Physicogeographical Regionalization

the subdivision of the earth’s surface into areas, or regions, that have a certain degree of internal uniformity and distinctive natural features; the identification of these regions is one of the synthesizing functions of physical geography.

Physicogeographical regionalization may be defined as a special kind of classification of natural territorial units, or geosystems, and as a method of identifying the distinctive features of individual parts of the geographic mantle; this is contrasted to the typological approach, which is used in physical geography to establish the degree of similarity between geosystems and thus to fit them into categories such as types, classes, or facies. Physicogeographical regionalization includes the study and comprehensive description of such subordinate geosystems as physicogeographical countries, zones, and districts; it does not usually include the study of small territorial units that are part of a given geographic landscape—for example, a facies or an isolated topographic feature—although some investigators consider the entire range of geosystems to fall within the province of physicogeographical regionalization. General physicogeographical, or landscape, regionalization is based on a set of indicators comprising all or virtually all the components of the natural environment; landscapes may also be subdivided into natural sections on the basis of such individual indicators as relief, climate, or soil.

Before the 19th century, the identification of natural regions lacked a scientific basis; in practice, it was based on such obvious external features as orographic characteristics, river basins, and political boundaries. Neither was there a clear distinction between physicogeographical and economic regional subdivisions. During the 19th century, and especially in the second half, with the proliferation of specialized geographic subdisciplines, various classification schemes were worked out for the identification of natural regions on the basis of climatic, biogeographical, or other individual elements. Classification based on economic indicators developed along independent lines.

The theoretical premises of general physicogeographical realization were first set forth by V. V. Dokuchaev in the late 19th century. The concept of natural zonality lay at the basis of the earliest physicogeographical classification systems devised for European Russia (G. I. Tanfil’ev, 1897) and Asian Russia (L. S. Berg, 1913). In the early 20th century the question of physicogeographical regionalization drew the attention of foreign geographers—for example, E. Herbertson and S. Passarge—in Germany, England, and the United States.

In the USSR, the 1920’s marked the beginning of wide-ranging efforts to identify the physicogeographical regions of individual oblasts and republics. The principle of zonality was adopted in practice, along with the demarcation of provinces as taxonomic regional units (long-term climatic changes and morphostructural factors being taken into account as playing a part in regional differentiation). Various classification schemes have been developed since the 1940’s for the USSR as a whole, including the ones used, respectively, by the Council for the Study of Productive Forces of the Academy of Sciences of the USSR in cooperation with the academy’s institutes (1947) and by the department of geography of Moscow State University (1968); another example is the classification of all land masses and continents in the Physicogeographical Atlas of the World (1964).

Numerous more-detailed classification schemes have been devised for specific political-administrative, economic, and natural regions. Regionalization studies have shifted toward practical applications; for example, since 1956 various higher educational institutions have been engaged in the subdivision of the USSR into regional units for agricultural purposes. In the other socialist countries, too, geographers are much concerned with such questions. Since 1965, three international symposia—in the German Democratic Republic, Poland, and Czechoslovakia—have been devoted to these issues. A detailed physicogeographical regionalization scheme has been developed in the Federal Republic of Germany. Attempts have been made to work out a comprehensive system of geographic regionalization that would include both natural and socioeconomic factors.

Most Soviet geographers recognize the objective existence of physicogeographical regions, each marked out by natural boundaries that are more or less clearly defined. The integrity and internal unity of any given region are determined by the uniformity of certain factors within that region—namely, historical development, geographic location, and such natural processes as atmospheric circulation, the hydrologic cycle, and the migration of chemical elements—as well as by the spatial conjunction of its various parts. Having evolved in the process of development and differentiation of the earth’s surface, physicogeographical regions have a definite history and a specific age, which dictates a historical-genetic approach to regionalization.

Every region is influenced by two sets of factors—zonal and azonal. The zonal factors are determined by the latitudinal distribution of solar radiation on the earth’s surface, while the hypsometric characteristics, material composition of the earth’s crust, movement of the crust, and ratio of land to sea within a given region constitute the azonal factors. Consequently, the objectively determined laws of territorial physicogeographical differentiation form the theoretical basis of physicogeographical regionalization. At the same time, the variously formed segments of the earth’s surface are joined together into complex territorial systems by the constant action of integrative processes—namely, by the circulation of air masses, runoff, slope displacement of solid material, and plant and animal migrations. The surface segments that are contiguous are found to be most closely and diversely linked together; such, for example, is the relationship between the slope and the foot of a mountain or between a body of water and its drainage basin. As a rule, the “closeness” of such relationships is diminished and the degree of spatial uniformity is lessened in inverse proportion to the size and complexity of the land area and depending, too, on the particular arrangement of the various parts of the given area with respect to such elements as predominant air masses and orographic barriers. Hence the need to establish a rank order of physicogeographical regions and to adopt a multilevel system of physicogeographical regionalization.

The identification of physicogeographical belts, physicogeographical zones, and physicogeographical subzones, in that order, is based on zonal factors, whereas physicogeographical countries and physicogeographical regions are identified on the basis of azonal factors. In addition, because the oceans’ effect on nature varies in degree from one continent to another, the continents are subdivided into physicogeographical sectors (oceanic, transitional from oceanic to continental, continental, and extreme continental). The relationship between zonal and azonal regional units is a complex one. Within each zone, the various physicogeographical countries and regions differ with respect to certain natural features; such differentiation results in regional units that are simultaneously zonal and azonal—that is, physicogeographical provinces, or zonal segments of physicogeographical countries. In many regional subdivision schemes, the final level of regionalization is represented by the physicogeographical district, which meets the criterion of homogeneity in both zonal and azonal respects. In common practice, the classification of physicogeographical characteristics is based on a regional subdivision system in which zonal and azonal criteria are alternately employed in identifying regional units (for example, countries, zones, regions, provinces, and districts).

In the case of mountain areas, altitudinal zonality is the major criterion in physicogeographical regionalization: each mountain province and district is distinguished by a specific set, or spectrum, of altitudinal zones depending on the latitudinal-zonal and longitudinal position of the particular mountain rise, absolute elevation, direction of the ridges, and slope exposure.

The identification of physicogeographical regional units of different ranks, combined with the textual description of their characteristics, proceeds in ascending as well as descending order, reflecting the unity of physicogeographical differentiation and integration. A basic scheme is drawn up for the consistent subdivision of an area “from the top down”—that is, from the highest levels of physicogeographical regionalization to the lowest—by analyzing the major zonal and azonal factors of regional physicogeographical differentiation; such analysis makes use of a variety of cartographic data and written source materials. The basic scheme is then refined and made more detailed “from the bottom up”—that is, by consistently integrating simple natural units into more complex ones; thus, for example, an isolated topographic feature becomes part of a landscape, and a landscape becomes part of a province. The location of natural units of various ranks and the relationship between them may be shown by means of landscape maps. Attempts are being made to identify “homogeneous” regions by statistical methods and to draw boundaries on the basis of mathematical calculations.

Physicogeographical regionalization serves as an important basis for the comprehensive reckoning and assessment of natural conditions and resources; as such, it is used for a variety of practical purposes—for example, in agriculture, construction engineering, transportation, medicine, and recreation—as well as in regional planning. The projected practical application of any given regionalization system determines the degree of detail in the classification and the extent to which the description of individual regions conforms to a given goal; the emphasis is on those natural environmental factors that are of substantive importance in resolving a given problem.