators: gator holes → hydrology, spp comp.

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