Revealing the Impact of Protected Areas on Land Cover Volatility in China

Protected areas are fundamental for maintaining ecosystem functions and have generally been considered to affect land use change. Here, we explored how protected areas affected land cover volatility in China from 2011 to 2020 with LandTrendr using the Google Earth Engine (GEE) platform by comparing the difference in volatility of the Normalized Difference Vegetation Index (NDVI) in protected and unprotected areas. The results show that the regions with frequent land cover volatility are mainly located in eastern, central, and southwestern China, indicating that land cover volatility with high NDVI loss values is spatially aggregated in most cases. Considering the impact of protected areas, land cover volatility is relatively consistent inside and outside the protected area throughout the study period, showing a trend of first fluctuating and then rising. Approximately 22% of detected land cover volatility occurred in protected areas, though the average NDVI loss value (0.56) for protected areas was greater than unprotected areas (0.51). Combined with the outliers, land cover volatility accompanied by larger NDVI loss values is still primarily distributed in unprotected areas in most years. The detection of NDVI gain values in protected areas shows that protected areas (average value is 0.48) are larger than unprotected areas (average value is 0.47) almost every year, even combined with the outliers, and land cover volatility accompanied by larger NDVI gain values is also primarily distributed in protected areas in most years. Elucidating land cover volatility is helpful in understanding land cover changes and how to formulate an effective land use policy.