Dominant species responses to drought in seasonal wetlands: evidence from reciprocal transplants across a moisture gradient

Seasonally flooded wetlands are periodically drained due to dry-season precipitation patterns. In the dry season, soil moisture can decrease to a level where wetland vegetation communities are subjected to drought stress. To understand the effects of drought conditions on the structure of seasonal wetland communities, we conducted a post-flooding reciprocal transplant experiment among three grass species across a soil moisture availability gradient at Archbold Biological Station, Florida, USA. We also manipulated the intensity of competition. We found that Cutthroat, the most upland species, responded physiologically to low soil moisture via root growth and leaf tissue moisture content, while the two flood-adapted species (Maidencane, Blue Maidencane), modulated growth and exhibited a dieback-resprout "drought deciduous'' mechanism. These differential phenotypic responses, and not competition, were responsible for growth patterns in Florida seasonal wetlands in drought conditions.