Most of the world's terrestrial carbon is found in the Critical Zone as soil carbon. Indeed, soils store approximately three times more carbon than the atmosphere. Yet large uncertainties exist as to whether soils will release carbon to the atmosphere faster than they can take it up when disturbed or experiencing new environmental conditions or extremes. These uncertainties arise owing to an incomplete understanding of the processes controlling soil carbon fate and the challenge of scaling up estimates of soil carbon from the plot to the landscape or global level.
Investigators are establishing the Reynolds Creek Critical Zone Observatory (RC CZO) to address the grand challenge of improving prediction of soil carbon storage and the processes governing its fate at the plot to the landscape scale. The RC CZO will be co-located with the Reynolds Creek Experimental Watershed (RCEW) in southwest Idaho, which has been administered by the United State Department of Agriculture -Agricultural Research Service (USDA-ARS) for over 50 years. The RCEW is particularly well suited for the CZO because of its strong gradients in climate, vegetation, and distributions of soil organic and inorganic carbon. The observatory will leverage existing scientific infrastructure that includes long-term, spatially extensive meteorological and soil monitoring.
An interdisciplinary team of scientists from Idaho State University, Boise State University, and the USDA-ARS will focus their initial efforts on extensive characterization of above and below ground plant biomass and soil carbon amounts and characteristics across the watershed. An intensively instrumented set of sites (CORE) along an elevation gradient will include measurements of evapotranspiration and the associated land-atmosphere exchange of carbon, sap flux, soil respiration, soil moisture, soil temperature, and other essential climate variables. Experimental research will include investigation of prescribed fire and grazing on soil carbon and processes. The CORE site data will support efforts to improve modeling of the soil-vegetation-atmosphere system and provide a rich dataset for collaborations. A suite of simulation tools will be used to distribute controlling climate input variables at a sufficiently high resolution to capture the natural heterogeneity on the landscape and predict the distribution of soil carbon and other key ecological and hydrologic stores and fluxes throughout the watershed.
This CZO will produce one of the largest coupled soil carbon- environmental variable datasets available. The dataset will provide a unique calibration target to develop and test modeling tools critical for regional and global climate and biogeochemical modeling. The intermediate scale research at the RC CZO will improve our ability to scale local observations to the landscape and the globe; an essential step to support accurate Earth system modeling. Evaluation of simulations at the intermediate scale will reveal areas of weakness in process representation and allow researchers to identify critical research needs. This CZO will become a community resource for carbon cycling research and education, and a magnet for global soil modeling community research to address the grand challenge of understanding soil carbon behavior. This observatory will also improve understanding of how land management activities like prescribed fire and grazing alter soil properties, carbon inputs and the fate of soil organic carbon at the landscape level. In additional to traditional training, this CZO will develop a field methods course on critical zone processes and develop K-12 curriculum to improve literacy of soils in the critical zone.
