6.5. Biogeocenosis. Theory of biogeocenology according to V. N. Sukachev
Any site must be considered
as a certain natural unity,
where all the vegetation, fauna and microorganisms,
soil and atmosphere are in close
interaction and interdependence.
V.N. Sukachev
In the history of ecology, 20-40s. XX century are noteworthy in that it was at this time that many ecologists were looking for that basic structural unit of the natural whole that could underlie biosphere processes. The Englishman Tansley proposed to consider an ecosystem as such a unit. In Russia, and then in the Soviet Union, the development of theoretical ecology followed a slightly different direction. Natural scientific views were formed under the influence of the views of scientists who belonged to the traditionally strong school of forestry and forestry in Russia. Among them, we should note, first of all, such outstanding scientists as G.F. Morozov, who published the classic work “The Teaching of Forests”, G.N. Vysotsky, M.E. Tkachenko and others. The ideas of the famous soil scientist V.V. also had a great influence on natural scientists of that time. Dokuchaev and geochemist, founder of the doctrine of the biosphere V.I. Vernadsky.
Back in 1899, Dokuchaev wrote that recently one of the most interesting disciplines in the field of modern natural science has been increasingly formed and isolated, namely the doctrine of multifaceted relationships and relationships (and at the same time about the laws governing secular changes) that exist between inanimate and living nature: between surface rocks, the plasticity of the earth, soils, ground and soil waters, the climate of the country and plant and animal organisms, including man, the proud crown of nature.
Such a discipline, which arose in the depths of forest geobotany and subsequently developed into a fundamental science with its own tasks and methods, is biogeocenology (bio... + geo... + Greek koinos - general). The founder of biogeocenology was the outstanding geobotanist, forester and ecologist Academician V.N. Sukachev, who proposed his interpretation of the structural organization of the biosphere. Sukachev devoted his life to the development of general issues of phytocenology - the science of plant communities (phytocenoses). In his works, he attached great importance to the study of interspecific and intraspecific relationships of plants in plant communities. V.N. Sukachev was born in 1880. He graduated from the Kharkov Real School, and then entered the St. Petersburg Forestry Institute, from which he graduated with a gold medal. Scientific work attracted him from his early youth (he published his first scientific work at the age of 18). From then on, V.N. Sukachev devoted himself entirely to science. The scientist's interests were unusually broad, which amazed his contemporaries. He left a piece of his “I” in such branches of biological science as plant taxonomy, floristry, ecology, swamp science, genetics and selection, biogeocenology.
V.N. Sukachev is the author of many classic works devoted to the life of the forest. And although the scientist began as a taxonomist, and later studied the relationships between individual species in a plant community, he gradually moves from studies of the relationships between living plants to the study of the inert environment affecting organisms, and to the study of biocenoses in general. He was captivated by the idea of unity and interconnection of the biocenosis and its habitat (biotope).
This evolution of views led to the formulation of the concept of “biogeocenosis”. Biogeocenology as a doctrine developed at the intersection of biological and physical-geographical sciences and reflected the complex nature of the study of living nature.
The meaning of biogeocenology V.N. Sukachev most accurately expressed in the following words: “Living things create their own habitat. The entire upper layer of our planet is created by life.”
According to V.N. Sukachev, biogeocenosis is an elementary cell of layers of the biosphere saturated with organisms, marked by phytocenosis - a plant community. This is an evolutionarily developed, relatively spatially limited, internally homogeneous natural system of living organisms and abiotic environment in which there is a constant exchange of matter and energy. Sukachev saw the essence of biogeocenosis in the process of mutual exchange of matter and energy between its constituent components, between them and the surrounding external environment, as well as between the biogeocenoses themselves. However, the scientist had an extremely negative attitude towards attempts to reduce biogeocenology only to the problem of the energy of biogeocenosis. Problems of biogeocenology are problems of complex analysis of the structure of flora and fauna, soil, identification of trophic levels, determination of biological productivity, etc. Although V.N. Sukachev developed the concept of biogeocenosis as a botanist and phytocenologist, it was accepted by the majority of modern ecologists. Its important feature is that biogeocenosis is associated with a specific area of the earth’s surface.
The initial concept in defining biogeocenosis was the geobotanical term “phytocenosis” - a plant community, a grouping of plants with a homogeneous nature of the relationships between themselves and between them and the environment. Plants (autotrophic organisms) develop on a very specific substrate - soil, which is an organic-mineral natural formation inhabited by microorganisms. Another natural component with which plants come into direct contact is the atmosphere. Any phytocenosis is always inhabited by a variety of animals (heterotrophic organisms).
Combining all these components into one whole, we obtain the structure of biogeocenosis. It includes five main functionally related parts. This is a phytocenosis - a plant community (autotrophic organisms, producers); zoocenosis - animal population (heterotrophs, consumers) and microbiocenosis - various microorganisms represented by bacteria, fungi, protozoa (decomposers). V.N. Sukachev classified this living part of the biogeocenosis as a biocenosis. The inanimate, abiotic part of the biogeocenosis is made up of a set of climatic factors of a given territory - the climatope and bioinert formation - the edaphotope (soil). Lastly
Over time, the structure of the abiotic environment of the biogeocenosis also includes hydrological factors - hydrotope (Fig. 6.19). This set of abiotic components of a biogeocenosis is called a biotope.
All interactions of the components of biogeocenosis are interconnected by a set of food chains and are interdependent. Each component in nature is inseparable from the other. The main creator of living matter within the biogeocenosis is the phytocenosis - green plants. Using solar energy, green plants create a huge mass of organic matter. The composition and mass of such a substance depend mainly on the characteristics of the atmosphere and soil conditions, which are determined, on the one hand, by the geographical location (zoning, reflected by the existence of certain types of biomes), and on the other, by the terrain and the location of the phytocenosis. The existence of the heterotroph complex depends on the composition and characteristics of vegetation. In turn, the biocenosis as a whole determines the composition and amount of organic matter entering the soil (rich steppe chernozems, low-humus soils of boreal forests and extremely poor soils of tropical rainforests). Animals in the course of their life activities also have a diverse impact on vegetation. The interactions between microorganisms and vegetation, microorganisms and vertebrate and invertebrate animals are extremely important.
Thus, developing the idea of biogeocenosis and the theory of biogeocenology, V.N. Sukachev understood biogeocenosis as a community of animals and plants along with the corresponding soil and atmospheric conditions. Of great importance for the formation of a new concept was Sukachev’s problematic article “Fundamentals of the Theory of Biogeocenology,” written in 1947, where he defines biogeocenosis as a section of the earth’s surface with homogeneous natural phenomena (atmosphere, rock, vegetation, fauna, microorganisms, soil, hydrological conditions) that are combined by metabolism and energy into a single natural complex.
As we can see, the proposed structural unit of the biosphere is similar to what Tansley understood by ecosystem. Indeed, both of these concepts are identical. Both formulations are based on the principle of the unity of living and nonliving components of biological systems. For ecologists who prefer the term “ecosystem,” its more attractive feature is the relativity of boundaries. With this approach, it is possible to distinguish micro-, macro- and meso-ecosystems. In this case, only the last ecosystem level, for example, a specific forest type, may fit the definition of biogeocenosis.
Biogeocenosis and ecosystem are similar concepts, but not the same. Biogeocenosis should be considered as hierarchically elementary complex, i.e. ecosystem consisting of a biotope and biocenosis. It is important to understand that every biogeocenosis is an ecosystem, but not every ecosystem corresponds to a biogeocenosis, although both formulations are based on the principle of the unity of living and nonliving components of biological systems.
First of all, any biogeocenosis is distinguished only on land. At sea, in the ocean and in the aquatic environment in general, biogeocenoses are not distinguished. Biogeocenosis has specific boundaries. They are determined by the boundaries of the plant community - phytocenosis. Figuratively speaking, biogeocenosis exists only within the framework of phytocenosis. Where there is no phytocenosis, there is no biogeocenosis. The concepts of ecosystem and biogeocenosis are completely identical only for such natural formations as, for example, forest, meadow, swamp, field: forest biogeocenosis = forest ecosystem; meadow biogeocenosis = meadow ecosystem, etc. For natural formations that are smaller or larger in volume than the phytocenosis, or where the phytocenosis cannot be distinguished, only the concept of “ecosystem” is used. For example, a hummock in a swamp is an ecosystem, but not a biogeocenosis; a flowing stream is an ecosystem, but not a biogeocenosis. Likewise, only ecosystems are the sea, tundra, tropical rainforest, etc. In the tundra, in the forest, not one phytocenosis can be distinguished, but many. This is a set of phytocenoses representing a larger formation than a biogeocenosis.
The concept of biogeocenosis as a certain element of the biosphere is biochorological (from the Greek chora - place, space), this is the difference between biogeocenosis and ecosystem, since an ecosystem can be spatially both smaller and larger than a biogeocenosis. Thus, the difference between the two concepts consists mainly in the fact that an ecosystem is a more general formation, without rank. This could be a piece of land or a body of water, a coastal dune, a drop of pond water, or the entire biosphere as a whole. Biogeocenosis is limited mainly by the boundaries of the phytocenosis. This is a certain natural object that occupies a certain space and is separated by specific boundaries from similar objects. This is a real zone in which the biogenic cycle occurs.
The main goal of biogeocenology, according to N.V. Dylisa, is " deciphering the structural and functional organization of elementary cells of the biogeocenotic cover, in the sense of Sukachev - biogeocenoses, and analysis of all the diversity of connections and interactions that exist between their constituent material components and which, with the leading importance of living components, create a complex, but holistic and real... bioinert system».
Question 1. Problems of the doctrine of biogeocenosis Specificity of the biogeocenotic level of organization of matter and the relationship between the concepts of biogeocenosis and ecosystem
In the series of biological objects, the organism - population - community, the latter occupy a very specific position.
One of the general criteria for comparing organizations at different levels may be degree of integration(Schmalhausen). Integration should be understood as the degree of unity of a given form of organization, its individuality, the strength of interaction and interconnection of parts and the degree of their obligatory nature for the existence of the whole. An indicator of high integration can be severe violations of vitality, death or a radical change in the properties of the whole when even small parts are damaged. On the contrary, low integration is the ability to maintain the basic properties of the whole even with significant disturbances or variations in the parts.
In the organization of communities of different forms and types, only certain general principles can be traced as common features, such as, for example, the relationships between trophic levels, dominants and subdominants, categories of spatial structure and functional blocks. Moreover, certain relationships between the components in the biocenotic organization can be traced only in a quantitative aspect, i.e. most often these are statistical patterns. The same types of communities, for example variants of meadows, swamps, aquatic ecosystems, can vary endlessly in the composition of species, forming intermediate and extreme variants. Thus, in forests of a certain type two or three edificators may be preserved, but at the same time many other indicators vary extremely greatly. Individual elements can be part of communities of various types, without changing or, on the contrary, varying within the widest limits. Situations are common when the same species act as the most important dominants or edifiers of a wide variety of communities.
Along with low integration, communities are characterized by greater differentiation. This is expressed in the presence of an infinite variety of their variants, in the different scale differences in their types, in the existence of many transitional categories. Relatively very low integration should probably be considered the main feature of the biocenotic level (compared to the population and organism level).
S.S. Schwartz called this aspect of the organization of biocenoses low level of consistency(compared to other forms of life organization). He considered the efficiency of energy use to be a good indicator of the level of systematicity. It falls strongly in the cell-organism-population-community series.
Let us present interesting calculations by S.S. Schwartz for different levels of integration.
Another indicator of the level of integration (systematicity) can be the efficiency and rigidity of regulatory processes. S.S. Schwartz noted the very low efficiency of the actual biocenotic regulatory mechanisms that stabilize the number of species (in comparison with population ones). Considering the issue of population dynamics and its regulation, he noted that due to the lower level of systematicity, the biogeocenosis behaves differently from how an organism would behave in a similar situation, since the control of the biogeocenosis “over the course of the cells composing it - species populations - is less strict .
The noted features of the biocenotic level are of great importance in the processes of understanding its essence and development. They, in particular, manifest themselves in a much greater discrepancy between structural and functional categories and the corresponding aspects of their study than at other levels.
The problem of the discrepancy between structural and functional categories at the biocenotic level was the leitmotif in the discussion about the concept of biocenosis, which took place on the pages of our biological press in the 20s. XX century The general result of the discussion was the conclusion that in its original version the Möbius biocenosis includes two aspects:
– topical (biocenosis as a set of organisms inhabiting a certain area) and
– trophodynamic (biocenosis as a mobile equilibrium system, as a complex of interacting organisms). It has been emphasized through many examples that these two aspects cannot be combined in one concept, that they require different approaches, principles and methods for study and, therefore, different concepts are needed that reflect the forms of organization of one or another aspect. This was reflected in the substantiation of the essence of such concepts as biocenosis by K. Mobius, Holocene by K. Friedericks, ecosystem by A. Tansley, biogeocenosis by V.N. Sukacheva and others, which were proposed not to replace each other, but to reflect certain aspects of the biocenotic level of life organization.
A lack of understanding of the differences between these aspects, in particular, an insufficiently clear distinction between structural and functional categories, has repeatedly been the cause of terminological disagreements in synecology. An example is the confusion that has arisen in connection with the use of the concepts of ecosystem and biogeocenosis.
Many authors have not seen and still do not see the fundamental semantic differences between these concepts and try to reduce them only to the degree of territorial extent, on the basis of which the concept of an ecosystem is most often explained as broader or even vague, and the concept of biogeocenosis as narrower and more specific. Meanwhile, the matter here is not at all a matter of broad and narrow scope, but of completely different criteria. The main initial meaning of an ecosystem is in trophoenergetic relations, and therefore the criteria of territoriality are not applicable to this concept. V.N. Sukachev introduced the concept of biogeocenosis as a biochorological unit. Its main meaning, as V.N. himself emphasized. Sukachev, in close connection with the landscape structure. The principle of interaction, according to Yu.I. Chernov, is completely incompatible with the principle of territorial certainty. The main functional connections in communities, as a rule, cross structural and chorological boundaries. A good example is the biocenoses of the Arctic islands with bird colonies that have their own structure and are clearly limited territorially. At the same time, this set of organisms depends on organic matter brought by birds from a huge area of water.
It must be borne in mind that many concepts introduced in relation to certain aspects of the consideration of community were later artificially endowed with features characteristic of other aspects. As a result, in the interpretation of most ecologists they have lost their original rational meaning and are used as very vague.
We will proceed from the fact that in the community there is no common unit that reflects all aspects of the phenomenon. In the practice of studying systems at the biocenotic level of organization, it is necessary to take into account the presence of several independent aspects that are not reducible to each other, of which the most important and developed are the structural and energetic ones.
Biogeocenology is the science of the laws of the structure, formation and development of biogeocenoses. Thus, the object of study of biogeocenology is considered to be biogeocenoses as elementary units of the biogeocenotic cover of the Earth. According to L.I. Nomokonov, such an idea of the object of biogeocenology is incomplete. He writes about the duality of the object of study of biogeocenology, including biogeocenosis and the biogeosphere as a whole. Biogeocenoses, which together form the biogeosphere of our planet, are usually considered as elementary integral ones, i.e. further indivisible without violating their functional unity and viability, hierarchically subordinate units of the biogeosphere. L.I. Nomokonov, as we see, is of the opinion about the unity of the biogeocenotic and biosphere levels of the organization of matter, which seems irrational to us. Therefore, in further presentation, we will consider only biogeocenoses as an object of biogeocenology.
The problem of continuity and discreteness of biocenotic cover. The main problem of modern biogeocenology is the relationship between the continuity and discreteness of the biogeocenotic cover. The idea of continuity of vegetation cover was expressed by L.G. Ramensky back in 1910. It is based on the “rule” he derived for the ecological individuality of plants, due to which each plant has its own distribution curve in the relief in accordance with the gradient of environmental factors. A gradual change in moisture conditions or some other environmental factor, according to L.G. Ramensky, entails an equally gradual change in the species composition of vegetation, which makes it impossible to divide it into plant groups - phytocenoses. The concept of continuity of vegetation cover, regardless of Ramensky, arose and has long been developed in a number of foreign countries - in the USA, France, England, Italy, etc. There are supporters of this concept in our country. However, the idea of vegetation as a “mirror of habitat” is mechanistic, greatly simplifying the real picture. With this approach, interspecific interactions are actually denied.
According to N.F. Reimers, within the framework of the organismic paradigm, the principle of continuum should be contrasted with the principle of biocenotic discontinuity: species form ecologically defined systemic assemblages (communities) that differ from neighboring ones, although relatively gradually transforming into them.
Contrasting each other with the idea of continuity of vegetation cover, on the one hand, and the idea of its discreteness, i.e. recognition of the presence of biogeocenoses in nature as elementary units, on the other hand, are methodologically untenable and therefore meaningless. Along with and simultaneously with the property of continuity, the biogeocenotic cover is also characterized by the property of discreteness , those. the ability to form relatively independent, spatially and qualitatively isolated elementary cenotic units. According to Timofeev-Resovsky, the continuous living film of the Earth breaks up into largely discrete units - biogeocenoses, which act as structural units (“blocks”) that make up the biosphere. One of the most important criteria for discreteness is the quantitative and qualitative predominance of connections within the system in comparison with the quantity and quality of relations of this system with the space surrounding it.
Biogeocenosis according to V.N. Sukachev. The concept of “biogeocenosis”, introduced in 1940 by V.N. Sukachev, has become widespread mainly in domestic literature. Of the colossal number of modern interpretations of this concept, the most adequate to the structural approach is the definition of N.F. Reimers, who considered biogeocenosis as an evolutionarily established, relatively spatially limited, internally homogeneous natural system of interconnected living organisms and the abiotic environment surrounding them.
Biogeocenosis is considered by V.N. Sukachev as a very complex bio-inert system, which includes five first-level components:
Phytocenosis is a plant component represented by one or another plant community, defining the boundaries and vertical structure of the biogeocenosis. Zoocenosis is an animal component consisting of vertebrates and invertebrates living both in the terrestrial (air) and in the soil or aquatic environment within the boundaries of a given plant community. Microbocenosis is composed of bacteria, lower fungi, actinomycetes and microorganisms. In the process of the coexistence of living components, various connections and relationships arise between them, as a result of which a biological unity of a higher rank is formed - a biocenosis.
In addition to the living components listed, the composition of the biogeocenosis, at least the land one, includes two inert components. Edaphotope - soil and subsoil layers of rock, including soil-groundwater to the depth to which the interaction with them of other components of the biogeocenosis extends, especially plants and soil-dwelling animals and microorganisms, resulting in the formation of an inert (biogenic origin) unity. Climatope is an atmosphere that includes biogenic gases (oxygen, carbon dioxide), atmospheric moisture, precipitation in solid and liquid form, movement of air masses (wind, vertical convection currents), etc. The last two components of biogeocenosis, related to inanimate nature, also interact with each other in the contact zone, forming an inert unity of a higher rank - a biotope.
Not only are all five components of the biogeocenosis in constant interaction with each other, but the biocenosis as a whole, as a set of living components, interacts with the ecotope as a set of components of inanimate nature. As a result, a natural unity of an even higher rank is formed - biogeocenosis, which is not biological, but bioinert. a system of very complex composition and structure.
Considering the question of the direction and nature of the relationships and interactions of the components of biogeocenosis, V.N. Sukachev points out their extreme complexity. Any of the components of biogeocenosis is in a variety of direct and indirect relationships with its other components. Thus, the nature and degree of development of vegetation within the boundaries of a biogeocenosis are to a certain extent dependent on the soil cover, the hydrological regime of the soil and parent rocks, the weather conditions of the local climate and the influence of animals and microorganisms. In turn, the plant community has a diverse and very significant impact on all of the listed components of the biogeocenosis, determining many of their characteristic features and properties. The same can be said about any other component of biogeocenosis, for each of them in its existence and development is closely interconnected and dependent on the influence of other components of biogeocenosis, exerting in turn one or another influence on their fate.
Biogeocenosis as a system. Most modern ecologists view biogeocenosis as a system that, in terms of the complexity of its composition and structure, fully meets the requirements for “very large systems,” and therefore allows for the use of a systematic approach to its study. The need for a systematic approach to the study of certain objects or phenomena is due, as is known, to the impossibility of covering them with conventional methods in all conceivable completeness due to their great complexity or long duration of existence in time.
There is no doubt that the living component of the biogeocenosis is formed from species populations that are the initial elements, and the inert part is formed from various factors of the air, soil or water environment interacting with each other. How does the unification of these elements, heterogeneous in nature, living and inert, take place into unities of a higher rank?
First of all, let us consider from these positions the unification of living beings into a biocenosis. There are three different points of view. Many of the modern biologists, following L.G. Ramensky, they believe that the unification of species populations into a biocenosis occurs directly, bypassing any intermediate structural and functional formations. Others recognize the presence of intermediate links between species populations and biocenosis, for example, consortia (see below for the content of the concept). Still others draw attention to the fact that in reality interactions are built between individuals of species populations. Apparently, it is necessary to talk about different levels of interaction corresponding to such structural units as an organism, a population, and some kind of supra-population associations. The most important of these subsystems are suprapopulation elements (which we will consider below using the example of consortia).
As for the inert component of biogeocenosis, the unification of its elements into such objectively existing natural unities as a climatope, which includes the entire complex of atmospheric phenomena in the air habitat of living components, an edaphotope, represented on land by soil and soil-groundwater, and a hydrotope in the aquatic environment , no doubt.
Structure of biogeocenosis. The main direction of development of the doctrine of biogeocenosis in the second half of the 20th century. was associated with the widespread introduction of the ideas of the structural approach into domestic ecology, which was expressed in the consideration of biogeocenosis as a functional, thermodynamically open system.
According to L.I. Nomokonov, from the idea of biogeocenosis as an open functional system and the heterogeneity from this point of view identified by V.N. Sukachev’s study of the components of biogeocenosis implies the need to clarify the component composition of biogeocenosis and their slightly different grouping. Summarizing the ideas of domestic ecologists, he proposes to distinguish the following components in the composition of biogeocenosis (Fig. 1):
Rice. 1. Scheme of the structure of biogeocenosis according to L.I. Nomokonov.
A. Living components of biogeocenosis that form a biocenosis.
I. The coenocomplex of autotrophs is composed of coenopopulations of plants and other living beings, photo- and chemosynthetics, creators of primary biological production from elements of the inert environment:
I.1. Phototrophs - green higher and lower plants and some species of flagellates;
I.2. Chemotrophs are non-chlorophyll chemotrophic bacteria.
II. A coenocomplex of biotrophs - from coenopopulations of animals and partly plants and microorganisms - consumers and transformers of living biomass and intravital secretions and creators of secondary biological products:
III. Cenocomplex of saprotrophs - from cenopopulations of microorganisms, as well as animals and plants, consumers and destructors of dead remains, waste and corpses of plant and animal origin:
B. Inert components of biogeocenosis, constituting an ecotope, transformed by the biocenosis into a biotope.
IV. Aerotope is the air environment transformed by biocenosis.
V. Edaphotope – soil environment transformed by biocenosis.
Justification for such a structure L.I. Nomokonov sees that “ the main, general function of biogeocenosis and biogeosphere, ensuring their existence and development, is material and energy exchange" As can be seen in the author’s initial statement and in his proposed vision of the structure of biogeocenosis, an attempt to classify the functional elements of a community is quite obvious. This approach does not solve the problem of the structure of biogeocenosis; This is a different methodology, which, in our opinion, is more rationally solved in terms of trophic chains (or networks).
Boundaries of biogeocenoses. Biogeocenosis, as a chorological system, occupies a certain area of territory or water area in a particular landscape. Dimensions of biogeocenosis, according to Timofeev-Resovsky and A.N. Tyuryukanov, depending on the degree of physical-geographical, soil-geochemical and hydrological homogeneity of the area it occupies, vary from several tens and hundreds of square meters to several square kilometers. The configuration and boundaries of a biogeocenosis are determined, according to Sukachev, by the boundaries of its characteristic phytocenosis, as its autotrophic base, physiognomically more clearly than other components that express it in space.
Horizontal boundaries between biogeocenoses, as well as between plant communities, according to J. Leme, can be sharp, especially in conditions of human intervention, but they can also be vague, as if smeared in the case of the interpenetration of components of neighboring biogeocenoses, forming a more or less wide transition zone , called an ecotone. However, ecotones are always spatially immeasurably smaller than the communities they delimit, therefore, these communities are different in essence and “... the boundaries between them (even if “blurred” by ecotones) are natural and therefore real” (Rafes).
B.A. Bykov distinguishes the following types of boundaries between plant communities and, consequently, between biogeocenoses: a) sharp boundaries are observed when there is a sharp difference in adjacent cenoses of environmental conditions or in the presence of dominants with powerful environment-forming properties; b) mosaic boundaries, in contrast to sharp ones, are characterized by the inclusion in the transition zone of adjacent cenoses of their individual fragments, forming a kind of complexity; V) bordered boundaries - when in the contact zone of adjacent cenoses a narrow border of a cenosis develops that differs from both of them; G) diffuse the boundaries between adjacent cenoses are characterized by a gradual spatial change in species composition in the contact zone during the transition from one to another.
The vertical boundaries of the biogeocenosis, like the horizontal ones, are determined by the location of the living plant biomass of the phytocenosis in space: the upper limit is determined by the maximum height of the above-ground plant organs above the soil surface, the lower limit by the maximum depth of penetration of the root system into the soil. At the same time, in tree-shrub biogeocenoses there are vertical boundaries, as T.A. writes. Rabotnov, do not change during the growing season, but in grass biogeocenoses (meadow, steppe, etc.) they vary by season, since there is either an increase in the grass stand, then a decrease in it, or complete alienation in hayfields and pastures, only the lower boundaries they are not subject to seasonal changes. Rabotnov draws attention to the presence of a number of serious difficulties that arise when drawing horizontal and vertical boundaries in some biogeocenoses, especially in aquatic and incomplete biogeocenoses formed by heterotrophs (animal populations and other organisms), due to the mobility of either the habitat or the living components of such biogeocenoses .
- Biogeocenosis – integral self-reproducing system . Abiotic factors regulate the existence and vital activity of populations. At the same time, these factors are constantly influenced by living organisms themselves. The flow of energy and substances connecting living organisms with their habitat ensures the integrity of biogeocenoses. The amount of mineral elements extracted from the soil by plant roots corresponds to the amount returned to the soil solution by decomposers, which decompose the biomass accumulated in the ecosystem. If people do not interfere with natural ecosystems, then ecological balance is maintained in them (constant species composition, level of productivity, circulation of substances).
- Sustainability - the ability of an ecosystem to withstand changes created by external influences. For example: if precipitation has decreased by 50% compared to the average for many years, and the amount of organic matter created by producers has fallen by only 25%, the number of herbivorous consumers has fallen by only 10% (due to the ability to tolerate adverse conditions and high potential reproduction and replacement of the main type of food with a secondary one), then we can say: this ecosystem is stable.
- Self-regulation – maintaining a certain population size, due to the fact that some species do not completely destroy other species, but only limit the number. Mass reproduction of species in biogeocenoses is regulated by direct and feedback connections existing in food chains. Good weather conditions lead to an increase in the yield of plants that herbivores feed on (whose numbers also increase). The more victims, the more food the predator has and the more intensively it reproduces. An increase in the number of predators leads to a decrease in the number of prey (herbivores). A decrease in the number of prey leads to the fact that the reproduction of the predator slows down, and the number of predator and prey returns to the normal - original ratio. The plant base is replenished due to the reproduction and mineralization of plant and animal residues. The number of herbivores increases again, which in turn entails an increase in the number of predators. And again the number of herbivores is decreasing. This phenomenon is called population waves. We understand the importance of self-regulation of numbers especially well when faced with the phenomenon when self-regulation is disrupted. This usually happens in cases where people disrupt the existing structure of ecosystems (example: rabbits in Australia).
Each type of living being in a biogeocenosis occupies some space and consumes certain resources at a certain time. The totality of all environmental factors that are necessary for the existence of a species (habitat, resources and the rhythm of their consumption in the ecosystem) is called ecological niche.
Biogeocenosis does not exist forever. Sooner or later he is replaced by another - ecological succession. Changes occur under the influence of environmental changes caused by living organisms themselves (biotic factors), with changing climatic conditions during the evolution of life on Earth (abiotic factors), under the influence of human economic activity (anthropogenic factors).
An example of a change in ecosystem under the influence of biotic factors is the colonization of rocks by vegetation:
| At the first stages of settlement - destruction, partial dissolution and change in the chemical properties of minerals. |
| First settlers: bacteria, hay-green algae, algae, crustose lichens. Blue-greens (as part of lichens) are producers - creators of organic matter. Many blue-greens fix nitrogen from the air and enrich the environment with it. Lichens secrete organic acids that dissolve rock and promote the accumulation of mineral nutrients. Bacteria and fungi destroy organic substances created by producers. |
| Organic substances are not completely mineralized. A mixture of organic and mineral compounds and plant residues enriched with nitrogen gradually accumulates. Conditions are created for the settlement of mosses and bushy lichens. The process of accumulation of organic matter and nitrogen accelerates and a thin soil layer is formed |
| A primitive community is formed that is capable of existing in unfavorable conditions (withstands dry, frost, etc.). Slowly they change their habitat and thereby create conditions for the introduction of new populations (herbaceous plants). The pioneer settlers are being replaced by new species in this struggle. |
| Shrubs take up residence behind the grasses. Which hold the formed soil together with their roots. |
| Herbaceous and shrub communities are replaced by forest ones, the number of species in which is growing. |
| Stage of a mature forest community. Well adapted to environmental conditions and possessing self-regulation. |
The described change of ecosystem in areas devoid of soil lasts consistently for thousands of years ( primary succession), but can occur quickly - overgrowing of water bodies, restoration of forests after fires, etc. - the soil or bottom sediments have not been destroyed ( secondary successions).
An example of a change in ecosystems under the influence of abiotic factors is the repeated change in climatic conditions on the globe: with warming in ecosystems, due to natural selection, more heat-loving species of plants, animals and microorganisms began to dominate, and with cooling, cold-resistant ones. Periods with low precipitation were characterized by an increase in the number of organisms resistant to lack of moisture. Periods with heavy precipitation led to the flourishing of organisms with increased requirements for moisture content.
An example of a change in ecosystems under the influence of an anthropogenic factor:
The change of biogeocenoses under the influence of anthropogenic factors is the fastest. May occur over several years (decades).
Forests, tundras, steppes, deserts, rivers, seas, etc. - natural ecosystems. Fields, vegetable gardens, orchards, parks, pastures, etc. are ecosystems created by man. They are called agrocenoses (agroecosystems) - This artificial ecosystems. The structure and functions of agrocenoses are created, maintained and controlled by people in their own interests. Agrocenoses, like biogeocenoses, contain all the necessary components (ecotope and biocenosis), but there are also big differences between agrocenoses and natural biogeocenoses:
| characteristics | biogeocenosis | agrocenosis |
| Number of species | big | the number of species is usually low, components are selected by humans |
| Selection | natural | artificial |
| Cycle of substances | natural | part of the pit. substances are removed from the system along with the harvest, so the natural cycle does not take place |
| Self-regulation of the system | self-regulating system | humans maintain species diversity because agrocenosis is not a self-regulating system |
| Energy sources | The sun is a source of energy | Sun + anthropogenic (fertilizers + human care - loosening, weeding, etc.) |
| Relationships between system components | there are different relationships between components | connections between components are controlled by humans |
| Dimensions | any within the biosphere | farm boundaries |
| Food chains | detrital, long ones predominate (3-4 links in terrestrial ecosystems, 4-6 in aquatic ones) | Pasture predominates, short (2-3 units) |
Intermediate biogeocenoses– biogeocenoses to which humans make more or less significant changes (forest parks, lands).
The totality of all biogeocenoses (ecosystems) of the Earth is a large ecological system - biosphere. Biogeocenoses are the elementary structure of the biosphere. The concept of “biosphere” was introduced into the language of science in 1875 by Austrian. geologist E. Suess (biosphere - the shell of the earth inhabited by living organisms). But doctrine of the biosphere how our compatriot V.I. created a global system of living organisms. Vernadsky (book “Biosphere”, 1926). IN AND. Vernadsky considered the biosphere as an area of life whose basis is the interaction of living and bone matter.
The modern idea of the biosphere is a kind of shell of the Earth, containing the entire totality of living organisms and that part of the planet’s substance that is in continuous exchange with these organisms.
There are several geospheres on earth:
Atmosphere - the gaseous shell of the Earth, consisting of a mixture of different gases (nitrogen-78%, oxygen-21%, argon-0.9%, carbon dioxide-0.03%), extending for about 100 km. The ozone layer is located at an altitude of 25-45 km. Triatomic ozone molecules are formed under the influence of ultraviolet radiation from diatomic oxygen molecules. The ozone layer protects the surface of the planet from short-wave ultraviolet rays, which adversely affect living organisms. The lower layer of the atmosphere is the troposphere, and the upper layer is the stratosphere.
Hydrosphere– the water shell of the Earth, including oceans, seas, rivers, lakes, groundwater and glaciers. 94% of it is represented by salty waters of oceans and seas. Three-quarters of fresh water is inaccessible to organisms, as it is conserved in mountain glaciers and polar caps. The world ocean occupies about 70% of the entire surface of the Earth, the average depth is 3.8 km, but there are depressions up to 11 km.
Lithosphere- the solid shell of the Earth, the thickness of which is 50-200 km. The upper layer of the lithosphere (earth's crust) is sedimentary rocks + granite, and the lower layer of the lithosphere is basalt.
These geospheres are in close relationship with each other and with the biosphere, which covers the lower part of the atmosphere (up to 20 km), the upper part of the lithosphere (6-7 km) and the hydrosphere (up to 11 km). The thickness of the biosphere is about 30 km - a rather thin film. The distribution of living organisms in the biosphere is determined by conditions beyond which their existence becomes impossible (low temperatures, high pressure, low light, etc.). Thus, the biosphere is a part of the geological shells of the Earth populated by living organisms. Moreover, the distribution of living organisms in the biosphere itself is uneven; dense accumulations of living beings are called films of life.
IN AND. Vernadsky showed that the biosphere differs from other spheres of the Earth in that the circulation of substances continuously occurs in it, regulated by the activities of living organisms. Since the biosphere receives energy from the outside - from the Sun, it is called an open system.
Functions of living matter: gas – absorbs and releases gases; redox – oxidizes, for example, carbohydrates to carbon dioxide and reduces it to carbohydrates; concentration – concentration organisms accumulate inorganic substances in their bodies and skeletons.
Inert substance(according to Vernadsky) is the totality of those substances in the biosphere in the formation of which living organisms do not participate.
Biogeochemical processes take place in the biosphere with the participation of living organisms. Bioinert substance created and processed by living organisms (soils, natural waters).
Nutrient is created and processed by life, by collections of living organisms. This is a source of extremely powerful potential energy (coal, bitumen, limestone, oil). Once a nutrient is formed, it is unlikely that it will contain living organisms.
In the biosphere, as in every ecosystem, cycle carbon, nitrogen, hydrogen, oxygen, phosphorus, sulfur and other chemical elements.
The concept of “ecosystem” was introduced in 1935 by A. Tansley, an English botanist. With this term he designated any collection of organisms living together, as well as their environment. Its definition emphasizes the presence of interdependence, relationships, cause-and-effect relationships that exist between the abiotic environment and the biological community, combining them into a certain functional whole. An ecosystem, according to biologists, is a collection of all kinds of populations of various species that live in a common territory, as well as the inanimate environment that surrounds them.
Biogeocenosis is a natural formation that has clear boundaries. It consists of a set of biocenoses (living beings) that occupy a certain place. For example, for aquatic organisms this place is water, for those living on land it is the atmosphere and soil. Below we will look at which will help you understand what it is. We will describe these systems in detail. You will learn about their structure, what types they exist and how they change.
Biogeocenosis and ecosystem: differences
To some extent, the concepts of “ecosystem” and “biogeocenosis” are unambiguous. However, they do not always coincide in volume. Biogeocenosis and ecosystem are related as a less broad and broader concept. An ecosystem is not connected to a certain limited area of the earth's surface. This concept can be applied to all stable systems of nonliving and living components in which internal and external circulation of energy and substances occurs. Ecosystems, for example, include a drop of water with microorganisms in it, a flower pot, an aquarium, a biofilter, an aeration tank, and a spaceship. But they cannot be called biogeocenoses. An ecosystem may also contain several biogeocenoses. Let's look at some examples. It is possible to distinguish biogeocenoses of the ocean and biosphere as a whole, continent, belt, soil-climatic region, zone, province, district. Thus, not every ecosystem can be considered a biogeocenosis. We found this out by looking at examples. But any biogeocenosis can be called an ecological system. We hope you now understand the specifics of these concepts. “Biogeocenosis” and “ecosystem” are often used as synonyms, but there is still a difference between them.
Features of biogeocenosis
Many species usually live in any of the limited spaces. A complex and permanent relationship is established between them. In other words, different types of organisms that exist in a certain space, characterized by a set of special physical and chemical conditions, represent a complex system that persists for a more or less long time in nature. To clarify the definition, we note that a biogeocenosis is a community of organisms of various species (historically established), which are closely related to each other and to their surroundings, the exchange of energy and substances. A specific characteristic of a biogeocenosis is that it is spatially limited and quite homogeneous in the species composition of the living creatures included in it, as well as in the complex of various Existence as an integral system ensures a constant supply of solar energy to this complex. As a rule, the boundary of a biogeocenosis is established along the boundary of a phytocenosis (plant community), which is its most important component. These are its main features. The role of biogeocenosis is great. At its level, all processes of energy flow and circulation of substances in the biosphere occur.
Three groups of biocenosis
The main role in the interaction between its various components belongs to the biocenosis, that is, living beings. They are divided according to their functions into 3 groups - decomposers, consumers and producers - and closely interact with the biotope (inanimate nature) and with each other. These living beings are united by the food connections that exist between them.
Producers are a group of autotrophic living organisms. By consuming the energy of sunlight and minerals from the biotope, they thereby create primary organic substances. This group includes some bacteria, as well as plants.
Decomposers decompose the remains of dead organisms, and also break down organic substances into inorganic substances, thereby returning mineral substances “removed” by producers to the biotope. These are, for example, some types of unicellular fungi and bacteria.
Dynamic equilibrium of the system
Types of biogeocenosis
Biogeocenosis can be natural and artificial. The types of the latter include agrobiocenoses and urban biogeocenoses. Let's take a closer look at each of them.
Natural biogeocenosis
Let us note that every natural biogeocenosis is a system that has developed over a long period of time - thousands and millions of years. Therefore, all its elements are “ground in” to each other. This leads to the fact that the resistance of the biogeocenosis to various changes occurring in the environment is very high. The "strength" of ecosystems is not unlimited. Profound and abrupt changes in living conditions, a reduction in the number of species of organisms (for example, as a result of large-scale fishing of commercial species) lead to the fact that the balance can be disturbed and it can be destroyed. In this case, a change in biogeocenoses occurs.
Agrobiocenoses
Agrobiocenoses are special communities of organisms that develop in areas used by people for agricultural purposes (plantings, crops of cultivated plants). Producers (plants), in contrast to natural biogeocenoses, are represented here by one type of crop grown by humans, as well as a certain number of weed species. Diversity (rodents, birds, insects, etc.) determines the vegetation cover. These are species that can feed on plants growing on the territory of agrobiocenoses, as well as be in conditions of their cultivation. These conditions determine the presence of other species of animals, plants, microorganisms and fungi.
Agrobiocenosis depends, first of all, on human activities (fertilization, mechanical tillage, irrigation, treatment with pesticides, etc.). The stability of the biogeocenosis of this species is weak - it will collapse very quickly without human intervention. This is partly due to the fact that cultivated plants are much more demanding than wild ones. Therefore, they cannot compete with them.
Urban biogeocenoses
Urban biogeocenoses are of particular interest. This is another type of anthropogenic ecosystem. An example is parks. The main ones, as in the case of agrobiocenoses, are anthropogenic. The species composition of plants is determined by humans. He plants them and also cares for and processes them. Changes in the external environment are most pronounced in cities - an increase in temperature (from 2 to 7 ° C), specific features of soil and atmospheric composition, a special regime of humidity, light, and wind action. All these factors form urban biogeocenoses. These are very interesting and specific systems.
Examples of biogeocenosis are numerous. Different systems differ from each other in the species composition of organisms, as well as in the properties of the environment in which they live. Examples of biogeocenosis, which we will dwell on in detail, are a deciduous forest and a pond.
Deciduous forest as an example of biogeocenosis
Deciduous forest is a complex ecological system. The biogeocenosis in our example includes plant species such as oaks, beeches, lindens, hornbeams, birches, maples, rowan trees, aspens and other trees whose leaves fall in the fall. Several of their tiers stand out in the forest: low and high trees, moss ground cover, grasses, shrubs. Plants inhabiting the upper tiers are more light-loving. They withstand fluctuations in humidity and temperature better than representatives of the lower tiers. Mosses, grasses and shrubs are shade-tolerant. They exist in the summer in the twilight formed after the leaves of the trees unfold. The litter lies on the surface of the soil. It is formed from semi-decomposed remains, twigs of bushes and trees, fallen leaves, and dead grass.
Forest biogeocenoses, including deciduous forests, are characterized by a rich fauna. They are inhabited by many burrowing rodents, predators (bear, badger, fox), and burrowing insectivores. There are also tree-dwelling mammals (chipmunk, squirrel, lynx). Roe deer, moose, and deer are part of the group of large herbivores. Boars are widespread. Birds nest in different layers of the forest: on trunks, in bushes, on the ground or on the tops of trees and in hollows. There are many insects that feed on leaves (for example, caterpillars), as well as wood (bark beetles). In addition to insects, the upper layers of the soil, as well as the litter, contain a huge number of other vertebrates (ticks, earthworms, insect larvae), many bacteria and fungi.
Pond as a biogeocenosis
Let's now consider a pond. This is an example of a biogeocenosis, in which the living environment of organisms is water. Large floating or rooting plants (pondweed, water lilies, reeds) settle in the shallow waters of ponds. Small floating plants are distributed throughout the water column, to the depth where light penetrates. These are mainly algae called phytoplankton. Sometimes there are a lot of them, as a result of which the water turns green and “blooms.” A variety of blue-green, green and diatom algae are found in phytoplankton. Tadpoles, insect larvae, and crustaceans feed on plant debris or living plants. Fish and predatory insects eat small animals. And herbivorous and smaller predatory fish are hunted by large predatory fish. Organisms that decompose organic matter (fungi, flagellates, bacteria) are widely distributed throughout the pond. There are especially many of them at the bottom, since the remains of dead animals and plants accumulate here.
Comparison of two examples
Having compared examples of biogeocenosis, we see how different the ecosystems of a pond and a forest are in both species composition and appearance. This is due to the fact that the organisms inhabiting them have different habitats. In a pond it is water and air, in a forest it is soil and air. Nevertheless, the functional groups of organisms are of the same type. In the forest, producers are mosses, grasses, shrubs, and trees; There are algae and floating plants in the pond. In the forest, consumers include insects, birds, animals and other invertebrates that inhabit the litter and soil. Consumers in the pond include various amphibians, insects, crustaceans, predatory and herbivorous fish. In the forest, decomposers (bacteria and fungi) are represented by terrestrial forms, and in a pond - by aquatic ones. Let us also note that both the pond and the deciduous forest are a natural biogeocenosis. We gave examples of artificial ones above.
Why do biogeocenoses replace each other?
Biogeocenosis cannot exist forever. It will inevitably sooner or later be replaced by another. This occurs as a result of changes in the environment by living organisms, under the influence of humans, in the process of evolution, and with changing climatic conditions.
An example of a change in biogeocenosis
Let us consider, as an example, the case when living organisms themselves cause a change in ecosystems. This is the colonization of rocks with vegetation. Weathering of rocks is of great importance in the first stages of this process: partial dissolution of minerals and changes in their chemical properties, destruction. At the initial stages, the first settlers play a very important role: algae, bacteria, blue-greens. The producers are free-living algae and lichens. They create organic matter. Blue-greens take nitrogen from the air and enrich it with it in an environment that is still unsuitable for habitation. Lichens dissolve rock with secretions of organic acids. They contribute to the gradual accumulation of mineral nutrition elements. Fungi and bacteria destroy organic substances created by producers. The latter are not completely mineralized. A mixture consisting of mineral and organic compounds and nitrogen-enriched plant residues gradually accumulates. Conditions are created for the existence of bushy lichens and mosses. The process of accumulation of nitrogen and organic matter accelerates, and a thin layer of soil is formed.
A primitive community is formed that can exist in this unfavorable environment. The first settlers were well adapted to the harsh conditions of the rocks - they withstood frost, heat, and dryness. Gradually they change their habitat, creating conditions for the formation of new populations. After herbaceous plants (clover, grasses, sedges, bellflowers, etc.) appear, competition for nutrients, light, and water becomes more intense. In this struggle, the pioneer settlers are replaced by new species. Shrubs settle behind herbs. They hold the emerging soil together with their roots. Forest communities are replaced by grass and shrub communities.
During the long process of development and change of biogeocenosis, the number of species of living organisms included in it gradually increases. The community becomes more complex, it becomes more and more branched. The variety of connections that exist between organisms increases. The community uses the resources of the environment more and more fully. This is how it turns into a mature one, which is well adapted to environmental conditions and has self-regulation. In it, species populations reproduce well and are not replaced by other species. The described change of biogeocenoses lasts for thousands of years. However, there are changes that occur before the eyes of just one generation of people. For example, this is the overgrowing of small bodies of water.
So, we talked about what biogeocenosis is. The examples with descriptions presented above give a clear idea of it. Everything we have talked about is important for understanding this topic. Types of biogeocenoses, their structure, features, examples - all this should be studied in order to have a complete understanding of them.
The beginnings of modern natural science. Thesaurus
Biogeocenosis
(from bio... + geo... and Greek koinos - general)
1) (simplified) a homogeneous area of the earth's surface with a certain composition of living and inert components;
2) an evolutionarily established, spatially limited, long-term self-sustaining homogeneous natural system in which living organisms and their surrounding abiotic environment are functionally interconnected, characterized by relatively independent metabolism and a special type of use of solar energy. The term was introduced by the Russian biologist V. N. Sukachev (1940). Currently, a synonym for biogeocenosis is ecosystem.
Dictionary of environmental terms and definitions
Biogeocenosis
a terrestrial ecosystem within the boundaries of a phytocenosis, i.e., a seemingly homogeneous area of vegetation.
Glossary of terms of the Ministry of Emergency Situations
Biogeocenosis
a set of homogeneous natural phenomena (atmosphere, rock, vegetation, animal life and the world of microorganisms, soil and hydrological conditions) over a certain area of the earth's surface, which has its own specific interactions of its constituent components and certain types of exchange of matter and energy among themselves and with others natural phenomena and representing an internally contradictory dialectical unity, in constant movement and development. B. is the main object of research in biogeocenology. B. is an elementary biochorological structural unit of the vitasphere and in this sense is synonymous with the concepts of facies and elementary landscape, although, unlike the latter, it necessarily includes living matter. The concept of biology is close to the concept of ecosystem, but the latter lacks a strict biochorological basis.
Encyclopedia "Biology"
Biogeocenosis
(natural community), a homogeneous area of the earth's surface with a certain composition of living organisms (biocenosis) and inert components (abiotic environment), united by the circulation of substances and directed energy flows into a single natural complex. Each biogeocenosis is qualitatively and quantitatively different from the others, and all of them together form the biogeocenotic cover of the Earth - the biosphere. The state of biogeocenosis is influenced by both its living and nonliving components (solar energy, water, rocks, etc.). Global climate change leads to a change in biogeocenoses over vast areas of land and water bodies. Human economic activity sometimes leads to such consequences (see). The boundaries of biogeocenoses usually coincide with the boundaries of plant biocenoses (phytocenoses), but, as a rule, they are vague. Groups of biogeocenoses located in the same climatic zone form natural land zones. The term “biogeocenosis” was proposed by V.N. Sukachev (1940). Western scientific literature uses a similar term – ecosystem. Biogeocenology studies biogeocenoses. A great contribution to the development of the biosphere-ecological direction in biology was made by V.V. Dokuchaev and G.F. Morozov, as well as the creator of the doctrine of the biosphere V.I. Vernadsky.
