Conceptualizing and Designing Corridors for Climate Change

In the rush to embrace corridors as an adaptation strategy, some ecologists have framed the strategy as using complex models to design corridors extending hundreds of kilometers from low-elevation, low-latitude sites to distant high-elevation, poleward sites along paths that capture the shifting climate envelopes of individual species. This conceptualization of corridors differs from traditional corridors designed to support gene flow and recolonization. In contrast, I argue that both short-distance and long-distance shifts to future climate space can be achieved by a combination of short movements within large, topographically and climatically diverse natural landscape blocks and short, coarse filter corridors between those blocks. These coarse-filter corridors can be designed in 3 non-mutually-exclusive ways. First, rivers areas provide natural conduits for movement of plants and animals and are therefore priorities for conservation and restoration as climate corridors. Second, linkages that provide continuity and interspersion of land facets (units defined by topographic or soil variables) should support movement under any future climate regime. This approach is best suited to link large topographically diverse blocks separated by distances < 30 km. The third approach, climate gradient corridors, is appropriate in landscapes where natural landscape blocks have low within-block topographic diversity (such as where blocks are small), especially if the blocks are dissimilar. The coarse filter approaches described here are reasonable and well-grounded in fundamental concepts of ecology, but conservation and restoration decisions should also be based on empirical evidence of how well coarse filter corridors protect demographic and genetic flows for today's focal species.