Assessing the spatial-temporal variability of net primary productivity in Qinghai-Tibet Plateau based on Google Earth Engine platform

Abstract:
Based on Google Earth Engine (GEE) platform, combined with NPP, land use and climate datasets, this study analyzed the spatial-temporal patterns of NPP variations in Qinghai-Tibet Plateau from 2001 to 2020 using linear trend analysis, and explored the response of NPP to climate change and human activities. The findings are as follows: From 2001 to 2020, the spatial distribution of NPP in the Qinghai-Tibet Plateau demonstrated a decreasing trend from southeast to northwest. Except for forested areas in the eastern and southeastern parts, NPP values were relatively low in other regions. The evolution trajectory of vegetation NPP in Qinghai-Tibet Plateau during the past 20 years exhibited significant spatial heterogeneity. Approximately 94% of the vegetation in the study area had been restored to some extent. There was significant spatial-temporal variability in the comparative roles of climate change and human activities during the NPP transformation in Qinghai-Tibet Plateau, and the restoration effect of climate change and human activities on vegetation was significantly more pronounced than the degradation effect. Compared with the traditional desktop remote sensing processing platform, GEE platform enabled rapid invocation of massive online resources, thus providing strong technical support for large scale and long time series remote sensing data.