New research from the Institute for Forest Research (BIFoR) at the University of Birmingham shows how large-scale tree death, mainly caused by fires, harvesting, windstorms, and insect outbreaks, has impacted the world’s carbon stocks.
“Large patches of dead forest make a dramatic impact on the landscape, be they caused by fires, harvesting, windstorms or insect outbreaks,” said lead author, Dr. Thomas Pugh, of the BIFoR. “But despite having been able to observe these events from space for many years, the contribution that they make to tree mortality and impact on forest carbon storage across the world has been unknown.”
To link tree deaths to dwindling carbon stocks, the research team studied satellite observations of forest loss between 2000 and 2014. They then assessed the normal time interval between large disturbance events, such as fires, storms, and insect plagues, across the world’s forests. Using a model to calculate the impact of these events on tree death, the team found that about 12% of all tree deaths were caused by these types of disturbances.
What’s more is that they found that if even the smallest change in frequency of large-scale disturbances took hold, that change could have a significant impact on forest carbon stocks in about 44% of the world’s forests.
This research is published in Nature Geoscience.
“Now we can see much more clearly where large disturbances play major roles and where forest carbon stocks are sensitive to changes in disturbance frequency,” Dr. Pugh said. “This year’s large fires across the Arctic may just be an anomaly, or they could be a sign that disturbances in that region are becoming more frequent relative to the historical norm.”
“If that’s the case, we can expect large amounts of carbon to be released from these forests over the coming century and perhaps wholesale changes in the mix of vegetation that make up the forests.”
Next, the team will focus on what causes the other 88% of world tree death, and add those findings to this current research.