Symbiotic Relationship: Termites and the threat of Global Warming
Most homeowners know about the threat that Termites can have on their property, but did you know that only 4% of termite species worldwide are considered capable of eating away your home?
Although these Termites can cause havoc for homeowners, overall, they play a much broader and important role in nature. By feeding on deadwood in their natural ecosystems, they recycle essential nutrients to the soil and release carbon back into the atmosphere.
New research is showing just how much termites love the warmth and how this affects their progress. Temperatures of 30℃ can cause Termites to consume deadwood up to seven times faster than regions with temperatures of just 20℃. This indicates an expanding role for termites in the coming decades, as global warming potentially increases habitat across the planet resulting in more carbon being released into the atmosphere as deadwood is consumed
Carbon in Deadwood
Trees absorb carbon dioxide from the atmosphere which contributes to approximately half of the plants mass as it grows and when trees die, their remains become deadwood. Carbon accumulates, in the deadwood until it’s either burned or decayed through consumption by microbes (fungi and bacteria), or insects such as termites.
When deadwood is consumed quickly, the carbon which is stored there will be rapidly released back into the atmosphere. With the impact of Global Warming upon us, this is an important observation, as the increased activity of Termites in their habitat can cause the rapid release of deadwood carbon into the atmosphere which could also, in turn, speed up the pace of climate change.
Scientists already understand the favourable conditions for deadwood consumption, such as the requirement for moist conditions and the doubling of Termite activity with every 10℃ increase in temperature. However, very little was known about the global distribution of deadwood-eating termites, or how they respond to different temperatures and moisture levels in different parts of the world.
To better understand this, Scientists in Australia developed a protocol for assessing termite consumption rates of deadwood and tested it in a savannah and a rainforest ecosystem in northeast Queensland.
Their method involved placing multiple mesh-covered wood blocks on the soil surface in various locations. Half of the blocks had small holes in the mesh, giving termites access. The other half didn’t have such holes, so only microbes could access the blocks through the mesh.
The blocks were examined every six months and they discovered that the blocks covered by mesh with holes decayed faster than those without, meaning the contribution of termites was the most significant factor to deadwood decay.
The next step was to expand the study globally to assess whether these finding could be replicated throughout different locations around the world.
The final study involved more than 100 collaborators throughout more than 130 sites, spread across six continents. This broad coverage provided a global perspective of how wood consumption rates by termites varied due to climatic factors, such as mean annual temperature and average rainfall.
For the wood blocks which were only accessible to microbes, the scientists confirmed what they already knew, the decay rates approximately doubled for every 10℃ increase in mean annual temperature. Furthermore, decay rates increased again at sites that had a higher annual rainfall.
The termite experiment observed a much steeper relationship between decay rates and temperature. Deadwood consumption was generally almost seven times faster at sites that were 10℃ hotter than others.
To put this in context, termite activity meant wood blocks near tropical Darwin at the northern edge of Australia decayed more than ten times faster than those in temperate Tasmania.
They also observed that termite consumption of the wood blocks was highest in warm areas with low to medium annual rainfall. For example, termite decay was five times faster in a sub-tropical desert in South Africa than in a tropical rainforest in Puerto Rico. It was suggested that this might be because termites safe in their mounds are able to access water deep in the soil in dry times, while water-logging can limit their ability to forage for deadwood.
Climate change and Termites
Over the coming decades, it’s predicted that termite activity will increase due to climate change as suitable termite habitats expand north and south of the equator.
This means carbon released from deadwood consumption will get faster, returning the carbon dioxide usually fixed by trees back into the atmosphere. The reduction of carbon stored on land could then create a feedback loop to accelerate the pace of climate change.
We have long known human-caused climate change would favour a few winners but leave many losers. It would appear the humble termite is likely to be one such winner, about to experience a significant global expansion in its prime habitat.