Publication Date:
2015-10-24
Description:
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 2 = 0.249, P = 0.005) and one out of five morphological traits (i.e. shoot elongation capacity; R 2 = 0.194, P = 0.015) between partially submerged and control treatments could predict the distribution pattern of the 30 wetland plant species. In contrast, means of plant traits in either control or submergence could not predict species distribution. The trait LnRRs, increasing from very negative to very positive, corresponded positively with the distribution, ranging from the zone furthest from the wetland waterline to that nearest to the waterline. Surprisingly, physiological trait LnRRs that had been expected to underpin performance trait LnRRs did not themselves predict the distribution pattern of these species. Analyses at the level of multivariate trait groups (based on PCA) showed that species LnRRs of the morphological trait group were positively correlated with LnRRs of the performance trait group. Conclusions Our findings demonstrate that screening wetland plant species for performance and morphological trait LnRRs under experimentally flooded conditions is an effective approach to understand and predict their distribution pattern along moisture gradients in the field. Trait responses of wetland plants to hydrological changes may reflect their habitat preference and thus field distribution along the hydrological gradient. We found that response ratios of performance and morphological traits between partially submerged and un-submerged treatments under experimental conditions could well predict field distribution pattern of wetland plant species.
Print ISSN:
1100-9233
Electronic ISSN:
1654-1103
Topics:
Biology
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