Water Resources Research Act Program

Details for Project ID 2018MA469B

Forest land cover as a tool in water quality management: Developing a valuable addition to the Cape Cod Commission’s 208 Technologies Matrix

Institute: Massachuseits
Year Established: 2018 Start Date: 2018-03-01 End Date: 2019-02-28
Total Federal Funds: $55,000 Total Non-Federal Funds: $118,012

Principal Investigators: Ivan Valiela, Javier Lloret, Anne Reynolds, Heather McElroy

Abstract: To protect quality of fresh and estuarine waters the Commonwealth of Massachusetts has issued regulations requiring reductions of nitrogen loads in every coastal municipality. Cost of conventional sewage treatment plants is currently prohibitive, so there is growing interest in assessing the potential of alternative options for controlling nitrogen loads. The Cape Cod Commission has assumed a leading role in compiling assessment and potential application of available alternative options, and reaching out to transfer the information to a diverse variety of stakeholders, agencies, and managers, by creation of a site that contains a Technical Matrix where information about options is provided. Because there is active research and application of the various options, a review committee considers updating the Matrix at intervals. During a recent review, it became clear that the Matrix needed to include a section of nitrogen retention by forested land covers. We hypothesize that forests provide significant water quality subsidies because forest intercept large fractions of nitrogen inputs, and because atmospheric deposition is the largest source of nitrogen to the surface of watersheds in Cape Cod. The water quality subsidy provided by forested tracts, however, is threatened by the persistent loss of forest area that follows growing urbanization in Cape Cod and elsewhere. These facts suggested the need to add a section to the Matrix that allows assessment of the potential N retention likely by management, restoration, or maintenance of forests. The core goal of this proposal is to quantify the potential of forested land cover management to reduce N loads to fresh- and N-sensitive coastal waters, and develop a section of the Matrix that conveys that assessment and its application to the Cape Cod region. Ancillary aims include informing users as to the application of that management tool, use this work as a pilot experience to apply to future updates of the Matrix, expand our own interdisciplinary interactions, develop training by students and staff, and leverage the results to obtain support for further collaborative work. To carry out these goals, we will model nitrogen inputs to 3 Cape Cod watersheds with different degrees of forest cover (high, intermediate, and low). We will 1) quantify decadal trajectories of forest cover and associated nitrogen retention; 2) partition retention of N in forests and other land covers; and 3) test whether degree of urban development, decreases in atmospheric nitrogen deposition, lag effects during transit through the watersheds, and land cover configuration alter nitrogen retention within forests. These tests will require 1) a meta-analysis of recent research to update terms, if needed, in the nitrogen loading model; 2) GIS-based compilations of land use imagery from different image sources; and 3) geostatistical and path analysis of trajectories to identify significant trends. The results of this work will be incorporated I to the Matrix, will be part of concerted outreach efforts to inform interested stakeholders, will serve as a model leveraging future updates and development of the Matrix, and as a career- and interdisciplinary-enhancing experience for a postdoctoral fellow and two undergraduate interns, as well as for the principal investigators.