College of Forestry
Alsea
Fish Population Response to Harvesting with Contemporary Forest Practice Regulations: The Alsea Watershed Study Revisited
Apr-18-2013
Coastal cutthroat trout Oncorhynchus clarkii clarkii are the most widely distributed native salmonid in the forested watersheds of western Oregon. The initial Alsea Watershed Study demonstrated negative impacts on the abundance of cutthroat trout due to logging practices of the day. Here we report on abundance, size, growth, and condition of coastal cutthroat trout before and after logging under the current forest management practice regulations using a before, after, control, impact (BACI) study design with Flynn Creek and Needle Branch as the control and impact streams respectively. Relative abundance estimates are from a census of pool habitats using single-pass electrofishing and relative growth is from the recapture of individuals implanted with passive integrated transponder tags. A significant increase in age 1+ cutthroat trout biomass and abundance was observed post-harvest in Needle Branch relative to Flynn Creek (p=0.04 and 0.01 respectively). There was also a significant shift in the spatial distribution of cutthroat biomass in Needle Branch (p=0.04) in an upstream direction post-treatment suggesting that increases in cutthroat trout were spatially linked to the location of the harvest unit. There was no evidence for a treatment effect on mean fork length or the 90th percentile of fork length for age 1+ cutthroat trout (p=0.32 and 0.24 respectively). This result was supported by an absence of evidence for a treatment effect on relative growth rate.
Herbicides in Needle Branch Streamwater
Apr-18-2013
Glyphosate, aminomethylphosphonic acid (AMPA), imazapyr, sulfometuron methyl, and metsulfuron methyl were measured in Needle Branch streamwater during and after application of herbicide(s). All herbicides were applied by helicopter in a single tank mix. Samples were collected at three sites: NBH (at the fish/no-fish interface in the middle of the harvest unit), NBU (at the bottom of the harvest unit), and NBL (well downstream). AMPA, imazapyr, sulfometuron methyl and metsulfuron methyl were not detected in any sample at 15 ng/L, 0.6 μg/L, 0.5 μg/L and 1 μg/L, respectively. However, a clear pulse of dissolved glyphosate manifested at NBH during the application (baseflow conditions). Subsequent baseflow samples collected three days after treatment (DAT) showed ≈25 ng/L dissolved glyphosate at all three sites. Samples collected during the first storm event (8 DAT) showed a clear pulse of dissolved glyphosate at NBU, but not at NBH or NBL. The maximum concentration observed during this pulse at NBU was 115 ng/L, and the pulse persisted for about six hours. During the next storm event (10 DAT) a clear pulse of dissolved glyphosate manifested at NBH, but not at NBU or NBL. The maximum co centration observed was 42 ng/L, and this pulse persisted for about ten hours. Results from all subsequent storm events showed dissolved glyphosate at <20 ng/L in all samples. A limited number of analyses on suspended sediment (SS) showed that SS held de minimis masses of glyphosate and AMPA.
Nutrient Response to Contemporary Forest Practices Regulations
Apr-18-2013
The original Alsea Watershed Study measured water quality before and after logging. For Deer Creek with patchcuts and streamside vegetation buffers, there were no changes in water quality post-harvesting. Needle Branch was harvested without streamside buffers and the slash burned. Nitrate concentrations increased from 0.70 to a maximum of 2.10 mg/L, and returned to pretreatment levels by the 6th year after logging. The loss of nitrogen was negligible when compared to the nitrogen capital (soils and vegetation) and loss of terrestrial productivity was not anticipated. Additional water quality monitoring in the study watersheds identified spatial and temporal variations instream water quality. Of particular note is the influence of landscape elements including vegetation, soils, slope, and hydraulic conductivity as related to water quality, particularly nitrogen. Also the first significant fall storm flushes oxidized nitrogen from the soil profile and results in higher stream water nitrate concentrations. The Alsea Watershed Study Revisited (AWSR) provides an assessment of water quality response to contemporary forest practices. Nested watersheds in Needle Branch, including immediately below the harvest unit (NBU) and the original gauge (NBL) were compared for water quality changes. During the pre-treatment monitoring, nutrient concentrations at NBU were generally higher but paralleled concentrations at NBL.
Dissolved Oxygen Response to Forest Management in the Alsea Watershed Study Revisited
Apr-18-2013
The original Alsea Watershed Study found dissolved oxygen (DO) concentrations at or near saturation in the control (Flynn Creek) and patchcut and buffered (Deer Creek) watersheds. DO concentrations in some reaches of the clearcut and unbuffered watershed (Needle Branch) were found to be substantially below saturation following the 1966 harvest. The depressed concentrations were thought to result from a combination of increased biochemical oxygen demand, reduced solubility due to stream heating, increased biological activity, and reduced reaeration. The Alsea Watershed Study Revisited (AWSR) returns to the same watersheds and provides an assessment of physical, chemical, and biological response to contemporary forest practices. During the pre-treatment phase of the AWRS low DO concentrations were observed in Needle Branch in the summer and fall. These low concentrations coincided with low flow periods. At these times flow becomes “discontinuously perennial” and portions of the stream network go subsurface. We now believe that despite having some of the highest reaeration rates ever measured, certain reaches of Needle Branch are prone to depressed DO concentrations. For some reaches, surface flow during critical late season periods is largely composed of recently emerged groundwater or hyporheic water. Both original study and AWSR findings show high spatial variability in DO concentrations.
The Alsea Paired Watershed - Revisited: Harvest Effects on Stream Temperatures
Apr-18-2013
This project explores the effects of harvesting on the temperature of the fish bearing streams. It also draws comparisons to the historical effects of the old best management practices in comparison to contemporary beast management practices. Some warming was found but significantly less than what had been found in old projects.
Alsea Watershed Study Revisited: Hydrologic Response to First Harvest
Apr-18-2013
The hydraulic response of the Alsea watershed study to the first harvest produced results to in the streamflow of Needle Branch creek. Deer creek was shown to be a suitable control and that Upper and Lower Needle Branch respond similarly. There is still a lot of work to be done and suspended sediment analysis to complete.
Alsea Watershed Study and Alsea Watershed Study Revisited
Apr-18-2013
The original Alsea Basin Logging and Aquatic Resources Study (1959-1973) was established in response to public and legislative concerns about the impact of timber harvesting and road construction on salmon. It was the first paired watershed study in North America to document these impacts. The study design utilized one watershed (Flynn Creek) as an untreated control for the duration of the study. Deer Creek was roaded and harvested with three small patch clearcuts covering about 25% of the basin. Harvest boundaries were kept 50 feet or more from the stream banks. The small clearcuts received a light slash fire following logging. Needle Branch was roaded and completely clearcut without stream protection buffers and, following logging, was burned with a very hot slash fire and channel cleaned of debris, which typified the logging practices of the day. Before and after treatments, streamflow, water quality and aquatic resources were carefully monitored on all three watersheds. Changes in streamflow, water quality and aquatic resource populations were small after road construction and logging in Deer Creek, even with the very narrow stream protection buffers. Large changes in water quality and suspended sediment were recorded after clearcutting without stream protection and the hot slash fire in Needle Branch. Temperature and suspended sediment levels returned to pretreatment levels within five years. Cutthroat trout numbers decreased significantly.
Short-term Relationship of Timber Management and Pacific Giant Salamander Populations, and the Response of Larval Stream Amphibian to Predators Under Different Sediment Levels
Mar-02-2010
In the Pacific Northwest, multiple studies have found negative effects of timber harvest on stream amphibians, but the results have been highly variable and region-specific. Over the last 30 years forest management practices have changed substantially, yet little work examines how modern forest management relates to the abundance or density of stream amphibians. I examined the influences of contemporary forest practices on Pacific giant salamanders as part of the Hinkle Creek paired watershed study. Density was positively associated with substrate, negatively associate with upstream area drained, and had a weak positive association with fish density, but I found no evidence of an effect of harvest. Pacific Northwest stream amphibians are often negatively associated with sedimentation, but the mechanism underlying this relationship is not clear. I found amphibian larvae were more visible as sediment level increased and some evidence that larvae were less visible in the presence of fish. These patterns are consistent with the hypothesis that sediment affects larval stream amphibians by increasing vulnerability to predation.
A Physical and Chemical Characterization of Stream Water Draining Three Oregon Coast Range Catchments
May-02-2007
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.
Local and Downstream Effects of Contemporary Forest Harvesting on Streamflow and Sediment Yield
Nov-19-2008
This dissertation is a collection of three manuscripts that serve to fill the knowledge gaps and advance methods of detecting the effects of contemporary forest harvesting in experimental catchment studies. The objective of this research was to develop change detection models using time-series records to detect and quantify the effects of forest harvesting on streamflow and sediment yield. To accomplish this, it was necessary to characterize streamflow and sediment processes at a temporal scale capable of describing daily, monthly, and seasonal dynamics following forest harvesting; increase sample sizes used to construct regression-based change detection models; and develop alternative methods to the paired-catchment approach in order to discern changes in streamflow and sediment using highly variable time-series data. The paired-catchment approach was used to detect and quantify relative changes in streamflow and sediment yield in 5 harvested catchments. The ability to detect statistically significant changes at certain time-steps was a function of accounting for all sources of variability in change detection models. In this study, we aimed to develop robust change detection models using time-series data to increase sample size and decrease false/missed detections of true treatment effects.
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