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