United States Department of A Landscape Plan Based on Agriculture Forest Service Pacific Northwest Historical Fire Regimes for a Research Station General Technical Managed Forest Ecosystem: Report PNW-GTR-422 May 1998 the Augusta Creek Study John H. Cissel, Frederick J. Swanson, Gordon E. Grant, Deanna H. Olson, Stanley V. Gregory, Steven L. Garman, Linda R. Ashkenas, Matthew G. Hunter, Jane A. Kertis, James H. Mayo, Michelle D. McSwain, Sam G. Swetland, Keith A. Swindle, and David O. Wallin Young Mature Old 1600 AD 1800 AD 1995 AD 2195 AD Authors JOHN H. CISSEL is the Cascade Center research coordinator, JAMES H. MAYO is a silviculturist, MICHELLE D. McSWAIN is a hydrologist, and SAM G. SWETLAND is a fire and fuels specialist, Blue River Ranger District, P.O. Box 199, Blue River, OR 97413; FREDERICK J. SWANSON is an ecosystem team leader, GORDON E. GRANT is a research hydrologist, and DEANNA H. OLSON is a research biologist, Forestry Sciences Laboratory, 3200 SW Jefferson Way, Corvallis, OR 97331; STANLEY V. GREGORY is a professor, LINDA R. ASHKENAS is a research associ- ate, and KEITH A. SWINDLE is a faculty research assistant, Oregon State University, Department of Fisheries and Wildlife, Nash Hall, Corvallis, OR 97331; STEVEN L. GARMAN is an assistant professor and MATTHEW G. HUNTER is a wildlife ecolo- gist, Oregon State University, College of Forestry, Forest Science Department, Corvallis, OR 97331; JANE A. KERTIS is an ecologist, Siuslaw National Forest, Corvallis, OR 97339; and DAVID O. WALLIN is an assistant professor, Huxley Col- lege of Environmental Studies, Western Washington University, Bellingham, WA 98225. Abstract Cissel, John H.; Swanson, Frederick J.; Grant, Gordon E.; Olson, Deanna H.; Stanley, Gregory V.; Garman, Steven L.; Ashkenas, Linda R.; Hunter, Matthew G.; Kertis, Jane A.; Mayo, James H.; McSwain, Michelle D.; Swetland, Sam G.; Swindle, Keith A.; Wallin, David O. 1998. A landscape plan based on historical fire regimes for a managed forest ecosystem: the Augusta Creek study. Gen. Tech. Rep. PNW-GTR-422. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 82 p. The Augusta Creek project was initiated to establish and integrate landscape and watershed objectives into a landscape plan to guide management activities within a 7600-hectare (19,000-acre) planning area in western Oregon. Primary objectives included the maintenance of native species, ecosystem processes and structures, and long-term ecosystem productivity in a federally managed landscape where substantial acreage was allocated to timber harvest. Landscape and watershed management objectives and prescriptions were based on an interpreted range of natural variability of landscape conditions and disturbance processes. A dendrochro- nological study characterized fire patterns and regimes over the last 500 years. Changes in landscape conditions throughout the larger surrounding watershed due to human uses (e.g., roads in riparian areas, widespread clearcutting, a major dam, and portions of a designated wilderness and an unroaded area) also were factored into the landscape plan. Landscape prescriptions include an aquatic reserve system comprised of small watersheds distributed throughout the planning area and major valley-bottom corridor reserves that connect the small-watershed reserves. Where timber harvest was allocated, prescriptions derived from interpretations of fire regimes differ in rotation ages (100 to 300 years), green-tree retention levels (15- to 50- percent canopy cover), and spatial patterns of residual trees. General prescriptions for fire management also were based on interpretations of past fire regimes. All these prescriptions were linked to specific blocks of land to provide an efficient transition to site-level planning and project implementation. Landscape and watershed conditions were projected 200 years into the future and compared with conditions that would result from application of standards, guidelines, and assumptions in the Northwest Forest Plan prior to adjustments resulting from watershed analyses. The contrasting prescriptions for aquatic reserves and timber harvest (rotation lengths, green-tree retention levels, and spatial patterns) in these two approaches resulted in strikingly different potential future landscapes. These differences have significant implications for some ecosystem processes and habitats. We view this management approach as a potential postwatershed analysis implementation of the Northwest Forest Plan and offer it as an example of how ecosystem management could be applied in a particular landscape by using the results of watershed analysis. Keywords: Landscape ecology, landscape management, landscape planning, fire history, range of historical variability, watershed analysis, fire ecology. Summary There is a growing awareness that to sustain human uses of an ecosystem, the ecosystem itself must be sustained. For the public forest lands considered here, we Introduction interpreted the goal of sustaining ecosystems to mean maintaining native species, ecosystem processes and structures, and long-term ecosystem productivity. In the Augusta Creek project, we developed a landscape plan to achieve these goals based on historical disturbance regimes and landscape conditions. A premise of this ap- proach is that native species have adapted to the range of habitat patterns resulting from historical disturbance events, and the probability of survival of these species is reduced if their environment is maintained outside the range of historical conditions. Similarly, ecological processes, such as nutrient and hydrologic cycles, have histori- cally functioned within a range of conditions established by disturbance and succes- sional patterns. Management activities that move structures and processes outside the range of past conditions may adversely affect ecosystems in both predictable and unforeseen ways. Another key component of our management approach recognized that existing conditions must be integrated with this historical template to meet long- term objectives. Human uses have substantially altered conditions in the project area and in the surrounding watersheds. Phase 1—Analysis A fire history study of the last 500 years revealed the fire patterns within the planning of Conditions, area. Plot-level data were used to map 27 of these fire events. The fire-event maps Processes, and Uses and field observations were used to describe and map characteristic fire frequencies, severities, and spatial patterns of nine general fire regimes. The fire-event maps also were used to reconstruct and analyze vegetation patterns within the same 500-year period. Several approaches were used to analyze the aquatic ecosystem and hillslope-to- stream disturbances. Landslide and debris-flow occurrences and relative potential for future occurrences were interpreted from aerial photographs, maps of existing condi- tions, and field surveys. Relative susceptibilities of the watershed to rain-on-snow peak flows and contributions to summer baseflows were assessed. A time-series of aerial photographs spanning the past 40 years were used to assess riparian vegeta- tion dynamics and disturbance history. Both prehistoric and contemporary human uses were described and mapped. Pre- historic and historical data for the general area were employed to construct a prob- ability-of-past-use map and narrative. Current human uses include hiking (two trails), camping (three campgrounds), angling, hunting, and harvest of timber and special forest products. Phase 2—Landscape In the first step, “special area reserves” allocated in the Willamette National Forest Plan Plan, as amended by the Northwest Forest Plan, were delineated. Prescriptions for these areas generally entail a “natural” succession approach. Prescribed natural fires were encouraged where feasible. The remainder of the planning area was then subdivided into zones with similar ecological conditions and disturbance regimes, termed “landscape areas.” General prescriptions were developed for each area based on the fire regime and the condi- tion of the vegetation. Rotation ages (100 to 300 years) were derived from fire fre- quency information, green-tree retention levels (15 to 50 percent) were based on fire severity interpretations, and guidelines for patch size came from historic fire and patch size analyses. Prescriptions for low-intensity fires were derived from fire regime descriptions and integrated with timber harvest patterns and schedules. In the third step, “aquatic reserves” were established to ensure that the full range of objectives in the Northwest Forest Plan would be met, with particular attention given to the Aquatic Conservation Strategy (USDA and USDI 1994). These reserves were based, in part, on the type and intensity of upslope management in the local land- scape area and were designed to reflect general patterns of disturbance processes. Small-watershed reserves were positioned throughout the basin, such that different habitat types and topographic-disturbance regions were represented in headwater, midbasin, and lower portions of the drainage, and such that species of concern (e.g., torrent salamanders [Rhyacotriton spp.]) were protected. Areas of high stream- drainage density and headwall areas were favored for reserve placement. Steep, unstable areas with simple drainage patterns and long debris flow runouts also were placed in reserves, as were two unstable hillslope areas. Aquatic reserves also included large