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.

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.

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.

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.