Applying trait-based method to investigate the relationship between macrophyte communities and environmental conditions in a eutrophic freshwater lake, China

- Trait-based community assembly analysis has not been sufficiently applied for freshwater system, especially at the level of functional trait.
- We used the RLQ and Fourth-Corner methods to explore the link between traits, species composition and water quality for macrophyte in a lake, China.
- The results suggested that the leaf nitrogen and SLA of macrophytes decreased with increasing environmental stresses caused by eutrophication.
- The trait-based methods can improve our understanding of the impacts of eutrophication on macrophytes from the view of plant functional traits.

Trait-based community assembly analysis, which links the plant traits to the variation of community composition along environmental gradients, has potential to improve the understanding of the impacts of eutrophication on macrophytes and responding process. In this article, we pioneered the use of RLQ and Fourth-Corner methods that establish in a quantitative way the link between macrophyte traits, macrophyte community and water quality in a eutrophic shallow lake, eastern China. A total of 9 environmental variables and 11 macrophyte traits were included in the analysis. We found that total phosphorus in water (25.7%, the contribution to total inertia in RLQ analysis), suspended solids (20.7%), water transparency (17.1%) and Chlorophyll a (14.0%) were the main environmental variables that were associated the macrophyte traits matrix. Among macrophyte traits, life form (15.7%), responded to the environmental conditions the most, followed by leaf nitrogen (13.8%) and specific leaf area (13.6%). The correlation between macrophyte traits and environmental gradients showed that macrophytes with higher leaf nitrogen and higher specific leaf area grew at locations with clear water condition, better water transparency and with less total phosphorus, Chlorophyll a and suspended solids in this shallow eutrophic lake. The results suggested that the leaf nitrogen and specific leaf area of macrophytes had a trend to decrease with the increasing environmental stresses caused by eutrophication. Moreover, we highlighted that total phosphorus in water should be prior considered for the future macrophyte conservation and restoration in this lake.