College of Forestry
Theses
Beyond the Paired-Catchment Approach: Isotope Tracing to Illuminate Stocks, Flows, Transit Time, and Scaling
Dec-19-2011
This dissertation integrates a process-based hydrological investigation with an ongoing paired-catchment study to better understand how forest harvest impacts catchment function at multiple scales. This is done by addressing fundamental questions related to the stocks, flows and transit times of water. Isotope tracers are used within a top-down catchment intercomparison framework to investigate the role of geology in controlling streamwater mean transit time and their scaling relationships with the surrounding landscape. We found that streams draining catchments with permeable bedrock geology at the Drift Creek watershed in the Oregon Coast Range had longer mean transit times than catchments with poorly permeable bedrock at the HJ Andrews Experimental Forest in the Oregon Cascades. We also found that differences in permeability contrasts within the subsurface controlled whether mean transit time scaled with indices of catchment topography (for the poorly permeable bedrock) or with catchment area (for the permeable bedrock). We then investigated the process-reasons for the observed differences in mean transit time ranges and scaling behavior using a detailed, bottom-up approach to characterize subsurface water stores and fluxes.
Setting the Landscape Context for Paired Watershed Studies in Western Oregon
Apr-01-2008
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.
Relationships Between Stream Discharge and Cutthroat Trout Abundance at Multiple Scales in Managed Headwater Basins of Western Oregon
Jun-17-2013
Relationships between resident cutthroat trout (Oncorhynchus clarkii clarkii) and six hydrologic indices were investigated using correlation analysis in two experimental headwater catchments in the foothills of the Cascade Mountains of western Oregon. This investigation was to determine if characteristics of discharge explained inter-annual variability in trout abundance. Eight years of continuous discharge and annual abundance data collected from two contiguous watersheds from the Hinkle Creek Paired Watershed Study were used for this study. Density-discharge relationships were identified separately in the watershed actively managed for timber harvest and in the control watershed. Correlation was determined at multiple stream segments and at the watershed scale to assess the roles of spatial scale and network location on the detectability of density-discharge relationships. A method for improving the spatial coupling of density and discharge measurements within the stream network was also investigated. No correlations (r ≤ ǀ0.50ǀ) between hydrologic indices and age-1+ trout density in either watershed were found. Two hydrologic indices were related to the density of age-0 trout: maximum annual discharge (r = 0.780) in the control watershed and Q90 summer discharge (r = 0.697) in the treated watershed. The correlation between the density of age-0 trout and each of these two indices were similar across individual stream segments, but variability in the magnitude of the...
Post-breeding habitat selection by songbirds in the headwaters of the Trask River, northwestern Oregon
Sep-17-2010
Little is known on the importance of riparian areas to birds near small headwater streams in mesic forests. Progress towards understanding limiting factors that affect bird populations has been difficult because of lack of information beyond the breeding period. I compared bird assemblages between headwater riparian and upland areas throughout the post-breeding period by capturing birds using mist-nets in six paired riparian and upland locations along six headwater streams of the Trask River in northwestern Oregon. In order to assess whether birds prefer headwater riparian areas, I also examined factors affecting habitat selection by juvenile Swainson's thrushes (n=37) using radio telemetry. While riparian and upland locations had similar coarse wood volume and fruiting and tall (> 1.3 m tall) shrub cover, riparian locations had less shrub cover (< 1.3 m tall) and different shrub composition than upland locations. Total capture rate was double that of upland in riparian locations, while bird species richness was similar. Similar numbers of birds were captured in mist-nets oriented perpendicular and parallel to the stream suggesting that birds were not using riparian areas as movement corridors. Adult capture rate was greater in riparian locations than adjacent uplands while results of juvenile capture rates were ambiguous. Riparian locations supported higher capture rates of Swainson's thrushes and winter wrens than adjacent uplands.
Transferability of Models to Predict Selection of Cover by Coastal Cutthroat Trout in Small Streams in Western Oregon, USA
Nov-07-2008
We assessed use and selection of cover by coastal cutthroat trout (Oncorhynchus clarkia clarkii) in six headwater streams in three watersheds in western Oregon, USA during the summer low flow period from 1 August and September 30, 2007. We tagged 1037 coastal cutthroat trout (>100 mm) with passive integrated transponder (PIT) tags across all streams. Selection of cover was analyzed by comparing characteristics of locations used for concealment by relocated fish relative to characteristics of randomly available habitat that could be used for concealment. We measured habitat characteristics for 190 relocated individual fish using cover and 797 randomly points potentially available as cover. Of the latter points, only 235 of 797 were potential cover, based on characteristics of cover actually used by fish. Coastal cutthroat trout used substrate as cover (78%) more often than all other cover types combined (22%). Availability of different cover types was variable, but overall substrate made up 92% of available cover and the remaining 8% represented all other cover types combined. Habitat characteristics measured for both used and available cover included depth at fish location (cm), surface area of cover (m2), proximity to depth of 20 cm for fish located in < 20 cm in depth, b-axis (mm) for substrate >2 mm, and distance under substrate. Each of these habitat characteristics was different for used and available cover.
Experimental Analysis of Intra- and Interspecific Competitive Interactions between Cutthroat Trout and Sculpins in Small Streams
Dec-02-2011
In the Pacific Northwest ecoregion of North America, sculpins represent a major constituent of freshwater assemblages in coastal rivers. Little is known of their interactions with co-occurring species, such as widely studied salmon and trout (salmonines). In this study, I evaluated inter- and intraspecific interactions involving cottids (Cottus sp.) and coastal cutthroat trout (Oncorhynchus clarkii clarkii). I used a response surface experimental design to independently evaluate effects of cutthroat trout and sculpin biomass on growth and behavior. There was evidence of both intra- and interspecific interactions between cutthroat trout and sculpins, but the interactions were asymmetrical with biomass of cutthroat trout driving both intra- and interspecific interactions, whereas sculpins had little influence overall. Cutthroat trout biomass was positively related to conspecific aggressive interactions and negatively related to growth. Sculpin exhibited increased use of cover during the day in response to greater biomass of cutthroat trout, but not sculpin biomass. Nocturnal use of cover by sculpins was unaffected by biomass of either species. This experiment provides insights into the species interactions and the mechanisms that may allow sculpins and salmonines to coexist in nature. As cutthroat trout appear to be superior competitors, coexistence between sculpins and cutthroat trout may depend on some form of refuge.
Seasonal Variability in Diet and Consumption by Cottid and Salmonid Fishes in Headwater Streams in Western Oregon, USA
May-27-2010
Coastal cutthroat trout (Oncorhynchus clarkii clarkii) and cottids (Cottus spp) commonly co-occur in headwater streams in western Oregon. Little is known about the comparative trophic ecology of these species or how they respond to seasonal scarcity of resources. In this study I evaluated the seasonal variability in diets and consumption as it related to food limitation for coastal cutthroat trout and cottids. Over 340 individual diets were quantified from seasonal samples collected in May, July and September of 2008. Diet overlap was relatively low among seasons and species. Coastal cutthroat trout exhibited a more diverse diet in terms of taxonomic richness of prey and consumed both aquatic and terrestrially-derived prey, whereas cottids appeared to specialize on aquatic prey. Based on diet composition and amount consumed, all species appeared to be increasingly food limited from July to September, relative to May. However when diet composition was integrated with a bioenergetic model, coastal cutthroat trout were found to be substantially more food limited than cottids. Differences in the cost of activity between these species may explain this result. Activity costs may be higher for trout, which reside in the water column and rely on active swimming, versus cottids, which lack a swim bladder and are more benthic oriented. Results of this work suggest that cottids are dietary specialists, feeding almost exclusively on benthic prey.
Processes That Influence the Downstream Propagation of Heat in Streams from Clearcut Harvest Units: Hinkle Creek Paired Watershed Study
Nov-27-2007
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.
Persistence of Spatial Distribution Patterns of Coastal Cutthroat Trout in a Cascade Mountain Stream
Dec-02-2005
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.
The Influence of Contemporary Forest Management on Stream Nutrient Concentrations in an Industrialized Forest in the Oregon Cascades
Dec-19-2011
The increased demand for wood and fiber from a continually shrinking land base has resulted in the use of intensively managed forest plantations. Because much of the water flowing in rivers in the U.S. originates as precipitation in forests, there is a justified concern about the impacts of forest management on water quality. Nutrient concentrations were measured in eight streams from October 2002 to September 2011 to assess nutrient response to contemporary forest practices at the Hinkle Creek Paired Watershed Study in the Oregon Cascades. This period of time included a two-year pre-treatment calibration between control and treatment watersheds, a fertilization treatment of both basins in October 2004, and a post-treatment period from 2005 to 2011. Stream water samples were analyzed for nitrogen, phosphorus, calcium, sodium, potassium, magnesium, sulfate, chloride, and silicon as well as specific conductance, pH, and alkalinity. All treatment watersheds showed a statistically significant increase in NO3 + NO2 concentrations after clearcutting (p < 0.001). The slope of the streambed through the disturbance was a stronger predictor of the magnitude of the response than was the magnitude of disturbance. Concentrations of NO3 + NO2 observed during the calibration period were similar to concentrations observed in an old-growth forest in the H.J. Andrews, suggesting that nutrient processing within the Hinkle Creek watershed had returned to levels that existed prior.
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