Zonation


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Related to Zonation: Vertical zonation

zonation

[zō′nā·shən]
(ecology)
Arrangement of organisms in biogeographic zones.
(geology)
The condition of being arranged in zones.

Zonation

 

(geographic), the pattern of differentiation of the geographic sphere (landscape) of the earth, manifest in the sequential and definite change of geographic belts and zones and resulting primarily from differences in the amount of solar energy reaching particular latitudes on the earth’s surface.

Zonation is also characteristic of most of the components and processes of the natural geographic regions—climatic, hydrological, geochemical, and geomorphological processes; the soil, plant cover, and animal life; and to some extent the formation of sedimentary rocks. A decrease in the angle of the sun’s rays as they strike the earth from the equator to the poles creates broad latitudinal belts of radiation: a tropical zone, two temperate zones, and two cold zones. The formation of analogous belts, especially climatic and geographic belts, is related to the characteristics of the atmosphere and atmospheric circulation, and these are strongly influenced by the distribution of land and oceans, which is not zonal. The differentiation of natural zones on land depends on the pro-portion of heat and moisture, which changes not only with latitude but also from the coastal area to the continental interior (patterns of sectionalization). Thus it is possible to speak of horizontal zonation, which is particularly well shown by the latitudinal zonation on the plains of the USSR. Each geographic belt and sector has its spectrum and sequential order. Zonation is also expressed in the regular progression of altitudinal zones, or belts, in mountains, which is originally determined by a nonzonal factor, the relief; moreover, definite spectra of altitudinal zones are characteristic of particular belts and sectors. Both horizontal and vertical zonation are expressed in oceans (by consecutive changes in temperature, salinity, biocomponents), over which geographic belts extend.

Zonation of thermal conditions was recognized as early as classical times. Climatic and plant zonation, including altitudinal zonation, was established by the German scientist A. von Humboldt. Zonation was first defined as a fundamental law of differentiation of major natural complexes by V. V. Dokuchaev in 1898.

E. N. LUKASHOVA

References in periodicals archive ?
Phylogeny, speciation and zonation of Siphonodella of shallow water facies (Conodonta, Early Carboniferous).
However, the crystals also display internal zonation under TL and FL: the low-optical-relief inner zones in the crystals are fluorescent, have an elongated triangular shape and sometimes display a "patchy" appearance, and the outer zone of the crystals has an elongated shape and high optical relief and is non-fluorescent (Figs.
Anderson (1961, 1964, 1976, 1983) and Anderson and Muller (1975) studied the domed topography of tropical peat deposits and the relationship between the concentric zonation of surface vegetation and increasing peat thickness, acidity and decreasing nutrient availability with horizontal distance between margin and centre of peat basin.
All adrenals from 0- to 11-year-old individuals (Cases 1-8) showed clearly layered zonation both histologically and immunohistochemically (Table 1, Figures 1(a) and 1(b), Pages 1-2 of Supplementary Figure 1).
Lobular zonation of ROS, demonstrated by a blue precipitate with the MnDAB-Co reaction, was observed.
Therefore, the problem of spatial zonation of landslides lies in the landslide inventorization, as well as in their integration with causal factors in a conceptual framework.
Two to 3 inches in diameter, the roots are medium to dark purple-red with somewhat pronounced zonation.
Age-dependent zonation of the periwinkle Littorina littorea (L.
In this gradient, the salinity and flooding cycles are widely recognized as the main abiotic drivers for plant community zonation (Greenwood and Macfarlane, 2009; Ribeiro et al.