Paired watershed studies provide valuable scientific understanding of the effects of disturbance on aquatic resources. Geographic information system (GIS) tools, combined with principal components and cluster analyses, were used to develop a landscape classification of forested headwater basins in order to support these paired watershed studies. Spatial and statistical analyses were applied to landform, geologic texture, forest cover, and climate variables that describe the biophysical and climatic setting of forested headwater catchments (300 – 58,000 km2) in western Oregon. Cluster analysis isolated 5 groups that account for major differences in environmental conditions across the landscape, but have a large ratio of among to within group dissimilarity. The first and second principal component axes correlate most strongly to differences in slope and elevation, and the percent coniferous tree cover and past harvest, respectively.
This research investigates the direct and downstream impacts of clearcut harvest units on stream temperature as a part of the Hinkle Creek Paired Watershed Study. The experimental design for the study was a Before-After-Control-Impact (BACI) design. Maximum daily stream temperatures (MDST) were analyzed for the four treatment streams for one year before and one year after harvest. The impact of timber harvest on MDST is small when compared to the spatial (between-stream) variation in MDST and this impact decreased downstream. At 300 meters, nominally, downstream of the harvest units the impact of timber harvest on MDST was not statistically significant for two streams and only moderately statistically significant for the other two streams. Stream velocity, discharge, and groundwater advection in the streams downstream of the harvest units were quantified using dye tracer dilution techniques. The One-dimensional Transport with Inflow and Storage (OTIS) model was used to quantify longitudinal dispersions, transient storage volumes, storage transfer rates, and hyporheic residence times in four 75 meter reaches in each of the four treatment streams. Latent heat, Sensible heat, Longwave Radiant heat and Photosynthetically Active Radiation (PAR) were calculated for August 7-17, 2006 at the center of the 300 meter study reach in Russell Creek.
Stream temperature is a water quality parameter that directly influences the quality of aquatic habitat, particularly for cold-water species such as Pacific salmonids. RMAs that contain overstory merchantable conifers are not required for small non-fish-bearing streams in Oregon, thus there is potential for increases in stream temperature to occur in headwater streams and concern that increases in stream temperatures and changes to onsite processes in these streams may propagate downstream and impair habitat in fish-bearing streams. The objectives of this work are to assess the effects of contemporary forest management practices on stream temperatures of small non-fish-bearing headwater streams and to develop new knowledge regarding the physical processes that control reach-level stream temperature patterns. Summer stream temperatures were measured for five years in six headwater streams in the Hinkle Creek basin in southern Oregon. After four years, four of the streams were harvested and vegetated RMAs were not left between the streams and harvest units. The watersheds of the two remaining streams were not disturbed. Post-harvest stream temperatures were monitored for one year in all six streams. Each harvested stream was paired with one unharvested stream and regression relationships for maximum, minimum and mean daily stream temperatures were developed.
Mark-recapture methods were used to examine watershed-scale survival rates of coastal cutthroat trout (Oncorhynchus clarkii clarkii) from two headwater stream networks located in the foothills of the Cascade Mountain Range, Oregon. Differences in survival were explored among spatial (stream segment, stream network [main stem or tributaries], and watershed) and temporal (season and year) analytical scales and assessed among specific abiotic (discharge, temperature, and cover) and biotic (length, growth, condition, density, and movement) factors. A total of 1,725 adult coastal cutthroat trout (>100 mm, FL) were implanted with half-duplex PIT (passive integrated transponder) tags and monitored seasonally over a 3-year period using a combination of electrofishing, portable remote tracking antennas, and stationary antennas. The effects of watershed, stream network, season, year, and fish length were the most important factors among the candidate survival models. The greatest source of variation in survival was associated with year-dependent differences among seasons. There was evidence suggesting that survival was negatively associated with periods of low stream discharge and with individual fish length. In addition, low (-) and high (+) extreme stream temperatures and boulder cover (+) were weakly associated with survival.
This document presents brief portraits of various aspects of the Trask River study area. For each portrait, there is more information that can be derived from it however, in an effort to at least provide an initial look at the watershed the narrative was kept brief. For example, the section on geomorphology is evolving with the linkage of the terrain map with the channel gradient map to help us predict where we would expect to find more sediment accumulation. This contextual analysis is meant to help bound expected responses to management given the physical and biological template of the watershed. In the next installment I will look in more detail at the small catchments and how they vary. Some of the salient features of the physical and biological Trask Study landscape are summarized below with the more detailed sections following.
Few studies have examined both long-term and fine-scale spatial variations in water quality of small streams in the Pacific Northwest. As such, a case study was conducted to determine if current physical and chemical properties of water in three streams located in the Oregon Coast Range differed from historically measured conditions, taking differences in past management regimes into account. In addition, this research provides an assessment of spatial and temporal variability in nitrogen (N) concentrations and summer stream temperatures within each catchment. In this revisit to the Alsea Watersheds, measurements were conducted continuously (discharge, turbidity), intermittently (suspended sediments), and at regular intervals (nitrate-N) for one year between October 2005 and September 2006. Summertime stream temperature was also measured every half-hour from mid-June to mid-September. Comparisons of recent data with historic data show no detectable changes over time for streamflow characteristics (annual runoff volume, peak flow discharges, and number of low-flow days), annual sediment yield, or summer maximum stream temperatures. Synoptically measured stream temperatures were variable along each stream’s longitudinal profile. The ability to meet Oregon’s water quality standard for temperature was dependent on measurement location and method of analysis.
This research addressed the opportunity to obtain baseline data for both stream chemistry and soil resources for an intensively managed forest watershed, encompassed by the North and South Forks of Hinkle Creek Watershed Research and Demonstration Area Project near Sutherlin, Oregon. A solid representative database for both stream and soil nutrients in these forest watersheds will provide a model upon which to help gauge the effects of current and expected intensive forest management practices on industrial forest land. Eight original sampling points were described for water chemistry. Newly published soil surveys from the National Resource Conservation Service and Douglas County SCS were used to set up a methodology for sampling the representative Hinkle Creek soil resources. Eight main soil types were mapped, 27 representative soil pits were dug in accordance with the location of the mapped soils, and standard soil survey descriptions were created. Soil cores were taken from different depths (0-15, 15-30 and 30-60 cm). These data were used to estimate total soil C, N, P, and S resources, soil cation exchange capacity, and available base cations (Ca, Mg, K, and Na).
Previous research in South Fork Hinkle Creek suggested that coastal cutthroat trout exhibit an aggregated spatial pattern across multiple spatial scales. To evaluate the persistence of the observed abundance patterns and identify factors that affect those patterns, half-duplex passive integrated transponders (PIT-tags) were implanted in 320 coastal cutthroat trout (> 100 mm, about age 1-plus fish) within our study sections, and in an additional 370 fish throughout the watershed. Nineteen habitat patches of high, or low relative fish abundance were delineated and monitored over a 13-month period. Seasonal habitat surveys quantified channel characteristics in each patch. Immigration and emigration were monitored using stationary and portable PIT-tag antennas along 2 km of stream, including mainstem and tributary habitats. In general, habitat patches that supported a high abundance of coastal cutthroat trout experienced less immigration and more consistent fish abundance. Mainstem study sections maintained the initial relative abundance patterns, but abundances in the tributary sections shifted during the study period. Abundances of PIT-tagged coastal cutthroat trout were consistent over time in mainstem habitats, even though some originally marked fish moved away. In tributary sections relative abundances were much more variable and few originally marked fish remained.
This report evaluates the general effects of forestry practices on biodiversity along streams in the Pacific Northwest and northern California.