Meta-analysis on a Decade of Testing Corridor Efficacy: What New Have we Learned?

Abstract

Corridors are widely considered as a strategy to mitigate effects of habitat fragmentation on biodiversity. There are, however, lingering concerns about whether corridors work as intended and whether managing for connectivity in fragmented landscapes is even important for biodiversity conservation. In response, numerous manipulative and natural experiments have been conducted to test the effectiveness of corridors. Gilbert-Norton et al. Conserv Biol. 2010;24(3):660-8 (2010) reviewed such studies published between 1985 and 2008 and concluded that corridors are generally effective at increasing inter-patch movement. The authors noted a lack of studies measuring responses at the population and community levels, responses that would better approximate corridor effects on population persistence and aspects of biodiversity. Here I explored what new insights can be gained on corridor effectiveness from studies published in the last decade, particularly with an eye toward insights going beyond effects on inter-patch movement. Following the same selection criteria as Gilbert-Norton et al. Conserv Biol. 2010;24(3):660-8 (2010), I reviewed studies published between 2008 and 2018 that tested corridor effectiveness by comparing ecological response variables from patches connected and not connected by corridors. Analysis of effect sizes showed that corridors increase response variables, reinforcing earlier conclusions that corridors function as intended. Whereas the previous review mainly included corridor effects on dispersal, recent research shows support for corridor efficacy at a variety of levels of organization, from individuals to communities. These findings provide further support for the conclusion that efforts spent creating and maintaining corridors are worthwhile for biodiversity conservation.