Methods for extracting vegetation phenology information and results analysis

As climate change and human activities exert their influence, significant changes have occurred in the phenology of vegetation on the Qinghai-Tibet Plateau. Identifying and studying the changes in vegetation phenology is an important foundational work for researching phenology and further investigating driving factors. Therefore, this study utilizes NDVI to invert the phenology of vegetation using three algorithms: dynamic threshold method, logistic function, and double logistic function. The phenology information is then identified and analyzed. Finally, Theil-Sen + Mann-Kendall algorithm is employed to analyze the spatiotemporal variation trends of phenology.