Impact of Spatiotemporal Variation in Precipitation Patterns on Dominant Species and Community Dynamics in Grasslands: A 35-Year Observation Case Study in East Ujimqin Banner

Against the backdrop of global climate change, altered precipitation patterns profoundly affect grassland ecosystems in arid and semi-arid regions. To clarify the spatiotemporal heterogeneity in the relationship between long-term precipitation variation and vegetation response, this study focuses on East Ujimqin Banner, Inner Mongolia. Utilizing 35 years of precipitation monitoring data (1983-2017) and field vegetation survey data from four key years (1983, 2009, 2013, 2017), nine Sums (townships) were categorized into three regions: northeast, central, and southwest. Methods including linear regression and ANOVA were employed to systematically analyze the long-term trends in precipitation and their relationships with the productivity and dominance of Stipa species, as well as community species richness. The results indicate that: (1) The long-term precipitation trend exhibited spatial heterogeneity, with more pronounced interannual fluctuations and a higher rate of change in the northeastern and southwestern regions compared to the central region; (2) Vegetation sensitivity to precipitation change displayed a pattern of higher responsiveness in the periphery and lower in the central region, as the response slopes of Stipa fresh weight, importance value index, and total community fresh weight per unit precipitation change were significantly greater in the northeastern and southwestern areas than in the central area. (3) Stipa populations showed a tendency to shift from the northeastern and southwestern regions toward the central area. Concurrently, species richness increased in the peripheral regions as Stipa declined, while it temporarily decreased in the central region. This study reveals the specific process of spatial range shifts in dominant grassland species and the reshaping of community structure driven by climate change, elucidating the regional differentiation in ecological sensitivity. It provides an important scientific basis for adaptive grassland management and biodiversity conservation in the region.