Water depth alters the trait network of submerged macrophytes in Nansi Lake: an impounded lake of South-to-North Water Transfer Project, China

Trait network analysis have been widely used to unravel the effects of variable environments on submerged macrophytes communities. However, few studies focused on the response of submerged macrophytes to variable water depths in impounded lakes from a whole plant trait network perspective. Here, we carried out a field study aimed to evaluate variation of functional traits, detect hub traits and clarify trait network topologies among different water depths. Overall, our results showed that internodes number, plant height,root number, stem diameter, rhizosphere diameter, root weight, specific leaf area, carbon content and phosphorus content significantly differed among different water depths. From shallow to deep water depth, the hub traits of submerged macrophytes communities gradually shift from resource-acquisitive traits to resource-conservative traits in response to light attenuation. The functional trait network exhibited high edge density and average clustering coefficient, low average path length and tight assemblages of three modules, indicating high-efficiency traits cooperation and resource acquisition at moderate water depth. This study explored the changing patterns and determinants of trait networks along water depth gradients to improve our understanding of ecological rules regulating trait correlations.