Quality or decomposer efficiency

Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Biogeosciences Discussions This discussion paper is/has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG if available. Abstract Introduction Conclusions References Tables Figures Back Close Full Screen / Esc Abstract Effects of temperature history on litter decomposition were evaluated using the GLUE modelling framework together with the Q-model calibrated to a needle litter incubation experiment. The needle litter incubation was a full factorial design with initial and final temperatures 5, 15 and 25 • C. Samples were moved from the initial to the final 5 temperature when approximately 12% of the initial carbon had been respired. We used four variations of the Q-model: one or two initial litter quality values and fixed or temperature-dependent decomposer efficiency. The model was calibrated to the constant temperature data subset. Evaluation against temperature shift subsets gave good results, except just after the change in temperature where the model predicted 10 a smaller response than observed. Using one or two initial litter quality values and fixed decomposer efficiency had little effect on final litter quality and respiration at the final incubation temperature. Allowing decomposer efficiency to vary with temperature showed that decomposer efficiency should decrease between 5 to 15 • C but with no change between 15 and 25 • C. A flexible decomposer efficiency resulted also in sub-15 stantial differences in litter quality at the end of the initial incubation in response to incubation temperature. The results suggests that it is important to consider other factors than the variation in temperature sensitivity with quality when evaluating effects of temperature changes on soil organic matter stability.