Leaf-Root Trait Coordination Among Dominant Herbaceous Species Across Three Marsh Habitats in Northeast China

Plant functional traits are key indicators of plant responses to environmental conditions and resource-allocation trade-offs, thereby providing insights into adaptive mechanisms across habitats. Wetlands are one of the major habitats worldwide, yet organ-level plant life adaptive strategies in different wetland types remain insufficiently understood. This study compared three representative marsh systems located in different regions of Northeast China. Forty-five plant community plots were established, and 10 leaf traits, 13 root traits, and 8 soil environmental variables were systematically measured for dominant herbaceous species. We examined above- and belowground trait trade-offs using Pearson correlation analysis and assessed their responses to environmental gradients using redundancy analysis (RDA). The results showed that trait variability differed markedly among marsh types. Inland salt marshes exhibited the greatest variation in leaf and root morphology, while morphological traits generally varied more strongly than ecophysiological traits. In inland salt marshes, root ecophysiological traits were closely associated with leaf morphology. Forested marshes showed multi-trait trade-offs and nutrient regulation, whereas freshwater herbaceous marshes displayed strong leaf-root trait correlations, indicating flexible inter-organ nutrient allocation. Soil environmental properties explained different proportions of functional trait variation across habitats, with the highest explanatory power in forested marshes (42.85%), followed by freshwater herbaceous marshes (34.56%) and inland salt marshes (34.41%). Soil carbon-to-nitrogen ratio significantly affected plant growth in all three habitats, although the other environmental drivers were habitat-specific. These findings reveal distinct community-level patterns of leaf-root trait variation and coordination among the sampled dominant herbaceous species across the three marsh habitats, providing empirical evidence for understanding wetland plant adaptation mechanisms in Northeast China.