Biogeochemical and Vegetational Responses to an ExperimentalSimulation of Ecosystem Warming

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Climate changes projected for ext century will impact ecosystems, yet the knowledge to foresee the direction and magnitude of these impacts is lacking. This study will improve our ability to predict these impacts by field manipulations, using overhead radiators to increase the downward heat flux on large plots within a subalpine meadow at the Rocky Mountain Biological Laboratory, CO. The heat flux will be set to match approximately the surface warming predicted in worst-case climate scenarios for the year 2050. Effects of this warming on soil moisture and temperature, soil nutrient pools and transformations, greenhouse gas fluxes, and plant production, species distribution, and phenology will be measured. Microclimate and nutrient cycle models, each to be calibrated with data from the control plots and validated with data from the warmed plots, will extend our knowledge of feedback mechanisms linking vegetation, greenhouse gas fluxes, soil nutrients, and soil microclimate, and will provide a basis for generalizing our findings to other sites. The research will also identify climate-sensitive ecological parameters that could be targets for geographically widespread monitoring of ecological symptoms of global warming.