Friday, August 7, 2009

PS 93-181: Experimentally enhanced native riparian buffer zones of the lowers St. Johns River reduce nutrient loading and increase plant and invertebrate diversity

Jason P. McGregor, Anthony Rossi, Dan Moon, Dale Casamatta, and Kelly Smith. University of North Florida

Background/Question/Methods

Riparian buffers are critical in the storage and uptake of nutrients and pollutants at the shore-water interface.  In the current study, the research objective was to enhance riparian buffers by experimentally increasing native plant diversity and density along highly disturbed tributaries of the lower St. Johns River.  Plant communities of ten established tributaries were surveyed for their initial diversity.  Species diversity of the plant communities was measured along transects perpendicular to the waterways.  Experimental native plant communities were established by planting native plants in five of the sites in an effort to improve species diversity and water quality of the tributaries and to increase invertebrate diversity and richness.  This study assesses the success of managing and improving riparian habitats by comparing the community diversity across sites.  The diversity of the sites was analyzed using species richness, Simpson’s Diversity index and the Shannon index.  Bray-Curtis similarity coefficients were used to analyze the differences in species composition among control and experimental sites.   

Results/Conclusions

In the experimental native plant communities there was a decrease in the soil nitrate and phosphorous and a marginal increase in the soil pH.  Across the experimentally manipulated sites there was an increase in species richness.  The Shannon index showed a significant increase in plant diversity but Simpson’s did not.  The Shannon index showed a significant increase in the invertebrate diversity in the experimental sites but Simpson’s did not.  The was a marginal increase in invertebrate species richness.