Dispersal limitations prompt early vegetation aggregation in counter-seasonal reservoir riparian zones: A case study of Longkaikou Reservoir, China

In global water management, the winter-storage, summer-drainage reservoir mechanism effectively mitigates summer floods and winter droughts. However, this counter-seasonal operation poses complex challenges to riparian ecosystems. To explore Nature-based Solutions (NbS), a deep understanding of the spatial development mechanisms of dominant species is crucial. Taking the Longkaikou Reservoir on China's Jinsha River as an example, we employed drone photogrammetry, quadrat surveys, and null model simulations to intuitively and quantitatively analyze the spatial patterns of dominant riparian species and the underlying ecological processes. Our results showed that a 40 m x 40 m area is the minimum sampling size for determining riparian plant communities. Habitat heterogeneity and dispersal limitation jointly influence population spatial patterns, modulated by spatial scale and species biology. At smaller scales, population aggregation is driven by reproduction and dispersal, while at larger scales, habitat filtering significantly impacts population distribution, leading to random or uniform patterns. Based on these findings, we propose an innovative NbS approach for riparian zones. Using the minimum sampling area as a unit, we suggest employing remote sensing and GIS for grid-based fine management. Within grids (at the community level), enhance habitat connectivity and prioritize native pioneer species with efficient dispersal mechanisms. Between grids (at the metapopulation and ecosystem levels), implement differentiated ecological strategies based on habitat heterogeneity. Additionally, fostering cross-regional and interdisciplinary collaboration will form an integrated research and application framework, supporting riparian ecosystem conservation.