Canopy closure

The Impact of Contemporary Forest Practices on Stream Temperature at a Watershed Scale: A case study from Hinkle Creek
Skaugset, A.

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.

DISCIPLINE: Hydrology & Water Quality    STUDY: Hinkle Creek    TYPE: Presentations    TAGS: Canopy closure, minimum and maximum daily temperature, residence time, groundwater influx, Stream temperature
The Influence of Contemporary Forest Harvesting on Summer Stream Temperatures in Headwater Streams of Hinkle Creek, Oregon
Kibler, K. M.

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.

DISCIPLINE: Hydrology & Water Quality    STUDY: Hinkle Creek    TYPE: Theses    TAGS: Stream temperature, forest harvesting, Riparian Management Areas (RMAs), Headwater streams, Canopy closure, logging slash
Effect of contemporary forest harvesting practices on headwater stream temperatures: Initial response of the Hinkle Creek catchment, Pacific Northwest
Kibler Kelly M., Skaugset, Arne, Ganio, Lisa M., Huso, Manuela M.

We investigated the effect of contemporary forest harvesting practices on warm-season thermal regimes of headwater streams using a Before-After-Control-Intervention (BACI) design within a nested, paired watershed study. We applied harvesting treatments to four headwater tributaries of Hinkle Creek, designed in accordance with the Oregon Forest Practices Act. Therefore, fixed-width buffer strips containing overstory merchantable trees were not left adjacent to the four non-fish-bearing streams. The summer following harvesting, we observed a variable temperature response across the four harvested streams. Mean maximum daily stream temperatures ranged from 1.5 C cooler to 1.0 C warmer relative to pre-harvest years. We also observed significantly lower minimum and mean daily stream temperatures, and recorded particularly low temperatures in treatment streams on days that minimum stream temperatures in reference streams were high. At the watershed scale, we did not observe cumulative stream temperature effects related to harvesting 14% of the watershed area in multiple, spatially-distributed harvest units across four headwater catchments. At the watershed outlet, we observed no change to maximum, mean, or minimum daily stream temperatures. We attribute the lack of consistent temperature increases in headwater streams to shading provided by a layer of logging slash that deposited over the streams during harvesting, and to increased summer baseflows.

DISCIPLINE: Hydrology & Water Quality    STUDY: Hinkle Creek    TYPE: Journal Articles    TAGS: Stream temperature, Forest management, Canopy closure, Impact assessment, Headwater streams, Cumulative effects, Hinkle, Oregon, Paired Watershed, Forest Hydrology
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