NERL Research Abstract EPA's National Exposure Research Laboratory GPRA Goal 8 - Sound Science Significant Research Findings Predicting Nutrient and Sediment Loadings to Streams from Landscape Metrics: A Multiple Watershed Study from the United States Mid-Atlantic Region Purpose Scientists and environmental managers are concerned about broad-scale changes in land use and landscape pattern and their cumulative impact on hydrological and ecological processes that affect stream conditions. One of our primary goals is to develop landscape models that establish quantitative relationships between landscape pattern indicators and nutrient and sediment loadings to streams. The purpose of this research was to examine quantitative relationships between landscape indicators and nutrient and sediment loadings to streams. Research Approach The work published by Jones et al in 1997, an Ecological Assessment of the United States Mid-Atlantic Region: a Landscape Atlas (EPA/600/R-97/137) generated a wealth of landscape indicator data for the Mid-Atlantic region. This research article uses the landscape indicator data generated for the Atlas and investigates the relationships between those data and nutrient and sediment loading data calculated from samples collected at known locations. Data for this research were compiled from two independent sources: nutrient and sediment loadings data were acquired from the United States Geological Survey (USGS), and the landscape indicator data were derived from the data generated by Jones et al, 1997. The USGS calculated annual nutrient and suspended- sediment yields for non-tidal streams within the Chesapeake Bay Basin. Their calculated yields were based primarily on measured concentration of analyte, measured discharge, and watershed area. Average annual nutrient and suspended-sediment yields were calculated for each site based on data from 1989 through 1994. Average annual yields were calculated for total nitrogen, total nitrate, total kjeldahl nitrogen, total phosphorus, and suspended sediment. Watershed support areas were calculated using Arc/Info GIS software for each of the water quality monitoring locations so that these areas consisted of only that part of the watershed actually contributing to the water quality monitoring point. From the atlas landscape indicator data, landscape indicators were calculated for each of the delineated watersheds. Relationships were evaluated using stepwise regression analysis for each of the dependent variables (nutrients and suspended sediments) and the suite of landscape indicators. The landscape indicators included in this analysis were: amount of agriculture, riparian agriculture, forested area, riparian ------- forested area, urban land cover, wetland land cover, barren land cover, slope gradient, slope gradient range, slope gradient variance, agriculture on slopes greater that 3 percent, forest fragmentation, road density, atmospheric nitrate deposition, potential soil loss, and roads near streams. Major Findings Landscape indicators consistently explained a high percentage of the total and Significance variation in nitrogen, phosphorus, and sediment yield. For example, 87 percent of the variation in total nitrate yield could be explained by the landscape metrics. The most significant indicators, for all variables, were the amount of agriculture, riparian forests, atmospheric nitrate deposition, and roads on the watershed. Although ecoregional differences in the models, effects of high discharge events, and other predictor information such as point source inputs remain to be investigated, these results hold promise for our ability to model loading risks to streams from continuous spatial data. This journal article results from scientific collaboration between the U.S. EPA's National Exposure Research Laboratory/Environmental Sciences Division in Las Vegas, Nevada, the U.S. Geological Survey in Research Triangle Park, North Carolina, and the U.S. Department of Energy's Oak Ridge National Laboratory, Oak Ridge, Tennessee. A portion of this work was also completed by Lockheed Martin under contract to the U.S. EPA. Publications from Mid-Atlantic research include: Jones, K.B., and K.H. Riitters. 1995. Evaluating wildlife habitat suitability using a multi-scaled landscape assessment approach. Pp. 140-146, in M.M. Meyers and J.L. Rosenberger (eds.), Proceedings of the 27th Symposium on the Interface: Computing Science and Statistics (1995), Pittsburgh, PA Jones, K.B., K.H. Riitters, J.D. Wickham, R.D. Tankersley, Jr., R.V. O'Neill, D.J. Chaloud, E.R.Smith, and A.C. Neale. 1997. An Ecological Assessment of the United States Mid-Atlantic Region: A Landscape Atlas. EPA/600/R-97/130. Jones, K.B., J.D. Wickham, K.H. Riitters, and R.V. O'Neill. 1999. Taking a broader landscape view: an ecological assessment of the mid-Atlantic Region of the United States from space. Pp. 572-588, in Pykh, Y., D.E. Hyatt, and R.J.M. Lenz, eds., Environmental indices systems analysis approach. EOLSS Publishers Co., Ltd. Oxford, United Kingdom. Jones, K.B., A.C. Neale, M.S. Nash, K.H. Riitters, J.D. Wickham, R.V. O'Neill, and R.D. Van Remortel. 1999. Landscape correlates of breeding bird richness across the United States Mid-Atlantic Region. J. Environ. Monitor, and Assess., in press. Kepner, W.G., K.B. Jones, and D.J. Chaloud. 1995. Mid-Atlantic landscape indicators project plan. EPA/620/R- 95/003, Washington, D.C. O'Neill, R.V., C.T. Hunsaker, K.B. Jones, K.H. Riitters, J.D. Wickham, P. Schwarz, I.A. Goodman, B. Jackson, and W.S. Baillargeon. 1997. Monitoring environmental quality at the landscape scale. Bioscience 47:513-520. Research Collaboration and Publications Riitters, K.H., R.V. O'Neill, and K.B. Jones. 1997. Assessing habitat suitability at multiple scales: a landscape- level approach. Biological Conservation 81:191-202. ------- Riitters, K.H., J.D. Wickham, and K.B. Jones. 1996. A landscape atlas of the Chesapeake Bay Watershed. Second Edition, Tennessee Valley Authority, Norris, TN. 29 pp. Wickham, J.D., R.V. O'Neill, K.H. Riitters, T.G. Wade, and K.B. Jones. 1997. Sensitivity of selected landscape pattern metrics to land cover misclassification and differences in land cover composition. Photogrammetric Engineering and Remote Sensing 63:397-402. Wickham, J.D., K.B. Jones, K.H. Riitters, R.V. O'Neill, R.D. Tankersley, A.C. Neale, E.R. Smith, and D.J. Chaloud. 1999. An integrated environmental assessment of the mid-Atlantic Region. J. Environ. Man., in Press. Future Research Research will continue to quantify relationships between landscape indicators and environmental endpoints. Other research that will be pursued with this USGS loadings data set will include adding point source information to the model. It will also include investigating changes in water quality over time and relating them to changes in land use over the same period of time. Finally, relationships between water quality and landscape indicators using other water quality data sets such as the Environmental Monitoring and Assessment Program data will be investigated. This research will continue in both the Mid-Atlantic region and in other areas of the United States. Questions about this research may be directed to: Bruce Jones, Ph.D. Anne Neale U.S. EPANERL Environmental Sciences Division 944 E. Harmon Ave Las Vegas, NV 89119 U.S. EPA, ORD, NERL Environmental Sciences Division 944 E. Harmon Ave Las Vegas, NV 89119 (702) 798-2671 (702) 798-2347 jones.bruce@epamail.epa.gov neale.anne@epamail.epa.gov ------- |