This archive contains data from the Aquatic Vertebrates and Habitats component of the Density Management and Riparian Buffer Study of Western Oregon. Data were collected for multiple purposes. The first aim was to characterize the instream habitats and vertebrate fauna of headwater stream ecosystems in stream reaches from study sites across Bureau of Land Management (BLM) and Forest Service lands in secondary forests of western Oregon. Data were collected to assess the extent of co-occurrence of fish and amphibians in headwater stream ecosystems, with some smaller streams likely being above the uppermost distribution of fishes. Headwater areas of Pacific Northwest forested watersheds had limited prior research to characterize small stream ecosystems. The second aim was to examine if and how different stream-riparian buffer widths within a thinned upland forest affected habitat attributes and the densities of aquatic vertebrate species. Some of those upland forest areas were managed according to other components of the study that tested heterogeneous stand density management practices, including the creation of circular leave islands (skips) and clearcut islands (gaps) within the thinned forest matrix. Skips and gaps were intended to accelerate the development of late-successional and old-growth forest conditions to sustain or restore native species associated with habitats of older forests. The U.S. federal Northwest Forest Plan established two Riparian Reserve widths, a two tree-height buffer for fish-bearing streams, and a one tree-height buffer for non-fish-bearing streams. These buffers were conceptually supported by earlier science but had not yet been explicitly field tested. For the second aim, the one tree-height and two tree-height buffers would be tested against two narrower alternative buffer treatments, variable width and streamside, to compare their efficacy.
Data for this project include the field-collected instream-habitat attributes and aquatic vertebrate species occurrences that were analyzed for this Before-After-Control-Impact experiment conducted in western Oregon from 1994 to 2023. Habitat attributes include parameters such as unit width, length, and depth, substrate composition, and down wood occurrence by log diameter within the wetted stream prism. There were 4 fish taxonomic groups and 13 amphibian species identified over the course of the study across all sites and stream reaches sampled, although several taxa occurred at low density and were not analyzed for buffer treatment effects owing to insufficient sample sizes. Data reflect changes in some aspects of the study design over the course of the study. Before-treatment data were collected and analyzed for 106 stream reaches across 12 study sites. Data contained in this package are compiled separately per habitat component (available habitat type, sampled habitat type, down wood, and substrate) or species occurrence (instream, streambank, or upslope), recorded at each time step, site, reach, unit, etc. The full data set is provided in a Microsoft Access database as well as individual comma-separated values files along with documents providing detailed information about the sites, sampling methods, and data variables. Final derived data and supplemental information used in the most recent analysis are also provided.As one component of a broader study, these data were collected to investigate aquatic-dependent vertebrates (fish and amphibians) in and along headwater streams in managed forests of western Oregon.For more information about this study and these data, see Olson et al. (in prep).
