Termites are often considered pests and munch on the foundations of homes and buildings. But in tropical forests, these skilled woodcarvers are actually important decomposers.Termites help break down rotting wood, releasing nutrients and carbon into the soil and atmosphere. And now, new findings from a large international effort spanning six continents show that the warmer the temperature, the faster termites scrape away rotting wood.

The rate of termite decomposition and consumption of wood increases more than 6.8 times for every 10°C (50°F) increase in temperature, a new study released Thursday found. chemistry clearly. In contrast, microbial decay of wood only doubles for the same temperature rise. “It’s like if he went from Boston to Miami and the temperature was 10 degrees for him. [Celcius] When temperatures rise, termites respond by increasing the rate of decomposition by a factor of seven,” said Amy Zanne, lead author of the new paper and professor of biology at the University of Miami. “What that means is that the wood cycles faster, so it releases carbon faster.”

Fallen trees, stumps, branches, leaf litter and other plant debris are major sources of sequestered carbon, collectively storing about 73 billion tonnes. This ‘dead tree’ contributes to the carbon cycle where stored carbon atoms are released and reused in the environment. This process influences global temperature and climate by encouraging new plant growth and releasing carbon dioxide and methane into the atmosphere. There are many factors that cause wood to rot, from wildfires to solar radiation to microbes to fungi. “Without putrefactive bacteria in the world, the world would be full of dead plants and animals,” explains Zanne, who specializes in decomposition and carbon cycling.

But insects such as termites also play an important role in wood rot, says Zanne. Termites are temperature-sensitive creatures that increase in number and diversity toward the equator. Unlike home-gnawing pests in temperate regions, termites are more abundant and diverse in the tropics. Certain species specialize in leaf litter, grass, or manure. Another group of termites found in Asia and Africa cultivate a “garden” of white-rot fungi, Zanne explains. The fungi’s ability to mineralize wood’s lignin (one of the most persistent substances in the world), combined with the metal-laced mandibles of termites, can easily destroy rotten wood.

To better understand these tree-devouring insects, Zanne collaborated with a team of 108 co-authors at 133 sites around the world, including equally representative temperate and tropical regions in the northern and southern hemispheres. assembled. Researchers chose wood from one type of radiata pine, also known as Monterey pine. It is found locally and accessible on all sites. Each participating group dried a block of wood, weighed it, and wrapped it in a tight mesh to allow only microbes to slip through. The researchers monitored the block for up to 48 months, looking for complex tunnels and canyons created by fungi and termites. (Several exotic creatures, such as small venomous snakes and black widow spiders, have also snuck into the pine blocks, says Zanne.)

[Related: Termites are nature’s most amazing skyscraper engineers]

After putting them all away, the team dried the wood and weighed it again to compare how much it degraded over time. Previous studies have shown that microorganisms have a faster rate of wood decay under warm conditions, and this was reflected in new data collected from wood blocks. But Zanne and her colleagues were surprised that termites are extremely sensitive to temperature. She was four times more sensitive to termites than microbes.

“These were just astronomical numbers,” says Zanne. “They are very sensitive to temperature increases, which means that even a small increase in temperature will dramatically increase the rate at which they cycle carbon out of the wood.”

These new findings are consistent with previous studies. Research in 2021 Nature We found that insect-dead wood rot rates increased with increasing temperatures. This is most pronounced in the tropics compared to cooler regions. However, Zanne and the authors of his study noted that termites are also sensitive to precipitation, but in an unexpected way. Termite decay was expected to be greatest in tropical environments, but the team found significant effects on decomposition in dry locations such as tropical savannas and subtropical deserts.

The study highlights important trends in carbon cycling under a changing climate, says Kenneth Knoll, emeritus professor of microbiology at the University of Connecticut. He is not involved in research. “I found this study interesting because it aims to fill a rather large hole in our knowledge of deadwood decomposition rates,” Noll wrote. pop science on mail. “The rate at which this stored carbon is released into the atmosphere will undoubtedly increase as the planet warms, so we need to better measure this to get better climate models.”

Climate change is expected to shift environments to more tropical conditions, creating more suitable habitats for termites and potentially expanding their populations. This could increase their role as wood decomposers in the carbon cycle, suggest Zanne and the study authors. However, Noll points out that the rate of global temperature increase is generally expected to only increase by about a factor of two. This means that global termite decomposition increases will not be nearly seven-fold, so “the impact is likely to be relatively small”. is a future challenge, he adds.

He also pointed out that termites are worth investigating as a source of methane, a potent greenhouse gas. Zanne agrees. “Termites are like little cows, releasing methane through their digestive system,” she says. “We also think it could change the amount that rises as methane instead of being trapped in the soil. So it could change the way carbon is emitted from wood.”

Scientists are trying to figure out how climate change will displace different organisms in the future, but it’s equally important to understand how it affects the carbon cycle. Zanne says yes.

It is important to think about the role of small things such as microbes and termites that we do not normally see. “They are so important to sustaining and impacting the planet we live in symbiosis with them.”