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Development of a Reference Coastal Wetland set in Southern New England (USA)
Citation:
WIGAND, C., R. A. MCKINNEY, M. M. CHINTALA, S. M. LUSSIER, AND J. HELTSHE. Development of a Reference Coastal Wetland set in Southern New England (USA). ENVIRONMENTAL MONITORING AND ASSESSMENT. Springer, New York, NY, 161(4):583-598, (2010).
Impact/Purpose:
This manuscript by scientists at NHEERL’s Atlantic Ecology Division will be submitted to the journal, Environmental Monitoring and Assessment. This research includes measures of plants, soils, and invertebrates for a reference set of ten salt marshes subject to increasing watershed nitrogen loadings and residential development. These measures of plants, soils, and invertebrates were analyzed using principal component analyses and a ranking system. Using cumulative frequency diagrams, the first principal component scores of each plant, soil, and invertebrate data set were plotted, and natural breaks and best professional judgment were used to rank the first principal component scores among the sites. All three ranked components were weighted equally and an overall salt marsh condition index was calculated by summing the three ranks and then transforming the index to a 0 -1 scale. The overall salt marsh condition index for the reference coastal wetland set significantly regressed with the residential land use (R2 = 0.76, p = 0.001) and watershed N loads (R2 = 0.74, p = 0.001). Overall, condition deteriorated in salt marshes and their associated discharge streams when subject to increasing watershed residential land use and N loads. The reference set data and ranking method provide a framework for assessing the condition of other southern New England salt marshes.
Description:
Various measures of plants, soils, and invertebrates were described for a reference set of tidal coastal wetlands in southern New England in order to provide a framework for assessing the condition of other similar wetlands in the region. The condition of the ten coastal wetlands with similar hydrology and geomorphology were ranked from least altered to highly altered using a combination of statistical methods and best professional judgment. Variables of plants, soils, and invertebrates were examined separately using principal component analysis to reduce the multi-dimensional variables to principal component scores. The first principal component scores of each set of variables (i.e., plants, soil, invertebrates) significantly (P < 0.05) regressed with both residential land use and watershed nitrogen (N) loads. Using cumulative frequency diagrams, the first principal component scores of each plant, soil, and invertebrate data set were plotted, and natural breaks and best professional judgment were used to rank the first principal component scores among the sites. We weighted all three ranked components equally and calculated an overall salt marsh condition index by summing the three ranks and then transforming the index to a 0 -1 scale. The overall salt marsh condition index for the reference coastal wetland set significantly regressed with the residential land use (R2 = 0.76, p = 0.001) and watershed N loads (R2 = 0.74, p = 0.001). Overall, condition deteriorated in salt marshes and their associated discharge streams when subject to increasing watershed residential land use and N loads.