Effectiveness of conservation easements for reducing development and maintaining biodiversity in sagebrush ecosystems

Conservation easements are the primary tool used globally by land trusts and governmental agencies to achieve conservation goals on private lands, but empirical evaluations of their effectiveness are lacking. Here we compared biodiversity in sagebrush ecosystems and recent rates of change in road and structure densities on properties with and without easements held by The Nature Conservancy in Wyoming, USA. To determine whether any differences between properties with and without easements were better explained by development pressure or by management practices, properties were stratified by low versus high residential development pressure and property managers were surveyed. In areas with high development pressure, easement properties had fewer structures and tended to have fewer, smaller roads than properties without easements. In the high-pressure areas, properties with easements also had greater use by some wildlife species than properties without easements. Regardless of easement presence, there was higher cover of exotic plant species and fewer mammal burrows in high than low-pressure areas. There were no significant differences in land management practices between properties with and without easements, but managers of properties with easements tended to seek management support more often than other managers. This may present an opportunity to provide support for specific management activities on easements to ensure that they continue to meet intended goals. Given the importance of easements as an alternative to nature reserves and the significant investment being made to acquire additional easements, it is essential to continue to evaluate whether easements are an effective tool in other locations.