[Spatiotemporal Evolution and Driving Factors of Net Primary Productivity in the Southwest Alpine Canyon Region of China from 2001 to 2020].

Abstract

As an important ecologically fragile region and ecological barrier in China， the Southwest Alpine Canyon Region of China plays a critical role in maintaining ecological security and enhancing carbon sink benefits in southwestern China. Investigating the spatiotemporal evolution of its carbon sequestration capacity and the contribution of driving factors is of great significance. Existing regional studies have mostly focused on vegetation cover and soil erosion， while analysis of changes in carbon sequestration capacity and its driving factors remains insufficient. Therefore， this study took vegetation net primary productivity （NPP） as an entry point and utilized the MOD17A3HGF （Version 6.1） dataset， along with Theil-Sen trend analysis， Mann-Kendall significance test， multiple partial correlation analysis， and residual analysis， to examine the spatiotemporal evolution of NPP and its driving factors in the Southwest Alpine Canyon Region of China from 2001 to 2020. The results indicated that： ① During the study period， the NPP （in terms of C） in the Southwest Alpine Canyon Region of China showed a non-significant decreasing trend [changing rate=-0.1 g·（m²·a）^-1， P=0.92]. Spatially， it exhibited a distribution pattern of "faster in the south than in the north， and faster in the east than in the west." Significant increasing trends were concentrated in the Water Conservation and Soil Retention Zone of the Northern Yunnan-Western Sichuan Alpine Gorge （zone Ⅲ）， while significant decreasing trends were mainly distributed in the Ecological Conservation Zone of the Southeastern Tibet Alpine Gorge Region （zone Ⅰ）. ② The response of NPP changes to meteorological variations showed significant differences， with temperature being the key driving factor， followed by solar radiation > precipitation > wind speed. ③ Changes in NPP were influenced by both climate change （accounting for approximately 50.1% of the area） and human activities （accounting for about 44.0% of the area）. Specifically， the increase in regional NPP was primarily driven by climatic factors （accounting for about 32.7% of the area）， while the decrease in NPP was mainly caused by human activities （accounting for approximately 19.3% of the area）. The findings reveal the spatiotemporal patterns and main driving factors of NPP in the Southwest Alpine Canyon Region of China， providing references for assessing the carbon sink development potential and implementing differentiated regional ecological management strategies in the area.