Doklady Biological Sciences, Vol. 383, 2002, pp. 141–143. Translated from Doklady Akademii Nauk, Vol. 383, No. 4, 2002, pp. 571–573. Original Russian Text Copyright © 2002 by Ostroumov.
GENERAL BIOLOGY
New Definitions of the Concepts and Terms Ecosystem and Biogeocenosis S. A. Ostroumov Presented by Academician L.M. Sushchenya November 14, 2001 Received December 6, 2001
The terms ecosystem and biogeocenosis were coined by Tansley in 1935 [1] and by Sukachev in the 1940s [2], respectively. These terms are widely used in biological research [3–10], and there are several definitions of the term ecosystem [4–8]. However, a large body of new biological information has been accumulated since the time of introduction of these terms. Therefore, a revision of the currently accepted concepts of natural objects and interpretation of basic ecological terms (e.g., ecosystem and biogeocenosis) may be proposed. It seems reasonable to continue the search for new variants of definitions of these terms. The goal of this work was to contribute to this search by suggesting and substantiating specific definitions of two basic ecological terms. I certainly realize that this problem is very complex and its exhaustive solution is practically unattainable, because it is impossible to find an ideal definition that would be adequate to all imaginable situations or satisfy all experts. Nevertheless, it is worth trying to propose modern variants of refined definitions capable of taking into account large volumes of new information concerning aquatic [6, 11–15] and terrestrial [7, 9, 10, 14] ecosystems. Sometimes, the terms used in the definition require additional explanation themselves (e.g., trophic structure, biocenosis, community, etc.) [3]. For example, according to a typical definition, ecosystem is a biological community together with its physical environment (see p. 679 in [5]). However, this definition by no means reflects the whole body of experimental findings and theoretical concepts accumulated in ecology during the past decades. Given the remarks made above in this work, the following variant of definition can be suggested: Ecosystem is the complex of interconnected living organisms inhabiting particular area or unit of space, together with their environment and all their interrelationships and relationships with the environment. Ecosystem is characterized by the description of popula-
Moscow State University, Vorob’evy gory, Moscow, 119899 Russia
tions (abundance) of individual species; interspecies relationships; activity of organisms; physical and chemical characteristics of environment; flows of matter, energy, and information; and description of changes of these parameters with time. This definition does not contain terms such as trophic structure, trophic levels, biocenosis, biotope, community, components, systems, and succession. Because this definition is applicable to both aquatic and terrestrial ecosystems, as well as to natural or model systems of various ranges and degrees of complexity, it seems to be quite universal. Specific features of this definition and their substantiation are briefly summarized in Table 1. The term biogeocenosis, suggested in the early 1940s by Sukachev [2], has gained wide recognition [7, 8]. This term is widely used in ecological research. The classical definition given by Sukachev is cited in many manuals and textbooks. However, a large body of new ecological information accumulated since the time of introduction of the term makes it reasonable to consider new variants of the definition. These definitions should take into account both recent progress in biological research and specific features of the current practice of the use of this term. For example, many researchers apply this term to aquatic ecosystems. To be applicable to aquatic ecosystems, the original definition of this term should be revised. According to the modern taxonomic system, fungi are excluded from the plant kingdom. New findings show that the information flow plays a significant role in the organization of superorganism structures [9, 14]. Based on a modified definition of V.N. Sukachev, the following definition of biogeocenosis can be suggested: Biogeocenosis is an aggregate of natural components (atmosphere, rocks, plants, animals, representatives of microorganisms and fungi, soil and hydrological conditions, and bottom sediments in the case of aquatic systems) in a particular area of land or water. Biogeocenosis is characterized by specific relationships between components; specific types of matter, energy, and information flows providing a certain degree of integrity (unity of components, indivisibility)
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Table 1. Specific features of the definition of ecosystem proposed in this work No. Specific feature of the definition
Examples and comment on the preceding column
Brief substantiation
1
Indication that “living organisms The universality of the definition is inhabit a particular area or unit of increased to include situations with space” aquatic and soil systems in which organisms inhabit the bulk of the water or the bulk of the soil
Biological organisms may inhabit a considerable fraction (in terms of size and environmental diversity) of the system volume in the bulk of the water [6] and the bulk of the soil [10]
2
Direct indication to the ecosystem The definition is more plain and characteristics that are important specific; the importance of biolofor its description gical and nonbiological (physical and chemical) characteristics of the system is emphasized
The following characteristics have been shown to be necessary: abundance of individual species, interrelationships between them [4, 7, 8], specific physical and chemical environmental parameters [6, 10], seasonal and succession changes and their dynamics with time
3
Activity of organisms is put on the list of ecosystem characteristics required for its description
The importance of the physiological activity of organisms (e.g., the rate of photosynthesis, primary productivity, community respiration rate, rate of water filtration by hydrobionts, etc.)
Type and functions of ecosystem are mainly determined by its productivity [5], which depends on the physiological activity of organisms. The rate of water filtration by hydrobionts is important to maintain the water quality in aquatic ecosystems at a sufficiently high level [11, 15]
4
Flows of matter and energy have been introduced instead of the terms “turnover of matter and energy” or “exchange of matter and energy between system components”
The essence of the processes of matter and energy transfer is defined more accurately; because some of these processes are unidirectional, the term flow is more correct than the term exchange
Transfer of pollutants (including radionuclides) along the trophic chain is unidirectional [13]. Transfer of matter and some chemical elements (C, N, P, Si, Al) by pellets settling in water [12] is also an example of unidirectional transfer (along the vector of gravity force)
5
Flows of information have been introduced in addition to flows of matter and energy
Flows of information are important to provide contact between organisms, regulation of their interaction in the ecosystem, and ecosystem stability
There are many examples of information transfer by pheromones [9], attractants, deterrents, and other ecologically important substances produced by organisms [14]
and their changes with time. Organisms usually contribute to environment formation or modification. Specific features of the new definition and its comparison with the classical Sukachev’s definition [2] are briefly described in Table 2. The following specific features of the variant should be emphasized. (1) Taking into consideration the modern concept of natural systems called biogeocenoses, the words about water surface; fungi; and flows of matter, energy, and information have been added; a new conclusion was added. (2) The word “uniformity” is omitted (in the definition by Sukachev it was used in the context of uniform natural phenomena); the word “exchange” (in the context of energy and matter exchange) has been replaced by “flows”; the last part of the definition has been omitted (replaced by a new variant discussed above). (3) It has been noted that living organisms usually contribute to environment formation or modification. (4) The problem of unity of the system’s components is considered as adequately and carefully as pos-
sible (“a certain degree of integrity” has been included). (5) It is noted that biogeocenoses tend to change with time. I realize that the variant of definition suggested in this work is far from ideal. In many cases other variants of definition of the term ecosystem are more useful [3– 8]. I hope that the use and discussion of different variants will promote further progress in the development of the definitions of these basic terms. The evolution of the terms inevitably occurs as new ecological data, are accumulated. ACKNOWLEDGMENTS I am grateful to V.D Fedorov, G.V. Dobrovol’skii, E.A. Kriksunov, V.L. Kontrimavichus, V.N. Maksimov, A.S. Vladychenskii, A.P. Melikyan and many other colleagues from Moscow State University and Russian Academy of Sciences for stimulating discussion of general ecological problems. I am also grateful to AcaDOKLADY BIOLOGICAL SCIENCES
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NEW DEFINITIONS OF THE CONCEPTS AND TERMS ECOSYSTEM AND BIOGEOCENOSIS
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Table 2. Specific features of the definition of biogeocenosis proposed in this work (see the text) No. 1 2
3 4 5
6
7
8
Difference from the classical definition by Sukachev (1972) [2]
The universality of the definition and its applicability to aquatic systems is emphasized
“Land and water surface” is used instead of “land The universality of the definition and its applicability to aquatic surface” systems is emphasized The term “uniform phenomena” is omitted Studies performed in the past decades gave many examples of heterogeneity of some parameters (temperature, illuminance, etc.) and variability of these parameters within the biogeocenosis. Synusias and consortiums are other examples of heterogeneity [8] Fungi are added to the list of biotic components Fungi were previously assigned to plants; however, according to the modern taxonomic system, they are excluded from the plant kingdom Bottom sediments are added to the list of The universality of the definition and its applicability to aquatic biogeocenosis components systems is emphasized The word “exchange” in the expression “exchange of This substitution is required to provide higher accuracy, because, in matter and energy” is replaced by the word “flows” many cases, unidirectional flows rather than bidirectional exchange take place The word “information” is added to the expression Studies performed in the past decades gave many examples of the “flows of matter and energy” important role of information transfer in the processes of formation of multiple connections and interactions between the components of biogeocenoses [8, 9, 14] It is noted that living organisms usually contribute It is emphasized that living organisms are involved in environment to environment formation or modification formation and modification. The examples of this involvement have been presented by many authors in studies on terrestrial (soil) [10] and aquatic [11, 15] systems The last part of the definition is omitted and reMore specific expressions are used; the possibility of changes with placed by a new variant time is emphasized. Specific features of community dynamics (reversible and irreversible changes, including seasonal and circadian rhythms, fluctuations, successions, etc.) were extensively discussed in ecological literature [2–5, 7, 8]
demician L.M. Sushchenya for reviewing the manuscript, to V.L. Kas’yanov, V.N. Pavlov, and A.I. Azovskii for valuable criticism of the preliminary version of the manuscript, and to Dr. Peter J. Wangersky for useful advise. This study was supported by IBG. REFERENCES 1. Tansley, A.G., Ecology, 1935, vol. 16, pp. 284–307. 2. Sukachev, V.N., Izbrannye trudy (Selected Works), Leningrad: Nauka, 1972, vol. 1. 3. Odum, Yu.P., Fundamentals of Ecology, Philadelphia: Saunders, 1971, vols. 1, 2. 4. Fedorov, V.D. and Gil’manov, T.G., Ekologiya (Ecology), Moscow: Mosk. Gos. Univ., 1980. 5. Begon, M., Harper, J.L., and Townsend, C.R., Ecology, Oxford: Blackwell Sci., 1996. 6. Alimov, A.F., Elementy teorii funktsionirovaniya vodnykh ekosistem (Principles of the Theory of Aquatic Ecosystem Functions), St. Petersburg: Nauka, 2000. 7. Shilov, I.A., Ekologiya (Ecology), Moscow: Vysshaya Shkola, 2000. 8. Rozenberg, G.S., Mozgovoi, D.P., and Gelashvili, D.B., Ekologiya: elementy teoreticheskikh konstruktsii sovremennoi ekologii (Ecology: Principles of the Theoretical DOKLADY BIOLOGICAL SCIENCES
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Structure of Modern Ecology), Samara: Samarskii Nauchnyi Tsentr RAN, 1999. 9. Isaev, A.S. and Girs, G.I., Vzaimodeistvie dereva i nasekomykh-ksilofagov (Interaction between the Tree and Xylophagous Insect), Novosibirsk: Nauka, 1975. 10. Dobrovol’skii, G.V. and Nikitin, E.D., Sokhranenie pochv kak nezamenimogo komponenta biosfery (Conservation of Soils As an Indispensable Component of the Biosphere), Moscow: Nauka, 2000. 11. Ostroumov, S.A., Biologicheskie effekty poverkhnostnoaktivnykh veshchestv v svyazi s antropogennymi vozdeistviyami na biosferu (Biological Effects of Surfactants as Related to the Anthropogenic Impact on the Biosphere), Moscow: MAKS, 2000. 12. Ostroumov, S.A. and Kolesnikov, M.P., Dokl. Akad. Nauk, 2001, vol. 379, no. 3, pp. 426–429. 13. Matishov, D.G. and Matishov, G.G., Radiatsionnaya ekologicheskaya okeanologiya (Radiation Ecological Oceanology), Apatity: Kol’skii Nauchnyi tsentr Ross. Akad. Nauk, 2001. 14. Ostroumov, S.A., Vvedenie v biokhimicheskuyu ekologiyu (Introduction to Biochemical Ecology), Moscow: Mosk. Gos. Univ., 1986. 15. Ostroumov, S.A., Dokl. Akad. Nauk, 2002, vol. 382, no. 1, pp. 138–141.