Restoration of Riparian Hardwoods: Influence of Deer and Elk Browsing

We studied  of the effects of wild ungulate browsing on native hardwoods planted as part of the overall effort to restore aquatic and riparian ecosystems within the Middle Fork John Day River (MFJD). Unconstrained stream reaches along the river have been highly modified to support forage production for domestic livestock. Comparisons between current conditions and descriptions from 1881 GLO land-survey records suggest that historic conditions were more complex: channels have been straightened and riparian vegetation has been converted from a patchy mixture of forests, shrubs, and wet meadows into expansive dry meadows. Today, the MFJD is poorly shaded and summer stream temperatures can exceed 28 ^oC. To restore shade, thousands of native hardwood seedlings were planted, but planting has had limited success, even in areas fenced to exclude cattle. We established small browsing exclosures in spring 2009 and remeasured the exclosures after one and two growing seasons. Our results showed that browsing by deer and elk prevented the growth of most hardwoods. Only ponderosa pine and mountain alder showed consistent growth over two years. Overall, our results indicate that browsing pressure from deer and elk may limit the potential to restore native riparian forests.