Pacific Northwest Forested
Wetland Literature Survey
Cooke Scientific Services, Inc.
Seattle, Washington
Cookescientific.com
Funding and Review Organizations
• Cooperative Monitoring Evaluation
and Research Committee (CMER)
Supplied grant
• Wetland Scientific Advisory Group
(WETSAG)
Project oversight
• Department of Natural Resources
Grant administrator
Timber Management Practices
PNW - Trends
o Forested wetlands may be harvested similarly
to upland areas.
o No restrictions to tree removal in non-bog forested
wetlands.
o WA Forest Practices Act (1990) emphasizes reducing
impacts to hydrology and soils in forested wetlands but
does not impose restrictions.
o Common timber management impacts:
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Removal of nutrients
Reduction of soil productivity
Increased soil temperature
Hydrologic changes
Changes in water yield and stream flow patterns
Reduction of available wildlife habitat
Timber Management in PNW
o Even Aged Management (Clear-cutting)
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Is the dominant harvest method in W. Washington and Oregon
Results in little or no difference in tree age within a stand
Alters forest community and habitat
Shortens growth cycle
Decreases the presence or absence of snags
o Uneven Aged Management (Selective Cutting)
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Results in 3 or more tree ages within a stand
Has no associated rotation age
Results in a multilevel forest of different sized trees
Provides habitat for various species throughout their life cycle
Provides stand-scale wildlife habitat with more spatial
homogeneity
PNW Forested Wetland
Characterization
o Classify by Wetland Type (montane, riverine)
o Classify by Soils (organic, mineral)
o Classify by Vegetation Community
Associations
• Organic
• Bog
• Mineral
o Classify by Hydrologic Regime
o Classify Wildlife Associations
Classification of Forested Wetlands
in Washington and Oregon
(Johnson and O’Neil 2001)
o Montane Coniferous-Wetlands
o Westside Riparian-Wetlands
o Eastside Riparian-Wetlands
Montane Coniferous Wetlands
(Washington and Oregon)
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Steep slopes
Mountains
Flat valley bottoms
2,000-9,500 feet msl
PFO or floodplains with snow pack
Annual precipitation 35 to 200 inches
Found adjacent to streams and herbaceous wetlands or
as small patches within a matrix of upland mixed
conifer forest (Johnson O’Neil 2001).
Eastside Riparian
Forested Wetlands
o 100-9,500 msl
o Along streams and
rivers
o Within 100-200 feet
of stream corridor or
water source
o Primary hydrologic
input overbank flow
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Photo Source: Rosgen 1996
Westside Riparian
Forested Wetlands
o Flat, gently sloping,
or steep terrain
o Common below 3,000
feet msl but found as
high as 5,500 msl.
o Primary hydrologic
input overbank flow, or
perennial flowing water
Photo Source: Rosgen 1996
PNW Forested Wetland
Community Types (Kunze 1994)
• Pinus contorta/Ledum
groenlandicum/Sphagnum spp.
• Pinus monticola/Ledum
groenlandicum/Sphagnum spp.
• Tsuga heterophylla/Ledum
groenlandicum/Sphagnum spp.
• Tsuga heterophylla/Sphagnum spp.
PNW Forested Bog
Community Types (Kunze 1994)
• Pinus contorta/Ledum
groenlandicum/Sphagnum spp.
• Pinus contorta-Thuja plicata/
Myrica gale/Sphagnum spp.
• Thuja plicata-Tsuga
heterophylla/Gaultheria
shallon/Lysichiton
americanum/Sphagnum spp.
• Tsuga heterophylla/Ledum
groenlandicum/Sphagnum spp.
Vegetation Communities
Associated with Organic Soils
Southern PNW (Oregon,
Washington, Idaho,
Montana, and southern
British Columbia)
Colonized by shrubs, herbs,
and sparse tree stands
• Lodgepole pine (Pinus
contorta)
• Western red cedar (Thuja
plicata)
• Western hemlock (Tsuga
heterophylla)
• Western white pine (Pinus
monticola)
• Sitka spruce (Picea
sitchensis)
Northern PNW (northern
British Columbia and Alaska)
Colonized by stunted tree stands
• Black spruce (Picea mariana)
• Tamarack (Larix laricina)
• Western hemlock (Tsuga
heterophylla)
• Lodgepole pine (Pinus contorta)
• Alaska cedar (Chamaecyparis
nootkatensis)
• Western red cedar (Thuja
plicata)
• Sitka spruce (Picea sitchensis)
• Mountain hemlock (Tsuga
maertensiana)
Vegetation Associated with Mineral
Soils Southern PNW
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Western hemlock (Tsuga heterophylla)
Western red cedar (Thuja plicata)
Sitka spruce (Picea sitchensis)
Lodgepole pine (Pinus contorta)
Black cottonwood (Populus balsmifera)
Red alder (Alnus rubra)
Paper birch (Betula papyrifera)
Oregon ash (Fraxinus latifolia)
Quaking aspen (Populus tremuloides)
Vegetation Communities
Associated with Mineral Soils
Northern PNW
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Black spruce (Picea marina)
Tamarack (Larix laricina)
Lodgepole pine (Pinus contorta)
White spruce (Picea glauca)
White/Engelmann spruce
(Picea engelmanii)
Balsam poplar (Populus balsamifera)
Quaking aspen (Populus remuloides)
Paper birch (Betula papyrifera)
Alaska Paper birch
(Betula neoalasana)
PNW Forested Wetland Soils
Organic Soils
• Develop under prolonged
saturated conditions
• Histosols (peat, muck, or
mucky peat)
• Gelisols (permafrost or
gelic materials 1m bgs)
• Organic carbon content of
12 to 18% or more organic
carbon
• Limited to depressions and
alluvial fans in southern
PNW (range from 0.5 to
250 ha in size)
• Large expanses on flat or
sloping terrain in NE
British Columbia and
Central/SE Alaska (range
from 5 to 800 ha in size)
Mineral Soils
• Majority of forested wetlands associated
with mineral soils (southern PNW)
• Alluvial floodplain, mountainside, hillside
seeps, depressions
• Fine grain clay loam/silty clay
loam/gravelly sandy loam, often with a
layer of decomposed organic material
• Support more diverse forested community
Hydrologic Characteristics
Not much is known!
o Information on coastal forested
water balances is primarily from
British Columbia
o Undisturbed watershed rainfall data is
available for the Cascade Mountains in
Oregon
o The hydrology of small forest streams has been intensively
studied in western Oregon.
o Alaskan water balances indicate that rainfall exceeds
evapotranspiration and that permafrost impedes drainage,
so most of the state would be considered wetland.
Recharge and discharge functions of wetlands near Juneau
have been examined
PNW Forested
Wetland Wildlife
Overall:
Little research has been conducted on characterization of
wildlife (amphibians, birds, mammals, fish) habitat
associations in PNW forested wetlands.
Forested wetlands often provide unique habitat features
required by many wildlife species:
• Large diameter trees
• Complexity Vegetation
• Snags
• Organic litter
• Downed wood
• Food
• Cover
 Matthew G. Hunter
Amphibians of PNW Forested
Wetlands
Overview:
No studies in the PNW have specifically investigated amphibian
association with forested wetlands.
Forest and Fish designated species:
H. Welsh
o Tailed Frog (2 species)
• Rocky mountain tailed frog
• Pacific tailed frog
 W. P. Leonard
o Seep or Torrent Salamander (3 species)
 W. P. Leonard
• Cascade torrent salamander
• Columbia torrent salamander
• Olympic torrent salamander
 W. P. Leonard
 W. P. Leonard
o Van Dyke’s Salamander
o Dunn’s Salamander
 Matthew G. Hunter
Birds of PNW Forested Wetlands
Overview:
No studies in the PNW have specifically investigated avian
communities associated with forested wetlands.
o 367 species found in OR and WA
• 72% use freshwater riparian and wetland habitats (all classes)
o 77% of all inland birds breed in riparian and wetland
environments
• 103 species closely associated
• 89 species generally associated
o Bird presence is strongly associated with habitat features
Preferred Habitat Features for Birds
Preferred Habitat Features*:
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Large dominant trees
Mixed tree species composition
Multi-layered canopy
Irregular crown structure
Patches of dense foliage
Large standing dead wood
Abundant woody debris on forest
floor
 *inferred from uplands
Photo Source: Knopf 1995
Mammals of PNW
Forested Wetlands
o PNW contains 156 species of mammals
o Greater than 50 species breed and feed in Montane
Coniferous Wetlands
o Greater than 60 species breed and feed in Western
Riparian Wetlands
o 70 species breed and feed in eastern Riparian
Wetlands
Mammals of PNW
Forested Wetlands
o There is little information on characterizing the life
history of most riparian and forested wetland
habitat obligate mammals
o Mammals use riparian and wetland sites for:
• Breeding
• Feeding
• Cover
o Aquatic habitat features most important in arid
environments
Fish Associated with PNW
Forested Wetlands
o 5 species of Pacific salmon and 3 species of anadromous trout utilize
streams and rivers in PNW
o Little is known about about salmonids’ relationships with forested
wetlands
Effects of Forest Management on
PNW Forested Wetlands
Overall:
Forest management effects on PNW forested
wetland function is virtually unresearched.
Categories:
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Vegetation
Soil
Hydrology
Wildlife
Effects of Forest Management on
Vegetation Communities
o Change in vegetation
community
o Reduces:
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Species richness
Genetic variability
Functional diversity
Structural diversity
Effects of Forest Management on
Soil Characteristics Include:
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Soil Compaction
Disruption of Forest Duff
Erosion
Alteration to Organic Soils
Frozen Soils
Soil Compaction Associated with
Harvest Include:
o Increases in bulk density
o Increases in erosion
o Increases in competition with weedy
species
o Decreases in air-filled porosity
o Decreases in infiltration rates
o Decrease in hydrologic conductivity
o Reduction in tree regeneration
o Changes in landscape hydrology
o Higher soil compaction when soil is
saturated
• McNabb et al. (2001) researched
affects of logging traffic on soil
and soil wetness on porosity and
bulk density
• Colin and van den Driessche
(1996) Laboratory study of soil
compaction and lodgepole pine,
Douglas fir and white spruce
reduced uptake of nutrients and
metals
• Bulmer (1998) Remediation
treatments to improve stripped,
compacted soils associated with
logging:
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tillage
mulches
revegetation
micobes
Soil Compaction Associated with
Harvest Include cont…..
• Disruption of forest duff that is an important
rooting medium or mulch layer
• Harvest Activities that reduce, spread, or
mix duff layer
• Decreases in soil physical, chemical, and
biological processes, and reduces soil
productivity and stability
• Impacts to tree regeneration
• Establishment of less-desirable pioneering
species (red alder, paper birch, black
cottonwood, balsam cottonwood)
• Disruption of soil macropores by moving
organic matter, clays, and sequioxides,
reducing rainwater infiltration and soil
aggregation
• Erosion
• Loss of topsoil that is
redeposited downslope,
resulting in areas of increased
productivity and also exposed
subsoil with lower productivity
• Most erosion immediately
following disturbance
• All the above is related to soil
types and degree of
disturbance
Alteration to Organic Soils
• Organic soils provide a wet
but partially-aerated surface
layer
• Ruts disrupt horizontal and
vertical flow of water through
surface layer
• Summer harvesting can cause
deep water-filled ruts
• Winter harvesting with
rubber tires reduced ruts and
disruption of duff/vegetation
• Harvest can change surface
or near surface hydrology and
runoff or drainage patterns
• Drainage can decompose and
oxidize organic soil causing
subsidence of soil surface and
increased nutrient load in
runoff
• Increases in water tables may
alter PFO vegetation,
converting it to a shrub or
herbaceous -dominated
wetland.
• Loss of phosphorus and
potassium
Effects of Forest Management on
Frozen Soils
o Frost is found from the ground surface to 15-60 cm bgs in
wetland soil
o Winter logging results in less environmental damage to soil
layers and microtopography
o Caution:
• Early winter logging or heavy snow cover can minimize depth of
freezing and leave soil fragile
• Vegetation removal may thaw permafrost and result in soil
subsidence, cryoturbation, or flooding
Effects of Forest Management on
Hydrology
There is Little or no peer
reviewed research on
forested wetland hydrology
or FM effects.
o Hydrology changes are
related to:
• Vegetation removal
(decreased transpiration)
• Rutting
• Soil compaction
• LWD removal
o Studies of pre/post harvest
hydrology are needed
Effects of Forest Management on
Forested Wetland Wildlife Habitat
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Birds
Amphibians
Mammals
Fish
Photo Source: Neiring 1985
Effects of Timber Management
on Birds
Little research on TM effects
on Forested Wetland Birds
o Effects of harvest are
varied and depend on:
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Species characteristics
Preharvest vegetation
Type of harvest intensity
Timing
Successional phase
o Birds requiring late successional
characteristics may be displaced
following TM
o TM may decrease:
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Bird density
Bird diversity
Nesting substrate
Simplify vegetation structure
o TM may increase:
• Habitat fragmentation
• Nest predation
Effects of Timber Management
on Birds
Selective harvest may benefit
avian communities when:
• Stands are allowed
to mature
• Coarse woody debris
accumulates
• Habitat components
are replaced
Photo Source: Niering 1985
Effects of Timber Management on
Forested Wetland Mammals
There has been Little research
on TM effects on forested
wetland mammals
o Most research studies riparian
zones
o Effects of harvest are varied
and depend on:
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Species characteristics
Preharvest vegetation
Type of harvest intensity
Timing
Successional phase
Photo Source: Niering 1985
o Mammals adapted to forested
wetlands may be displaced
following TM
o TM may decrease:
• Mammal density
• Mammal diversity
• Simplify vegetation structure
o TM may increase:
• Habitat fragmentation
Effects of Timber Management
on Amphibians
Little research on TM effects
on Forested Wetlandassociated amphibians
o TM influence appears to vary
with harvest type and species
affected
o TM can displace amphibians
by disrupting life cycle
requirements through:
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Sedimentation of egg sites
Increased water temperature
Soil compaction
Hydrologic changes
o In upland sites:
• Control sites had 3.5 times the
amphibians as clear-cut sites
• Species richness has shown high
variability
• Thought to reflect amphibians, close
association with habitat requirements
like CWD and structural components
o Amphibians may benefit from
alternative timber management
practices:
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Retaining CWD
Litter depth
Large trees
Canopy closure
Soil moisture
Effects of Timber Management
on Fish
o In riparian communities TM
affects fish by:
• Increasing water temperature
• Siltation
• Altering prey species
composition
• Decreasing large woody debris
• Decreasing LWD inputs
There has been little research
done on TM effects on forested
wetland associated fish
o Pess et al. (2002) studied
distribution of salmon and
land use patterns in PNW
• Significant correlation between
land use and salmon abundance
• Wetlands had consistent positive
correlations to spawner
abundance
Conclusions and Future Research
• Conclusions:
o Little information is published
on PNW forested wetland
characterization and wildlife
associations
o Little research has been
published regarding Timber
Management’s effect on PNW
forested wetland hydrology,
vegetation changes, soils, and
wildlife.
o Most literature discussed is
based on upland communities,
riparian communities, or
forested wetlands in other
regions.
PNW Forested Wetland
Research Needs:
• Characterize PNW forested
wetland hydrology, soils, and
wildlife associations
• Investigate how different TM
practices effect vegetation
change, hydrology, soils and
wildlife associations in the
PNW.
How to Find
the References?
Products of this research include:
o Annotated Bibliography (701 references)
o Synthesis paper (summary of current knowledge)
o Slide show
All can be found (by June?) as PDF files at:
Cookescientific.com
Published by:
Washington State Department
of Natural Resources