Nutrient Response to Contemporary Forest Practices Regulations
Stednick J. D., V. C. Hale, G. Ice, D. Cook, T. Bousquet, and J. Light

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.

DISCIPLINE: Hydrology & Water Quality    STUDY: Alsea    TYPE: Presentations    TAGS: Nitrate concentration, ammonia, phosphorus
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