March 2003
From Society for Conservation Biology
Rock climbing decreases biodiversity When rock climbers are clinging to a cliff face, the health of the ecosystem is probably the last thing on their minds. But new research shows that rock climbing cuts snail diversity in half in the Canadian Niagara Escarpment, adding to the growing body of evidence that some cliffs should be off limits to climbers."Our work suggests that rock climbing has significant negative effects on all aspects of the snail community on cliffs," say Jeffery Nekola of the University of Wisconsin in Green Bay, and Michele McMillan and Douglas Larson of the University of Guelph in Canada in the April issue of Conservation Biology. This study builds on the researchers' previous work showing that rock climbing can decrease the diversity and abundance of plants and lichens on cliffs. The Niagara Escarpment is a series of limestone cliffs that extends from Ontario, Canada, to Michigan, Wisconsin, Illinois and Iowa. Noted for having eastern white cedar trees that are nearly 1,000 years old, the Escarpment is also a hotspot of snail diversity, with about half of the 80-odd land snail species found in Ontario. Most of the snails found in the Escarpment are known as "minute" snails because they are less than a tenth of an inch across. They live inside soil and many graze on the algae that grows on the cliffs. Nekola and his colleagues compared the diversity and abundance of snails in climbed and unclimbed cliffs along a two-mile section of the Niagara Escarpment near Milton, Ontario. They studied snail shells in soil collected from three parts of the cliffs: the top edge, the cliff face and the base. Altogether, the researchers found 40 species of snails and more than 14,000 intact shells. The results showed that climbed cliffs had less snail diversity and abundance. Climbed cliffs had only half as many snail species (about 5 vs. 10 per cup of soil, respectively) and only about a fifth as many snails (roughly 15 vs. 78 per cup of soil, respectively) as unclimbed cliffs. How could rock climbing harm snails on cliffs? They live mostly in ledges and cracks along the cliffs' vertical surfaces and these are also the parts that rock climbers use for hand and foot holds. Rock climbers gouge out the soil where the snails live, either incidentally or on purpose. To help protect snails and other species on cliffs, Nekola and his colleagues recommend limiting new rock climbing routes along the Niagara Escarpment. "Allowing climbing to expand to new areas is equivalent to giving up on our ability to protect this vertical wilderness," says Larson. The researchers also recommend similar protections for the many other cliffs around the world that are also snail hotspots. CONTACT:
Jeffery Nekola (902-456-2937, [email protected]). Douglas Larson (519-824-4120 X56008, [email protected]). WEBSITE:
University of Guelph Cliff Ecology Research Group http://www.uoguelph.ca/botany/research/cerg/. For PDFs of papers, contact Robin Meadows [email protected]. For any photos provided by the authors:
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