Terrestrial protected areas are not effective in mitigating human pressure on biodiversity

Global biodiversity is declining rapidly and protected areas are a major conservation measure aiming to reverse this negative trend by limiting pressures on biodiversity in particular locations. There are increasing calls to protect larger areas, but also growing evidence that an increase in area alone is insufficient. At least as important is the effectiveness of existing and new protected areas. We apply a novel biodiversity pressure index that encompasses the five direct drivers of biodiversity loss identified by IPBES to analyse pressures in protected areas globally. We use a GLMM to assess which variables shape the pressure levels within protected areas. We find that there are still notable human pressures in protected areas globally. Strict protection and larger size of protected areas result in lower pressures, while high national-level corruption levels result in higher pressures. The results confirm that an increase in the number of protected areas will not necessarily conserve biodiversity effectively, unless they achieve greater control of the underlying drivers of biodiversity loss, including spatially diffuse pressures and those that currently compromise small protected areas in countries with unstable governance.