From: Andy Soos, ENN
Published September 8, 2010 04:42 PM

Termite Mounds

Termites are a group of social insects usually classified at the taxonomic rank of order Isoptera. Along with ants and some bees and wasps which are all placed in the separate order Hymenoptera, termites divide labor among gender lines, produce overlapping generations and take care of young collectively. They live in giant mounds in Africa. Scientists have discovered that the size and distribution of termite mounds in South Africa can be used to predict ecological shifts from climate change. The research is published in the advanced online edition of Nature Communications.

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Termite workers build and maintain nests to house their colony. These are elaborate structures made using a combination of soil, mud, chewed wood/cellulose, saliva, and faeces. A nest has many functions such as to provide a protected living space and to collect water through condensation. There are reproductive chambers and some species even maintain fungal gardens which are fed on collected plant matter. Nests are punctuated by a maze of tunnel like galleries that effectively provide air conditioning and control the internal CO2/O2 balance, as well as allow the termites to move through the nest.

Mounds occur when an above ground nest grows beyond its initially concealing surface. They are commonly called "anthills" in Africa and Australia, despite the technical incorrectness of that name.

In tropical savannas the mounds may be very large, with an extreme of 30 feet high in the case of large conical mounds constructed by some species. ABout 8 feet, however, would be typical for the largest mounds in most savannas.

In southern Africa, as in most parts of the world, soil properties strongly influence vegetation patterns — but most of the time we can only infer soil properties because we cannot dig everywhere," said co-author Oliver Chadwick, professor of geography at University of California Santa Barbara. "In this research, we were able to use the distribution of termite mounds to evaluate the controls on below ground properties, and how their spatial differences affect plant distributions."

Mound building termites in the study area of Kruger National Park in South Africa tend to build their nests in areas that are not too wet, nor too dry, but are well-drained, and on slopes of savanna hills above boundaries called seeplines. Seeplines form where water has flowed below ground through sandy, porous soil and backs up at areas rich in clay. Typically, woody trees prefer the well-drained upslope side where the mounds tend to locate, while grasses dominate the wetter areas down slope.

Using airborne imaging and structural analysis, scientists mapped more than 40,000 termite mounds over 192 square miles in the African savanna. They found that their size and distribution is linked to vegetation and landscape patterns associated with annual rainfall. The results reveal how the savanna terrain has evolved and show how termite mounds can be used to predict ecological shifts from climate change.

"These relationships make the termite mounds excellent indicators of the geology, hydrology and soil conditions," commented lead author Shaun Levick of Carnegie Institution's Department of Global Ecology. "And those conditions affect what plants grow and thus the entire local ecosystem. We looked at the mound density, size, and location on the hills with respect to the vegetation patterns."

Termite mounds indicate where the water is and are then indicative of changing weather patterns and climate.

For further information: http://www.universityofcalifornia.edu/news/article/24026

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