Work

Expand or better manage protected areas: A framework for minimizing extinction risk when threats are concentrated near edges

Year: 2025

Type: article

Abstract: Several international agreements have called for the rapid expansion of protected areas to halt biodiversity declines. However, recent research has counterintuitively shown that spending precious resources on expanding protected areas may be less cost-effective than redirecting these resources towards threat management in existing reserves. These findings may be due to the assumption that threats are homogeneously distributed in the landscape. In some cases, threats are more concentrated near the edge of protected areas. As protected areas expand, core habitat in the centre expands more rapidly than its edge, potentially creating a refuge from threats. Where threats are concentrated near edges, estimates of population extinction risk must account for both an edge population that is impacted by some threats and a core portion that is not impacted. In this paper, we present a framework linking protected area expansion and threat management, to reduce extinction risk via their impact on population carrying capacity and growth rate within core and edge habitats. We demonstrate the framework using a population model of poaching in a circular protected area, where poachers only penetrate the protected area to a certain distance. We parameterize the model for Peter’s Duiker (Cephalophus callipygus), which is harvested using snares. Expanding protected areas reduces extinction risk more dramatically compared to an equivalent investment in snare removal, and the relative benefit of expansion is greatest for larger protected areas that already sustain core unhunted habitat. Our results demonstrate the importance of protected area expansion in buffering susceptible populations from hunting pressure.

Source: Biological Conservation

DOI: 10.1016/j.biocon.2025.111469

Authors: Brendan G. Dillon, Hugh P. Possingham, Matthew H. Holden

Institution: The University of Queensland

Language: English

Topic: Conservation, Biodiversity, and Resource Management

Subfield: Global and Planetary Change

Field: Environmental Science

Domain: Physical Sciences

SDG: Life on land

Open Access status: hybrid

Estimated APC paid: $3,830