Protected areas (PAs) are a key strategy in global efforts to conserve biodiversity and ecosystem services that are critical for human well-being. Most PAs have some built-up structures within their boundaries or in surrounding areas, ranging from individual buildings to villages, towns and cities. These structures, and the associated human activities, can exert direct and indirect pressures on PAs. Here we present the first global analysis of current patterns and observed long-term trends in built-up areas within terrestrial PAs and their immediate surroundings. We calculate for each PA larger than 5 km² and for its 10-km unprotected buffer zone the percentage of land area covered by built-up areas in 1975, 1990, 2000 and 2014. We find that globally built-up areas cover only 0.12% of PA extent and a much higher 2.71% of the unprotected buffers as of 2014, compared to 0.6% of all land (protected or unprotected). Built-up extent in and around PAs is highest in Europe and Asia, and lowest in Africa and Oceania. Built-up area percentage is higher in coastal and small PAs, and lower in older PAs and in PAs with stricter management categories. From 1975 to 2014, the increase in built-up area was 23 times larger in the 10-km unprotected buffers than within PAs. Our findings show that the development of built-up structures remains limited within the boundaries of PAs but highlight the need to carefully manage the considerable pressure that PAs face from their immediate surroundings.

保护区（PAs）是全球努力保护对人类福祉至关重要的生物多样性和生态系统服务的一项关键战略。大多数PA都在其边界内或周围区域具有一些建筑物，范围从单个建筑物到村庄，城镇和城市。这些结构以及相关的人类活动可以对PA施加直接和间接的压力。在这里，我们呈现了对当前模式的首次全球分析，并观察到了地面PA内及其周围地区建筑面积的长期趋势。我们为每个大于5 km ^2的PA计算对于其10公里无保护缓冲区，1975、1990、2000和2014年建成区覆盖的土地面积所占的百分比。我们发现，全球建成区仅覆盖了PA范围的0.12％，高得多的2.71％截至2014年，未受保护的缓冲区的总数为0.63％，而所有土地（受保护或未受保护）的0.6％。在欧洲和亚洲，巴勒斯坦权力机构及其周围地区的建设程度最高，在非洲和大洋洲则最低。沿海和小型PA的建筑面积百分比较高，而较旧的PA和管理类别更严格的PA的建筑面积百分比较低。从1975年到2014年，在10公里无保护缓冲区中，建筑面积的增加是在保护区中的23倍。