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Summary Autotrophic respiration is a major driver of the global C cycle and may contribute a positive climate warming feedback through increased atmospheric concentrations of
CO 2. The extent of this feedback depends on plants' ability to acclimate respiration to maintain a constant carbon use efficiency (CUE ).We quantified respiratory partitioning of gross primary production (GPP) and
CUE of field‐grown trees in a long‐term warming experiment (+3°C). We delivered a13C–CO 2pulse to whole tree crowns and chased that pulse in the respiration of leaves, whole crowns, roots, and soil. We also measured the isotopic composition of soil microbial biomass and the respiration rates of leaves and whole crowns.We documented homeostatic respiratory acclimation of foliar and whole‐crown respiration rates; the trees adjusted to experimental warming such that leaf‐level respiration rates were not increased. Experimental warming had no detectable impact on respiratory partitioning or mean residence times. Of the13C label acquired by the trees, aboveground respiration consumed 10%, belowground respiration consumed 40%, and the remaining 50% was retained.
Experimental warming of +3°C did not alter respiratory partitioning at the scale of entire trees, suggesting that complete acclimation of respiration to warming is likely to dampen a positive climate warming feedback.
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Abstract Temporal variation in soil nitrogen (N) availability affects growth of grassland communities that differ in their use and reuse of N. In a 7‐year‐long climate change experiment in a semi‐arid grassland, the temporal stability of plant biomass production varied with plant N turnover (reliance on externally acquired N relative to internally recycled N). Species with high N turnover were less stable in time compared to species with low N turnover. In contrast, N turnover at the community level was positively associated with asynchrony in biomass production, which in turn increased community temporal stability. Elevated
CO 2and summer irrigation, but not warming, enhanced community N turnover and stability, possibly because treatments promoted greater abundance of species with high N turnover. Our study highlights the importance of plant N turnover for determining the temporal stability of individual species and plant communities affected by climate change.
