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The Relationship Between Forest Management and Forested Wetland Ecology

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Title: The Relationship Between Forest Management and Forested Wetland Ecology


1
The Relationship Between Forest Management and
Forested Wetland Ecology
  • A review of current literature
  • Sarah Spear Cooke, Ph.D., Cooke Scientific
    Services, Inc., Seattle, WA 98115

2
WA State Forest Practices Act
  • Under the Forest Practices Act in Washington
    State, Type 3 waters are defined as having lt 1
    acre of open water at low water and an outlet to
    a stream containing anadromous fish, or being
    between 0.5 and 1 acre of water at low water
    Type 5 waters are wetlands without open water.
  • The Forest Practices Act provides very little
    protections for Type 4 and 5 waters.
  • The Forest Practices Act allows for logging to
    the edge of Type 2 and 3 waters.

3
General Literature Trends
  • The literature emphasizes timber managements
    effect on
  • Upland forest (forest seral stagesold growth)
  • Wildlife habitats
  • Riparian wildlife habitats
  • Wildlife use
  • In some cases, forested wetland environments are
    grouped with riparian characterizations.
  • Little information is published on forested
    wetlands, their associated hydrology, their
    associated soils, their wildlife habitat
    associations, and secondary timber management
    effects.

4
Standard Forest Management Practices
  • Logging removing trees (including clearfelling
    and cable logging)
  • Constructing roads
  • Site clearing (including snagging)
  • Planting
  • Thinning
  • Slashing (burning slopes after logging), or
    suppressing fire
  • Draining wetlands to increase merchantable timber
    production
  • Grading hillslopes
  • Adaptive Ecosystem Management Creating old
    growth conditions by thinning trees, creating
    snags and downed logs, and introducing fungi

5
Hydrology-
Characterization
  • Information exists on coastal forested
    water balances from British
    Columbia (Sagar 1995).
  • Undisturbed watershed rainfall data is available
    for the Cascade Mountains in Oregon (Martin and
    Harr 1988).
  • Harr (1975) characterized the hydrology of small
    forest streams in western Oregon.
  • Alaskan water balances indicate that rainfall
    exceeds evapotranspiration and that permafrost
    impedes drainage, so most of the state would be
    considered wetland (Ford and Bedford 1987).
    Recharge and discharge functions of wetlands near
    Juneau have been examined by Siegel (1988).

6
Impacts from forest management
Hydrology-
  • Increasing peak flow (Beschta et al. 2000, Jones
    and Grant 1996, Harr, Harper and Krygier 1975).
  • Disrupting surface and groundwater drainage
    patterns through road construction.
  • Reducing groundwater exchange by filling springs,
    compacting soils, and generally reducing points
    of recharge and discharge (Canning and Stevens
    1990).
  • Reducing baseflow through the introduction of
    early successional species, such as cottonwoods,
    which utilize more water and lose it through
    evapotransp. (McKee 1994).
  • Increasing water level fluctuation in watersheds
    with less than 14 forested area (Taylor 1993).

7
Future research needs?
Hydrology-
  • Basic, descriptive, inter-disciplinary
    pre-/post-harvest wetland studies using a block
    design. This has worked decently in some eastern
    studies (Courtesy of Rhett Jackson)

8
Characterization
Water Quality-
  • Water quality information is available for all
    western states in the National Water Summary
    1990-1991 (USGS 1994).
  • Coarse sediments have been found to be trapped in
    ephemeral streams and associated flow-through
    wetlands. (Duncan et al. 1987).
  • Annual dust inputs and associated N and P
    deposition from dust have been measured in Oregon
    Cascade Ranges.
  • N and P budgets including inputs and outflows
    were also determined (Fredriksen 1975).
  • Streamwater chemistry data is available for
    undisturbed watersheds in the Cascades of Or.
    (Martin and Harr 1988).
  • Naimann (1982) has characterized the sediment and
    organic carbon export from pristine boreal forest
    watersheds.

9
Impacts from forest management
Water Quality-
  • Loss of water quality filtering.
  • Fertilizer runoff.
  • Nutrient release from clear cuts.
  • Fine sediment release from logging
    roads.
  • Rutting from yarding within the wetland.
  • Slash deposition from harvest within wetland.
  • Loss of shading (temperatures increase in summer
    and decrease in winter (Canning and Stevens
    1990).
  • Loss of LWD to trap sediments organics allows
    for restricted movement out of wetland (McKee
    1994).
  • Destabilized banks through the loss of trees
    (McKee 1994)

10
Water Quality-
Future research needs?
  • Short-term effects of silviculture on light and
    temperature in wetlands and streams (Gray 2000)
  • Measuring and predicting fine sediment resulting
    from different forest practices (Hall et al.
    2000)
  • Tree density needed to protect hydrology and
    water quality
  • Buffer strip widths and planting treatments
    needed to protect hydrology and water quality
  • Effects of road closure on water quality
  • Assessing sediment routing at the drainage basin
    scale in order to understand delivery of sediment
    from side scars, road surfaces, and other
    sources.

11
Characterization
Vegetation-
  • Description of old growth, young and middle-aged
    forest west and east of the Cascades (Johnson et
    al. 1994, Bingham and Sawyer 1991, brown et al.
    1979, halpern and Spies 1995, Hibbs and Bower
    2001, Spies 1991).
  • Mixed coniferous/deciduous, coniferous, hardwood
    bottomlands and wetlands (willow, alder,
    cottonwood, and ash) (Dixon and Johnson 1999,
    Frenkel and Heinitz 1987, Kovalchik,et al. 1988,
  • Kunze 1994, Mckenzie and Halpern 1999,
    Nierenberg and Hibbs 2000, Pabst and Spies 1999).
  • Primary production in the Oregon Cascades
    (Gregory 1976).

12
Impacts from forest management
Vegetation-
  • Direct effects
  • Vegetation removal (trees logged and shrubs and
    herbs graded out). Forest harvesting reduces the
    functional and structural diversity or forest and
    wetland ecosystems (Canning and Stevens 1990)
  • Weed invasion that suspends succession,
    especially reed canarygrass (Phalaris
    arundinacea) and Himalayan blackberry (Rubus
    armenicus) (Canning and Stevens 1990).
  • Drainage of wetlands for timber production
    (Canning and Stevens 1990)

13
Impacts from forest management
Vegetation-
  • Direct effects cont.
  • Loss of species diversity due to selective
    cutting (Canning and Stevens 1990).
  • Loss of buffer, which reduces the edge effect and
    decreases overall wetland/buffer species
    diversity (Canning and Stevens 1990).
  • Compaction of soils, which reduces the
    reproductive ability in trees in wetlands due to
    stress of flooding and associated asexual
    reproductive strategies (Canning and Stevens 1990)

14
Impacts from forest management
Vegetation-
  • Indirect effects
  • Deposition of LWD that changes stream channel
    configuration and results in changes in the
    hydrologic regime and shifts in the vegetation
    (Reeves et al. 1995 and Benda and Dunne 1997).
  • Suspension of succession by weeds (DeFerrari et
    al.1994).
  • Overloading wildlife populations by reducing
    their habitat, and increasing herbivory (Canning
    and Stevens 1990).
  • Selective cutting of species, which reduces
    species richness and decreases gene exchange and,
    therefore, genetic variability.

15
Vegetation-
Future research needs?
  • Identify the forest practices that cause
    significant hydrologic changes and determine if
    vegetation shifts are occurring as a result of
    these changes.
  • Look at the relative natural abundance of
    conifers vs. hardwoods along streams (Nierenberg
    1996).
  • Loss of forested wetland acreage little is
    known about losses to logging, although much is
    known about loss to agriculture and coastal
    conversions (Canning and Stevens 1990).

16
Soils-
Characterization
  • Mineral (sand, silt, loam) vs. organic (peat,
    muck, diatomaceous earth).
  • Have highly variable erosion characteristics.
  • Soil carbon and nutrients have been evaluated in
    coastal Oregon Douglas fir plantations with and
    without red alder additions (Cromack et al.
    1999).
  • Soil N cycling was evaluated in western Oregon
    forest soils by Perry and Choquette (1987) and
    Swanston and Myrold (1997).
  • Soils in Washington and Oregon east of the
    Cascades have been characterized by Harvey et al.
    1994), McNabb et al. 1985.
  • Slope failure due to soils with poor cohesive
    properties has been identified by (Schroeder and
    Brown 1994).
  • Soils and areas prone to debris slides and other
    mass failure processes are identified in Swanson
    et al. (1987).

17
Impacts from forest management
Soils-
  • Compaction.
  • Puddling, causing rutting in tracks 6 inches deep
    or more.
  • Displacement (loss of 50 percent or more of
    surface horizons).
  • Mass failures, especially rapid debris slides
    that produce sediment (Swanson et al. 1987,
    Sedell and Beschta 1991).
  • Repeated landslides over time after forest
    management and road construction (Swanson et al.
    1982, 1987 in Gray 2000). Slide areas often had
    smaller trees due to logging and salvage
    activities
  • Uneven aged management causes an increase in soil
    damage (Harvey et al. 1994.)

18
Soils-
Future research needs?
  • Developing techniques that locate soils and sites
    susceptible to accelerated erosion.
  • Mitigation measures for disturbed areas that are
    displaying accelerated erosion.

19
Wildlife-
Characterization
Fish
  • WA Stream Atlas describing fish use dates from
    the 70s.
  • Salmonid stocks associated with old-growth
    forests in the PNW have been catalogued
    (Marcot 1997).

20
Wildlife-
Impacts from forest management
Fish
  • Migratory impediments from LWD deposition after
    logging, loss and degradation of freshwater and
    estuarine habitats due to logging and road
    construction, causing repeated landslides
    (Nehlsen et al. 1991, FEMAT 1993 ).
  • Salmonid stocks associated with old-growth
    forests in the PNW have been catalogued (Marcot
    1997).
  • Altering the input of fine-scale organic inputs
    into streams during the winter that provide
    primary production for the aquatic community
    (McKee 1994).

21
Wildlife-
Impacts from forest management
Fish cont.
  • Forestry-related mortality was associated mostly
    with increased sediment load and alterations in
    the riparian environment that reduce refuge
    habitat during winter storms (Cederholm and Reid
    1987).
  • The overall effect of decreased large woody
    debris (Grette 1985, Bilby and Ward 1991), more
    sediment (Everest et al. 1987 and others), and
    more frequent channel forming flows (Chamberlain
    et al. 1991) has been simplified stream habitat
    (Hicks 1991).
  • Sediment increase from adjacent logging affects
    salmonid reproductive success (Chapman 1988 and
    Kondolf 1988).

22
Wildlife-
Impacts from forest management
Fish cont.
  • The general response of alluvial channels to
    widen and become shallow with higher sediment
    loads decreases rearing space available for
    salmonids during the summer growing season.
  • Indirect habitat changes such as redistribution
    of LWD and change in channel geometry are
    long-lasting effects. Immediate effects include
    frequency and depth of streambed scour, attendant
    loss of incubating eggs (Poulin and Tripp 1986),
    and displacement of juveniles.

23
Wildlife-
Characterization
Amphibians
  • 33 species of amphibians are known to occur in
    Washington and Oregon (Leonard et al. 1993).
  • Requirements for breeding habitat, foraging
    habitat, foraging areas, cover, reproductive
    sites, and habitat for aquatic larvae have all
    been characterized (Irwin et al. 1989, Bury et
    al. 1991 in OConnell 1995).

24
Wildlife-
Impacts from forest management
Amphibians
  • Increased sedimentation often fills rock cracks
    and crevices used by some amphibians for egg
    laying (Corn and Bury).
  • Loss of habitat.
  • Amphibians decline as a result of clear-cutting
    (Raphael 1998 in OConnell et al. 1995, Bury 1983
    and OConnell et al. 1995).
  • Loss of LWD that provides habitat for Pacific
    Giant salamanders (Kauffmann et al. 2001).
  • Numerous authors have indicated that removal of
    the forest overstory has resulted in decline or
    disappearance of tailed frogs (Kauffmann et al.
    2001 and others).

25
Fixes that protect and re-establish forested
wetland systems
  • Decommissioning and upgrading forest roads.
  • Leaving large woody debris (LWD) and allowing it
    to build up. Areas with LWD have been shown to
    have higher uptake of nitrate and phosphate per
    unit area than areas of just sand and gravel
    (Nicholas et al. 1990).
  • Protection of trees near streams, both
    intermittent and perennial (Sedell and Beschta
    1991).
  • Placing logs in streams to create pools and side
    channels.
  • Planting conifers in riparian stands (Sedell and
    Beschta 1991).

26
Fixes that protect and re-establish forested
wetland systems cont
  • Thinning existing trees to accelerate growth
    (Sedell and Beschta 1991).
  • Closing roads.
  • Partial logging with leave trees.
  • Increase woody vegetation along wetland and
    riparian edges (Larson and Larson 1996) to
    increase bank stability and stream debris and
    provide shade for temperature control (Beschta
    1991). The Oregon Department of Forestry
    requires 40 live conifer trees per 1,000 feet
    along large streams and 30 live conifer trees per
    1,000 feet along medium streams (Oregon Dept. of
    Forestry 1994).

27
Fixes that protect and re-establish forested
wetland systems cont
  • Keeping soil in place by avoiding grading and
    soil erosion
  • Minimizing practices that cause soil compaction
  • Minimizing loss of soil organic matter (no slash
    and burn)
  • Identifying erosion prone sites and limiting any
    forest practices in those areas
  • Predicting erosion rates and direct effects of
    debris flows, earth flows, and sediment on
    existing channels prior to logging a proposed
    timber production area
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