Effects of prescribed fire on habitat of beaver (Castor canadensis) in Elk Island National Park, Canada.

摘要

Fire, flooding, herbivory, and the effects of climate are all topical issues for today's land managers. Effective resource management requires a balance among these processes, which in turn, requires a better understanding of their interactions. Beaver (Castor canadensis) are strong colonizers and have been successfully reintroduced to much of their former range. Prescribed fire has also been introduced in many areas as a management tool to restore ecological function. Resource managers have often assumed fire would also benefit non-target species like beaver; however, its effect on beaver has not been well studied. In this study, part of a broader project in Elk Island National Park, Alberta, Canada, the effect of prescribed fire on beaver lodge occupancy in the context of high ungulate populations was examined. Elk Island National Park has an active beaver population, high ungulate densities, and a well-established prescribed fire programme. It was examined whether frequency, size, and timing of burns influence beaver lodge occupancy and the establishment of new lodges. Since 1979, over 51% of the park (99.3 km2) has been burned with prescribed fire. By comparing lodge occupancy over a period prior to and after a series of prescribed burns, beaver occupancy rates pre- and post-burn was analysed. The results showed that repeated burning dramatically decreased beaver lodge occupancy, and that even after one burn the number of active colonies declines and does not recover to pre-fire populations. Especially when combined with drought and herbivory, prescribed fire does not improve beaver habitat..