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Out in the Cold
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17433 |
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Section : |
NATURAL SCIENCE
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| Issue
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1 / 1990 |
1,695 Words |
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Scott Elias
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Most North Americans look forward to the changing seasons of the year. Whether we relish the coming of one season, or loathe the arrival of another, we can take comfort that each season represents only about one-quarter of the year. There is a region, however, where there are only two seasons worth mentioning. One is a short, cool summer, the other a very long, very cold winter, in which temperatures may stay well below 0º F for weeks or months at a time, dropping as low as –60º F. Surprisingly, such extreme conditions are not restricted to the vicinity of the north pole. In fact, roughly one-quarter of the North American continent experiences this kind of winter every year. Most of this frozen territory lies north of 660 latitude, but some of it extends as far south as New Mexico, at high elevations. This cold realm encompasses the arctic and alpine regions of our continent.
Relatively few people have successfully occupied these lands of ice and snow. Only the Eskimos (or Inuit, as they prefer to be called) found ways to survive in the arctic regions without the aid of space-age technology, and while a few turn-of-the-century miners were smitten enough by "gold fever" to spend a few winters in cabins above the tree line in the Rocky Mountains, there are no permanent settlements there today. In both the arctic and alpine regions, the combination of low summer temperatures and other factors such as wind and lack of liquid water prohibit the growth and reproduction of even the hardiest trees.
The region beyond the tree line (both in the arctic and in the alpine) is called tundra, a word that the Laplanders of northern Scandinavia coined to describe the cold, marshy plains of western Siberia. While these regions may seem harsh to us, there are large numbers of plants and animals that not only survive, but thrive there.
Recent research has cast light on the patterns and processes of biological adaptation to the cold climates of the arctic and alpine. Many plants and animals avoid the harshness of winter by some form of dormancy. Most tundra plants carry out a frantic biological race in the short summer season, with the whole process from growth of new seedlings through blossoming and setting of seed often lasting less than a month. Once in the ground the seeds of such tundra plants as arctic sedge, alpine clover, and arctic willow may lie dormant for several years, waiting for a summer that is sufficiently warm to allow the whole reproductive cycle to be repeated. Other tundra plants, including many shrubs and cushion plants, such as alpine sorrel, manage to survive for decades or even centuries with out any sexual reproduction. They do this by sending out underground shoots, or rhizomes, which come up to produce "new" individuals from the old stock, creeping across the tundra at a truly glacial pace. This vegetative form of reproduction will eventually give way to the production of viable sees, when a suitably mild summer comes along to give the plant the extra energy it needs to make them.
Energy, solar energy to be more specific, is the crucial ingredient that is so scarce in the tundra. All living things there must be able to conserve this precious commodity to survive. While there are the same number of daylights hours per year in the arctic and alpine regions as in any other region, the quality and daily duration of that light is quite different. In the arctic, it is either feast or famine. In the arctic winter, the sun dips below the horizon and stays there for months on end. Summer brings
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