Threatened taiga forest habitats

The taiga or boreal forest exists as a nearly continuous belt of coniferous trees across North America and Eurasia in a circumpolar belt of the far northern hemisphere immediately south of the Arctic Circle. Within this boreal zone, forests and other wooded land cover 1.2 billion hectares (ha) of which 920 million ha are closed forest. The latter number corresponds to about 29% of the world's total forest area and to 73% of its coniferous forest area. The boreal forest region is variously reported as occupying between 11 to 17 percent of the earth's land surface area and is equivalent to about 18 percent of the earth's total biomass. The biomass is so huge and so vital that when the taiga is in maximum growth phase during the northern spring and summer, the worldwide levels of carbon dioxide fall and the worldwide levels of oxygen rise.

Extensive parts of the boreal forest occur on permafrost soils and formerly glaciated areas. and corresponds with regions of subarctic and cold continental climate. Primary productivity is often limited by cold soil temperatures. Long, severe winters and short summers are characteristic, as is a wide range of temperatures between the lows of winter and highs of summer. Mean annual precipitation is 15 to 20 inches, but low evaporation rates make this a humid climate.

Of all the major forest regions of the world, the boreal zone supports the lowest density of settled human populations.

Needleleaf coniferous trees are the dominant plants of the taiga biome. A very few species in four main genera are found: the evergreen spruce [Picea] sp., fir [Abies] sp. and pine [Pinus] sp., and the deciduous larch or tamarack [Larix] sp. In North America, one or two species of fir and one or two species of spruce are dominant. Across Scandanavia and western Russia the Scots pine is a common component of the taiga. Broadleaf deciduous trees and shrubs are members of early successional stages of both primary and secondary succession. Most common are alder [Alnus] sp., birch [Betula] sp., and aspen [Populus] sp. So-called climax communities in the taiga undergo an approximately 200-year cycle between nitrogen-depleting spruce-fir forests and nitrogen-accumulating aspen forests.

A distinctive feature of the flora of boreal forest is the abundance and diversity of mosses. An estimated one third of the ground cover under boreal forest as a whole is dominated by moss. It is probable that in no other major ecosystem region of the earth are mosses more prominent. Moss makes up much of the ground cover in older conifer stands, and grow on rocks, tree boles, and in the pits formed by upturned trees. Extensive peaty wetlands in the boreal region are often thick accumulations of dead sphagnum, other mosses, sedges, and other plants; a living moss layer continually grows at the surface. Lichens make up a significant part of ground cover in the lichen woodland or sparse northern taiga. Lichens are also generally well distributed on tree boles and especially in the canopy of older conifers throughout the boreal forest. Much of the boreal forest still supports most of its native wildlife including free-ranging large predators such as wolves, lynx and bear; also various members of the weasel family ([eg] wolverine, fisher, pine martin, mink, ermine and sable). The mammalian herbivores on which they feed include the snowshoe or varying hare, red squirrel, lemmings and voles. Large herbivores are more closely associated with successional stages where there is more nutritious browse available and include elk or wapiti [Cervus elaphus] known as red deer in Europe) and moose [Alces alces] known as elk in Europe).