Treesearch

'New requirements for evaluating environmental conditions in the Pacific Northwest have led to increased demands for interdisciplinary analysis of complex environmental problems. Procedures for watershed analysis have been developed for use on public and private lands in Washington State (Washington Forest Practices Board 1993) and for federal lands in the Pacific Northwest (REO 1995). In both cases, analyses are intended to provide integrated, interdisciplinary evaluations of the biological, physical, and socio-economic interactions that influence the ecoscape and to describe environmental...

Point counting has been widely accepted as a method for monitoring trends in bird populations. Using a rigorously standardized protocol at 210 counting stations at the San Joaquin Experimental Range, Madera Co., California, we have been studying sources of variability in point counts of birds. Vegetation types in the study area have not changed during the 11 years of the study, so annual variability in counts must refelect some normal range of variation associated with other factors. Here we show that counts of breeding species varied markedly from year to year, we suspect primarily in...

Biodiversity mapping (e.g., the Gap Analysis Program [GAP]), in which vegetative features and categories of land use are mapped at coarse spatial scales, has been proposed as a reliable tool for land use decisions (e.g., reserve identification, selection, and design). This implicitly assumes that species richness data collected at coarse spatiotemporal scales provide a first-order approximation to community and ecosystem representation and persistence. This assumption may be false because (1) species abundance distributions and species richness are poor surrogates for community/ecosystem...

Fishers (Martes pennanti) and American martens (M. americana) have been protected from trapping in California since the mid-1900s, yet in portions of each of their historic ranges their numbers are extremely low, perhaps due to the effects of timber harvest. We propose a method capable of detecting declines in the occurrence and distribution of fishers or martens using baited track-plate stations. The proposed sampling unit is a small grid of stations that has a high probability of detecting animals when they are present. These multistation units are sufficiently spaced to meet the...

We describe the current distribution of the American marten, Martes americana, in California based on field surveys conducted between 1989 and 1995 that used either sooted track-plates or cameras. The Sierra Nevada marten, M. a. sierrae, occupies much of its historic range from northwestern Shasta County to the southern Sierra Nevada. The Humboldt marten, M. a. humboldtensis, in Humboldt and Del Norte counties, is extremely rare or extinct. We recommend defining the current distributions of rare or secretive species by techniques that produce verifiable records rather than relying on...