Revealing the erosion control mechanism of grassland communities in the source area of the Yellow River based on the vegetation response–effect trait framework

• An integrated response-effect trait framework quantifies direct and indirect pathways of vegetation-driven erosion control. • Seasonal precipitation drives trait variation, while stem-specific density directly governs erosion control. • Seed traits indirectly regulate erosion via stoichiometric (N:P) mediation of plant-soil feedbacks. • Trait correlations reveal hidden constraints on erosion resilience, such as leaf C:N:P trade-offs. • This research provides mechanistic guidelines for trait-targeted vegetation restoration in erosion-prone ecosystems. Soil erosion threatens ecological security and human well-being, with plants playing a vital role in its prevention. However, studies linking plant response and effect traits to reveal their erosion prevention mechanisms remain limited. In this research, thirteen selected plant functional traits were classified into two categories, namely, response traits that exhibit a response to environmental factors and effect traits that exert a significant effect on soil conservation. Soil conservation was used to quantify the vegetation’s erosion prevention capacity. (1) Critical plant functional traits, including leaf area, leaf N:P ratio, stem specific density, and lateral root spread, that serve both as response traits to climatic drivers (particularly seasonal precipitation) and as effect traits directly influencing soil conservation. (2) This overlap indicates that environmental change can indirectly alter ecosystem soil conservation capacity by selecting plant communities possessing specific dual-function traits. (3) Furthermore, traits such as seed length and dispersal unit length indirectly influence soil conservation through their association with leaf N:P ratio. Collectively, this study elucidates how dual-function traits serve as key pathways linking environmental change to the ecosystem. These findings provide a theoretical basis for soil conservation management in the Yellow River source area and help to further elucidate the mechanism of plants in preventing soil erosion.