TAIGA
Taiga is the northern coniferous forest, primarily spruce, hemlock, and fir,
that extends across vast areas of Eurasia and North America. It is characterized
by winters that are long and cold, in which the cold air contains little moisture;
most of the precipitation falls during the summer- Because of the latitude
where taiga occurs, the days are short in winter (as little as 6 hours) and
correspondingly long in summer. During the summer, plants may grow rapidly,
and crops often attain a large size in a surprisingly short time. Marshes,
lakes, and ponds are common here, and they are often fringed by willows or
birches. Most of the trees in the taiga tend to , occur in dense stands of
one or a few species. Alders, which are common, harbor nitrogen-fixing bacteria
in nodules on their roots, partly for this reason, they are able to colonize
raw, infertile soils such as those left behind by the recent retreat of glaciers
or other ice.
In winter, the taiga receives a deep blanket of snow. During the long, snowy
season, animals must adapt to a way of life different from the one they pursue
during the brief summer, or they may migrate to escape the snow. There are
changes in color, in food habits, and in many other basic aspects of life.
The snow protects the ground irom freezing in the taiga, and thus allows the
growth of forest, in the less snowy :iindra biome, further north, ice lies
too close to the surface of the soil for forest to -tow. Beneath the thick
cover of snow in the taiga there exists an active community ,'f rodents and
other animals, completely protected from most predators.
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Many large mammals live in the taiga, including elk, moose, deer, and carnivores
such as wolves, bear, lynx, and wolverines. Traditionally, much fur trapping
has gone on in this region, which is also an important lumber-producing region.
To the south, taiga grades into forests or grasslands, depending on the amount
of precipitation. Northward, it gradually gives way to open tundra. Coniferous
forests also occur in the mountains to the south, but these are often richer
and more diverse in species than those of the taiga. In the early Tertiary
Period, 40 to 60 million years ago, all ofthes conifers grew in richer, mixed
forests that extended far to the north, above the Arcti Circle. As more severe
winters developed over much of the region and sufficient sum mer rainfall
disappeared from the ranges of western North America, ecosystem formed that
were poorer in their representation of species, such as taiga.
