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Abstract

Leaf mitochondrial ('dark') respiration (Rd) is a key process influencing the feedback between climate change and atmospheric CO2 concentration. Yet no accepted theory accounts for its widely observed acclimation to temperature. Because Rd is closely linked to the maintenance of photosynthetic capacity (Vcmax), we propose that Rd thermal acclimation is predictable via the 'co-ordination hypothesis' whereby optimal Vcmax is just sufficient to use average available resources. Predictions are compared to a global set of measurements from 110 sites spanning all biomes. Acclimated Rd and Vcmax (at growth temperature) are predicted to increase by 3.7% and 5.5% per °C respectively; whereas after correction to 25 °C, both are predicted to decline with growth temperature. These predictions are closely and quantitatively supported by the data. Thus we provide a parsimonious theory for Rd and its thermal acclimation, whose fidelity to observations implies that field-measured Rd is driven by photosynthetic demand.