A global-level assessment of the effectiveness of protected areas at resisting anthropogenic pressures

Abstract

One-sixth of the global terrestrial surface now falls within protected areas (PAs), making it essential to understand how far they mitigate the increasing pressures on nature which characterize the Anthropocene. In by far the largest analysis of this question to date and not restricted to forested PAs, we compiled data from 12,315 PAs across 152 countries to investigate their ability to reduce human pressure and how this varies with socioeconomic and management circumstances. While many PAs show positive outcomes, strikingly we find that compared with matched unprotected areas, PAs have on average not reduced a compound index of pressure change over the past 15 y. Moreover, in tropical regions average pressure change from cropland conversion has increased inside PAs even more than in matched unprotected areas. However, our results also confirm previous studies restricted to forest PAs, where pressures are increasing, but less than in counterfactual areas. Our results also show that countries with high national-level development scores have experienced lower rates of pressure increase over the past 15 y within their PAs compared with a matched outside area. Our results caution against the rapid establishment of new PAs without simultaneously addressing the conditions needed to enable their success.

Keywords: Human Development Index; counterfactual; human footprint; impact assessment; management effectiveness.

Fig. 1.

Map of the 12,315 PAs existing in 1995 (blue) from the 152 countries included in the analysis, across Afrotropic = 2,278, Australasia = 871, Indomalaya = 927, Nearctic = 2,468, Neotropic = 1,033, and Palearctic = 4,738 as well as the 407 PAs for which METT data existed (crimson). Dark gray shows the countries for which we had METT data.

Fig. 2.

Mean change in pressure between 1995 and 2010 based on (A) the THPI, (B) human population density, (C) stable night lights, and (D) agricultural crop cover for protected area (green), matched outside (light brown), and all unprotected areas in the region (dark brown). Positive values indicate that pressure has increased in the 15 y. Error bars are 1 SE. Scales in B–D have not been standardized, thus absolute values should only be compared within plots.

Fig. 3.

Standardized parameter estimates for the most parsimonious model, based on AIC for (A) the global sample (n = 11,491) and (B) the subset for which we had METT scores (n = 407). Boxes indicate 50% confidence interval; lines indicate 95% confidence interval. The parameter estimates are based on the relative effectiveness score (THPI in PA – THPI in the counterfactual), thus, negative parameter estimates mean that PAs are more effective (i.e., increases are smaller inside PAs than the counterfactual) as explanatory variables increase in value.