Impact of ecological reserves on the local residents' health: Evidence from a natural experiment in China

The potential influence of natural ecosystems on human health has been widely acknowledged globally. Nevertheless, the causality of such a correlation among the middle-aged and older populations in developing countries awaits further investigations. This study aims to understand how a specific natural ecosystem change, namely the establishment of ecological reserves, improves the physical and mental health of middle-aged and older residents in China. Two batches of national key eco-function zones (NKEFZs) in 2011 and 2016 are selected as a quasi-experiment; and a total of 128,755 middle-aged and older residents from a combined data set from the China Family Panel Studies (CFPS) and China Health and Retirement Longitudinal Studies (CHARLS) from 2010 to 2020. A difference-in-differences method was used to identify the causal effects of the natural ecosystem improvement on human health outcomes. The results indicate significant and sustained improvements in the physical health of local middle-aged and elderly residents following the implementation of the NKEFZs policy. Notably, ecological reserves with a water conservation function and those in Karst area have the most salient effects on physical health. Furthermore, this study shows that the creation of ecological reserves improves the mental health of middle-aged and older residents, with the effect varying based on changes in physical health. This study provides new insights into the positive impact of natural ecosystem improvement on human health outcomes, in particular physical and mental health.