wetland restoration definitions motivations types and approaches costs design issues ecological...

Wetland Restoration

DefinitionsMotivationsTypes and ApproachesCostsDesign IssuesEcological Theory MonitoringCase StudiesSouthern California Restoration Projects

Wetland Restoration

Restoration - Returning a degraded wetland or former wetland toa pre-existing condition or as close to that condition as possible.

Creation - Converting a non-wetland (either dry land or unvegetated water) to a wetland.

Enhancement - Increasing one or more of the functions performedby an existing wetland beyond what currently or previously existedin the wetland. There may be a decrease in other functions.

Mitigation - the actual restoration, creation or enhancement of wetlands to compensate for permitted wetland losses.

Restoration/Creation Motivation

•US - No Net Wetland Loss Policy

•Treating Urban Runoff (excess nutrients, contaminants)

•Excess sedimentation

•Mitigation - To compensate for loss:on site or off sitein kind or out of kindbanking

•Improve habitat quality and function, expand existing wetlands

Forms of Restoration•Grading of upland to intertidal levels (marsh, mangrove, tidal flat)

•Hydrological improvement (e.g., dredging, opening lagoons to flushing)

•Creation of habitat via dredge spoil islands (often planted)

•Planting unvegetated bottom with seagrass or marsh grass

•Amending soils with nutrients or organic matter (e.g., peat, straw, alfalfa, kelp)

Restoration Costs - Louisiana examples

Approach Restoration Rate Size (ha) $/ha

Crevasse Splays 1.1% 10-300 48Agric. Impoundments 1 300-7,000 1Backfilled canals 1.5 1-50 1,000Spoil Bank Rest. 2.5 10-1000 10Terracing 5 10-100 4,686Dredge Mat. wetlands >50 <1-100 0-23,600Excavated wetlands >20 1-100 44,600Thin Layer Placement ? 1-100 ???

FROM Turner and Streever 2002

Who Pays?•Power companies•Transit Authorities•Port Authorities•Cities, Counties, States (taxpayers)•Federal Government

Attempts to value wetlands: LA salt marshes valued at 9-17K per acre (must be per year). Kendall Frost property: 1.6 million for 2.1 acres

Restoration Design Issues1. Site limitations - in So. Calif. available space is limiting, especially for local mitigation. Land is expensive!

2. To plant or not. What to plant, Where to get plants from (genetic concerns)Rarely are animals introduced - it is assumed that if you build it, they will come.

3. Hydrology, creek design, edge habitat,

4. Ratios of low, mid, upper, transitional marsh Seagrass vs unvegetated

5. Need for upland and ocean end management as well. Difficult to create and manage a coastal wetland in isolation without control over adjacent habitats.

6. Incorporating science into the restoration effort (e.g., Mission Bay) Major limiting factor is knowledge about what maximizes productivity and health Prior history of habitat existence important. Failure greater where there was no historical wetland

DANGERTHAT ABILITY TO MITIGATE WILL ENCOURAGE DESTRUCTION OF

NATURAL HABITAT

To avoid this, we must have strict rules about loss of natural wetlands.

Monitoring• Comparison to reference sites• Frequency and duration - 5 years is not enough!• Adaptive monitoring - change in response to events• Community involvement• What and how to monitor….• Plants, animals, fishes, birds, • Increasing emphasis on function• Should science be part of monitoring?• Need success criteria • Comparison to less disturbed reference wetlandsOften these aren't available in urbanized estuaries.• Standardized methods? - usually not.

Structure vs Function

•Difference between structure (who and how many are there) and function (ecological processes: productivity, nutrient cycling,trophic support, resistance to invasion). •Success criteria try to incorporate both but it is difficult. Structure is easier to measure.

•Sometimes endangered species or top carnivores drive criteria. More often plants dominate.

Restoration Approaches

Passive - Removing source of problem Benefits - low cost, compatibility with surrounding landscape Examples:

Removing dikes, pondsRemoving grazing cattle

Active - Physical intervention*Recontouring to achieve desired topography and elevation*Changing water flow (e.g., inlet opening, channel

construction wiers, culverts)*Planting and seeding*Non-native species control*Soil enhancement

Incorporating Research/Experiments(mensurative or manipulative)

*Allows for development and testing ofrestoration theory (Zeder 2005)

*Allows for Adaptive Restoration; modification of restoration plan over time.

Relevant Ecological Theory and Practice(Zedler 2005)

•Controls and Reference sites (natural variability)

•Biodiversity and Ecosystem Function(productivity, invasion resistance, nutrient cycling)(critical function species)

•Eutrophicationeffects on wetland diversitywetlands as the cure

•Island Biogeography/Connectivity(applications may differ among organisms)

Ecological Theory (con’t)•Succession

primary successionmicrobial feedbacksplant-animal interactions

•Facilitation

•Competition

•Predator-Prey Interactions (e.g., birds in So. San Diego Bay)

•Food Web Theory/ Trophic Cascades

•Assembly Rules

•Extended phenotypes/ Hybridization: genetic influences

•Invasion Biology: how to prevent establishment of invasives

•Resilience

Port Marsh, North Carolina•Created in 1990 by grading 2.2 acre dry dredge spoil to sea level. •Planting with S. alterniflora. 9 culm/m2. • Isolated from adjacent natural system by oysters, sediment and land plants. •3 blocks each with OM treatments applied to 2 x 7 m plots.

•Spartina grew rapidly. By 1993 there were no differences in biomass or stem densities in created and adjacent natural marsh. By 1994 biomass and stem densities in created marsh were 2x those of natural marsh.

•Despite rapid vascular plant recovery, the animals did not recover as quickly.After 27 mo some epifauna like mussels, oysters, mud crabs and littorine snails never appeared.

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Levin et al. 1996, MEPS

Natural Unplanted Planted

Density Spp. number

Port Marsh Infauna

Organic Amendments - Straw Alfalfa, Peat, plus inorganic N. Initially killed plants and reduced animal densities in NC (figure) . Effects disappeared after 6 months, except for straw treatments which exhibited reduced densities for several years.



Levin et al. 1997

Macrofaunal density

Straw

Natural

Macrofauna Succession

•Early opportunistic polychaetes (S. benedicti, Capitella, Polydora cornuta)•Total macro density and species richness reached ambient (natural) levels at 6 mo.•For first few years these and turbellarians were 75-95% of fauna•At year 4 diversity higher but sediments remained different. No oligochaetes (coarser and lower OM in created marsh).




BUT species composition and functional groups did not resemble natural marsh.Species without dispersive stages (lecithotrophs/direct developers) were slow to recover.Species with dispersive stages (planktotrophs, swimmers) overshot natural marsh





Planktotrophs Direct Developers

Lecithotrophs Swimmers



Oligochaetes were 50% of natural marsh fauna but rare in the created marsh. Instead of a subsurface deposit- feeder dominated fauna, the created marsh was surface-feeder dominated.



Surface Feeders

Subsurface Feeders

Carnivores & Omnivores

Recommendationsfrom Port Marsh study

•Connections with natural marsh/direct contact desirable•Seeding animals may help, particularly for non-dispersers•Attention to sediment properties (Grain size, OM)



Craft & Sacco 2003Marsh restoration sitesin North Carolina





Dill’s Creek

Created fromupland pineforest



Craft & Sacco 2003Surface feeders recover more quickly than subsurface feeders.



Craft & Sacco2003 MEPS

Soil organic matteris correlated withfaunal density.



Craft&Sacco2003

MEPS

Created marshes may overshootnaturalones.



Zedler 1996

Southern California has29 small embayments, manywith restoration projects plannedor in progress.

Southern California Restoration ProjectsZedler 1996 - Ecol. Applications

Goleta Slough Remove obstructions to increase tidal flowsCarpinteria Marsh Excavate adjacent site to increase area of tidal influenceBalona Wetland Open tide gates, increase tidal flow to salt marshLos Cerritos Wetland Increase access to tidal flow in diked marshesSeal Beach NWR Maintain tidal systemsBolsa Chica Wetland Entrance tidal access to diked marshes and mudflatsSanta Margarita Estuary Dredge mouth to extend periods of tidal influenceAgua Hedionda Lagoon Dredge mouth periodically to sustain tidal influenceBatiquitos Lagoon Dredge mouth to change nontidal to tidal wetlandSan Elijo Lagoon Dredge mouth to change nontidal to tidal wetlandSan Dieguito lagoon Restored wetland, enhance hope water areas, open mouthLos Penasquitos Lagoon Dredge mouth to extend periods of tidal influenceFamosa Slough Enlarge culverts to extend tidal influenceMission Bay Dredge to create salt marshSweetwater Marsh/So. Bay Excavate to create salt marsh/ Restore salt pondsTijuana Estuary Excavate upland to create salt marsh and tidal creeks


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Diversity is lower in lagoons that close periodically.



Zedler

Macrofaunal Recovery - Salicornia marshes in southern California



Talley & Levin 1999



Talley & Levin 1999Comparison of macrofaunal composition in created and naturalSalicornia marshes

Created marsh

Naturalmarsh

Crown Point Mitigation Site, Mission Bay CA

Graded and Restored to tidal flushing Dec. 1995

Crown Point Mitigation Site, Mission Bay

Southern California - Crown Point Mitigation Site



Crown Point Mitigation Site - Opened Dec. 1995

Summer 2001 ( 5 yr 6 mo)

January 1996 (1 mo) April 1998 (2 yr 4 mo)

0

1

2

3

4

5D

etri

tus

(gra

ms/

18 c

m2 c

ore)

1996 1997 1998 1999 2001

Belowground Plant Detritus

Natural NWP)

Created (CPMS)

Levin & Talley 2002

CPMS =created average

NWP = natural average

Levin & Talley 2002

0

25

50

75

100

Per

cen

t of

Tot

al M

acro

fau

na

1996 1997 1998 1999 2001 2001 (fall)

Mission Bay Macrofauna-Created Marsh

Other

Tubificid Oligochaetes

Enchytraeid Oligochaetes

Nadid Oligochaetes

Peracarids

Molluscs

Polychaetes

Insect Larvae

------------------April------------------

0

25

50

75

100

Per

cen

t

1996 1997 1998 1999 2001 2001 (fall)

Mission Bay Macrofauna-Natural marsh

Other

Tubificid

Enchytraeid

Nadid

Peracarid

Mollusc

Polychaete

Insect

-----------------April------------------

-1.5

-1

-0.5

0

0.5

1

1.5

Stress 0.16-1.75 -0.75 0.25 1.25

Dimension 1

B. Macrofauna

19991999199819981997199719961996

Levin & Talley 2002

MDS indicatingsimilarity of macrofaunalcomposition.

Created Natural MarshDuring the El Niño (98)the created and naturalmarsh macrofauna were most similar

Tijuana Friendship Marsh

20 acresOpened in Feb. 2000Constructed creeks, Planted Spartina

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3 tidal creeks

kelpamendments

2 plantdensities

0

25

50

75

100

Per

cen

t

Spring 2000 Fall 2000 Spring 2001 Fall 2001

Other

Insects

Crustacea

Gastropods

Polychaetes

Oligochaetes

data from Moseman et al.

Friendship Marsh Macrofauna

Upcoming Restoration Projects•San Dieguito Lagoon

Permanent inlet openingWetland grading, planting

•Tijuana Estuary380 additional acres salt marsh

•San Elijo and Los Penasquitos Lagoon Episodic inlet openings

•South San Diego Bay Wildlife RefugePond conversion to tidal habitatGrading of fill

•Kendall Frost - ? Frost Property, Campland Acquisition - 2017?

wetland restoration definitions motivations types and approaches costs design issues ecological...

Documents

historical wetland slide

degraded wetland

coastal wetland

restoration effort

actual restoration

kelp slide

restoration design issues

permitted wetland losses