Flooding and wetland plants: Localized versus whole-plant response

Background/Question/Methods

Wetlands are found throughout the world with 30% in North America. They are ecologically significant for water treatment, nutrient uptake, carbon sinks, to recharge ground aquifers, as well as to provide critical habitat for diverse wildlife species. In the past, wetlands have been shown to effectively phytoremediate agrichemicals from surface waters prior to their flow into receiving waters. Clonal wetland plants may simultaneously exploit both flooded and non-flooded soils through vegetative propagation and clonal integration; however, to do so, plants must acclimate to this heterogeneous environment at a hierarchical level below that of the genetic individual.  In this study, genetic individuals of Leersia oryzoides (rice cutgrass) were exposed to three flooding treatments: drained, flooded, and heterogeneous flooding.  Redox measurements (Eh), chlorophyll content index (CCI), leaf count, stem count and stem length were assessed over a five week period followed by destructive measurements taken of above- and belowground mass. The heterogeneously flooded treatment includes individuals exposed to either flooded or drained conditions at the sub-individual level. 

Results/Conclusions

There were local morphological responses reflected in heterogeneous soil conditions. Plants in drained environment had more biomass than flooded plants. Flooded plants had a higher survival rate and maintained the integrity of their rhizomes. Plants adapt to their environment and share nutrients with their clonal self, increasing survivorship. This species can be considered for a buffer for excess nutrients from surface waters prior to their flow into receiving waters.