The role of scale in designing protected area systems to conserve poorly known species

Abstract

Possingham. 2015. The role of scale in designing protected area systems to conserve poorly known species. Ecosphere 6(11):237. http://dx.doi.org/10.1890/ES15-00346.1Abstract. Systematic conservation planning has a substantial theoretical underpinning that allows optimization of tradeoffs between biodiversity conservation and other socioeconomic goals. However, this theory assumes perfect spatial information about the locations of biodiversity features (e.g., species distributions). In practice, planners represent well-known taxa and other biodiversity ''surrogates'' in protected area systems, hoping that unmapped species will also be conserved. However, empirical research finds that surrogates predict species presence imperfectly, and sometimes rather poorly, at scales relevant to planning, and existing theory provides no further guidance. We developed new theory, explicitly incorporating aspects of spatial scale, for the representation problem when the locations of species distributions are unknown. Using probability theory and simulated and real species distributions, we found that the probability of adequately representing an unmapped species in a protected area system will be low unless the total fraction of the region being protected is larger than the species representation target. Furthermore, successful conservation depended critically on the relative sizes of the species distribution and of the individual protected areas; fewer, larger protected areas allowed the entire species distribution to fall into an unprotected gap. This scale-dependence varied with the configuration of the protected area system, with the conservation objective most likely to be attained if the individual protected areas were hyperdispersed (evenly spaced across the planning region). Using these results, we developed three design principles for representing unmapped species in protected areas: (1) The fraction of the region placed in protected areas should be substantially larger than the species-level representation target; (2) Individual protected areas must be at least one to two orders of magnitude smaller than the unmapped species' distribution; and (3) Protected areas should be evenly dispersed over geographic space. We also performed preliminary investigations of the effects of surrogates and socio-economic cost data on the probability of adequately representing unmapped species, finding that the primary effect of surrogates may simply be to promote hyperdispersion of protected areas across the planning region, and that seeking to minimize opportunity costs gives poorer conservation results than random protected area placement.

Equitable Representation of Ecoregions is Slowly Improving Despite Strategic Planning Shortfalls

“…Our multivariate model and sensitivity analyses support this point, revealing that rapid area accumulation improves changes in PE when implemented through multiple, smaller PAs rather than fewer, larger PAs. Previous studies have found similar results, showing that large selection units (in our case, PAs) drive the overrepresentation of features (Pressey & Logan 1998) or allow entire features to fall into unprotected gaps (Kendall et al 2015). With large PA expansion predicted to increase in coming years in an effort to meet percent coverage targets (Blomley et al 2013), and others promoting the need for "mega reserves" (Laurance 2005), it will be important to consider the role of scale in achieving conservation outcomes.…”

“…Previous studies have found similar results, showing that large selection units (in our case, PAs) drive the overrepresentation of features (Pressey & Logan ) or allow entire features to fall into unprotected gaps (Kendall et al . ). With large PA expansion predicted to increase in coming years in an effort to meet percent coverage targets (Blomley et al .…”

Evaluating trade-offs between quantitative and qualitative protected area objectives

“…The positive relationship between total area protected and total PE further supports this point, as well as our model, which revealed that despite the overall increasing trends in PE, the annual Our multivariate model and sensitivity analyses support this point, revealing that rapid area accumulation improves changes in PE when implemented through multiple, smaller PAs rather than fewer, larger PAs. Previous studies have found similar results, showing that large selection units (in our case, PAs) drive the overrepresentation of features (Pressey & Logan 1998) or allows entire features to fall into unprotected gaps (Kendall et al 2015).…”

Optimising sample sizes for animal distribution analysis using tracking data

“…r packages) to easily assess adequacy of sample size, which is concerning, particularly if management strategies (e.g. boundaries of marine protected areas) are then based on insufficient sampling (Hebblewhite & Haydon, 2010; Kendall et al., 2015). A common approach to address this issue applies a pre‐defined volume contour of a UD for each tracked animal (e.g.…”