Roads imperil South American protected areas

Protected areas (PAs) in South America play a crucial role in safeguarding biodiversity and ecosystem services. However, the widespread presence of roads within PAs poses a major yet largely overlooked threat to their ecological integrity. In this study, we used the most recent and consistent global roads dataset to evaluate the extent and spatial distribution of road networks within South American PAs. Our analysis revealed approximately 150,000 km of roads—equivalent to 3.5 times the Earth’s circumference. This extensive network exacerbates habitat fragmentation, increasing the number of PA patches from 1,230 to over 43,000, with 75% of these fragments smaller than 1 km². Consequently, seven out of nine terrestrial biomes on the continent have their protected interiors, on average, less than 4 km from the nearest road or unprotected surroundings. Roads infiltrate PAs through multiple entry points (13 per PA, on average), with 36% classified as highways or primary roads facilitating rapid transit and 20% paved, further amplifying their vulnerability to potential anthropogenic stressors. Only remote regions, such as flooded grasslands and savannas, Sub-Antarctic forests, and large areas of the Amazon basin, exhibit low road presence within PAs. Immediate conservation action is essential, with a focus on transparent road monitoring and management to maintain the ecological functions of these vital landscapes and ensure the long-term conservation of nature.