Segan, Daniel B., Carwardine, Josie, Klein, Carissa, Grantham, Hedley, and Pressey, Robert L. (2010) Can we determine conservation priorities without clear objectives? Biological Conservation, 143 (1). pp. 2-4.

PDF (Published Version) - Published Version Restricted to Repository staff only

 

11

4

Abstract

Wilhere et al. (2008) recently proposed a new index, "average optimacity", to guide investment in biodiversity conservation. They suggested that average optimacity, by being goal-independent, overcomes the subjectivity in target-based approaches. We argue that conservation value cannot be informed by average optimacity because the notion of value is inherently goal-dependent. We begin with a clarification of current terminology around conservation value, then give an illustration of how average optimacity might actually confound decision-making.

Spatial conservation prioritization identifies areas for conservation action that collectively meet a set of explicit conservation objectives (hereafter "targets"). Within this framework, value is the contribution of an area to targets. "Irreplaceability" (Pressey et al., 1993) is one measure of value. While Pressey et al. (1993) were principally focused on representation targets, their definitions of irreplaceability were broader: "the potential contribution of a [n area] to a reservation goal" or "the extent to which the options for reservation are lost if the [area] is lost".

Wilhere et al. correctly state that Marxan's selection frequency (Ball and Possingham, 2000) and C-Plan's irreplaceability (Pressey et al., 2009) are used synonymously, but are estimated differently. Marxan uses simulated annealing and incorporates heterogeneous costs and varying emphasis on spatial compactness. C-Plan uses a statistical estimator, with constraints only on the number of areas allowed in the solution. While we sympathize with Wilhere et al.'s desire for semantic clarity, we believe that a new term for Marxan's estimate (“optimacity”) creates an unnecessary precedent. Since (and even before) its incorporation into the conservation planning vernacular, irreplaceability has been estimated with various techniques for diverse objectives (Table 1). Using optimacity to refer to Marxan's selection frequency implies the need for separate terms for other estimation techniques and objectives, and this would create much unnecessary confusion.

Actions (Repository Staff Only)

Item Control Page