Source components and interannual variability of soil CO2 efflux under experimental warming and clipping in a grassland ecosystem

Partitioning soil CO2 efflux into autotrophic (RA) and heterotrophic (RH) components is crucial for understanding their differential responses to climate change. We conducted a long‐term experiment (2000–2005) to investigate effects of warming 2°C and yearly clipping on soil CO2 efflux and its components (i.e. RA and RH) in a tallgrass prairie ecosystem. Interannual variability of these fluxes was also examined. Deep collars (70 cm) were inserted into soil to measure RH. RA was quantified as the difference between soil CO2 efflux and RH. Warming treatment significantly stimulated soil CO2 efflux and its components (i.e. RA and RH) in most years. In contrast, yearly clipping significantly reduced soil CO2 efflux only in the last 2 years, although it decreased RH in every year of the study. Temperature sensitivity (i.e. apparent Q10 values) of soil CO2 efflux was slightly lower under warming (P>0.05) and reduced considerably by clipping (P