“Skylights” increase exposure levels and reduce the maximum depth of nature reserves “天窗”增加自然保护区的暴露水平，降低最大深度

Spatial contradictions between nature conservation and social development are prominent in the integration and optimization of nature reserves (NRs) in China. Due to restrictions from the farmland “red line” policy and territorial spatial planning, scattered urban areas and farmland distributed within NRs form many “skylights”. Perforating NRs alters their shape and continuity and may have negative effects on long-term conservation. Through remote sensing data, we identified urban areas and farmland “skylights” in NRs in Guangdong Province, China. This study evaluated four scenarios: maintaining both urban areas and farmland (current state), maintaining farmland while removing urban areas, maintaining urban areas while removing farmland, and removing both urban areas and farmland. Two indicators, the exposure level and the maximum depth of NRs, were used to preliminarily assess the impacts of “skylights”. We found that urban “skylights” accounted for a relatively low proportion (5.81%) of total “skylights” and farmland “skylights” accounted for 94.19%. The current exposure level of NRs in Guangdong Province was very high, and approximately 82.83% of the NR areas were within 1 km of an unprotected matrix. If “skylights” were removed without exception, the 1 km exposure level would decrease to 61.37%, and the maximum depth would significantly increase. We recommend further assessment of the influence of “skylights” on the conservation effect of NRs and suggest first removing small “skylights” to reduce their negative impact.