Conservation

the United States, committing more than $24 billion to fund land acquisition and easements for open space, habitat protection and other conservation objectives (Trust for Public Land 2003). Non-governmental organizations, such as The Nature Conservancy and local land trusts, have become increasing popular due to their investments in private land conservation (Merenlender et al. 2004). Nonetheless, conservation budgets are typically far less than the cost of protecting all the remaining desirable lands, and tradeoffs must be made when targeting available sites for protection. The literature in conservation biology has focused much attention on reserve site selection (Margules, Nicholls and Pressey 1988; Pressey et al. 1993). Conservation biologists often frame the selection of reserve sites as covering the maximum number of species when constrained to select only a specified number of reserve sites. In this “site-constrained” optimization framework, a species is considered protected if it is represented at any of the chosen sites (Church, Stoms and Davis 1996). Two extensions for the site-selection framework have been to incorporate heterogeneity in either the land costs (Ando et al. 1998) or in the vulnerability to future land