Termites are often thought of as pests that eat away at the foundations of houses and buildings. But in tropical forests, these master woodcarvers are actually important decomposers. Termites help break down rotting wood, releasing nutrients and carbon back into the soil and atmosphere. And now, new findings from a large international effort spanning six continents show that the hotter it is, the faster termites cut through decaying wood.
The rate of decomposition and consumption of wood by termites increases more than 6.8-fold with every 10°C (50°F) rise in temperature, according to a new study published Thursday in Sciences revealed. By comparison, the microbial decomposition of wood only doubles with the same increase in temperature. “It’s like if you go from, say, Boston to Miami, and if it’s 10 degrees [Celcius] increase in temperature, termites will respond by increasing their decomposition rates sevenfold,” he says. amy zane, lead author of the new paper and a professor of biology at the University of Miami. “What it means is that the wood is recycled more quickly: you’re releasing carbon more quickly.”
Fallen trees, stumps, branches, leaf litter and other plant debris are the main sources of carbon locked up, in total storage. about 73 billion tons. This “dead wood” contributes to the Carbon cycle, in which stored carbon atoms are released and reused in the environment. The process promotes the growth of new plants and influences the planet’s temperature and climate by emitting carbon dioxide and methane into the atmosphere. There are many factors that cause wood decay, from forest fires to solar radiation, microbes and fungi. “If we didn’t have blasters in the world, the world would be full of dead plants and animals,” explains Zanne, who specializes in decomposition and the carbon cycle.
But insects, like termites, also play a big role in decaying wood, Zanne says. Termites are temperature sensitive creatures, increasing in abundance and diversity towards the equator. Unlike pests that bite homes in more temperate regions, termites are more abundant and diverse in the tropics. Certain species specialize in leaf litter, grasses, or dung. Another group of termites found in Asia and Africa cultivate a “garden” of white-rot fungi, Zanne explains. The ability of the fungus to mineralize the lignin of wood, one of the most difficult materials to decompose in the world, along with that of termites. metal laced jaws can easily decimate rotten wood.
To better understand these wood-eating insects, Zanne partnered with 108 co-authors at 133 sites around the world, including equal representation from temperate and tropical regions in the Northern and Southern Hemispheres. The researchers selected a type of wood, radiata pine, also known as Monterey pine, that could be found locally and accessible at all sites. Each participating group would dry blocks of wood, weigh them, and wrap them in a tight mesh that only microbes could pass through; half had holes cut into the bottom for termites to colonize. The researchers monitored the blocks for up to 48 months, looking for fungus and the intricate tunnels and canyons created by termites. (Some exotic creatures, including a small venomous snake and a black widow spider, also snuck into the pine blocks, Zanne says.)
[Related: Termites are nature’s most amazing skyscraper engineers]
Cleaning all of that up, the teams dried the wood and reweighed it to compare how much it had decomposed over time. Previous studies have shown that microbes have faster rates of wood decay in warmer conditions, which was reflected in the new data collected from the wood blocks. But Zanne and his colleagues were surprised at how much more sensitive the termites were to temperature: the termites were four times more responsive than the microbes.
“These were just astronomical numbers,” says Zanne. “They are super sensitive to increases in temperature, which means that with a small increase in temperature, they will actually increase how quickly they remove carbon from the wood.”
These new findings align with previous research. A 2021 study in Nature found that the rate of decomposition of dead wood by insects increased with rising temperatures, particularly in the tropics compared to cooler regions. But Zanne and the study authors noted that termites were also sensitive to precipitation, but in an unexpected way: while termite decomposition was expected to be greater in tropical environments, the team found that they had a noticeable effect on decomposition in three places such as tropical savannahs. and subtropical deserts.
The study highlights important trends in carbon cycling under a changing climate, says Kenneth Noll, an emeritus professor of microbiology at the University of Connecticut who was not involved in the research. “I found the study interesting because it aims to plug a fairly large hole in our knowledge about the rate of decomposition of dead wood,” Noll wrote to pop science in the email. “The rate of release of this stored carbon back into the atmosphere will certainly increase as the planet warms, so we need to have better measurements of this to have better climate models.”
As climate change is expected to shift environments toward more tropical conditions, it could create more suitable habitat for termites and cause populations to expand. This could increase their role as wood decomposers in the carbon cycle, Zanne and the study authors suggest. However, Noll notes that, overall, global temperature rates are only expected to increase by about twice that, which would mean that the increase in termite decay globally would not increase nearly seven-fold, so “the implications could be relatively small. What remains to be seen, he adds, is how termite communities in temperate and boreal regions will respond to climate change, where temperature increases will be greatest.
He also noted that termites would be worth investigating as a source of methane, a powerful greenhouse gas. Zanne agrees. “Termites are like little cows, and they are releasing methanethrough their digestive systems, she says. “We also think they have the potential to age how much goes up as methane instead of being trapped in the ground. So they could alter the way the carbon comes out of the wood.”
As scientists work to figure out how climate change will displace various organisms in the future, Zanne says it’s just as important to understand how it will influence the carbon cycle.
It’s important to consider “the role of some of these little things in the world, like microbes and termites, that we often can’t see,” she says. “They are incredibly important in maintaining and affecting the Earth that we co-inhabit with them.”