Impact of large-scale tree death on carbon storage

Largescale 'disturbances', including fires, harvesting, windstorms and insect outbreaks, which kill large patches of forest, are responsible for more than a tenth of tree death worldwide, according to new research at the University of Birmingham. The research also showed wide regional variation, with parts of Scandinavia, the USA, Canada and Russia having a particularly high frequency of these disturbances. Mapping the causes of tree death is important because it helps scientists understand how the world's carbon stocks - stored in forests - are affected by these disturbances and the frequency with which they occur. Researchers in the Birmingham Institute for Forest Research (BIFoR) at the University of Birmingham studied satellite-based observations of forest lost between 2000 and 2014, and assessed the typical time interval between large disturbance events across the world's forests. The team then used a computational model to calculate the impact of these events on tree deaths - measured as the amount of carbon stored in the wood of dead trees - and found that they accounted for 12 per cent of tree death overall. Their simulations showed how even small changes to the frequency of large-scale disturbances can have a significant effect on forest carbon stocks in 44 per cent of the world's dense forests. The model will enable scientists to better understand the context of events such as the recent wildfires which devastated parts of the Arctic.