Our research programs are designed to advance predictive understanding of ecosystem ecology and biogeochemistry under the global environmental change via data-model integration. Major issues we are addressing include (1) how global change alters structure and functions of terrestrial ecosystems, and (2) how terrestrial ecosystems regulate climate change. Our research is aimed at quantifying dynamics of carbon, nutrient, and water resources in ecosystems in responses to environmental changes.

The approaches we used include modeling, field experiment and data synthesis. With respect of modeling, we focus on development, test and improvement of biogeochemical models of terrestrial ecosystems at ecosystem, regional, and global scales. Our current effort is on development and applications of inverse modeling, data assimilation, and benchmark analysis to improvement of land models.

We have been conducting long-term global change experiments in the Great Plains to examine interactive effects of warming and clipping (since 1999); and interactive effects of warming, clipping and precipitation (since 2008) on community structure and ecosystem functions. We have particularly examined various mechanisms underlying terrestrial carbon cycle feedback to climate warming.

We have also conducted data synthesis to better understand how coupled carbon and nitrogen cycles respond to global change. We apply various data synthesis techniques, such as meta-analysis and data mining, at global change experiments, FLUXNET (including AmeriFlux), and other data sources to identify general mechanisms and estimate parameters for model improvement.

Our research is highly multidisciplinary, employing techniques from plant physiology, soil sciences, ecology, biogeochemistry, modeling, mathematics, and computer science to improve our predictive understanding of terrestrial ecosystems in response to global change. We are encouraging students and young scientists with diverse background to join our endeavor.

Current Topics

  1. Carbon and Nitrogen Interaction
  2. Experimental and modeling study of interactive effects of warming and altered precipitation on function and structure of a tallgrass prairie in the Great Plains
  3. Regional and Global Modeling to be Improved by Data Assimilation
  4. Soil Respiration
  5. Model intercomparisons on terrestrial biogeochemistry

Current Projects

  1. RCN: Forecasts Of Resource and Environmental Changes: data Assimilation Science and Technology (FORECAST). NSF, 2009-2017. (Principal Investigator)
  2. Data Synthesis and Data Assimilation at Global Change Experiments and FLUXNET toward Improving Land Process Models. DOE, 2012-2017. (Principal Investigator)
  3. Grassland sensitivity to climate change at local to regional scales: assessing the role of ecosystem attributes vs. environmental context. NSF, 2012-2017. (Co-PI, PI: Alan Knapp, Colorado State University)
  4. Adapting Socio-ecological Systems to Increased Climate Variability. NSF, 2013-2018 (Co-I, PI: Ray Huhnke, Oklahoma State University)
  5. Spruce and Peatland Responses Under Climatic and Environmental Change. ORNL, 2015-2017. (Co-I, PI: Paul J. Hanson and Daniel M. Ricciuto)
  6. Improved Parameterization of Carbon Cycle Models Across Scales Using OCO-2 Measurements of XCO2 and SIF. NASA, 2015-2018. (Co-I, PI: Sean Crowell, University of Oklahoma)
  7. Regional Vulnerability of Permafrost Carbon to Climate Change: A Multifactor Experiment and Model Network. DOE, 2015-2018. (Co-PI, PI: Ted Schuur, Northern Arizona University)

Past Projects

  1. Modeling studies of forest responses to elevated CO2
  2. Data assimilation to quantify regional and continental carbon sequestration
  3. Long-term responses of grassland ecosystems of experimental warming
  4. Mercury dynamics in terrestrial ecosystems in response to global change
  5. Effects of Warming the Deep Soil and Permafrost on Ecosystem Carbon Balance in Alaskan Tundra: A Coupled Measurement and Modeling Approach. DOE, 2011-2014. (Co-PI, PI: Ted Schuur, University of Florida)
  6. Model-Data Synthesis of Terrestrial Responses to Elevated CO2: Phase 2 of an ongoing collaboration between ecosystem and global modelers and empirical scientists from long-term CO2 enrichment experiments. DOE, 2012-2014. (Co-PI, PI: Rich Norby, ORNL)
  7. IRCEB Project
  8. Development of a Data Assimilation Capability towards Ecological Forecasting in a Data-Rich Era. NSF, 2009-2012. (Principal Investigator)
  9. A cyberCommons for Ecological Forecasting. NSF EPSCoR, 2009-2012. (Co-PI and lead scientist for Oklahoma, PI: Paul Risser, University of Oklahoma)
  10. LTREB: Effects of Warming and Clipping on Coupling of Carbon and Water Cycles in a Tallgrass Prairie. NSF, 2008-2013. (Principal Investigator)
  11. From Community Structure to Functions: Metagenomics-Enabled Predictive Understanding of Temperature Sensitivity of Soil Carbon Decomposition to Climate Warming. DOE, 2013-2016. (Co-PI, PI: Jizhong Zhou, University of Oklahoma)
  12. Ecosystem Modeling in the South Central US: A Synthesis of Current Models toward the Developments of Coupled Models. USGS-SCCSC, 2015-2016. (Principal Investigator)