The boreal forests stretch across the northern hemisphere toward the Arctic shores. The dense cover of evergreens casts an unbroken shadow on the ground beneath for measureless distances. Undergrowth is scanty, and the somber mood is but rarely relieved by the brighter hues of flowers and grasses. But the forest is far from continuous. Flat areas are often too poorly drained to support tree growth and become bogs or muskegs in which mosses and grasses are abundant. Exposed slopes may grow bald as winter winds whip only low-growing, heathy shrubs and herbaceous plants, like those in high mountain ranges, or in the continuous tundra to the north. In the forest proper, no species of coniferous tree has the same demand and gradually segregate in almost pure stands of one or another.
             Nations grew among the tall, straight softwoods which were convenient for building and had many other uses. The environment nurtured a stable economy with a large range of plant (and animal) raw material, and the forest soil could be converted into grasslands or arable soils which maintained their fertility or even increased it. Much of the former virgin boreal forest has been very much modified ~ felled and burned, and species of deciduous trees as birch, poplar, willow and alder cover large areas where formerly they occurred in small, infrequent clumps or as isolated individuals. In a certain sense therefor it can be spoken of as a ‘mixed forest' (though science will note that if left alone it will become once again truly boreal, while the true mixed forest remains so by dictates of climate and soil).