Rhizosphere effects and plant functional traits collectively determine the ecological strategy of Suaeda salsa across heterogeneous habitats in the Yellow River Delta

Background and Aims: Understanding the adaptation strategies of plants to heterogeneous environments is crucial for elucidating plant and community distribution and dynamics. Rhizosphere effects (REs) and plant functional traits (PFTs) are key components of plant adaptation strategies, but their synergistic contributions remain poorly understood. In this study, we selected Suaeda salsa , the pioneer species in coastal wetlands, to explore its ecological adaptation strategies under complex habitats. Methods We conducted a field experiment in the Yellow River Delta, selecting three sites with distinct salinity levels. REs, the key PFTs and soil microbial community compositions of rhizosphere soil (RS) and bulk soil (BS) of S. salsa were quantified. Results RS maintained lower soil pH, while higher soil moisture content, NH ₄ ⁺ -N content and enzyme activities than BS. Soil microbial communities in RS were also more stabilized and stress-resilient. Concurrently, PFTs shifted under higher salinity. The increased specific leaf area, tissue proline content and sodium to potassium ratio indicate a resource-conservation strategy with enhanced osmotic adjustment. Soil NH ₄ ⁺ -N and salinity were the most two important factors affecting the growth of S. salsa . Interestingly, we found a significantly negative correlation between soil salinity and plant individual biomass, which means smaller individuals tend to exhibit stronger rhizosphere-mediated responses to salt stress. Conclusions This study demonstrates the multidimensional integration strategy of S. salsa through both rhizosphere optimization and physiological trait plasticity. This mechanistic insight improves understanding of halophyte adaptation and informs strategies for restoring degraded coastal ecosystems.