Wildlife & Biodiversity

Global warming increased appetite of termites that feed on wood needed to store carbon: Study 

Termites release carbon dioxide by decaying deadwood

By Rohini Krishnamurthy
Published: Friday 23 September 2022

Global warming has introduced an unusual new player in Planet Earth’s carbon cycle — termites: Their appetite for carbon-storing wood has increased, found a new study.

The wood biomass consumption of these insects has increased more than 6.8 times for every 10 degrees Celsius rise, the study published in Science journal estimated.

The Isoptera sp. release carbon dioxide by decaying deadwood — dead parts of a tree, the authors of the study said.

“Termites play a big role in eating deadwood with the highest levels in warm, dry places,” Amy Zanne, professor at the University of Miami and lead author of the study, told Down To Earth.

“Termites don't perform too well if it is cold and dry but will do better as the world gets hotter,” Paul Eggleton, a merit researcher at the National History Museum, said in a statement.

An international team of scientists studied how climate influenced the decomposing activity of termites. They also included microbes, which are also known to feed on deadwood.

Previous regional studies showed microbe-driven wood decay almost doubled with a 10°C temperature increase, the researchers pointed out. 

The role of termites in the global carbon cycle is often overlooked, the study pointed out. Not much is known about their climate sensitivity, it added.

So, researchers studied 133 sites across Asia, Africa, Europe, North America, South America and Australia.

“This includes 20 countries with equal numbers in the northern and southern hemispheres and tropical and temperate regions,” Zanne explained.

At each site, researchers recorded how termites and microbes decayed the wood of Pinus species for up to 48 months. 

Termites, according to the findings, were discovering or seeking more food in arid and semiarid sites than in humid sites and sites with moderate moisture levels. 

Microbial-driven decay was fastest at low latitudes and elevations where temperatures and precipitation are high, the results showed.

As for termites, decay rates were higher at low elevations and high-temperature regions, the researchers wrote in the paper.

Termites were more sensitive to temperature changes than microbes, the study concluded.

"Termites had their biggest effects in places like tropical savannas and seasonal forests and subtropical deserts," Zanne explained in a statement. "These systems are often underappreciated in their contributions to the global carbon budget,” she added.

The researchers think termites’ increased appetite can be explained by the fact that these social insects are ectothermic. Their body temperature is regulated by external sources such as sunlight.

The activity of decay enzymes in their guts relies on temperature, Zanne explained.

“There are other possibilities such as the number of termites or particular species of termites increasing in warm places,” she added.

The researchers, however, think that they could be underpredicting termite effects in Africa and Asia, home to fungus-growing termites.

These termites act as farmers, growing white rot fungi. These organisms are known to break down lignin –the second most common carbon compound in wood and are also hardy.

The termites relegate their wood decomposition work to rot fungi. 

“It is thought that as termites let the white rot fungi do this decay work, it may allow for even faster decay rates,” she said.

In the future, termites will likely expand their range in a warming world. And this could have important consequences for carbon cycling, the researchers warned.

Climate models predicted an expansion of termite discovery in tropical and subtropical regions under all warming scenarios, with most impacts felt in high warming scenarios, the report indicated.

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