The results presented here have important implications for the persistence of species restricted to engineered habitats. In this landscape, where beaver-modified areas comprise the only open wetland habitat, the fates of 25% of the species found in the riparian zone are directly linked to the patches created by the engineering activities of beaver. Furthermore, some species that are present in both beaver-modified and forested riparian zone habitats may depend on engineered patches as sources of propagules if populations in forested areas are acting as “sinks” (Hanski and Gilpin 1997). As populations of the ecosystem engineer change, the amount of habitat available for these habitat-specialist species will vary as well (Johnston and Naiman 1990a). Thus, factors that control the dynamics of populations of ecosystem engineers may indirectly control the species richness of the landscape. Ecosystem engineers move about landscapes in response to resource availability and biotic interactions, as opposed to more commonly studied abiotic agents of heterogeneity such as fire and wind. As a result, the dynamics of the patches created by ecosystem engineers may be quite different from those created by physical forces (Pickett et al. 2000). Although current trends in conservation are to move away from singlespecies management and towards ecosystem management, these results suggest that for ecosystem engineers, it may be important to manage a single species in order to conserve landscape-level diversity.