Nutrient uptake and community metabolism in streams draining harvested and old-growth watersheds: A preliminary assessment

Abstract

The effect of timber harvesting on streams is assessed using two measures of ecosystem function: nutrient spiraling and community metabolism. This research is being conducted in streams of the southern Appalachian Mountains of North Carolina, the Ouachita Mountains of Arkansas, the Cascade Mountains of Oregon, and the redwood forests of northern California, in order to understand similarities and differences among stream ecosystem responses to timber harvesting across diverse geographic regions. Data from Cedar and Peacock Creeks in the redwood forest are used to illustrate the principles and usefulness of measuring stream ecosystem function for assessing watershed disturbances. Streams draining logged watersheds had smaller dominant substrate size and more sand and fine sediments in the channel. Nutrient uptake (NH₄⁺¹ , PO₄^-3 ) and community metabolism (primary productivity, respiration, P:R, net daily metabolism) were measured in streams draining old-growth (Cedar Creek) and harvested (Peacock Creek) watersheds. Phosphate uptake length was significantly shorter in Cedar Creek (212 m) than in Peacock Creek (1020 m). Ammonium uptake length was not significantly different in these streams (111 m vs. 109 m, respectively). Preliminary analyses of stream metabolism suggest that primary productivity is greater in streams draining logged watersheds, but community respiration is greater in stream draining old-growth watersheds, resulting in subtantial differences in P:R and NDM.

Parent Publication

• Ouachita and Ozark Mountains symposium: ecosystem management research

Citation

Hill, Brian H.; McCormick, Frank H. 2004. Nutrient uptake and community metabolism in streams draining harvested and old-growth watersheds: A preliminary assessment. Gen. Tech. Rep. SRS-74. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. p. 214-220.