Responses of leaf and fine root functional traits to water-salt gradients in the Fuzhou section of the Minjiang River Basin

Leaves and fine roots are the most important organs for plant resource acquisition. Exploring the relationship between their functional traits and responses to environmental gradients can reflect the adaptive strategies of plants to cope with environmental change. Here, we examined wetland herbage in the Fuzhou section of the Minjiang River Basin, establishing three belts and 108 quadrats across four typical wetlands, and selected seven leaf functional traits and five fine root functional traits to analyze their responses to water and salt gradients using single-factor analysis of variance, correlation analysis, and redundancy analysis. Results showed that the coefficients of variation for leaf index and root tissue density were notably high. Leaf thickness, leaf dry matter content, root volume, and specific root length increased with increasing water and salt content, while specific leaf area and root tissue density decreased. Redundancy analysis showed that soil water content was the most significant. Leaf area was negatively correlated with leaf thickness, leaf area. Leaf tissue density, and leaf dry matter content were positively correlated with specific root length and specific root area. Under different water and salt gradients, the functional traits of the above-ground and below-ground parts showed a synergistic trend. Overall, this study revealed the leaves and fine roots trait dynamics of wetland herbaceous plants under varying water-salt conditions, enhancing our understanding of their response mechanisms to water-salt gradients as well as wetland plant resource acquisition and adaptation strategies in southeast China.