| |
Presented at the NABS Annual meeting, Athens, Georgia, 2003
in Disturbance Ecology
Response of water quality and macroinvertebrate communities to forest harvests in small watersheds of the Catskill Mountains, New York, USA
B.P. Baldigo1, P.S. Murdoch1, and G. Lester2. 1US Geological Survey, 425 Jordan Rd., Troy, NY, USA 12180, 2Ecoanalysts, Inc., 105 East 2nd St., Moscow, ID, USA 83843
Macroinvertebrates, discharge, and chemistry in two small Catskill streams were monitored during 1995–2000 to evaluate effects of two forest–harvest practices. Harvests in two subbasins removed 73% (clear cut) and 20% (timber–stand–improvement; TSI) of tree basal area. Catchment basal area for a site below their confluence was reduced 15%. Water quality and macroinvertebrate communities were significantly affected (p≤0.05) only at the clear–cut steam site. Acidity, nitrate, and inorganic monomeric aluminum (Alim) concentrations increased to toxic levels during high flows after harvest. Toxic episodes persisted for 3 years, but their magnitude and duration decreased with time. Small changes in community indexes occurred after the clear cut, but none were significant, nor did they differ from indexes at a control site. Major shifts to acid– and Alim–tolerant taxa, however, occurred after the harvest, as indicated by increases in a metals–tolerance index. Relative abundance of collector–gatherers also dropped from 60% to 25%, and shredders increased from 15% to 60% of the sample. Full recovery generally occurred within 2–3 years. Despite acute toxicity of high flows after the clear cut, the absence of long–lived or major changes in the structure and function of macroinvertebrate communities indicate they are resilient to perturbations resulting from normal forest–harvest practices.
|
|
