Steppe, sometimes called short-grass prairie, is a formation class consisting of short grasses tending to be bunched and sparsely distributed. Scattered shrubs and low tress may be found in the steppe and there exist all gradations into semidesert and woodland formation classes. Ground coverage is small and much bare soil is exposed. Many species of grasses and other herbs occur; a typical grass of the America steppe is buffalo grass, other typical plants are the sunflower and loco weed (Oxytropis lambertii).
The world distribution of steppe vegetation is extremely wide in terms of latitude, ranging in location from the equator to 55 N and 45 S. Steppes of low latitude are transitional from vegetation of the wet-dry tropical climates into the dry deserts. Steppes of North Africa are transitional from Mediterranean climate, with its sclerophyll forests, to the African desert. Steppes of middle latitudes are associated with a semi-arid continental climatic regime in which, despite a summer rainfall maximum, evaporation exceeds precipitation on the average. Winters in the middle-latitude steppes are cold and dry; the summers warm to hot. In this climatic regime the dominant pedogenic process is calcification, with salinization in poorly drained sites. Soils contain a large excess of precipitated calcium carbonate and are very rich in bases. Brown soils are typical. Humus content is relatively small because of the sparseness of the vegetation.
Grassy tundra (including alpine meadow) is a grassland biochore having formation limited to very cold climates having ample available moisture and often saturated soils. Grassy tundra of the arctic regions flourishes under a regime of long summer days during which time the ground ice melts only in a shallow surface layer. The frozen ground beneath(permafrost)remains impermeable and melt water cannot readily escape. Consequently, in summer a marshy condition prevails for at least a short time over wide areas. Humus accumulates in a well-developed layer.
Plants of the arctic grassy tundra are low and mostly herbaceous, although dwarf willow(Salix herbacea) occurs m places. Sedges, grasses, mosses and lichens dominate the tundra in a low layer. Typical species are ridge sedge, arctic meadow grass and snow lichen (Cetraria nivalis). There are also many species of forbs, which flower brightly in the summer. Considerable variations in composition of the tundra are seen in the range from wet to well-drained habitats. One form of tundra consists of sturdy hummocks of plants with low, water-covered ground between. In the regions~ of grassy tundra will also be found areas of arctic scrub vegetation' composed of willows and birches.
Under the sub arctic climate and a condition of poor soil-water drainage, the pedogenic regime tends toward gleization. Size of plants is in part limited by the mechanical rupture of roots during freeze and thaw of the surface layer of soil, producing shallow-rooted plants. In winter drying winds and mechanical abrasion by wind-driven snow tend to reduce any portions of a plant that project above the snow.
In all latitudes, where altitude is sufficiently high, an alpine tundra is developed above the limit of tree growth and below the vegetation-free zone of barren rock and perpetual snow. Alpine tundra resembles arctic tundra in many physical respects
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