Impact of the Project of Returning Farmland to Forest on Promoting Forest Coverage Rates in Mountainous Areas: An Empirical Analysis Based on Remote Sensing in Yunnan

The large–scale Project of Returning Farmland to Forest (PRFF) is a major strategic measure taken against the background of the catastrophic floods in 1998, and its policy effect urgently requires an accurate evaluation. Yunnan Province is an ecologically fragile province that integrates border areas, mountainous areas, ethnic groups, and underdeveloped areas. It is of great significance to study the effect of PRFF in Yunnan, which began in 2000, on promoting forest coverage rates (FCRs) in mountainous areas. In response to the shortcomings in the existing research, such as the lack of direct exploration and the limited policy evaluation tools of the effect of PRFF on improving FCRs in mountainous regions, this study takes Yunnan as an example based on land use/land cover (LULC) data interpreted from seven periods of RS images, aiming to study the effect of PRFF on promoting FCRs. After dividing 129 counties into 3 types (flatland county, semi-mountainous and semi-flatland (SMSF) county, and mountainous county), the Difference-In-Differences (DID) model and spatial DID models are used to measure the specific effect of PRFF on promoting FCRs based on county-level administrative units. The results indicate that PRFF has increased FCRs in non-flatland counties by 1.8082%, and the impact of PRFF on increasing FCRs in mountainous counties slightly exceeds that in SMSF counties. Although PRFF has converted some steep slope farmland into forest land, there is no evidence to suggest that the implementation of PRFF has significantly reduced the proportion of farmland and total grain production in non-flatland counties. Therefore, PRFF is an excellent project that promotes the increase in FCRs and benefits in the country and the people. The results can provide a reference for China to achieve the modernization of harmonious coexistence between humans and nature and also offer a reference for other countries to improve FCRs and the local ecology.