Understanding the whole process of carbon release of dead trees has not been fully explained and no finding was able to estimate an exact number to it. However, new experiments suggest that this process plays a major role on Earth's carbon cycle.
It is given that trees help store around 8 percent of carbon in the atmosphere, but what happens to these carbons when the tree dies?
Researchers estimate about 10.9 gigatons of carbon released from decaying trees or woody matter globally. This is equivalent to 115 per cent of annual fossil fuel emissions and a quarter of carbon released from soils. However, this part of carbon cycle should have been already anticipated since decay is a natural part of forest renewal and a crucial part of the forest life cycle.
Experts said that insects play an 'invisible, yet major' part
"Until now, little has been known about the role of dead trees," says ecologist and conservation biologist David Lindenmayer from The Australian National University (ANU).
"We know living trees play a vital role in observing carbon dioxide from the atmosphere. But up until now, we didn't know what happens when those trees decompose. It turns out, it has a massive impact."
Studies confirm that 90 percent of carbon emissions in tropical forests come from disintegrating wood, while nearly 30 percent is freed through decomposing insects. Typically, not all carbon from dead woods is released straight into the atmosphere, as some are trapped in soils and decomposers. However, it was found that dead trees not just emit greenhouse gases from its own soil, but acts as straw that sucks up carbon or methane from the ground as well and emits it into the atmosphere.
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Decay process of trees does not mainly rely on decomposition
Though deeper understanding on the insect's role in decomposing process is insufficient, "their role in the global carbon cycle seemed to heavily depend on the local climate," authors wrote.
Researchers noted that dead trees weathered and decomposed faster in areas with higher local temperatures and humid, which suggests that "climate change might increase wood decomposition in tropical or subtropical areas as temperatures rise, as long as moisture still exists."
On the other hand, wood decomposition in dry areas is significantly slower, even if temperatures are high.
It is important to also note the role of precipitation in the decomposition process. This breaks down woody material easily and encourages insects' productivity. However, this is not the case for everyone. For instance, precipitation seemed to slow down decomposition in temperate and boreal forests further north.
Furthermore, researchers discovered that boreal and temperate forests reduce carbon release from deadwood by less than 7 percent every year, and the rest comes from the tropics.
First author and conservation biologist Sebastian Seibold said that both climate change and loss of insects shares a significant relationship with deadwood decomposition and carbon cycles around the world.
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