Animals

Power of Termite Mounds to Hold-back Deserts

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Fungus-growing termites from the genus Odontotermes. Photo by Robert Pringle, Department of Ecology and Evolutionary Biology.

What outwardly looks like thousands of termites forming a complex system of tunnels, are, in fact, also creating an oasis for life to survive, sustain and thrive. Unknown to them their mounds prevent the advancement of deserts into drylands and semi-arid regions and make the land more resilient to climate change.

Termite mounds act as a store-house of nutrients and moisture and through tunnel complexes they help for better seepage of water into the soil. As a result, vegetation thrives on and around mounds in an environment which otherwise would have degenerated to a desert.

In a new study from Princeton University, researchers have found that, drylands with termite mounds can sustain life with significantly less rain than those without them. This fact holds good for all variety of termites, which increase resource availability on and around their nests.

In addition, they help to preserve seeds and plant life. This aids the dryland ecosystem to bounce back with vegetation at the onset of the next rainy season.

As Dr. Corina Tarnita, Assistant professor in ecology and evolutionary biology at Princeton University explains, “The rain is the same everywhere, but because termites allow water to penetrate the soil better, the plants grow on or near the mounds as if there were more rain.

She further adds, “The vegetation on and around termite mounds persists longer and declines slower. Even when you get to such harsh conditions where vegetation disappears from the mounds, re-vegetation is still easier. As long as the mounds are there the ecosystem has a better chance to recover.

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Two pattern-inducing mechanisms at work. Termite mounds self-organize to form a pattern on the scale of tens of meters (top and bottom left). The dense vegetation on each mound (top and bottom center) gradually thins, moving outward from the mound’s center. Off the mounds, vegetation self-organizes to form a pattern on the scale of centimeters (top and bottom right).
Model images courtesy of Science/AAAS.

In light of this new understanding of the role of termite mounds in dryland ecosystems, there may be a need to revamp the existing early-warning signals for the onset of desertification. The transition of grasslands to desert is classified into five stages. Scientists use satellite images to know in which stage the savanna is and into which stage it is heading toward.

Spotty vegetation pattern in savannas and grasslands is considered as the onset of desertification. This is deceptively wrong as termites can also produce spotty patterns. Theoretical studies and field data collected from Kenya by these Princeton researchers, clearly shows that termite mound patterns are not a prelude to desertification. In fact, these researchers say, the truth is quite the opposite- drylands with termite mounds are more resilient to climate change than those without.

In their field study, researchers found two plant growth patterns at work. Dense vegetation grows on termite mounds, which self-organize on a large scale- one of tens of meter and away from the mound center, the vegetation thins down to a smaller scale- one of centimeters.

Images taken from far-off satellites of these plant patterns might be wrongly interpreted as the onset of desertification, while in actual reality, these evenly spaced termite mounds are large areas of biological abundance and are more robust to aridity and desertification.

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In drylands, termite mounds can be important resources for other animals. They can provide a source of lush vegetation for zebras and other foraging herbivores (left), or serve as a vantage point for predators to spot prey over the tall grass of the savanna. Photos by Robert Pringle, Department of Ecology and Evolutionary Biology.

Jef Huisman, an aquatic microbiology professor and theoretical ecologist at the University of Amsterdam who was not part of this work, but is aware of Princeton research study says, “The coexistence of multiple patterns at these scales makes ecosystems more robust and less prone to collapse. In that sense, we have to adjust our models for drylands because these ecosystems are much more resistant to desertification than we previously believed.” He further adds, “Climate models for every ecosystem need to better account for organisms such as termites and mussels that ‘engineer’ their own environment.

Robert Pringle, co-author of the paper agrees with Dr. Huisman as he says, “This unexpected function of termites in savannas and grasslands suggests that ants, prairie dogs, gophers and other mound building creatures could also have important roles in ecosystem health.

Nature is much more complex than we know, and life reorganizes itself to thrive as this Princeton research has revealed, in this case, termite mounds creating micro-climate for plants in dryland ecosystem.

Source:

Princeton University, press release.

Further Reading:

Termite mounds can increase the robustness of dryland ecosystems to climatic change,” Juan A. Bonachela, Robert M. Pringle, Efrat Sheffer, Tyler C. Coverdale, Jennifer A. Guyton, Kelly K. Caylor, Simon A. Levin, Corina E. Tarnita, Science, Feb. 6, 2015.

Ravindra Krishnamurthy

Ravindra Krishnamurthy is a freelance science writer covering science, tech, the environment, health, food, and culture.

4 Comments

  1. Gosh, soil rehydration by water harvesting and nutrient capture. . . .where have we heard of this before? The authors need to add humans to the list of organisms that perform the function.

  2. Only some termite species create mounds. I live in central Sahel Africa and have observed various termite species extensively. It is obvious even to the casual observer that termite mounds are the site of “intensive nuclei” or mini forests of impressive diversity. Additionally, however, non mound building species store digested carbon (with added nitrogen from nitrogen fixing bacteria in their gut) in the structure of their tunnels that run litterally EVERYWHERE in the soil. This is absolutely crucial to the ecosystem, because in this region of the world, there is not a drop of rain for six to nine months of dry season. Without the termites’ storage of carbon into the soil, glued together in their own feces, the soil nutrient would simply dissappear to wind erosion. When the rains finally come in violent thunder storms, the termites’ tunnels are ready to absorb the water and provide the rapid gas exchanges to facilitat an explosion of vegetation in a matter of weeks. The challenge for the permaculturalist is to have all the pieces of a system strategically arranged to obtain a maximum benefit of this explosion of growth, both for human consumption and for the long-term health of the soil.

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