The rate of termite wood decomposition increases more than 6.8 times with every 10°C increase in temperature, according to a new study by an international collaborative of scientists spanning six continents, which could have worrying consequences under a climate expected to become increasingly hot and dry.
While termites are generally known in Australia for the destruction they cause to property, in tropical forests they play a vital role in supporting decomposition. By breaking down rotting wood, they help release nutrients and carbon back into the soil and atmosphere. As a result, they have an important role in the carbon cycle.
The findings of this latest study clearly demonstrate the hotter the climate, the faster decaying wood can be decomposed with the support of termites, shedding light on how significant termites could be in the carbon cycle as the climate continues to change.
“It’s like if you go from, say, Boston to Miami, and if there’s a 10°C increase in temperature, termites will respond by increasing their decomposition rates sevenfold,” said Amy Zanne, lead author of the new paper and Biology Professor at the University of Miami.
For comparison, the same rise in temperature only increases the level of microbial wood decay two-fold.
In the world’s forests, fallen trees, branches and stumps continue to store carbon. As termites break down this timber, carbon atoms are released back into the environment. And while the positives of this process include the promotion of new plant growth, the flip side is that emitting carbon dioxide back into the atmosphere plays a role in increasing the planet’s temperature.
Professor Zanne collaborated on the study with a total of 108 co-authors across 133 locations worldwide, spanning temperate and tropical regions across the northern and southern hemispheres.
The research, which focused exclusively on radiata pine, saw each participating group dry out blocks of timber, which were then weighed and wrapped in a mesh that only microbes could slip through. Half of the samples then had holes cut into them, allowing easy access for termites to make their ways in and start to colonise.
After four years, the wood was unwrapped and reweighed, to compare the rates of decomposition. While the scientists expected, based on previous research, that microbes would be shown to have faster wood decay rates under warmer temperatures, they were surprised by how much more active termites were under increased heat.
“These were just astronomical numbers. They’re super sensitive to increases in temperature, meaning that with a small increase in temperature, they’re going to really jump how fast they’re cycling the carbon out of the wood,” Professor Zanne said.
The results of the study could help inform more accurate future climate modelling by taking into consideration the increased rate of release of stored carbon back into the atmosphere as a result of termite activity as the planet continues to warm.
Source: Forest & Wood Products Australia