Understanding ecosystem carbon-cycling responses to atmospheric CO2 enrichment is critical to preserve biodiversity and maintain vital ecosystem services in grasslands impacted by global change. We conducted an 8-y experiment enriching CO2 concentrations from preindustrial to midtwenty-first century levels on grassland plant communities on upland, lowland, and alluvial soils. CO2 enrichment increased the CO2 efflux from soils to atmosphere in amounts depending on whether the dominant limitation was CO2 or feedbacks (net positive or negative) from soil moisture and plant species turnover. These findings highlight how multiple concurrent limitations, not single limitations in sequence, regulate the impacts of global change drivers in diverse grasslands. Incorporating multiple limitations will improve forecasts of terrestrial carbon sequestration and ecosystem services.
Multiple constraints cause positive and negative feedbacks limiting grassland soil CO2 efflux under CO2 enrichment Philip A. Fay, Dafeng Hui, Robert B. Jackson, Harold P. Collins, Lara G. Reichmann, Michael J. Aspinwall, Virginia L. Jin, Albina R. Khasanova, Robert W. Heckman, H. Wayne Polley Proceedings of the National Academy of Sciences Jan 2021, 118 (2) e2008284117; DOI: 10.1073/pnas.2008284117