Contrasting spatial and temporal trends of protected area effectiveness in mitigating deforestation in Madagascar

Abstract

Networks of protected areas (PAs) form the backbone for biodiversity conservation worldwide. The effectiveness of protected areas has been studied and it has been shown that confounding factors, such as remoteness and accessibility, correlated with both presence of protection and extractive behaviors, affect the outcomes. We investigated the effectiveness of Madagascar's PA network in decreasing deforestation pressures, using a novel counterfactual methodology, accounting for distance to roads, rivers, major cities and altitude, slope and annual rainfall. The assessment was independently conducted for two different time periods, 1990–2000 and 2000–2010, and for Madagascar's three major forest types. We found that PAs were effective to some extent in reducing deforestation and that some of this decrease can be attributed to the presence of PAs, not just to the confounding factors rendering the land assigned for protection less likely to be deforested. We found differences in PA effectiveness between the two time periods, and in general lower deforestation in the later time period has meant that the PAs have less pressures to resist. However, in the spiny forest, even if deforestation had overall diminished, the pressure on reference areas used to compare PAs seemed to have increased showing that PAs have indeed a mitigation effect and thus increased in effectiveness in the second time period. Our study highlights the alarming trend of what happens once enough forest has been lost in easily accessible areas and the pressures starts to spread to also more remote areas and lands comparable to PAs (remote and inaccessible).