The importance of protected areas for overexploited plants: Evidence from a biodiversity hotspot

Abstract

Overexploitation is a main driver of biodiversity loss globally. Protected areas may have a key role in reducing overexploitation, yet their actual effectiveness in maintaining high-density and viable populations of overexploited species has rarely been evaluated. For overharvested plants, in particular, available information is extremely limited, making it unclear whether protected areas are indeed effective at protecting species. Here, we provide the first biome-wide assessment of the effectiveness of protected areas in maintaining populations of overexploited plants. We analyzed data from 50 populations of the overexploited and threatened palm Euterpe edulis, an ecologically and economically important species of the Atlantic Forest biodiversity hotspot. By integrating these data with species distribution modelling and matrix population modelling, we were able to evaluate the most likely causes and possible consequences of differences in population density inside and outside protected areas. Forest sites located inside protected areas had, on average, almost three times higher adult density of E. edulis than sites located outside protected areas, and a corresponding higher frequency of viable populations (≥60 adults/ha). Our analyses indicate that these differences are a direct consequence of the lower frequency of palm heart harvest inside protected areas, rather than differences in climatic suitability or forest cover. The matrix model showed that the higher density and lower harvest frequency inside protected areas may significantly increase long-term persistence of E. edulis populations, reducing their extinction risk. Our findings provide new and compelling evidence that terrestrial protected areas may be crucial for long-term conservation of overexploited plants.