Pilot Study on the Effects of Partially Restored Riparian Plant Communities on Habitat Quality and Biodiversity along First-Order Tributaries of the Lower St. Johns River

摘要

The St. Johns River is one of the premiere waterways in the southeastern United States, but it is increasingly affected by anthropogenic disturbances and influences such as excessive loading of nutrients. In the current pilot project, small native plant communities (“garden sites”) were established along sections of riparian corridors of five first-order tributaries in residential-commercial areas that drain into the lower St. Johns River in north Florida. In addition, four “non-garden” (control) tributaries were monitored for comparison. Garden sites included five species native to the area; 20 plants of each species on both banks (200 total plants). These sites were used to assess the ability of partially restored riparian areas to ameliorate nutrient loading and water quality and determine their impact on local biodiversity in disturbed suburban drainage systems. Partially restored sites showed a significant reduction in both NO3- and P concentrations in both soil and water samples compared to control sites. For instance, soil NO3- levels were reduced by 14% in garden sites, while water samples were 30% lower. Moreover, both plant species richness and Shannon diversity (H’) were significantly higher at partially restored sites, 33 and 19% respectively, compared to control streams after two years. Garden sites also had significantly higher terrestrial and invertebrate diversity than non-restored tributaries. Intermittent patches of partially restored habitat along suburban riparian corridors may provide a practical cost-effective technique for improving ecosystem function, water quality and increasing biodiversity along these frequently disturbed lotic habitats. Trends detected in the current study may have general implications for riparian restoration and reduction of nutrient loading in these small tributaries and, ultimately, effect water quality of the lower St. Johns River basin.