Abstract: Stem respiration (Rs) is an essential destination of forest gross primary productivity. But unlike leaf respiration, limited by the lack of theory and data, climate sensitivity of this part gets less attention. Whether the stem respiration show thermal acclimation at a larger scale remains unclear. Here we assume that the whole stem respiration follows an optimal behavior related to constructing carrier to support the whole transpiration, so that woody plants can balance between the risk of xylem embolism and excessive carbon cost. To test this theory, we compared the predictions with a global dataset of 174 species from 115 sites compiled by ourselves. The theory predicts that the rates of mass-based stem respiration at basal 25℃ and growth temperature (rs25 and rs.gt) should decrease by 10% and 2.26% per degree increase in growth temperature (mGDD5). While the instantaneous response to temperature is positive, which increases by 7.88% per degree of temperature for rs. The data-fitting results reveal that the stem respiration indeed shows thermal acclimation, and the sensitivity is close to our theoretical predicted value. Also, this theory is highly consistent with the results of warming experiment. These results again prove the assignable plant acclimation to changing environment, and provide a simpler way to improve the estimation of plant autotrophic respiration in Land Surface Model.
