COASTAL
WETLANDS
I. Distribution
A. Sites
B.
Losses
conversion to deep water
urban use
conversion to non-vegetated types
transition to freshwater
agriculture
II. Elements which control vegetation structure and establishment
A. Sediment
B. Salinity
C. Elevation/tides
D. Salinity x elevation
E. Energy
F. Soil
G. Drainage
H. Seed source
I . Spartina invasions
III. Restoration approaches
A. Dike breaching, Salmon River, Oregon (R. Frenkel
and J. Morlan 1990. Restoration of the Salmon River
marshes: Retrospect and prospect. Final Report to EPA.
Department of Geosciences, Oregon State University,
Corvallis, 142 p.)
1.Breaching
dikes
2. Recontouring upland or filled former wetland
3. Hydrologic modification to induce accretion
4. Recommendations
Restore
complete hydrologic connection
Connect
through dikes at former creek locations
Survey
elevations
If planting,
collect salinity and soil data
Planting may
be optional
You can
contour, but beware
Post-project
monitoring
B. Connector Marsh, San Diego
(Josselyn
et al in J. Kusler and M. Kentula
1990. Wetland Creation and Restoration: The Status of the Science.
Island Press, Washington, D.C., 591 p.), Langis et al
1991 in Ecological Applications, Zedler 1993 in
Ecological Applications, Gibson et al 1994 in Ecological Applications)
1. Tidal
marsh
2. Spartina foliosa
3. Clapper rail
4. Nutrient
cycling
5. Organic matter
C.
Gog-le-hi-te Wetland, Tacoma in (Josselyn
et al in J. Kusler and M. Kentula
1990. Wetland Creation and Restoration: The Status of the Science. Island Press, Washington, D.C., 591 p.)
1. Goals
2. Judgement of success
3. Unanticipated
results
D. Bracut Marsh mitigation bank, Arcata
Bay, CA in (Josselyn et al in J. Kusler
and M. Kentula 1990. Wetland Creation and
Restoration: The Status of the Science. Island Press,
Washington, D.C., 591 p.)
1. Restore tidal action to a diked area that had been filled with wood debris, gravel
2. Import
soil to encourage vegetation growth
3. Remove
debris
4. Plant Spartina foliosa
5. Problems:
Plant list
used was for another, more southern, area
Wood debris decay
Spartina is not growing
E. Hayward Regional Shoreline, Alameda County, CA in (Josselyn et al in J. Kusler and
M. Kentula 1990. Wetland Creation and
Restoration: The Status of the Science. Island Press,
Washington, D.C., 591 p.)
1. To restore tidal action to
a former salt crystallizer and recreate emergent marsh
2. Specific goals:
Create area
to be colonized by Spartina foliosa
Excavate
channels to retain water and provide shorebird habitat at low tide
Create
nesting islands
3. Success:
Salt
concentration in lower soil layers stayed high
Fish,
invertebrates and birds colonized
Vegetation
did not establish
F. Shorebird Marsh, Marin County, CA in (Josselyn
et al in J. Kusler and M. Kentula
1990. Wetland Creation and Restoration: The Status of the Science. Island Press, Washington, D.C., 591 p.)
1. Mitigation for regional
shopping center
2. To provide
flood control during winter and create tidal saltmarsh
during summer
3. Goals:
Create
extensive habitat for, and plant, Spartina foliosa
Make islands
and channels
Construct
pump and structure to pump out water during floods
and limit maximum tide during growing season
4. Success:
Facility was
to be managed for flood control from 15 Oct to 15 Apr, then
operated
as a
tidal marsh. Public works employees did not grasp this the first year.
Flap gate
failed second year; outflow channel silted up.
Citizens'
committee took over management of marsh; experimental plantings failed
because of lack of tidal action.
In third
year, tidal action was implemented in summer.