We used extensive data derived from inventories and remote sensing and CMIP6 models to examine the current and 21st century dynamics in the proportion of biomass and SOC across global forests. We hypothesize that climate warming and increases in atmospheric CO2 concentrations will increase the proportion of carbon stored as biomass, particularly in colder regions of the boreal and temperate vs. tropical and subtropical forests.
The extent to which biomass and soil carbon pools may change over the 21st century is uncertain. Alterations in the structure of global forests and the distribution of carbon within ecosystems, leading to a higher proportion of carbon stored in plant biomass, will have important implications for surface energy balances, disturbance regimes, ecosystem carbon balance, and thus feedbacks with the climate system.
A large amount of carbon is stored in global forests. However, the fraction of carbon stored as plant biomass vs. soil organic carbon (SOC) varies among forest types, and potential changes over the 21st century are uncertain. Here, we used extensive data derived from inventories and remote sensing and CMIP6 models to examine the current and 21st century dynamics in the proportion of biomass and SOC across global forests. We found that precipitation, elevation, soil, and wildfire were the primary controls of these differences in carbon pools. Under the SSP5–8.5 climate scenario, CMIP6 models project that the ratio of biomass to ecosystem carbon in global forests will increase across the 21st century, with the largest increases in boreal forests (95±37%) compared to moist tropical forests (16±15%). Changes in forest carbon pools resulting in greater biomass fraction will affect disturbance, wildfire, and ecosystem carbon and energy balances, all of which interact with the climate system.