Responsiveness of performance and morphological traits to experimental submergence predicts field distribution pattern of wetland plants

Question: Plant trait mean values and trait responsiveness to different environmental regimes are both important determinants of plant field distribution, but the degree to which plant trait means vs trait responsiveness predict plant distribution has rarely been compared quantitatively. Because hydrological regime is a key determinant of wetland plant distribution, we hypothesized that both plant trait means and trait responsiveness to experimental submergence could predict plant adaptation to a wet or a dry part of hydrological gradients in wetlands. Location: Beijing, China. Methods: We measured mean values for 14 plant traits by growing 30 wetland species both on land (control) and partially submerged in a greenhouse, and calculated log response ratios (LnRRs) of these traits to submergence. A distribution pattern index of wetland plants along the moisture gradient (from the zone furthest from the wetland waterline to that nearest to the waterline) was developed based on plant survey data in 3988 field plots in 24 wetlands in Beijing, China. Results: LnRRs of performance traits (shoot biomass, root biomass, plant height and total root length; R