A major regional community (* biome ) in which the vegetation is poor, the few species being mainly lichens, mosses, heaths, sedges, grasses, and some herbaceous plants, but no trees. It is a region of cold * desert , the temperature rarely exceeding 10°C. The topsoil is frozen for about nine months of the year and the subsoil is subjected to permafrost. The plants are thus subjected both to extreme cold and physiological drought as the soil water is frozen. The topography, type of soil, degree of shelter, etc., give rise to differences in vegetation from one locality to another. Arctic tundra is found north of the tree line of North America and Eurasia in a band of varying width circling the Arctic Ocean. In the Antarctic, there are only small scattered areas of arctic vegetation consisting of mosses and lichens on some of the islands. See also alpine . |
