Spatiotemporal evolution and driving factors of vegetation carbon use efficiency in Xinjiang

Research on vegetation carbon use efficiency (CUE) enhances our understanding of regional carbon cycle mechanisms and provides a basis for achieving carbon neutrality goals. This study investigated the spatiotemporal variations and driving factors of vegetation CUE in Xinjiang from 2001 to 2023 using MODIS images; meteorological data; and analytical methods including the Hurst exponent, partial correlation analysis, and residual analysis. During 2001-2023, the CUE of vegetation in Xinjiang exhibited a fluctuating and gently decreasing trend, and the high values were mainly distributed in the Tianshan and Kunlun Mountains. Approximately 55.97% of the areas where the current vegetation CUE is decreasing, mainly located in regions such as the Ili River Valley, the periphery of the Junggar Basin, and the oasis areas along the edge of the Tarim Basin, are likely to experience an increase in the future. In most areas of Xinjiang, the vegetation CUE was negatively correlated with potential evapotranspiration. The correlations of CUE with temperature and precipitation displayed spatial differences between northern and southern Xinjiang. In northern Xinjiang, CUE was negatively correlated with temperature and positively correlated with precipitation, whereas the opposite was found in southern Xinjiang. Moreover, the vegetation CUE had a stronger response to potential evapotranspiration. Approximately 58% of the vegetation CUE changes across the regions were jointly driven by climate change and human activities. The regions where human activities played a promoting role in vegetation CUE were mainly distributed in low-altitude areas and regions with relatively frequent human activities around urban agglomerations.