Text 9. Immigrant fox alters plant life on alaska islands

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Population Fears

Scientists now predict that by the year 2050 the population will be doubled what is today. The fact remains that the rate of food production fell behind population growth in many of developing countries. The annual fish catch already exceeds what the world ‘s oceans can successfully sustain. If we go on using our natural recourses at today’s rates, we will have used up the intire reserves of cooper, natural gas and oil by the year 2054.

But the problem ahead lie not so much in what we use but in what we waste. What faces us is not so much a recourse crisis as a pollution crisis. The only solution is to try to change the areas of consumption, technology and population. Changes in technology must be baked by slower population growth. And it can be achieved by education in health and women’s rights. And there is a little hope of reducing consumption over the next half century.

(Source: http://www. popsci.com)

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Foxes may not graze, but a new scientific study describes how their arrival on Aleutian islands destroyed rich grass­lands and left only sparse tundra. The authors of the report say this transformation shows how an entire ecosystem may decline if just one new top carnivore shows up.

The inadvertent experiment began in the late 1700's and continued into the early 20^th century as fur traders looking to expand the supply released nonnative arctic foxes and, in some cases, red foxes on more than 400 Alaskan islands.

The new habitats included much of the Aleutian archipe­lago that curves west toward Asia. Except for the occasional polar bear rafting on winter ice, the windswept islands had few predators before.

The botanical impoverishment that has resulted is the reverse of what usually happens when a new meat-eater comes along. "Traditionally, the predator eats the grazer; the grazer no longer eats the green stuff; and the habitat gets more green," said Dr. Donald Croll, a professor of biology at the University of California.

An example of the more usual routine is in Yellowstone National Park in the western United States, where returning wolves, preying on sapling-browsing elk and confining the wary survivors to areas where they can see wolves coming, have touched off a resurgence of willow, aspen and other vegetation.

The contrary effect in the Aleutians has a simple explana­tion. The grazers on these islands were grass- and seed-eating Aleutian geese. The foxes drove the geese near extinction, which would have been a boon for grasses except that the foxes also feasted on the eggs and hatchlings of puffins, auklets and other ocean-feeding seabirds they found brooding almost everywhere.

Some islands lost almost all birds except for cliff-nest­ing species. And as ground-nesting birds faded, so did their nutrient-rich excrement, or guano, which had been a natural fertilizer.

Without the regular subsidy of nitrogen and potas­sium-rich nutrients brought in from the sea, grasses lost their competitive edge over tundra shrubs and herbaceous plants.

Vernon Byrd, a Fish and Wildlife Service biologist, has been paying attention to one ecosystem for decades. Despite foxes, the islands remain home to more than 10 million sea-birds of 29 species. Mr. Byrd is an avid birder. For several years, Mr. Byrd and others in the refuge have been eradicat­ing foxes with traps.

One of the cleanest islands is called Rat, which brings up another twist in a never-ending battle against alien, bird-eating Aleutian predators. Shipwrecks are not uncommon. When a vessel runs ashore, Fish and Wildlife personnel work as hard to protect the land as they do to protect the sea from their contents. Rodents can run amok in seabird colonies too or, as Mr. Byrd put it, "rat spills are a lot worse than oil spills in the long term".

(Source: http://www. popsci.com)

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