A leaf out of the ecosystem

Published: Saturday 31 January 1998

Scientists have known for years that leaves falling from trees and flowing downstream are important to the ecosystem of the waterbody. Now, researchers at the University of Georgia and Virginia Polytech have come out with the results of a three-year study that further explain the functions of fallen leaves. The researchers say that the leaves are much more crucial to the food chain than previously thought. Bruce Wallace, entomologist and ecologist, began the research after he read an article claiming that there was no clear link between leaf litter and abundance of invertebrates in streams. "I just did not believe it," he says. The researchers constructed an overhead canopy consisting of metal fence posts, a wooden frame and gill netting to prevent fallen leaves from reaching a 180-metre-long stream flowing from a spring in a dense oak-hickory forest in North Carolina, USA. It revealed "major changes in abundance, biomass and production of invertebrate fauna" in the canopised stream. "What the study shows is that leaf litter is fuel for these streams," Wallace says (Popular Science , Vol 251, No 6).

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