Monday, June 9, 2008

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Knife River Delta

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Snow geese migrate each spring to the shores of Hudson Bay, Canada, to breed and to raise their chicks. Over the past few decades, the numbers of geese descending upon the Bay's Knife River delta area have increased substantially. Their impact on coastal vegetation can clearly be seen in this pair of satellite images. In the image on the right, notice how the vegetation (green) has receded from the shoreline north of the delta. Snow geese have overgrazed this area and turned the shoreline into an enormous mudflat. Having denuded the shoreline of vegetation, the geese have also moved inland in search of food on the tundra, where overgrazed soil quickly becomes barren and develops a crust of salt due to evaporation. The salty layer prevents the regrowth of plants, and ultimately leads to erosion. Some researchers have suggested lifting restrictions on the hunting of snow geese in an attempt to reduce their numbers and control the overgrazing problem. Others believe such measures are "too little, too late." View detailed information

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