Stream size influences stream temperature impacts and recovery rates after clearfell logging

Water temperature has profound effects on stream ecosystems. We studied effects of clear-fell logging Pinus radiata plantations on mid-summer water temperatures and recovery times in streams with 212 m wide channels. Post-logging increases were 2-3.8 degrees C for summer daily means and 4-7.3 degrees C for summer daily maxima. Rates of recovery of thermal regimes after logging were strongly negatively correlated with stream size, as indexed by catchment area, channel width or baseflow (r(2) = 0.80-0.93). Summer daily mean and maximum temperatures declined during the riparian vegetation regrowth phase by 0.18 and 0.47 degrees C year(-1), respectively, for the largest stream and 1.4 and 1.9 degrees C year(-1) in the smallest stream. Thermal regimes were restored in small streams (2-4 m wide channels) about 6-8 years after clearfelling. In medium-sized streams (6-12 m wide channels), we predict this recovery will take 12-16 years. (C) 2008 Elsevier B.V. All rights reserved.