Alpine valley wisconsin time zone1/3/2024 In North America and Eurasia treeline is variable according to latitude. The arctic-alpine zone vegetation of the mid-latitudes bears many similarities with the true Arctic. Patches of stunted conifers mark the upper limit of tree growth in the krummholz on Mount Washington, NH. MID-LATITUDE ARCTIC-ALPINE LIFE ZONE VEGETATION Soils may be stony entisols or lithosols, deep inceptisols with clear development of A and B horizons, or histosols, the bog soils found in depressions and other poorly drained sites. Early in the growing season soils may be saturated from snow melt later in summer the top inch or so may dry out. Windblown materials trapped by plants add fine particles and nutrients. Peat bogs, shallow stony soils, and deep grassland soils may be found a relative short distance apart. On-site weathering, landslides, and glacial deposition often produces a mix of very large and very fine particles. Frost action and downslope slippage and erosion disturb upper horizons. Soil development is slow due in part to low soil temperatures that inhibit the activity of microorganisms. An intricate mosaic of microclimates may develop over very short distances in response to shelter from or exposure to wind and drainage conditions. The actual climatic conditions on any given mountain vary with elevation, latitude, aspect, and general regional climate. Upslope winds rise in response to warming during the day, but reverse after sunset as the alpine area quickly cools and denser cold air drains down into the valleys below. In rugged terrain, wind can be an important element of the climate. Snow cover, however, will reflect solar radiation back to apace during the day but insulate the ground during the night. It can also produce extreme diurnal temperature changes. The thin atmosphere typically subjects alpine life to intense solar radiation. Low temperatures also inhibit evaporation, further contributing to general aridity. Little water vapor can be held in thin, cold air, so high mountains are usually dry. Ambient temperature also decreases with elevation at the normal lapse rate of 3.5° F/1000 ft increase in elevation. Less dense air translates to less carbon dioxide available to plants for photosynthesis and less oxygen for animals. asl is only 50 percent of sea level barometric pressure. Air density diminishes with increasing altitude, so that at 8,550 ft asl air pressure is 26 percent lower than at sea level and at 19,000 ft. However, a significant factor in all alpine regions is atmospheric pressure. This concept works well in the western US where it was designed, but falls apart in the tropics, where high elevation communities do not at all resemble low elevation vegetation or (usually) fauna.Ĭlimate. The climate of a particular mountain depends on location. He defined a life zone as a belt of vegetation and animal life that is similarly expressed with increases in altitude and increases in latitude. Hart Merriam, who described six “Life Zones” on the San Francisco Peaks outside Flagstaff, AZ. In North America, the study of altitudinal zonation was pioneered in 1889 by C. He illustrated his findings in now classic drawings of the distribution of plants on many of the world’s highest peaks, one of which is shown below. The study of the zonation of vegetation according to elevation is still informed and inspired by the 19th century writings of the German geographer Alexander von Humboldt, who traveled through South America and climbed some of the continent’s highest peaks, most notably Chimborazo in Ecuador. The elevation of treeline generally occurs at lower elevations as latitude increases, but can also reflect mountain mass, regional climate (arid versus humid), and continental versus maritime influences. Introduction. Communities designated “alpine” exist on mountains and high plateaus above treeline, a zone of stunted woody plants that marks the upper limits of tree growth.
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