Rethinking the donut: the case for hydrologically relevant buffer zones

The role of buffer zones as biomechanical filters and mediators of impacts, particularly on aquatic resources, is reviewed. Practical application of buffer zones, for example in forest harvesting, can result in forested ribbons lining streams and rivers or ringing lakes, with harvesting activity on the remainder of the landscape. Calls to reconsider this approach in Canada have come from the forest industry, which seeks better access to timber resources. Debate about hydrological processes in buffer zones and their effectiveness in protecting aquatic ecosystems is exemplified by the case of brook trout, which requires groundwater seepage into lakes or streams at some life history stages. Some research shows that buffer zones may not encompass the groundwater recharge zone that supplies such seepage, but data on hydrogeological conditions in lake catchments often are not available. The potential use of digital elevation models to derive topographical indices, for predicting groundwater discharges, is discussed.