Physical Sciences and Mathematics Commons^™

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

Biology Faculty Research

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 …