Protected areas provide species a first line of defense against human encroachment, the primary driver of extinction rates. Although protected areas presently comprise ~13% of the planet's surface, this reserve network constitutes a piecemeal patchwork of disconnected parcels created without any overarching common goal. As such, current protected areas provide inadequate protection of biodiversity patterns at a global scale. How much protection is necessary for the preservation of biodiversity, and how do we expand the current network in a manner that effectively protects biodiversity? We address these questions using an integer programming approach to find an optimal reserve network that protects an adequate amount of habitat for 32,000+ terrestrial vertebrate species, while accounting for preexisting protected areas and patterns of human encroachment.
Results/Conclusions
We find that ~30% of global surface area is sufficient to meet conservation targets of all known mammals, birds, amphibians and reptiles, and that increasingly stringent targets lead to reserve networks that more closely correspond to patterns of biodiversity.