Differences in functional traits of herbaceous plants in Sanjiang plain wetland under human disturbance gradient and their response strategies to environmental changes

Using the Honghe Nature Reserve in the Sanjiang Plain as a case study, this research tests the central hypothesis that increasing anthropogenic disturbance intensity shifts the ecological strategies of dominant plant species along a resource-conservative to acquisitive spectrum, thereby progressively enhancing the role of soil properties as proximate drivers of trait variation. This hypothesized process unfolds sequentially: under low-intensity disturbance, direct physical stress acts as the primary filter on traits; at moderate intensity, disturbance begins altering soil conditions, shifting plant adaptation toward soil resource competition and increasing the explanatory power of soil factors; under high-intensity disturbance, profoundly transformed soil environments become the dominant proximate filter, selecting strongly for resource-acquisitive traits. We examined this framework by measuring leaf and root traits of 14 dominant herbaceous species and soil factors across 24 disturbance-gradient plots. Findings confirm distinct adaptive strategies: phosphorus-limited growth in light disturbance, conservative resource use in moderate disturbance, and a shift toward fast-return strategies in fertile, heavily disturbed soils. This study mechanistically traces the cascade from ultimate (anthropogenic disturbance) to proximate (soil) drivers of plant adaptation, providing a scientific basis for targeted wetland restoration that addresses disturbance legacies.