Grantee Research Project Results
2000 Progress Report: Effects of N Deposition on Gaseous N Loss from Temperate Forest Ecosystems
EPA Grant Number: R827674Title: Effects of N Deposition on Gaseous N Loss from Temperate Forest Ecosystems
Investigators: Groffman, Peter M.
Current Investigators: Groffman, Peter M. , Verchot, Louis V. , Potter, Christopher , Adams, Mary Beth , Fernandez, Ivan , Rustad, Lindsey
Institution: Cary Institute of Ecosystem Studies
Current Institution: Cary Institute of Ecosystem Studies , University of Maine , USDA
EPA Project Officer: Packard, Benjamin H
Project Period: October 1, 1999 through September 30, 2002
Project Period Covered by this Report: October 1, 1999 through September 30, 2000
Project Amount: $894,361
RFA: Regional Scale Analysis and Assessment (1999) RFA Text | Recipients Lists
Research Category: Aquatic Ecosystems , Ecological Indicators/Assessment/Restoration
Objective:
The objectives of this project are to: (1) determine the importance of gaseous loss of N from temperate forest ecosystems, (2) determine the impacts of N deposition on gaseous loss of N from these ecosystems, (3) test a mechanistic model that relates N gas emissions to N availability and soil moisture content, and (4) develop a new and more mechanistic version of the daily NASACASA ecosystem model for N gas emissions that can be applied at the regional level using satellite remote sensing and other spatial data sets in a geographic information system (GIS) format. This new simulation model will be used to assess trends in N cycling over gradients of N deposition in the northeast United States and to project changes in N gas fluxes with changing air pollution.Progress Summary:
While much effort has gone into determining the fate of atmospheric N in temperate forest ecosystems, many uncertainties remain as to just where N is stored and what processes and pathways influence N retention and/or loss. One of the largest areas of uncertainty is gaseous loss. This flux may be large and may be very sensitive to N deposition. To accomplish our objectives, we will sample gas fluxes (NO, N2O, N2) on a monthly basis at five sites along an N deposition gradient in the northeast United States: Fernow Experimental Forest (FN), WV; Catskills State Forest (CS), NY; Hubbard Brook Experimental Forest (HB), NH; Harvard Forest (HF), MA and Bear Brook Watershed (BB), ME. We will make several additional measurements of factors known to control flux rates (e.g., N pool sizes and turnover rates, denitrification rates, soil temperature, soil pH, and soil moisture). We will sample in both N fertilized and unfertilized plots at each location. These data will then be used to develop a new and more mechanistic version of the daily NASACASA ecosystem model for N gas emissions that can be applied across a 10 state region (ME, NH, VT, MA, RI, CT, NY, NJ, PA, WV.) using satellite remote sensing and other spatial data sets in a GIS format. This new simulation model will be used to assess trends in N cycling over gradients of N deposition in the northeast United States and to project changes in N gas fluxes with changing air pollution. One of our first tasks was to establish experimental designs to capture the main factors influencing N gas fluxes at our different sites (e.g., topographic position, N availability, species composition). Gas flux measurements began in summer 2000. Regional data sets from modeling and scaling are being assembled. Because sampling began just this summer, only preliminary results are available. However, several encouraging trends emerge from the research: ? N gas fluxes may be more important in northeastern temperate forests than previously thought. Data from the Harvard Forest site (Figure 1) shows that NO fluxes are significant relative to N inputs to the site and are much larger than N2O fluxes previously measured at this site. An NO flux rate of 10 ng N cm-2 h-1, extrapolated over 270 days, equals 6.5 kg N ha-1 y-1, which is equivalent to 13 percent of the annual fertilizer input to the low N plots and nearly 5 percent of annual fertilizer input to the "high N" plots. Figure 1: ? N gas fluxes appear to be sensitive to atmospheric deposition. In addition to responding to fertilizer inputs (Figure 1), in the first month when we had data from all five sites along our N deposition gradient (August 2000), fluxes were highest at the high N deposition sites. ? There appear to be coherent ecosystem controllers of N gas fluxes. For example, plots dominated by different vegetation in the Catskills, NY consistently have distinct patterns of NO flux (Figure 2). These patterns are consistent with other N cycling data collected in these and other studies, i.e., sugar maple has more active cycling than oak or beech. These results suggest that our ecosystem modeling and regional scaling approaches will work. Figure 2: Figure 3:Future Activities:
Over the next year, we will continue routine monitoring of N gas fluxes, conduct analysis of ancillary soil variables and begin to develop our models.Journal Articles on this Report : 1 Displayed | Download in RIS Format
| Other project views: | All 15 publications | 5 publications in selected types | All 4 journal articles |
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Venterea RT, Groffman PM, Verchot LV, Magill AH, Aber JD, Steudler PA. Nitrogen oxide gas emissions from temperate forest soils receiving long-term nitrogen inputs. Global Change Biology 2003;9(3):346-357. |
R827674 (2000) R827674 (2001) |
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Supplemental Keywords:
scaling, regional analysis, landscape analysis, nitrous oxide, nitrification, microbial., RFA, Scientific Discipline, Air, Toxics, Waste, Ecosystem Protection/Environmental Exposure & Risk, Ecology, Ecosystem/Assessment/Indicators, Ecosystem Protection, Environmental Chemistry, climate change, VOCs, Fate & Transport, Ecological Effects - Environmental Exposure & Risk, Forestry, Regional/Scaling, fate and transport, ecological exposure, nitrogen deposition, N deposition, forest ecosystems, forest inventory and analysis, modeling, biogeochemical, air pollution, regional scale impacts, sulfur compounds, atmospheric pollutant loads, GIS, nitrogen compounds, air quality, atmospheric models, nitrogen, acid rain, scaling methodsRelevant Websites:
http://www.ecostudies.org
http://www.hbrook.sr.unh.edu
Progress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.