Management strategies along headwater streams typically focus on aquatic resources, but riparian forests also are habitat for many terrestrial wildlife species. Increasing the understanding of mechanisms that underlie the riparian associations of these species can help integrate management of aquatic and terrestrial environments in headwater forests. We investigated the diets of and food availability for four bird species associated with riparian habitats in the headwaters of the Trask River, in northwestern Oregon. We tested the hypotheses that 1) emergent aquatic insects were a food source for insectivorous birds in headwater riparian areas, and 2) the abundance of arthropod prey did not differ between streamside and upland areas during the bird breeding season. We found that adult aquatic insects represented a relatively small proportion of available prey abundance and biomass and were present in less than 1% of the diet samples from the four riparian-associated bird species. Nonetheless, arthropod prey, comprised primarily of insects of terrestrial origin, was more abundant in streamside than upland samples. We concluded that food resources for birds in headwater riparian areas are primarily associated with terrestrial vegetation, and that bird distributions along the gradient from streamside to upland may be related to variation in arthropod prey availability.
The Hinkle Creek Paired Watershed Study was initiated to carry out two overarching goals: to investigate the environmental impact of contemporary forest practices on non-fish-bearing streams and downstream in tributary and main stem fish-bearing streams. This presentation serves as a summary of some of the results for the studies in Hinkle Creek. Statistically significant increases in water yield, summer low flows, peak flows, and storm flows were detected as a consequence of timber harvest and the subsequent silvicultural activities. Statistically significant increases in sediment yield were also detected. The increases in sediment yield were not consistent with the literature; however they were highly correlated with the observed increases in water yield. Statistically significant increases and decreases were detected in maximum and minimum daily stream temperatures in the non-fish-bearing tributaries, fish-bearing tributaries, and the main stem as a consequence of the two harvest entries. Statistically significant increases in nitrogen were detected as a consequence of the timber harvest and the subsequent silvicultural activities. Nitrogen was the only nutrient that responded to the silvicultural activities. In Hinkle Creek the pacific giant salamander was the only amphibian that was abundant enough to study. In the two years after the first harvest entry, the data did not support the hypothesis that there was any change in the abundance of salamanders.
The Trask watershed study is an extensive pre- and post-harvest study to quantify effects of forest harvest on the physical, chemical and biological characteristics of small non-fish headwater streams and the extent to which harvest on these small streams influences downstream fish reaches. The effects on fish, amphibians, macro invertebrates, birds, hydrology, stream temperature, sediment routing, are considered in this long-term and multidisciplinary project. This project also offers tours for public, research, regulatory and environmental groups.
One of the overarching objectives of the Hinkle Creek Paired Watershed Study was to investigate the impact of contemporary forest practices on stream temperature for non-fish-bearing streams and the cumulative impacts downstream on the fish-bearing tributaries and the main stem. This presentation is a large collection of data gathered about to conditions in Hinkle including canopy closure, minimum and maximum daily temperature, residence time, and groundwater influx. Statistically significant decreases in minimum daily temperature were detected for all of the treatment streams. Clearcuts adjacent to the fish-bearing tributaries and the main stem resulted in statistically significant increases and decreases to maximum daily stream temperatures. There was no empirical evidence that the changes in stream temperature detected at the scale of individual stream reaches were propagated downstream.
The evolution of concepts in stream ecology has resulted in a collective recognition that location within a landscape matters to aquatic biota. Although it is known that location-related conditions have implications for aquatic biota, the contribution of location that most greatly influences a population has yet to be understood. Stream-living fish populations in headwater stream locations are affected by a juxtaposition of influences between more dynamic environmental regimes (i.e., flow, temperature, turbidity) and relatively fixed site-specific physical characteristics of streams also referred to as the physical ‘habitat template’ (e.g., channel geomorphology, instream habitat). Simulation experiments using the inSTREAM individual-based coastal cutthroat trout (Oncorhynchus clarkii clarkii) population model explored the role of environmental regimes and a habitat template for four headwater streams in the Trask River Watershed. We paired the suite of historic environmental regimes (i.e., flow, temperature, turbidity) from each site with the habitat template from each site (i.e., channel shape, velocity shelter availability, spawn gravel availability, distance to hiding refuge) using a full factorial design resulting in 16 different scenarios for both summer and winter over 4 years. We present evidence demonstrating that the role of the habitat template predetermines population dynamics by setting hierarchical boundaries to alternative environmental regimes.
This study measured the impacts of two harvest entries on the monthly streamflow and other measures of the streams below and adjacent to harvest. Statistically significant increases in sediment yield, as suspended sediment, were detected as a consequence of timber harvest in the South Fork Hinkle Creek. These increases were detected at the small, headwater watershed scale as well as the large watershed scale. Unlike the increases in water yield, these increases were not consistent with the literature. The results of the seminal paired watershed studies showed very large increases in sediment yield, often as much as two or three times greater than sediment yields before timber harvest. The results from contemporary forest practices are much more muted and the increases are in the range of 20 to 30 percent increases in sediment yield. The increases are in order with and correlate well with the increases in water yield. That the increases in sediment yield are a result of increased stream power due to increases in water yield is a reasonable hypothesis to put forward to explain these observations. The greatest improvement in forest practices over the past several decades were directed toward reducing the impacts of timber harvest on sediment yield. These improvements include; clearcut size limits and adjacency constraints, improved yarding systems (in this case slackline, skyline cable systems), the prescription of buffer strips, and changes in site preparation practices.
The Trask Watershed Study is a multi-disciplinary, long-term research project in the Oregon Coast Range that is designed to examine the effects of current forest management practices on aquatic ecosystems. Extensive physical (e.g., water quantity and quality, channel morphology) and biological data (e.g., primary productivity, macro-invertebrate communities, amphibian movement and fish populations and behavior) has been collected in both the small and large watersheds since 2006 and will continue until 2016. One of these key parameters we have been collecting at multiple scales is stream temperature.
Understanding the variability in stream temperature patterns and processes prior to harvest in both small non-fish headwater streams and downstream in larger fish-bearing basins allows us to anticipate potential responses to harvest and subsequent potential changes in biota. Using the pre-harvest stream temperature data we examine variability in maximum and minimum temperatures across the 15 small headwater streams. We also examine how well both small treatment streams and the larger downstream basins correlate to un-harvested reference streams to determine the best match to compare post-harvest response. Finally we examine how stream temperature patterns vary longitudinally in the downstream direction through time.
Nutrients are one of the factors which limit primary production and can be a water pollutant. Fertilizer can be applied to increase the Nitrogen and therefore increase the growth. The Hinkle Creek Paired Watershed Study addresses concerns about the loss of essential plant nutrients in Douglas-fir plantations and assesses the impacts of forest management on stream water chemistry of fish-bearing streams. The objective is to determine the cumulative impacts to fish-bearing streams of non-fish-bearing streams which are not afforded the protection of un-harvested and unfertilized riparian strips and to compare those impacts with the local impacts of different treatments.
At the Sediment Symposium, researchers review and summarize our overall understanding of current scientific knowledge of in-stream sediment. The video archive of the presentations is available.
To view the presentations, please visit this website: http://oregonstate.edu/conferences/event/2013sedimentsummit/videoarchive...
Streamside habitat is important for many terrestrial wildlife species. However, mechanisms underlying the riparian associations of some terrestrial species have not been well studied, particularly for headwater drainages. We investigated the diets of and food availability for four bird species associated with riparian habitats in montane coastal forests of western Oregon, USA. We examined variation in the availability of arthropod prey as a function of distance from stream. Specifically, we tested the hypotheses that (1) emergent aquatic insects were a food source for insectivorous birds in headwater riparian areas, and (2) the abundances of aquatic and terrestrial arthropod prey did not differ between streamside and upland areas during the bird breeding season. We found that although adult aquatic insects were available for consumption throughout the study period, they represented a relatively small proportion of available prey abundance and biomass and were present in only 1% of the diet samples from only one of the four riparian-associated bird species. Nonetheless, arthropod prey, comprised primarily of insects of terrestrial origin, was more abundant in streamside than upland samples. We conclude that food resources for birds in headwater riparian areas are primarily associated with terrestrial vegetation, and that bird distributions along the gradient from streamside to upland may be related to variation in arthropod prey availability.