关键词: 干播湿出, 绿洲-荒漠过渡带, NDVI, 植被退化

Abstract: We elucidated the impact of the “dry sowing and wet emergence” technique on the stability of vegetation in the oasis-desert ecotone of southern Xinjiang, with Xiaohaizi Irrigation District in Tumxuk City as a case. Based on GF-1 remote sensing imagery from 2020 to 2024, we established buffer zones extending from the cotton field edges into the surrounding desert and compared the spatiotemporal characteristics of the normalized difference vegetation index (NDVI) in the transition zone before and after the implementation of this technique. We then assessed the ecological stability by using Theil-Sen trend analysis, local spatial autocorrelation, and gravity migration model. The results showed that following the application of the “dry sowing and wet emergence” technique, vegetation in the transition zone experienced significant drought stress, leading to a marked reduction in ecosystem stability. Temporally, the most prominent NDVI degradation occurred in summer, with a 10.3% decrease within a 1-3 km range from the cotton fields, identifying it as the core degradation area. Spatially, the area of high vegetation coverage patches (NDVI>0.7) contracted by 52.2%, while the proportion of low-coverage areas (NDVI 0-0.1) increased from 33.4% in 2020 to 42.5% in 2023. Furthermore, the original “high-high” NDVI clustering area in the south completely transformed into a “low-low” clustering zone, exhibiting a trend of contiguous degradation. The dynamics of vegetation center of gravity revealed that, after the implementation of this technique, the inter-annual migration distance increased significantly, reaching a maximum of 409 m, with intensified directional fluctua-tions, reflecting a decline in the spatial stability of vegetation distribution. By reducing deep percolation and lateral subsurface flow from the farmland, the “dry sowing and wet emergence” technique effectively cut off the subsurface water supply to the transition zone vegetation, ultimately leading to vegetation degradation within a 3 km radius of cotton fields.

Key words: dry sowing and wet emergence, oasis-desert ecotone, NDVI, vegetation degradation