Operational and economic feasibility of logging within forested riparian zones

The placement of riparian setbacks around water bodies has been shown to reduce logging impacts on aquatic and riparian communities and processes. However, the systematic application of no-harvest riparian setbacks can result in unnatural, linear patterns of older-growth forest across the landscape, a pattern that is inconsistent with the goal of emulating natural disturbances. Partial harvesting within riparian zones could provide a partial solution to this problem. As part of a larger project to evaluate the environmental consequences of partial harvesting within stream riparian zones of boreal mixedwood forests, we measured wood volumes removed from riparian zones and compared feller buncher productivity between partially harvested riparian zones and adjacent clearcut uplands. On average, from 20% to 33% of the total basal area (27% to 39% of the spruce/pine/fir basal area) was removed from the riparian zones. The riparian harvest resulted in considerable heterogeneity in residual stand structure, however, with basal areas within 50-m segments along the streams ranging from just over 50% to >95% remaining. Our results suggest that, even though the absolute effort required to harvest trees was greater in riparian zones, the larger average size of the trees more than compensated, so that the wood volume removed per unit effort was higher in riparian zones than in clearcuts. Key words: machine productivity, partial harvest, residual stand structure, riparian zone