Mention habitat and most of us think in general terms: mountains, plains, forest, wetlands. But these large, regional landscapes are each a mosaic of natural habitats and they, in turn, are composed of sub-habitats which possess micro-habitats. Mountains offer a prime example; since their elevation range is often significant, they harbor multiple life zones, from foothill brushlands to alpine tundra. Each life zone may contain forest, grassland and wetland areas and portions of these habitats will vary depending upon their exposure to sun, wind and precipitation.
When crossing the vast Plains of North American, many see a monotonous landscape of prairie and crop fields while students of nature recognize vegetation patterns related to streams, soil conditions and sun exposure. Trees cluster along drainages or on the northern slope of escarpments where the shaded soil retains more moisture. Even in desert areas, vegetation is more dense along the dry arroyos, reflecting seasonal torrents and their residual, sub-surface moisture.
On a smaller scale, micro-habitats are often produced by minor variations in temperature, sun exposure and soil moisture. The giant saguaro cactus, a classic symbol of the Sonoran desert, relies on a "nurse plant" that provides protection from the intense sunshine during its early years of growth. At the other extreme, alpine plants often cluster on the south side of boulders, which absorb and radiate heat and offer protection from brutal northerly winds. While larger wildlife species are readily associated with the major habitats of Earth and migratory species visit numerous habitats in the course of a year, many plants and small creatures are restricted to micro-habitats; unless we are adventurous enough to visit those remote and highly restricted habitats, we will never fully appreciate the natural diversity that is so vital to the welfare of our planet. Furthermore, since all life is dependent upon the the health of natural ecosystems, conservation efforts must be devoted to the protection of micro-habitats as well.
