Geobotany(redirected from geobotanic)
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(or phytogeography), a science concerned with the earth’s vegetation as an aggregate of plant communities, or phytocoenoses. The term “geobotany” was coined by the German plant geographer A. Grisebach in 1866 to designate “plant geography.” There is still no consensus on the meaning of the word. Some Soviet botanists consider it a synonym of “phytocoenology” (V. V. Alekhin, V. N. Sukachev, and A. P. Shennikov), and others, like V. B. Sochava, understand it to include all botanical geography. An even broader definition including plant ecology is prevalent among the scientists of some countries outside the USSR.
In the initial period of the development of geobotany, attention was focused mainly on the species composition of plant communities and dependence on the environment, as well as the elaboration of theoretical ideas about the characteristics of a plant community. The Polish botanist I. K. Paczoski (1891) called this science “Horology” and later “phytosociology” (now used mainly in non-Soviet literature). As geobotany grew as an independent science in the late 19th and early 20th centuries, it was divided into general and specialized geobotany. General geobotany mainly studies the structural patterns of plant communities reflected in species composition, the quantitative relations between species in vertical (layer structure) and horizontal (mosaic structure) divisions, the existence of ecologically similar specialized and relatively isolated plant groups (synusiae), the relative position of individuals of different species, and the age composition of the species populations. Other tasks of general geobotany include the study of the interrelationship between the structure of plant communities and the environment, the study of periodic (including seasonal) and more or less irreversible changes in plant communities over time (so-called successions), and the elaboration of classification principles for plant communities. The depth, richness, and similarity of classification patterns established by general geobotany are largely due to the progress made by specialized geobotany. The task of the latter is to study specific zones of vegetation and demonstrate the variety of plant communities in them and the actual pattern of their geographic distribution. Accordingly, it outlines the local classifications of plant communities and the main aspects of their dependence on external conditions and the direction of changes in plant communities over time. In view of the specific nature of the objects of study and the consequent need for special research methods, such branches of specialized geobotany as forestry, meadow culture, and bog science became more or less independent.
The history of geobotany can be divided into three stages. During the first, which lasted from the late 18th to late 19th century, scientists developed the concept of plant communities as peculiar natural objects and collected the initial data on their structure, relations with the environment, and variety. The statement of the German naturalist A. Humboldt that vegetation is a unique element of nature dates to the very beginning of the 19th century. Somewhat later the Swiss botanist A. De Candolle proposed the important concepts that plants struggle for existence and that some plants influence others. These ideas were later incorporated in a more sophisticated form into the concept of plant communities. Finally, the results of practical studies on meadows and forests provided an important foundation for geobotany.
The second stage (late 19th to early 20th century) was marked by efforts to devise methods for describing plant communities and the bases for classifying them. The decision was made by the Third Botanical Congress in Brussels (1910) that an association should be the main unit of classification of vegetation. The precise identification of the characteristics of plant communities and methods for studying them, efforts to use the results of measurements, and the first attempts to apply the statistical method to the study of plant communities date to this period. At this time, geobotanists were energetically elaborating their teachings on the interrelationship of plant communities with the environment, the causes and directions of successions, and radical changes in vegetation resulting from climatic changes—specifically, glaciation in the northern hemisphere. The appearance and development of several Russian, Franco-Swiss, Anglo-American, and Scandinavian geobotanical schools of thought, which are still in existence, are characteristic of this stage in the history of geobotany. Each one is different in its attack on the problems of geobotany, its interpretation of the main units of vegetation, and its unique approach to the classification of plant communities.
The third stage in the history of geobotany began in the 1930’s, when the interaction of the plants in a community was recognized as the criterion for distinguishing a real community from several plants that are simply growing together. The first classification of the ways in which plants influence one another was devised by V. N. Sukachev in 1956. The various forms of root competition, allelopathy, and so forth are analyzed, as well as the standard “struggle for light.”
Because of the work of the Soviet geobotanist T. A. Rabotnov, the population of each species in a plant community is increasingly regarded as a population whose status and prospects for existence in the coenosis are largely determined by its age composition. A plant coenosis is treated as a complex system functioning on a planetary scale. Its function consists of the accumulation of more solar energy than is possible for a single-species population and the recycling of the elements of mineral nutrition. As a result of Rabotnov’s research, it became necessary to study the dependence of plants on one another and on the animals and microorganisms inhabiting the community and to investigate the interaction of the biocoenosis with its habitat.
The concept of vegetation as a continuum is now prevalent, especially outside the USSR. The geobotanical mapping of extensive areas is typical of modern geobotany. The work initiated in the 1920’s under the direction of N. I. Kuznetsov played a fundamental role in this effort.
Geobotanical research is organized according to the specific task on hand, either in the field or at permanent stations (in natural coenoses or among cultivated crops and plantings). In descriptions of plant communities, extensive use is made of test plots of such a size that each reflects the main properties of the community as a whole. Investigators also describe small plots that in the aggregate should characterize the coenosis in a statistically significant manner. Methods are also being worked out for exact quantitative estimates—for example, of the aerial and underground mass and the relative area of light utilization by plants. To penetrate deeper into the life of a plant community, investigators study its components by physiological methods in the field and by experimentation.
As in other branches of botany, the comparative method is important. It is used chiefly to classify plant communities into different categories, which is useful for surveying material and evaluating land (also for economic purposes), regionalizing it geobotanically, and mapping it. The comparative method is also essential in research conducted within the framework of the concept of continuity of vegetation. The extensive use of statistical methods has linked geobotany to mathematical modeling, which is not yet widespread in geobotany but which should play an important role in developing methods for controlling plant communities from a cybernetic standpoint.
Geobotany is closely linked to some earth sciences— physical geography, meteorology, hydrology, climatology, and soil science—because plant communities are largely dependent in their composition and structure on the environment and have, in turn, a profound effect on it. Geobotany is even closer to the botanical disciplines, especially morphology, classification, ecology, and geography of plants. Some aspects of the history of the vegetation link geobotany to historical geology, historical geography, plant phylogeny, and paleobotany. Geobotany is also closely related to several agronomic disciplines, specifically meadow culture and forestry.
Geobotany is used widely in the agriculture of many countries. Estimation of the area and determination of the productivity of the vegetation and the possibilities of improving it are of important practical value. They are also related to the apportioning and organization of the land of sovkhozes and kolkhozes and to the development of sparsely inhabited regions, notably those in the tundra and desert zones. Geobotanists played a major role in expanding the theory and implementing the plans for shelterbelts.
Agrophytocoenoses of fields and sown and semicultivated meadows are coming increasingly into the purview of geobotany.
Soviet geobotanists are members of the All-Union Botanical Society, and they participate in international botanical congresses. Their research is published in Botanicheskii zhurnal (since 1916), Biulleten’ Moskovskogo obshchestva ispytatelei prirody (since 1887), Geobotanika (transactions of the V. L. Komarov Institute of Botany of the Academy of Sciences of the USSR, series 3; since 1932), and in similar journals issued in the Union republics, in the transactions of research institutions, and in Lesovedenie (since 1967). Foreign botanical journals, both general and specialized, have great international significance—for example, Journal of Ecology (London-Cambridge, since 1913), Ecology (New York, since 1920), Pflanzensoziologie (Jena, since 1931), Vegetatio (The Hague, since 1949; a publication of the International Phytosociological Association), Excerpta botanica (Stuttgart, since 1959; a journal devoted to botanical cartography).
REFERENCESPaczoski, I. K. Osnovy fitosotsiologii. Kherson, 1921.
Sukachev, V. N. Rastitel’nye soobshchestva, 4th ed. Leningrad-Moscow, 1928.
Ramenskii, L. G. Vvedenie v kompleksnoe pochvenno-geobo-tanicheskoe issledovanie zemel’. Moscow, 1938.
Morozov, G. F. Uchenie o lese, 7th ed. Moscow-Leningrad, 1949.
Bykov, B. A. Geobotanika, 2nd ed. Alma-Ata, 1957.
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Iaroshenko, P. D. Geobotanika. Leningrad, 1969. (Textbook; bibliography, pp. 195-98).
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Du Rietz, G. E. “Vegetationsforschung auf soziationsanalytischer Grundlage.” In Handbuch der biologischen Arbeitsmethoden, section 11, vol. 5, fasc. 2. Berlin-Vienna, 1930.
Lüdi, W. “Die Methoden der Sukzessionsforschung in der Pflanzensoziologie.” In Handbuch der biologischen Arbeitsmethoden, section 11, vol. 5, fasc. 3. Berlin-Vienna, 1930.
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Klika, J. Nauka o rostlinných spolecenstvech (Fytocenologie). Prague, 1955.
Scamoni, A. Einführung in die praktische Vegetationskunde, 2nd ed. Jena, 1963.
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A. A. URANOV