22-year dynamic analysis of vegetation cover in karst area: a case study in Guangxi, China

Karst areas are usually dry due to the thin thickness of the soil, posing challenges to the local vegetation ecology such as soil erosion and water scarcity, resulting in sparser vegetation than in other areas, further contributing to ecological imbalances and affecting human societies. This paper investigates the changes of vegetation cover over 22 years for Guangxi, which has been biggest karst area in global. Based on MOD13Q1 remote sensing imagery data, we conducted an analysis of the spatiotemporal patterns of vegetation dynamics in Guangxi using NDVI index. Additionally, this study employed residual analysis to investigate the contributions of anthropogenic and natural factors on vegetation NDVI. The results indicate that, (1) from 2001 to 2022, the vegetation NDVI fluctuations have increased, with a gradual decrease in spatial distribution from the periphery to the center. (2) In most areas, vegetation NDVI has shown significantly improved conditions, accounting for 59% and 20% of the total area, respectively, while degraded areas constitute only 6%. (3) Residual analysis indicates that 88.5% of the regions are influenced jointly by climate and anthropogenic factors, with the latter's contribution predominating over the former, primarily concentrated in the southern regions of Guangxi. (4) Interaction detection revealed that the strongest effects were produced by interactions centered on land use, while the influence of interactions between temperature, precipitation, and slope is relatively small. These findings can provide data support for the green low-carbon transformation and the development of green productivity in Guangxi.