Termites have quite a craving for wood, but turns out they really like to eat when it’s hot. New research published today in Science suggests these energetic wood-eaters will play a more significant role in both wood decay and the global carbon cycle as temperatures rise.
An international study from the University of Miami with co-authors from UNSW Sydney found that termites’ appetite for wood increases sharply with temperature. Although warm temperatures are known to boost the activity of these wood decomposers, researchers were surprised by how much they can affect wood decomposition rates.
“The activity of wood-eating termites increases more with temperature than we previously thought,” says associate professor Will Cornwell, co-author of the study from the School of Biological, Earth and Environmental Science, UNSW Science. “Because the climate is warming very quickly, the main implication is that this activity is likely to increase in certain parts of the world.”
Preference of termites for heat
Many people think of termites and their infestation of wooden walls and roofs in homes, but these termites are just a small subset of species. One of the few species that can feed on wood, some termites help ecosystems recycle plant matter.
“There is about as much biomass of termites on Earth as there are people. Most of this is in the tropics, where they can eat up to half of the deadwood in forests. So they are much more important than you might think at first,” A/Prof. Cornwall says.
Wood degradation through microbial decomposition is key to the functioning of the forest ecosystem, recycling of the nutrients in the wood, and creating and promoting biodiversity. Termites in natural forests and savannas are also important wood decomposers, but they are rarely studied as they are not found in many seasonally cold parts of the world. They are ubiquitous in the tropics.
For the study, more than 100 researchers worldwide monitored the decay rate of Pinus radiata Wood blocks at 133 locations on six continents. They compared how quickly termites and microbes like fungi break down deadwood in different environments.
Using the activity on the pine logs as an index of termite activity, the researchers were able to consistently measure the activity of native termites around the world. They found that the presence of termites and their rate of consumption were very sensitive to temperature – even more so than microbes. The rate of wood decay caused by termites increased 6.8-fold per 10°C.
“Microbes are important around the world when it comes to breaking down deadwood, but we have largely overlooked the role of termites in this process. That means we don’t consider the massive impact these insects could have on the future carbon cycle and interactions with climate change,” says the study’s lead author, Professor Amy Zanne of the University of Miami.
Chew through the carbon cycle
According to the study, termites had their greatest impacts in places like tropical forests and subtropical deserts — systems often overlooked in carbon cycle models. As tropization increases — shifts to more tropical climates around the world — researchers predict the zone of high termite activity will likely expand away from the equator as the Earth warms.
“The results suggest that we are likely to overestimate tropical carbon storage in our current projections and models. Since termite activity is likely to increase with global warming, this means that carbon in dead material will return to the atmosphere faster than we currently think,” says A/Prof. Cornwall says.
A/Prof. Cornwell says in addition to increased termite activity in existing habitats, termites may also spread to new areas as the tropics expand with warming temperatures.
“The tropical region will only expand as the climate warms, so more attention to the crucial role that termites play is crucial,” A/Prof. Cornwall says. “Although we don’t know if this will affect other buildings and populated areas, we do know that termites like it hot and it’s going to get hotter everywhere.”
The study results could be used to make more realistic predictions for the impact of climate change on charcoal stores, A/Prof. Cornwall says. More research on termite activity will help better represent the role termites play in global carbon models used to predict climate change.
“Understanding how termite decay responds to a warming world will be critical to our ability to predict future global carbon balances in terrestrial ecosystems,” says Professor Amy Austin, a co-author of the study from the University of Buenos Aires.
“More attention should also be paid to termite activity, particularly in places like the northern parts of Australia, to more closely monitor their behavior as the climate continues to warm,” A/Prof. Cornwall says.