Spatiotemporal Analysis of Vegetation Dynamics Based on Multi-Resolution Vegetation Products in the Three Parallel Rivers Basin from 2000 to 2018

The Three Parallel Rivers Basin (TPRB) is a global biodiversity hotspot in the southeast of Qinghai-Tibet Plateau. The vegetation ecosystem has undergone significant changes due to global environmental changes, necessitating the long-term and fine-scale monitoring. The Hi-GLASS FVC product, derived from Landsat 8 data, has a fine spatial resolution of 30 m, but spatial gaps caused by clouds and shadows are prevalent. To address this issue, a 16-day, 30 m resolution FVC dataset was generated from 2000 to 2018 for the TPRB by fusing Hi-GLASS FVC and GLASS FVC time-series data. Combining the annual average FVC and growing-season average FVC, trend analysis of vegetation cover was conducted at two different spatial resolutions (30m and 500m) using the Sen's slope and Mann-Kendall test at a 95% confidence level. The results indicated that more areas exhibited significant improvements in vegetation than degradation. The improvements were characterized by the increase of the annual average FVC as well as the growing-season FVC for two decades. This study provides scientific supports for the development of ecological conservation plans in the TPRB region.