Termites emerge as unlikely climate heroes

In the past several years, designers have looked to termite nests, earthen mounds that dot grasslands throughout the tropics, as a model for energy-efficient dwellings. Now, a study suggests that these mounds may also make their own landscapes more resilient to climate change, preventing savannas from turning into deserts during periods of drought.

Termite mounds store nutrients and moisture, and their complex system of tunnels makes it easier for water to penetrate the soil. In the new study, a team of scientists from Princeton University used a computer model to analyze how these characteristics affect vegetation growing near the mounds of fungus-cultivating termites called Odontotermes in Kenya.

Termite mounds help protect against desertification in three ways, the researchers reported last week in the journal Science. They enable plants to keep growing with less rainfall; act as refugia for vegetation during droughts so that plants are better able to reestablish when rains return; and slow down desertification so that it is easier to recognize and guard against.

Competition between neighboring termite nests often keeps the mounds evenly spaced from each other, resulting in a landscape that appears spotted with vegetation. This polka-dot pattern, easily visible in aerial or satellite vegetation surveys, is typically considered a warning sign of impending desertification. According to the prevailing model, it’s the last of five stages of increasingly sparse vegetation before ecosystem collapse.

But the new results change our view of these spots. An arid landscape dotted with vegetation atop termite mounds isn’t necessarily on the edge of catastrophe but may be resistant to it; the mounds act as bulwarks holding the desert at bay. (In a previous study, the researchers showed that the even spacing of the mounds also helps increase diversity of other savanna creatures like spiders, lizards, and insects.)

The findings provide a tiny oasis of good news in climate change research, suggesting that tropical grasslands may be less vulnerable to desertification than previously assumed.

They’re also a reminder that, for all the focus on how our own species is reorganizing the earth’s climate and ecosystems, we’re not the only species capable of acting as ecosystem engineers. (In addition to termites, other burrowing animals such as ants and prairie dogs could have similar effects, the researchers suggest.) That’s not to say we should let ourselves off the hook for our actions. But perhaps it’s not so bad to let termites nibble at the foundations of our hubris every now and then. – Sarah DeWeerdt | 10 February 2015

Source: Bonachela J.A. et al. 2015. Termite mounds can increase the robustness of drylands ecosystems to climatic change Science DOI: 10.1126/science.1261487

Header image: Termite on a fragment of its nest. Credit: Photo by Robert Pringle, Princeton University Department of Ecology and Evolutionary Biology.

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