Pacific Northwest Research Station - Ecological Process & Function - Wildlife Ecology Team

Riparian Research Projects

Riparian Ecosystem Management Study (REMS)

Riparian zones are recognized as fundamentally important interfaces between aquatic and terrestrial ecosystems (Agee 1988; Gregory et al. 1991; FEMAT 1993). In addition to mediating the transfer of materials between land and water, riparian zones provide key habitat elements for many species of fish and wildlife. Virtually all aquatic species and many terrestrial plant and animal species closely associated with riparian zones are sensitive to management-induced changes in riparian condition (Thomas et al. 1979; Naiman et al. 1995). The way in which these species respond to anthropogenic disturbance is usually complex and strongly influenced by successional processes at a particular site (Hayes et al. 1996); therefore, it is often difficult to predict how a particular aquaticriparian ecosystem will change following a management activity. Recent studies have demonstrated a reduction in aquatic and terrestrial biodiversity in watersheds containing primarily young managed forests (Reeves et al. 1993; Thomas et al. 1993), and the emerging application of ecosystem-based forestry in the Pacific Northwest has embraced deliberate attempts to restore riparian areas to conditions more like those produced by natural processes (FEMAT 1993; Quigley et al. 1996).

Despite the acknowledged importance of riparian zones to fish and wildlife, relatively few studies have examined the response of riparian systems to active management alternatives for commodity production, riparian protection or restoration. The Coastal Oregon Productivity Enhancement (COPE) program in Oregon has initiated a number of investigations of riparian rehabilitation, chiefly involving the re-establishment of conifers in alder- and brush-dominated riparian zones (e.g. COPE Report, Vol. 9, No. 3, Aug. 1996), but similar research programs are only now beginning in the coastal areas of Washington (Berg 1995; and an unpublished Timber, Fish & Wildlife RMZ study). In addition to the challenge of re-establishing conifers in riparian zones dominated by deciduous trees or herbaceous vegetation, a number of other important questions exist pertaining to riparian management, e.g., what buffer widths and configurations are needed to protect fish and wildlife habitat along different stream types, what proportion of riparian zones should remain in different seral stages over larger landscape scales, whether acceleration of mature forest and old-growth conditions can be achieved through thinning and other silvicultural treatments in a cost-effective manner, and whether riparian vegetation can be deliberately managed for the benefit of certain aquatic or terrestrial wildlife species.

Management of streamside vegetation is a major component of the Northwest Forest Plan. Conservation objectives for riparian buffer systems include meeting habitat needs not only of fish but other aquatic and terrestrial organisms. As a preliminary effort in better understanding the importance of riparian buffers in supplying habitat of associated organisms, the team initiated a retrospective study of responses of aquatic and terrestrial organisms and processes to alternative streamside management options. The team has lead responsibility for the terrestrial component of this study and directs research on streamdwelling and streamside amphibians, small mammals, birds, and vegetation. The retrospective phase of this work includes existing sites with varying buffer width, varying buffer condition (old, mature, young forest), and management level within the buffer (thinned, unthinned). Results of retrospective studies will be presented through workshops, conferences, presentations at scientific meetings, and publication in peer-reviewed journals. The longer-term objective is to move into a more experimental approach with planned treatments to compare levels of active management within buffers using a before/after design. The Wildlife Ecology Team, again in cooperation with Pete Bisson with the Aquatic and Land Interactions program, has begun the pilot phase of such a study. We are working with the Washington Department of Natural Resources to determine the possible impacts and consequences of different management approaches on Type 5 (intermittent or non-fish bearing) streams in western Washington. During the summer of 2002, we are starting pre-treatment measurements on approximately 10 sets of Type 5 streams located on State Lands in western Washington. The study design will test the potential downstream impacts of different management approaches. The following key questions define the objectives of the study:

• How does timber harvesting effect Type 5 stream functions, i.e., sediment delivery, channel morphology, water chemistry, and changes in plant communities, water levels, and amphibian & invertebrate populations?

• What specific Type 5 stream functions should be protected and how will these be measured?

• What are the environmental consequences of options for protecting Type 5 stream functions within the scope of the WADNR Habitat Conservation Plan riparian management strategy?

The study design will impose a range of management configurations on adjacent Type 5 streams. The three buffer configurations that we would like to compare are, variable buffer widths, fixed widths, no buffers, and use an unmanaged stream as a control (Figure 2). We Wildlife Ecology Team Problem Analysis October 10, 2002 Page 8 of 33 will control treatments within the entire Type 5 stream basin (typically 4 to 12 Ha). Currently, we are studying the effects these buffer configurations have on discharge/water levels, sediment storage, invertebrates/amphibians, organic matter transport, changes in plant community, and water chemistry. Figure 2. Conceptualized configuration of Type 5 research sites established by Washington Department of Natural Resources

Team lead: Martin G. Raphael and Randall Wilk

Cooperators: Peter A. Bisson (PNW Research Station, ALI Program); Richard Bigely, Washington Department of Natural Resources; USGS Biological Resources Division, Olympic Natural Resources Center, Center for Streamside Studies, Olympic National Forest, US Fish and Wildlife Service, Simpson Timber Company, Crown Pacific Industries, Rayonier Timberlands.

USDA Forest Service - Pacific Northwest Research Station - Olympia Forestry Sciences Laboratory
Last Modified: Monday, 31 January 2011 at 16:52:52 EST