Reducing the cumulative effects of timber harvest and livestock grazing using debris barriers

The cumulative effects of timber harvesting and livestock grazing can affect water quality and quantity, hydrologic function and other important resource values near small headwater streams. Following timber harvest in British Columbia, Canada, small streams are often left without a reserve zone, likely because of the lack of a legislative requirement in B.C.. On a multiple use land base with livestock grazing, this can lead to increased use of unprotected riparian areas where quality forage and water exist. The objectives of this study were to test the effectiveness of using coarse woody debris barriers to minimize the cumulative effects of livestock grazing and timber harvesting on small stream, riparian values. Debris barriers were strategically placed within four recently harvested cutblocks where livestock graze seasonally on extensive, forested rangeland in the Okanagan region of B.C.. Cover, species richness, bare soil, litter, biomass, trampling, manure and utilization were sampled to determine the effectiveness of the barriers between control and barrier treatments over two grazing seasons. Debris barriers were effective in maintaining higher vegetative cover when compared with control treatments. Other positive outcomes were reduced trampling and utilization in the barrier treatments. This study has shown that debris barriers can be effective at minimizing some of the negative effects of livestock grazing following timber harvest. With this greater understanding of debris barriers and their effectiveness in protecting small, headwater streams the goal is to promote their use and adoption by forest licensees as another tool to mitigate the loss of riparian vegetation. The results suggest that debris barriers ought to be a best management practice as a cost-effective tool to mitigate the potential negative cumulative effect of timber harvest and livestock grazing in and around small headwater streams.