Abstract: | BackgroundThermal acclimation of foliar respiration and photosynthesis is critical for projection of changes in carbon exchange of terrestrial ecosystems under global warming.Methodology/Principal FindingsA field manipulative experiment was conducted to elevate foliar temperature (T
leaf) by 2.07°C in a temperate steppe in northern China. R
d/T
leaf curves (responses of dark respiration to T
leaf), A
n/T
leaf curves (responses of light-saturated net CO2 assimilation rates to T
leaf), responses of biochemical limitations and diffusion limitations in gross CO2 assimilation rates (A
g) to T
leaf, and foliar nitrogen (N) concentration in Stipa krylovii Roshev. were measured in 2010 (a dry year) and 2011 (a wet year). Significant thermal acclimation of R
d to 6-year experimental warming was found. However, A
n had a limited ability to acclimate to a warmer climate regime. Thermal acclimation of R
d was associated with not only the direct effects of warming, but also the changes in foliar N concentration induced by warming.Conclusions/SignificanceWarming decreased the temperature sensitivity (Q
10) of the response of R
d/A
g ratio to T
leaf. Our findings may have important implications for improving ecosystem models in simulating carbon cycles and advancing understanding on the interactions between climate change and ecosystem functions. |