Research Title: Ecological Processes
Funding Level (millions of dollars):
Committee on Environment and Natural Resources (CENR) Component:
(a) Subcommittee: Global Change Research Subcommittee (100%) Task Group on Observations and Data Management
(b) Environmental Issue: Large-scale changes in land-use, including deforestation, aridification, ecosystem migration (60%); Climate change: direct radiative effects, including greenhouse gases, tropospheric aerosols, and volcanic aerosols (20%); Natural variability, including seasonal-to-interannual forecasting and past changes in climate (20%)
(c) Research Activity: System structure and function: Understanding (100%)
Office of Mission to Planet Earth, Code YS
Washington, DC 20546
Point of Contact:
To contribute to an improved understanding of the function of global terrestrial ecosystems, their interactions with the atmosphere, and their role in the cycling of the major biogeochemical elements and of water, emphasizing the use of remotely sensed data.
The Ecological Processes and Modeling Program is concerned primarily with (1) changes in land use and their effects on ecosystem structure and function, (2) the effects of climate and potential climate changes on terrestrial ecosystems and their functioning, and (3) the biogeochemical feedbacks to the atmosphere resulting from changes in ecosystems. The general strategy is to use airborne and spaceborne remote sensing observations of surface properties and their changes over space and time, ground- based measurements, and the results of ecosystem process studies, as inputs to ecological and land-atmosphere exchange models that capture mechanistic understanding, can be scaled or linked to simulate regional and global ecosystem function, and can, ultimately, be used in a predictive mode. Research spans a continuum from basic biophysics of remote sensing, through the development of practical methods and procedures for the application and use of remote sensing, to the characterization of land surface characteristics and change, to studies of ecosystem carbon cycling and trace gas biogeochemistry. Periodic airborne and five field campaigns, such the Boreal Ecosystem-Atmosphere Study (BOREAS), are mounted. FY 1995 includes:
Remote sensing science (10%): Basic research into the physics and biophysics of electromagnetic radiation reflectance, scattering, and emission from terrestrial ecosystems is necessary to quantitatively relate remotely sensed signals to ecosystem properties. Studies involve theoretical modeling, controlled field and laboratory observations at visible, infrared, thermal infrared, and microwave wavelengths, calibration of sensors, and validation of data interpretations.
Methods and procedures to characterize land surfaces by remote sensing. (30%): Algorithms and techniques are developed to test, improve, and extend simple operational models describing the relationships between surface characteristics (i.e., ground cover, leaf area index, biomass, vegetation height and structure, surface energy balance components, albedo, canopy chemical composition) and remotely sensed electromagnetic fluxes from those surfaces.
Distribution and change of land surface characteristics. (20%): Available models and remotely sensed surface characteristics are utilized to assess spatial and temporal changes in various land cover types. Satellite data are analyzed to produce local and regional land cover classifications, to quantify habitat fragmentation in ecosystems where losses in biodiversity are a threat, to estimate the global extent of deserts and recent changes in their spatial extent, to document seasonal changes in the extent of wetlands inundation, and to capture freeze/thaw transitions in boreal forests.
Carbon balance and carbon dioxide fluxes. (30%): Research on carbon dynamics focuses on developing and testing process-based models, especially models driven by variables derived from remote sensing, to calculate carbon dioxide stores and fluxes and changes in the carbon balance of ecosystems at various scales. Ground- based measurements of carbon dioxide fluxes and changes in below- and above-ground biomass for selected ecosystems as well as small-scale ecosystem manipulations are conducted. Intensive field measurements, as in BOREAS and individual projects elsewhere, are complemented by carbon dynamics or productivity models for the boreal forest, western U.S., Russia, the Pacific Northwest, and the Amazon Basin.
Trace gas biogeochemistry. (10%): Research in this area is focused on measuring trace gas (primarily methane and nitrous oxide) fluxes, characterizing the processes affecting them, and assessing the extent to which they are affected by changes in land use, land surface characteristics, and biomass burning. Models describing trace gas exchanges and their relationship to landscape properties that can be estimated through remote sensing are being developed. Current investigations are focused on northern wetlands, tropical wetlands, and tropical forest regions converted to agriculture.
The NASA led BOREAS involves close collaboration with NOAA, EPA, NSF, USGS, and USFS within the U.S. and six Canadian government agencies. BOREAS has been recognized as contributing to several IGBP core projects as well as WCRP's research agenda. Other collaborations exist with most U.S. Global Change Research Program agencies and several international partners. Projects are underway with Japan (satellite calibration/validation), France (HAPEX-Sahel and BOREAS), the European Space Agency and the European , Russia Union. Planning with Brazil and the European Union for a future campaign focused on the effects of forest conversions in the Amazon Basin is underway.
March 1995: new analyses of regional land cover using Pathfinder data sets initiated; May 1995: Remote Sensing Science future directions workshop report; Sept. 1995 New program plan for ecological processes and modeling; Late 1995: Scientific assessment of current understanding of carbon dynamics in the moist tropics; Early 1996: Completion of first round of BOREAS investigations and solicitation of follow-on studies; solicitation of Amazon Basin research focused on the effects of tropical forest land conversion; Mid 1996: Assessment of progress on methane research; Late 1996: Selection and funding of Amazon Basin study team.
Results of Terrestrial Ecology Program research have been incorporated into recent discussions of international conventions on climate, forestry, desertification, and biodiversity and are playing a central role in IPCC assessment activities. Recent studies of tropical carbon dynamics have reduced uncertainties about the size of the tropical land-use source of carbon, and it is anticipated that BOREAS will clarify our understanding concerning the proposed northern hemisphere temperate/boreal carbon sink. Satellite data analyses quantifying habitat fragmentation are providing new, objective ways of assessing the impacts of land conversion on biodiversity. Regional studies of land use change will yield understanding of the sustainability of various land management practices that could lead to better land utilization practices in the future.