Leaf N and P content play a key role in species’ adaptation to the environment. However, there are limited studies in how leaf N and P content respond to flooding duration in wetlands, and some findings are contradictory. Particularly, it’s still unclear how responses of leaf N and P content change at different organization levels. We hypothesized two pathways of flooding impacts on leaf N and P content: 1) a direct effect of flooding on the supply of the N and P availability (changes in soil fertility), or 2) and indirect effect of flooding on the ability to absorb or metabolize the nutrients (changes in production).
During the dry season (non-flooding season), we investigated responses of leaf N and P content to flooding duration gradient along an elevation gradient in a lakeshore meadow in Poyang Lake, China.
Results/Conclusions:
- Consistent to the indirect pathway, community biomass increased with elevation. Soil P content decreased with elevation, but soil N content had no significant response to elevation.
- At community level, leaf N and P content increased with community biomass. Leaf P content of community increased with soil P content, but leaf N content showed no significant correlation with soil N content.
- At inter-species level, leaf N content did not correlate with elevation while leaf P content showed U-shaped responses to elevation. Our results did not support neither direct nor indirect pathway hypothesis that leaf N and P had no significant responses to soil fertility or community biomass.
- At intra-species level, leaf N and P content of most species showed significant responses to either community biomass or soil fertility.
Therefore, our study found that responses of leaf N and P content to flooding duration depends on organization level. Because community biomass showed greater contributions to variations in leaf N and P content than soil fertility at both intra-species and community level, our study suggested that indirect pathway was more important than direct pathway to responses of leaf N and P content to flooding duration.