The Impact of Inundation Frequency on the Distribution of Floodplain Vegetation in the Jingjiang Section of the Yangtze River

Floodplain vegetation is an essential part of riverine wetland ecosystems. Hydrological fluctuations significantly influence its survival and distribution. This study examines the floodplain vegetation of the Jingjiang section of the Yangtze River. This study uses annual mean NDVI data over six time periods from 2000 to 2023 to represent the changes in floodplain vegetation. The driving factors include inundation frequency, annual mean temperature, annual mean precipitation, elevation, and slope gradient. To analyze the data, this study employs multiple analytical methods, including threshold segmentation, pixel-by-pixel linear regression (using the least squares method), Geodetector, and Pearson’s correlation analysis. This study clarifies the spatiotemporal evolution of the NDVI and the distribution of vegetation in these floodplain. It also quantitatively assesses the influence of multiple drivers and reveals the areas and extent of vegetation distribution affected by different inundation frequencies. The findings indicate: (1) Over six time periods from 2000 to 2023, NDVI values and the area covered by vegetation in the Jingjiang section of the Yangtze River floodplain exhibited fluctuating growth trends. The area covered by vegetation increased by 66.94 km2 in 2023 compared with that in 2000. (2) NDVI values were influenced by multiple interacting drivers, with inundation frequency being the dominant factor affecting vegetation change in the Jingjiang section (q-value: 0.79–0.86), followed by slope (q-value: 0.46–0.56). Interactions between different drivers amplify their impact on the annual average NDVI value. (3) Areas with inundation frequencies of 20%–40% exhibit positive spatial correlation with NDVI values. The maximum area of positive correlation is 112.51 km2, which is predominantly distributed across the central and marginal bars of the Jingjiang section. Within this range, inundation frequency has the strongest positive effect on vegetation growth.