Source: AGU Advances
The world’s oceans, forests, and soils soak up about half of anthropogenic CO2 emissions, thus moderating climate change, but how long that benefit will continue is uncertain. Foresters and ecologists know that young forests with many spindly trees grow into mature forests with fewer, larger trees, in a process called “self-thinning,” which typically follows predictably constant rates. But are self-thinning rules changing with climate change and CO2 fertilization, and how will forest biomass and carbon uptake be affected?
Marqués et al.  document mature forests of Switzerland shifting away from constant self-thinning during the last 60 years. Mature forest biomass increased as trees grew faster, but the rate of biomass increase was dampened by increased mortality, which must be studied to understand changing carbon dynamics. Future work should test whether this grow-fast-die-young hypothesis applies elsewhere, such as the Amazon, where rates of carbon sequestration appear to be slowing or reversing.
Citation: Marqués, L., Weng, E., Bugmann, H., Forrester, D. I., Rohner, B., Hobi, M. L., et al. (2023). Tree growth enhancement drives a persistent biomass gain in unmanaged temperate forests. AGU Advances, 4, e2022AV000859. https://doi.org/10.1029/2022AV000859
—Eric Davidson, Editor, AGU Advances