Interactions among CO2, Nitrogen, and Diversity in Grassland Ecosystems

BioCON (Biodiversity, CO2, and Nitrogen) is an ongoing climate-change field experiment, started in 1997, in which atmospheric CO2, soil N supply, and plant species richness and composition have been simultaneously manipulated in a temperate perennial grassland. The study explores ways in which plant communities will respond to three environmental changes already occurring on a global scale: increasing nitrogen deposition, increasing atmospheric CO2, and decreasing biodiversity. Research focuses on the effects and interactions of atmospheric CO2 and soil nitrogen supply on the dynamics of plant communities and the pools and fluxes of plant and soil carbon and nitrogen.

BioCON is located at the Cedar Creek Ecoscience Reserve in east central Minnesota, USA about 50 km north of Minneapolis/St. Paul (Lat. 45N, Long. 93W). The site is located on a glacial outwash sandplain and production is nitrogen limited. The experiment was set up in a secondary successional old field after the existing vegetation was cleared. BioCON consists of 371 2-meter x 2-meter plots, arranged into 6 circular areas or "rings" (20 meter diameter), each containing 61, 62, or 63 plots. Sixteen species of herbaceous perennial prairie species, native or naturalized to the Cedar Creek area, were planted in the experiment. FACE technology is used to deliver additional carbon dioxide to three of the six rings of plots.

A water x CO2 x N experiment , called Interactive effects of carbon dioxide, water, and nitrogen on grassland ecosystem processes, is nested in BioCON.

A warming manipulation was incorporated in BioCON in 2012.

Descriptions of the experiments in BioCON, including information on species, photo galleries, publications, photo galleries, and other information can be found at the BioCON website.

Funded by:
National Science Foundation (Long-Term Ecological Research and Long Term Research in Environmental Biology)

Recent results:

Reich, P.B., S.E. Hobbie, T.D. Lee. 2014. Plant growth enhancement by elevated CO2 eliminated by joint water and nitrogen limitation. Nature Geoscience 7:920–924, doi:10.1038/ngeo2284

Mueller, K.E., S.E. Hobbie, D. Tilman, P.B. Reich. 2013. Effects of plant diversity, N fertilization, and elevated carbon dioxide on grassland soil N cycling in a long-term experiment. Global Change Biology 19:1249-1261.