Conservation Easements: Biodiversity Protection and Private Use ADENA R. RISSMAN, ∗ †† LYNN LOZIER,† TOSHA COMENDANT,‡ PETER KAREIVA,§ JOSEPH M. KIESECKER, ∗∗ M. REBECCA SHAW,† AND ADINA M. MERENLENDER ∗ ∗ Department of Environmental Science, Policy and Management, 137 Mulford Hall, University of California, Berkeley, CA 94720-3114, U.S.A. †The Nature Conservancy, California Chapter, 201 Mission Street, 4th Floor, San Francisco, CA 94105-1832, U.S.A. ‡The Nature Conservancy, World Office, 4245 N. Fairfax Drive, Arlington, VA 22203, U.S.A. §The Nature Conservancy, World Office, 217 Pine Street, Suite 1100, Seattle, WA 98101, U.S.A. ∗∗ The Nature Conservancy, Wyoming Chapter, 258 Main Street, Suite 200, Lander, WY 82520, U.S.A. Abstract: Conservation easements are one of the primary tools for conserving biodiversity on private land. Despite their increasing use, little quantitative data are available on what species and habitats conservation easements aim to protect, how much structural development they allow, or what types of land use they com- monly permit. To address these knowledge gaps, we surveyed staff responsible for 119 conservation easements established by the largest nonprofit easement holder, The Nature Conservancy, between 1985 and 2004. Most easements (80%) aimed to provide core habitat to protect species or communities on-site, and nearly all were designed to reduce development. Conservation easements also allowed for a wide range of private uses, which may result in additional fragmentation and habitat disturbance. Some residential or commercial use, new structures, or subdivision of the property were permitted on 85% of sampled conservation easements. Over half (56%) allowed some additional buildings, of which 60% restricted structure size or building area. Working landscape easements with ranching, forestry, or farming made up nearly half (46%) of the easement proper- ties sampled and were more likely than easements without these uses to be designated as buffers to enhance biodiversity in the surrounding area. Our results demonstrate the need for clear restrictions on building and subdivision in easements, research on the compatibility of private uses on easement land, and greater public understanding of the trade-offs implicit in the use of conservation easements for biodiversity conservation. Keywords: biodiversity protection, conservation easement, land trust, land use, private-land conservation, The Nature Conservancy, working landscape Concesiones para Conservaci´ on: Protecci´ on de Biodiversidad y Uso Privado Resumen: Las concesiones para conservaci´ on son una de las herramientas primarias para la conservaci´ on de biodiversidad en tierras privadas. No obstante que su uso ha incrementado, existen escasos datos cuantita- tivos sobre las especies y h´ abitats que se busca proteger con las concesiones para conservaci´ on, cu´ anto desar- rollo estructural permiten o que tipos de uso de suelo permiten. Para atender estas lagunas de conocimiento, encuestamos a personal responsable de 119 concesiones para conservaci´ on establecidas entre 1985 y 2004 por el mayor concesionario sin fines de lucro, The Nature Conservancy. La mayor´ ıa de las concesiones (80%) trataban de proporcionar h´ abitat para proteger especies o comunidades in situ, y casi todas estaban dise˜ nadas para reducir el desarrollo. Las concesiones para conservaci´ on tambi´ en permitieron una amplia gama de usos privados, lo que puede resultar en fragmentaci´ on y perturbaci´ on de h´ abitat adicionales. En 85% de las con- cesiones para conservaci´ on muestreadas se permit´ ıa alg´ un uso comercial o residencial, nuevas estructuras o la subdivisi´ on de la propiedad. Mas de la mitad (56%) permiti´ o la construcci´ on de edificios adicionales, de ††email arissman@nature.berkeley.edu Paper submitted June 22, 2006; revised manuscript accepted October 13, 2006. 709 Conservation Biology Volume 21, No. 3, 709–718 C 2007 Society for Conservation Biology DOI: 10.1111/j.1523-1739.2007.00660.x