Abstract:

This study aimed to clarify the carbon sequestration capacity and its change mechanisms in the drylands of China. The study used the AI index to delineate the extent of drylands. Based on the MODIS Vegetation Gross Primary Productivity (GPP) dataset, the temporal and spatial characteristics of vegetation carbon sequestration capacity in China’s drylands from 2001 to 2020 were investigated. This investigation considered meteorological data, including temperature, precipitation, Vapor Pressure Deficit (VPD), soil water content, and human activities such as land use. The results reveal the following: (1) Over the 20 year period, GPP in China’s drylands elevated significantly in 64.72% of the regions. (2) Temperature had the lowest impact on GPP, with a relative contribution rate of 21.70%. Precipitation and soil water content emerged as the dominant factors driving GPP growth, with their combined contribution rate exceeding 55%. As drought intensified, the effect of water stress gradually strengthened. In different vegetation types, except for mixed forests and alpine vegetation, precipitation was the most critical climate factor influencing GPP changes. (3) Differences in soil and landform types were the dominant factors influencing the spatial variation of GPP. Moisture and land use type factors also played important roles, with the explanatory power of the interaction between any two factors exceeding that of a single factor. The interaction between soil type and the other factors was particularly remarkable. The study’s findings hold essential theoretical implications for a deeper understanding of the evolution characteristics of carbon sinks in arid ecosystems in China and their response mechanisms to external environmental factors.

Key words: gross primary productivity, climate change, response mechanism, geographic detector, China’s drylands