The Relationship Between Forest Management and

Forested Wetland EcologyA review of current

literature

Sarah Spear Cooke, Ph.D., Cooke Scientific Services, Inc., Seattle, WA

98115

WA State Forest Practices Act

Under the Forest Practices Act in Washington State, Type 3 waters are defined as having < 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.

General Literature Trends

The literature emphasizes timber management’s effect on:

Upland forest (forest seral stages–old 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.

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

Hydrology-

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).

Characterization

Impacts from forest management

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).

Hydrology-

Future research needs?

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)

Hydrology-

Characterization

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.

Water Quality-

Impacts from forest management

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)

Water Quality-

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.

Water Quality- Future research needs?

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,

Vegetation-Characterizatio

n

Kunze 1994, Mckenzie and Halpern 1999, Nierenberg and Hibbs 2000, Pabst and Spies 1999).

Primary production in the Oregon Cascades (Gregory 1976).

Vegetation-

Impacts from forest management

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)

Vegetation-

Impacts from forest management

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)

Vegetation-Impacts from forest

management

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.

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).

Vegetation-Future research needs?

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).

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.)

Soils-Impacts from forest

management

Developing techniques that locate soils and sites susceptible to accelerated erosion.

Mitigation measures for disturbed areas that are displaying accelerated erosion.

Soils-Future research needs?

Wildlife-

WA Stream Atlas describing fish use dates from the 70’s.

Salmonid stocks associated with old-growth forests in the PNW have been catalogued (Marcot 1997).

CharacterizationFish

Wildlife-

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).

Fish

Impacts from forest management

Wildlife-

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).

Fish cont….

Impacts from forest management

Wildlife-

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.

Fish cont….

Impacts from forest management

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.

Wildlife-

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 O’Connell 1995).

Amphibians

Characterization

Wildlife-

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 O’Connell et al. 1995, Bury 1983 and O’Connell 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).

Amphibians

Impacts from forest management

“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).

“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).

“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