| Summary: | Increasing light is widely recognised to be harmful to the wilderness of protected areas (PAs). However, minimal studies revealed the spatiotemporal distribution and variation of nighttime lights (NTLs) at the regional and single protected area levels on a continuous time. We assessed the extent and intensity of NTLs within and around the PAs during 1992–2012 in mainland China. Lighted area index (LAI), lighted intensity index (LII), potential LAI (PLAI) and potential LII (PLII) were developed as indicators to represent the total quantity and the intensity in a PA and in a 5-km buffer zone around the PA on the basis of the Defense Meteorological Program Operational Line-Scan System NTL data. NTL in PAs covered 7192 km2 in 2012, accounting for 0.73% of the total area of PAs. The highest values of LAI and LII were observed in Northeast and South Central China among the six geographical divisions. The LAI and LII increased by 3.22 and 3.51 times from 1992 to 2012, which showed that the area and intensity of NTL in PAs experienced simultaneous growth. We identified a significant increase of NTL within 36% of PAs and outside 60% of PAs, indicating the persistent increase in the intensity of human disturbance in and around these PAs. The NTL growth rates in marine and coastal and wild plant PAs were the greatest and lowest among different types of PAs, with values of 76.47% and 15.79%, respectively. We suggested that development of targeted countermeasures for each PA should comprehensively consider the conservation objectives, the type of PA, and the lighting conditions inside and outside the PA. The findings can provide useful information for targeting management strategies to alleviate light pollution and human disturbance.
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