Taiga (Boreal forest) - The boreal forest or taiga exists as a nearly continuous belt of coniferous trees across North America and Eurasia. Overlying formerly glaciated areas and areas of patchy permafrost on both continents, the forest is mosaic of successional and subclimax plant communities sensitive to varying environmental conditions. Taiga is the Russian name for this forest which covers so much of that country. However, the term is used in North America as well.
The taiga corresponds with regions of subarctic and cold continental climate (Koeppen’s Dfb, Dfc, and Dwd climate types). Long, severe winters (up to six months with mean temperatures below freezing) and short summers (50 to 100 frost-free days) are characteristic, as is a wide range of temperatures between the lows of winter and highs of summer. For example, Verkhoyansk, Russia, has recorded extremes of minus 90 ° Fand plus 90 ° F. Mean annual precipitation is 15 to 20 inches, but low evaporation rates make this a humid climate. Vegetation:
Needleleaf, coniferous (gymnosperm) trees are the dominant plants of the taiga biome. A very few species in four main genera are found: the evergreen spruce (Picea), fir (Abies), and pine (Pinus), and the deciduous larch or tamarack (Larix). 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. A spruce is a tree of the genus Picea a genus of about 35 species of coniferous evergreen trees in the Family Pinaceae, found in the northern temperate and boreal (taiga) regions of the earth. Pines are trees in the genus Pinus in the family Pinaceae. There are about 115 species of pine, although different authorities accept between 105 and 125 species. Fir (Abies) is a genus of 48–55 species of evergreen coniferous tree in the family Pinaceae. It is found through much of North and Central America, Europe, Asia, and...