Association Analysis of the Spatial and Temporal Changes in Vegetation Photosynthesis Levels with Land Cover Changes in China Based on Solar-Induced Fluorescence

Understanding the relationship between vegetation photosynthesis levels and land use changes is crucial for assessing ecosystem health and plant growth status. Existing studies have not fully considered temporal and spatial dimensions, resulting in an incomplete understanding of the relationship between vegetation photosynthesis levels and land use. Based on solar-induced fluorescence (SIF) data from 2001 to 2022, this study used the Mann-Kendall (MK) test and spatial association analysis to explore the associations between temporal and spatial changes in vegetation photosynthesis levels and land cover change (LCC) in China. The contributions and findings are as follows: (1) A computational framework was utilized to comprehensively measure the spatial correlation between LCCs and chlorophyll levels based on their spatial co-occurrence. (2) The MK test results of the annual and monthly average vegetation photosynthesis levels revealed that most regions in China exhibited increasing trends, accounting for 90.01% and 91.78%, respectively. Moreover, the vegetation photosynthesis levels in western China had a downward trend, indicating that the vegetation ecosystem in this region may be under a certain degree of pressure or may face the risk of degradation. (3) Some economically developed provinces are facing ecological pressures caused by urbanization and industrialization, which have led to the degradation of vegetation ecosystems and a decrease in vegetation photosynthesis levels. (4) Highly supportive areas of the land use-vegetation photosynthesis level association analysis were mainly distributed in grassland and forest areas, indicating the effectiveness of forest protection and grassland management policies. Moreover, the decrease in vegetation photosynthesis mainly occurred in barren areas, illustrating that the management and protection of this type of land still need to be strengthened. These findings underscore the complex interplay between land use and vegetation health, providing insights for sustainable land management policies.