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AmeriFlux Network

Nations of the world face challenges in developing sound policies and directions for addressing global change. The scientific community has the responsibility to provide the scientific basis for those policies. This includes developing the understanding of the influence of land, ocean and atmospheric processes in climate change. The goal of AmeriFlux is to develop a coordinated research network of long-term flux sites in the Americas for quantifying and understanding the role of the terrestrial biosphere in global climate change. Specifically, the network aims to provide reliable estimates of carbon stocks in plants and soil, biological and environmental controls on carbon dioxide and water vapor exchange between the land and atmosphere, and improve our description and understanding of variation from ecosystems to continents and from seasons to decades. The network provides quantitative information to adequately predict large-scale long-term responses to changing environmental conditions. This is accomplished using micrometeorological and biological measurements at intensive sites coupled with extensive measurements (e.g. surveys and remote sensing) and modeling. For ecotype and instrumentation details for all AmeriFlux research sites nationwide, visit the AmeriFlux website.

 

Key science questions of AmeriFlux are:

  • What are the magnitudes of carbon storage and the exchanges of energy, CO2 and water vapor in terrestrial systems? What is the spatial and temporal variability?
  • How is this variability influenced by vegetation type, phenology, changes in land use, management, and disturbance history, and what is the relative effect of these factors?
  • What is the causal link between climate and the exchanges of energy, CO2 and water vapor for major vegetation types, and how does seasonal and inter-annual climate variability and anomalies influence fluxes?
  • What is the spatial and temporal variation of boundary layer CO2 concentrations, and how does this vary with topography, climatic zone and vegetation?

Highlights

  • As of January 2011, the AmeriFlux data archive contains 787 site-years of data from 140 sites. Of these 140 sites, 92 are still active and 48 are inactive. 90 sites are in the United States, 1 in Brazil, and 1 in Mexico.

  • Across sites, an average of 83% of the total amount of carbon taken up by the terrestrial systems in photosynthesis was respired back to the atmosphere.

  • Volcanic aerosols from the 1991 Mt. Pinatubo eruption greatly increased diffuse radiation worldwide for the following two years.

  • AmeriFlux sites bolster progress towards verifiable regional carbon cycle flux estimates.

  • Validation of the satellite remote sensing MOD17 algorithm (GPP and NPP) is on-going (Running & Heinsch)

  • A preliminary study on how representative AmeriFlux sites are of the ecoregions in the coterminous US showed that southern, southwestern, and Pacific Northwest environments are less well represented by the existing tower sites (Hargrove et al. 2003). Further analysis will be conducted over the next three years.

  • Integrating flux tower methods with ground-based biometry reveals the importance of disturbance dynamics in controlling large-scale carbon balance in the Amazon of Brazil.

  • AmeriFlux data were used to demonstrate the importance of phenology to seasonal and interannual variation in NEE (Gu et al. 2003b).

  • AmeriFlux tower flux data were used to examine the role of climate on soil C decomposition rates.

  • Several studies in seasonally drought affected or well-drained sites have observed large soil respiration responses to pulse rain events.

  • Flux tower data analysis methods continue to be developed and explored to produce quality data for synthesis activities and reduce uncertainty in flux estimates.

 

 

Terrestrial Ecosystems Research & Regional Analysis - Pacific Northwest
Oregon State University, Corvallis, OR 97331
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