Identification of Spatial Variations and Influencing Factors of Forest Degradation in the Zagunao Watershed, China

The Zagunao, as a typical alpine forested watershed in the upper Yangtze River Basin, China, plays an important role in providing valuable forest ecosystem services such as water purification, water supply, climate regulation, and carbon sequestration for downstream cities in the Chengdu plain. However, alpine forests in the Zagunao watershed are confronted with growing disturbances including climate changes and anthropogenic disturbances. These disturbances can impact ecological patterns and processes, resulting in degraded forest ecosystem functions and services. Thus, detecting degraded forests and associated driving factors in the Zagunao watershed is urgently needed. In this study, we combined the meteorological data and multiple remote sensing datasets to investigate the spatial distribution of forest degradation and its driving factors in the Zagunao watershed. The key findings are: (1) from 2001 to 2017, degraded forests accounted for 9.71% of the forested area in the Zagunao watershed, and the natural coniferous broadleaved mixed forest was the main degraded vegetation type; (2) 95% of the degradation was driven by anthropogenic activities while only 5% of it was caused by climate drivers. This study is beneficial for forestry sectors to effectively detect forest degradation and provides scientific guidance for future forest restorations and management in alpine forested watersheds.