When we think of termites, we might think of the danger they can pose to our homes once they have settled down and started eating firewood. But in fact, only about 4% of termite species All over the world, they are considered pests that may eat your home at some point.
In nature, wood-eating termites play a wide and important role in warm tropical and subtropical ecosystems. When they feed on wood, they recycle essential nutrients in the soil and release carbon back into the atmosphere.
Our new search Published today in ScienceFor the first time, termites love their warmth. The results were startling: We found that termites eat dead wood faster in warmer conditions. For example, termites in an area with temperatures of 30 will eat wood seven times faster than in a place with temperatures of 20 ℃.
Our results also indicate an increasing role for termites in the coming decades, as climate change increases their potential habitat across the planet. This, in turn, can cause more carbon stored in dead wood to be released into the atmosphere.
Dead wood in the global carbon cycle
the trees They play a pivotal role in the global carbon cycle. Carbon dioxide is absorbed from the atmosphere through photosynthesis, and approximately Half From this carbon is incorporated into the new plant mass.
While most the trees They slowly grow in length and diameter each year, and a small percentage die off. Then their remains enter the pond of dead wood.
Here carbon accumulates so dead wood also collects burnt or decomposed By consumption by microbes (fungi and bacteria), or insects such as termites.
If a pool of dead wood is quickly consumed, the carbon stored there will be quickly released back into the atmosphere. But if decomposition is slow, the pool of dead wood can increase in size, slowing the buildup of carbon dioxide and methane in the atmosphere.
For this reason, understanding the community dynamics of organisms decomposing dead wood is vital, as it can help scientists predict the effects of climate change on carbon stored in Earth’s ecosystems.
This is important because the release of dead carbon into the atmosphere could accelerate climate change. Storing it for a longer period may slow climate change.
Test how fast termites eat dead wood
Scientists generally understand the conditions that favor microbial consumption of dead wood. We typically know their activity my husband With every 10 ℃ increase in temperature. Microbial decomposition of dead wood is usually faster in humid conditions.
On the other hand, scientists have known relatively little about the global distribution of dead wood-eating termites, or how this distribution would respond to different temperatures and moisture levels in different parts of the world.
To better understand this, we first developed a protocol to assess termite consumption rates of dead wood, and tested it in savannah and rainforest ecosystems. In northeastern Queensland.
Our method involved placing a series of wooden blocks covered with mesh on the soil surface in a few locations. Half of the blocks have small holes in the mesh, allowing termites access. The other half had no such holes, so only microbes could access the blocks through the network.
We collected wooden blocks every six months and found that blocks covered with mesh with holes degrade faster than those without, which means that the contribution of termites to this decay was, in fact, significant.
But while the pilot test told us about termites in Queensland, it didn’t tell us what they could do elsewhere. Our next step was to reach out to colleagues who could publish the woodblock protocol at their study sites around the world, and they enthusiastically accepted the invitation.
Ultimately, more than 100 collaborators joined the effort in more than 130 locations in a variety of habitats, spread across six continents. This wide coverage allows us to assess how rates of wood consumption by termites vary with climatic factors, such as average annual temperature and precipitation.
Termites like warmth and not much rain
For woodblocks that only microbes have access to, we confirmed what scientists already know—that decay rates roughly doubled across sites for every 10 increase in average annual temperature. Decay rates increase further when annual rainfall falls on sites, such as in the Queensland rainforest.
For termite woodblocks, we observed a much steeper relationship between decay rates and temperature—dead wood generally decomposed about seven times faster at sites that were ten degrees Celsius warmer than others.
To put this in context, termite activity means woodblocks near tropical Darwin on the northern edge of Australia are decomposing ten times faster than those in temperate Tasmania.
Our analyzes also showed that termite consumption of wood blocks was higher in warm regions with low to medium mean annual precipitation. For example, termite decomposition was five times faster in the subtropical desert of South Africa than in the tropical rainforests of Puerto Rico.
This may be due to the termites safe in their mounds being able to reach water deep in the soil in times of drought, while waterlogging can limit their ability to scavenge for dead wood.
Termites and climate change
Our results are aggregated into a model to predict how termites’ consumption of dead wood will change globally in response to climate change.
Over the coming decades, we expect termite activity to increase as climate change projections show that a suitable termite habitat will expand north and south of the equator.
This will mean that the carbon cycle through the deadwood basin will accelerate, causing the carbon dioxide fixed by trees to return to the atmosphere, potentially limiting carbon storage in these ecosystems. Reducing the amount of carbon stored on Earth could then start a feedback loop to accelerate climate change.
We’ve known for a long time that human-caused climate change will favor few winners but leave many losers. The humble termite seems likely to be one of those winners, on the verge of experiencing a major global expansion in its main habitat.