Conservation planning and priorities

Maybe the first law of conservation science should be that human population—which of course drives both threats to biodiversity and its conservation—is distributed unevenly around the world (Cincotta et al. 2000). This parallels a better-known first law of biodiversity science, that biodiversity itself is also distributed unevenly (Gaston 2000; Chapter 2). Were it not for these two patterns, conservation would not need to be planned or prioritized. A conservation investment in one place would have the same effects as that in another. As it is, though, the contribution of a given conservation investment towards reducing biodiversity loss varies enormously over space. This recognition has led to the emergence of the sub-discipline of systematic conservation planning within conservation biology. Systematic conservation planning now dates back a quarter-century to its earliest contributions (Kirkpatrick 1983). A seminal review by Margules and Pressey (2000) established a firm conceptual framework for the sub-discipline, parameterized along axes derived from the two aforementioned laws. Variation in threats to biodiversity (and responses to these) can be measured as vulnerability (Pressey and Taffs 2001), or, put another way, the breadth of options available over time to conserve a given biodiversity feature before it is lost. Meanwhile, the uneven distribution of biodiversity can be measured as irreplaceability (Pressey et al. 1994), the extent of spatial options available for the conservation of a givenbiodiversity feature.Analternative measure of irreplaceability is complementarity—the degree to which the biodiversity value of a given area adds to thevalueof anoverall networkof areas. This chapter charts the history, state, and prospects of conservation planning and prioritization, framed through the lens of vulnerability and irreplaceability. It does not attempt to be comprehensive, but rather focuses on the boundary between theory and practice,where successful conservation implementation has been explicitly planned from the discipline’s conceptual framework of vulnerability and irreplaceability. In other words, the work covered here has successfully bridged the “research–implementation gap” (Knight et al. 2008). The chapter is structured by scale. Its first half addresses global scale planning, which has attracted a disproportionate share of the literature since Myers’ (1988) pioneering “hotspots” treatise. The remainder of the chapter tackles conservation planning and prioritization on the ground (and in the water). This in turn is organized according to three levels of increasing ecological and geographic organization: from species, through sites, to seascapes and landscapes.