PARENT SESSION
Oral Session # 47: Rare, Threatened, and Endangered Species II: Mammals, Birds, Fish, and Insects.
Presiding: KE Sukkestad
Wednesday, August 6. 8:00 AM to 11:30 AM, SITCC Meeting Room 202.
A dynamic landscape approach to maintain and restore freshwater habitat for U.S. Pacific Northwest anadromous salmonids.
Benson, Gary*,1, Reeves, Gordie2, 1 USDA Forest Service, Portland, Oregon, USA2 USDA Forest Service, Corvallis, Oregon, USA
ABSTRACT- Populations of all Pacific salmon species (Oncorhynchus spp.) in the Pacific Northwest (PNW) of the United States are in need of special management consideration because of low or declining numbers. A major factor responsible for these declines is the loss of freshwater habitat quantity and quality. To preserve and recover these populations, both long- and short-term processes that create and maintain freshwater habitat must be protected and restored. Streams in the PNW are highly dynamic in space and time, and lack of consideration of their dynamic nature has limited the effectiveness of habitat management and recovery programs. Riverine-riparian ecosystems used by Pacific salmon are periodically subjected to large disturbance events. These ecosystems then move through a series of recovery states over time periods extending from decades to centuries. Large natural disturbance events such as wildfires, floods, and debris flows may result in the extirpation of local populations, followed by re-colonization from surrounding areas as more favorable conditions develop. Every stream in a watershed cannot be expected to have good habitat and abundant fish populations at all times. Rather, natural landscapes consist of a mosaic of patches in various successional stages, with conditions that are favorable or less favorable to Pacific salmon. Spatial and temporal configuration of successional stages will vary widely within river basins and across eco-regions. Over time, less productive streams can become more productive and streams with more favorable conditions can transition to less favorable conditions. Life-history attributes of Pacific salmon suggest that they are adapted to a dynamic environmment. The long-term cycles of aquatic ecosystems haven't been adequately addressed in current management schemes. Management regimes should be based on maintaining historical disturbance patterns and drainage systems to the extent possible, in order to provide a landscape context similar to the conditions in which salmonid populations evolved.
Key words: landscape management, disturbance ecology, northwest US freshwater ecosystems, Oncorhynchus spp.