Tiny termite, not lion, lords over African Savannah

May 26th, 2010 - 5:20 pm ICT by IANS  

Washington, May 26 (IANS) The tiny termite eclipses much larger and mightier animals likes lions, elephants and giraffes when it comes to lording over African grasslands.
Ecologists say they’ve found these humble creatures significantly contribute to grassland productivity in central Kenya via a network of uniformly distributed colonies.

Termite mounds greatly enhance plant and animal activity at the local level, while their even distribution over a larger area maximises ecosystem-wide productivity.

“One of the typical things I think that people think about is, what drives Savannah in terms of its structure and function?” said Todd Palmer, study authors and an assistant professor of biology at the University of Florida.

“We think about big animals, but these termites are having a massive impact on the system from below,” he added.

Said Robert M. Pringle, research fellow at Harvard University and the lead author, “As (famed biologist) E.O. Wilson likes to point out, in many respects it’s the little things that run the world”.

Prior research on the Kenya dwarf gecko initially drew Pringle’s attention to the peculiar role of grassy termite mounds, which in this part of Kenya are some 30 feet in diameter and spaced some 180 to 300 feet apart.

Each mound teems with millions of termites, who build the mounds over the course of centuries.

After observing unexpectedly high numbers of lizards in the vicinity of mounds, Pringle, Palmer and their colleagues began to quantify ecological productivity relative to mound density.

They found that each mound supported dense aggregations of flora and fauna: Plants grew more rapidly the closer they were to mounds, and animal populations and reproductive rates fell off appreciably with greater distance.

What was observed on the ground was even clearer in satellite imagery. Each mound - relatively inconspicuous on the Kenyan grassland - stood at the centre of a burst of floral productivity.

More important, these bursts were highly organised in relation to one another, evenly dispersed as if squares on a checkerboard. The result is an optimised network of plant and animal output closely tied to the ordered distribution of termite mounds.

Pringle and Palmer suspect termites import coarse particles into the otherwise fine soil close to their mounds, said a University of Florida release.

These coarser particles promote water infiltration of the soil, even as they discourage disruptive shrinking and swelling of topsoil in response to precipitation or drought.

The mounds also show elevated levels of nutrients such as phosphorus and nitrogen.

These findings were published in PLoS Biology.

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