Vegetation and Nutrient Dynamics of Forested Riparian Wetlands in Agricultural Settings

Abstract

Exported agricultural nutrients have been a major supply of excess nutrients into the environment. Riparian wetlands may play an important part in mitigating these nutrients and thus preventing them from migrating downstream in high concentrations. Two riparian wetland systems, one was influenced by agriculture (agricultural site) and one was not (reference site), were studied in Maryland. Both the plant community structure and abiotic factors were studied. The agricultural site had lower overall species richness and tree diversity than the reference site. Also the tree leaf litter and herbaceous leaves at the agricultural site had higher nitrogen and phosphorus concentrations and higher productivity based on fixed carbon than the reference site. Two nutrient enrichment experiments were conducted at the reference site to determine the nature of nutrient limitation. The results from these studies indicate that both plant communities are nitrogen limited. Furthermore, individual species showed a response to increased nutrients.