As a result of rising sea levels, coastal plant species habitat become at risk of being wiped out. In order to combat sea level rise, plant species may move up the salinity gradient or may be “squeezed out” whereby a loss of biodiversity may occur. The question that we wanted to address was: “How does an increase in sea level rise, which comes as a result of climate change, impact the productivity and existence of wetland plant species?” In May of 2015 two pine island-marsh complexes, spanning a gradient from salt marsh to pine woodland, were burned, and two complexes were left unburned within at Grand Bay Natural Estuarine Research Reserve in coastal Mississippi. In this study, physiological traits were investigated to explain why some species expand following disturbance while other species are incapable. We compared water potentials, light availability, and stomatal conductance of these species in control and burn plots along the salinity gradient. Sods excavated in the dominant vegetation types were reciprocally transplanted into four zones, including their own “home” zone.
Results/Conclusions
Our results showed that Juncus roemerianus, the brackish marsh dominant, showed no significant differences and exhibited consistent predawn and midday water potentials across the varying locations and treatments. This indicates that J. roemerianus was successfully established and increased its cover in downslope, “home”, and upslope positions. This species also had higher cover in burned plots compared to control plots. The salt marsh dominant Spartina alterniflora persisted only at “home” and brackish marsh zones, indicating that distribution is limited. Additionally, Spartina patens exhibited varying midday and predawn water potentials. It was also found that S. patens influenced the location effect in the midday burn area. From our results we can conclude that more frequent monitoring may be required for species such as S. alterniflora and S. patens. Our results indicate that assisted migration may be needed in order for species such as S. alterniflora and S. patens to move up the salinity gradient. These physiological responses may also help us predict future responses of dominant coastal species to disturbances and chronic sea level rise.