Don't tread on it

The Arctic's delicate tundra plants support Large populations of animals such as caribou and provide nesting habitat for huge numbers of birds. The Bush administration's plan for oil drilling in the Alaskan wilderness, plus the advent of global warming, has environmentalists worried about the tundra ecosystem. New research shows that minor alterations caused by human intrusions into both the High and the Low Arctic landscapes may be just as detrimental as the more apparent, larger-scale menaces. Bruce C. Forbes, of the Arctic Centre at the University of Lapland in Finland, and colleagues recently summarized the results of numerous studies examining small-scale threats to the tundra of Alaska, Canada, Greenland, and Siberia.

The researchers compared the plant communities in undisturbed patches with those in patches that had previously suffered damage from humans but had subsequently been on the mend for several decades. They found that only the smallest, wettest patches of tundra recovered on their own from extreme injury--the sort that removes all aboveground plant matter. But even patches that retained an intact plant layer were often permanently altered.

Some of the most severe damage was caused by trucks, vans, and other heavy vehicles. Just one pass of such a vehicle during the summer months left ruts that drained the water from wetlands. The explosive growth of ecotourism has also wounded the habitat; hiking, for example, has compacted soils and destroyed vegetation. Willows, horsetails, and certain grasses have readily regenerated in these trampled areas, taking over where a formerly diverse plant community once flourished. The researchers warn that a series of seemingly insignificant disturbances will nibble away at species diversity, changing the sensitive landscape forever. ("Anthropogenic Disturbance and Patch Dynamics in Circumpolar Arctic Ecosystems," Conservation Biology 15:4, 2001)

COPYRIGHT 2001 Natural History Magazine, Inc.
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