Modeling The Production of Salt Marsh Grasses

Salt marsh grass species change as one moves from high marsh areas to low marsh areas. This is a result of many factors including light, salinity and nutrient availability. We are in the process of developing a model to understand how environmental factors control species shifts from high marsh to low marsh. This model is being developed for salt marsh grasses at Sapelo Island (GA) and uses data from the Georgia Coastal Ecosystems Long Term Ecological Research program located there. We present results from the initial development of the model as well as comparisons of output from this initial model with long-term data. The development and accuracy of the model depends on the availability of data, which is not uniform across the three species being studied (Spartina alterniflora, Juncus Roemerianus and Borrichia Frustescenes) as well as on the model structure. Our results suggest that including a below-ground production component will improve model predictions. We discuss future developments and uses of the model.