04 April 2019

Thinning Can Reduce Losses in Carbon Use Efficiency and Carbon Stocks in Managed Forests Under Warmer Climate

Examining the impact of forest management in global earth system models.

Science

Forest carbon use efficiency (CUE, the ratio of net to gross primary productivity) represents the fraction of photosynthesis that is not used for plant respiration. Here we assess the potential impact of thinning on projected carbon cycle dynamics and implications for forest CUE.

Impact

The results suggest that the combined impacts of climate change and changing CO2 concentrations cause forests to grow faster, mature earlier, and die younger. Altogether, our results show that thinning can improve the efficacy of forest-based mitigation strategies and should be carefully considered within a portfolio of mitigation options.

Summary

Forest carbon use efficiency (CUE, the ratio of net to gross primary productivity) represents the fraction of photosynthesis that is not used for plant respiration. Although important, it is often neglected in climate change impact analyses. Here we assess the potential impact of thinning on projected carbon cycle dynamics and implications for forest CUE and its components (i.e., gross and net primary productivity and plant respiration), as well as on forest biomass production. Using a detailed process-based forest ecosystem model forced by climate outputs of five Earth System Models under four representative climate scenarios, we investigate the sensitivity of the projected future changes in the autotrophic carbon budget of three representative European forests. We focus on changes in CUE and carbon stocks as a result of warming, rising atmospheric CO2 concentration, and forest thinning. Results show that autotrophic carbon sequestration decreases with forest development, and the decrease is faster with warming and in unthinned forests. These results suggest that the combined impacts of climate change and changing CO2 concentrations cause the forests to grow faster, mature earlier, and die younger. In addition, we show that under future climate conditions, forest thinning could mitigate the decrease in CUE, increase carbon allocation into more recalcitrant woody pools, and reduce physiological-climate-induced mortality risks. Altogether, our results show that thinning can improve the efficacy of forest-based mitigation strategies and should be carefully considered within a portfolio of mitigation options.

Contact
William J. Riley
Lawrence Berkeley National Laboratory
Publications
Collalti, A, C Trotta, T Keenan, A Ibrom, B Bond-Lamberty, R Grote, S Vicca, et al.  2019.  "Thinning Can Reduce Losses in Carbon Use Efficiency and Carbon Stocks in Managed Forests Under Warmer Climate."  Journal of Advances in Modeling Earth Systems 10(10): 2427-2452.  https://doi.org/10.1029/2018ms001275.