Termites likely to contribute to greenhouse gas emissions

The decaying woody biomass that litters forest terrains worldwide, particularly in warm tropical regions, plays an important role in the global carbon cycle. Carbon storage in forested systems depends partly on the decay rates of deadwood, which can vary depending on climate. In a report in the latest issue of the journal Science, the researchers Amy Zanne of the University of Miami and colleagues said that termites were likely to play a significant role in wood decomposition.

According to them, although microbes are widely recognised as perhaps the most important decomposers globally, other animals, including termites, are crucial to tropical woody decomposition, particularly at local and regional scales. “... we have largely overlooked the role of termites in this process. This means we are not accounting for the massive effect these insects could pose for future carbon cycling and interactions with climate change,” Zanne added. Like cows, termites release carbon from the wood as methane and carbon dioxide, two of the most important greenhouse gases, and therefore, termites may increasingly contribute to GHG emissions.

While previous studies have shown that microbial wood decay rates respond to changing climate conditions, far less is known about the sensitivities of termites to climatic conditions. To address this, the researchers performed identical experiments at 133 sites across all continents (except Antarctica),to quantify the climate-related variation in wood decomposition by bacteria and fungi (microbes) and termites.

Climate influences both, but termites are more sensitive to temperature. While microbes need water to grow and consume wood, termites can function at relatively low moisture levels. In fact, termites can search for their next meal even if it is dry and carry what they want back to their mounds or even move their colony into the wood they are consuming.

The research indicates that termites could soon be moving beyond the tropics and towards the North and South poles as global temperatures increase. “The inclusion of arid, hot bioregions, particularly in the Southern Hemisphere, where termites are often plentiful and active, allowed for novel insight into their role in carbon turnover,” said Amy Austin of Universidad de Buenos Aires, a collaborator. According to the findings, termite-associated decay increased 6.8 times for every 10 degree C increase in temperature.