The concept of ecosystems. The doctrine of biogeocenoses
The concept of "ecosystem" was introduced in 1935 by A. Tensley, an English botanist. By this term, he designated any set of organisms that live together, as well as their environment. Its definition emphasizes the presence of interdependence, relationships, causal relationships that exist between the abiotic environment and the biological community, combining them into a kind of functional whole. An ecosystem, according to biologists, is a collection of various populations of various species that live in a common area, as well as the inanimate environment surrounding them.
Biogeocenosis is a natural formation with 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 who live 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 of them 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. The ecosystem is not associated with a certain limited area of the earth's surface. This concept can be applied to all stable systems of non-living and living components in which there is an internal and external circulation of energy and substances. Ecosystems, for example, include a drop of water with microorganisms in it, a flower pot, an aquarium, a biofilter, an aeration tank, a spaceship. But they cannot be called biogeocenoses. An ecosystem may include several biogeocenoses. Let's turn to examples. It is possible to distinguish the biogeocenoses of the ocean and the biosphere as a whole, the mainland, belt, soil-climatic region, zone, province, district. Thus, not every ecosystem can be considered a biogeocenosis. We figured it 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 confined spaces. A complex and constant relationship is established between them. In other words, different types of organisms that exist in a certain space, characterized by a complex of special physico-chemical conditions, are a complex system that persists for a more or less long time in nature. Clarifying the definition, we note that biogeocenosis is a community of organisms of various species (historically established), which are closely related to each other and to their environment, the exchange of energy and substances. A specific characteristic of biogeocenosis is that it is spatially limited and rather homogeneous in terms of the species composition of living beings included in it, as well as in terms of a complex of different ones. Existence as an integral system ensures a constant supply of solar energy to this complex. As a rule, the boundary of the biogeocenosis is established along the boundary of the phytocenosis (plant community), which is its most important component. These are its main features. The role of biogeocenosis is great. At its level, all the processes of energy flow and the circulation of substances in the biosphere take place.
Three groups of biocenosis
The main role in the implementation of 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 food connections existing between them.
Producers are a group of autotrophic living organisms. Consuming the energy of sunlight and minerals from the biotope, they 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 ones, thereby returning the mineral substances "withdrawn" 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 species of the latter include agrobiocenoses and urban biogeocenoses. Let's take a closer look at each of them.
Biogeocenosis natural
Note that each natural natural biogeocenosis is a system that has developed over a long time - thousands and millions of years. Therefore, all its elements are "lapped" to each other. This leads to the fact that the resistance of biogeocenosis to various changes occurring in the environment is very high. The "strength" of ecosystems is not unlimited. Deep and abrupt changes in the conditions of existence, a reduction in the number of species of organisms (for example, as a result of a large-scale catch of commercial species) lead to the fact that the balance can be disturbed and it can be destroyed. In this case, there is a change of biogeocenoses.
Agrobiocenoses
Agrobiocenoses are special communities of organisms that develop in areas used by people for agricultural purposes (planting, sowing cultivated plants). Producers (plants), in contrast to biogeocenoses of a natural species, are represented here by one type of crop grown by man, 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 the 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, pesticide treatment, 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 whimsical than wild ones. Therefore, they cannot compete with them.
Urban biogeocenoses
Urban biogeocenoses are of particular interest. This is another type of anthropogenic ecosystems. Parks are an example. The main ones, as in the case of agrobiocenoses, are anthropogenic in them. The species composition of plants is determined by man. He plants them, and also takes care of them and their processing. The most pronounced changes in the external environment are expressed precisely in cities - an increase in temperature (from 2 to 7 ° C), specific features of the soil and atmospheric composition, a special regime of humidity, illumination, 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 composition of the biogeocenosis in our example includes plant species such as oaks, beeches, lindens, hornbeams, birches, maples, mountain ash, aspens and other trees whose foliage falls in autumn. Several of their tiers stand out in the forest: low and high woody, moss ground cover, grasses, shrubs. Plants inhabiting the upper tiers are more photophilous. They better withstand fluctuations in humidity and temperature than representatives of the lower tiers. Mosses, grasses and shrubs are shade-tolerant. They exist in the summer in the twilight, formed after the foliage of the trees unfolds. The litter lies on the surface of the soil. It is formed from semi-decomposed remains, twigs of shrubs and trees, fallen leaves, dead grasses.
Forest biogeocenoses, including deciduous forests, are characterized by rich fauna. They are inhabited by many burrowing rodents, predators (bear, badger, fox), and burrowing insectivores. There are also mammals living on trees (chipmunk, squirrel, lynx). Roe deer, elk, deer are part of the group of large herbivores. Boars are widespread. Birds nest in different tiers 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 the upper layers of the soil, as well as in the litter, besides insects, a huge number of other vertebrates (mites, earthworms, insect larvae), many bacteria and fungi live.
Pond as a biogeocenosis
Consider now the pond. This is an example of biogeocenosis, in which the living environment of organisms is water. Large floating or rooting plants (weeds, water lilies, reeds) settle in the shallow water of ponds. Small floating plants are distributed throughout the water column, to the depth where light penetrates. These are mainly algae, which are called phytoplankton. There are sometimes a lot of them, as a result of which the water turns green, "blooms". Many blue-green, green and diatom algae are found in phytoplankton. Tadpoles, insect larvae, 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 ones. Organisms that decompose organic matter (fungi, flagellates, bacteria) are widespread 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
Comparing examples of biogeocenosis, we see how dissimilar both in species composition and in appearance are the ecosystems of the pond and the forest. This is due to the fact that the organisms inhabiting them have a different habitat. 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, herbs, shrubs, trees; in the pond - algae and floating plants. In the forest, consumers include insects, birds, animals and other invertebrates that inhabit the litter and soil. The 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 the pond - by aquatic ones. We also note that both the pond and the deciduous forest are natural biogeocenosis. We gave examples of artificial ones above.
Why do biogeocenoses replace each other?
Biogeocenosis cannot exist forever. It will inevitably change sooner or later. This occurs as a result of changes in the environment by living organisms, under the influence of man, in the process of evolution, with changing climatic conditions.
An example of a change in biogeocenosis
Let us consider as an example the case when the living organisms themselves are the cause of the change of ecosystems. This is the settlement of rocks with vegetation. Of great importance in the first stages of this process is the weathering of rocks: partial dissolution of minerals and a change in their chemical properties, destruction. At the initial stages, the first settlers play a very important role: algae, bacteria, blue-green. The producers are in the composition of lichens and free-living algae. They create organic matter. Blue-greens take nitrogen from the air and enrich it with an environment that is still unsuitable for habitation. Lichens dissolve rock with secretions of organic acids. They contribute to the fact that the elements of mineral nutrition are gradually accumulated. Fungi and bacteria destroy the organic substances created by the producers. The latter are not fully mineralized. Gradually, a mixture of mineral and organic compounds and plant residues enriched with nitrogen accumulates. Conditions are created for the existence of bushy lichens and mosses. The process of accumulation of nitrogen and organic matter accelerates, a thin layer of soil is formed.
A primitive community is being formed that can exist in this unfavorable environment. The first settlers are well adapted to the harsh conditions of the rocks - they withstand frost, heat, and dryness. Gradually, they change their habitat, creating conditions for the formation of new populations. After the appearance of herbaceous plants (clover, cereals, sedges, bluebell, etc.), competition for nutrients, light, and water intensifies. In this struggle, the pioneer settlers are displaced by new species. Shrubs settle for herbs. They hold the soil in place with their roots. Forest communities are replaced by grass-shrub communities.
In the course of a long process of development and change of biogeocenosis, the number of species of living organisms included in it is gradually growing. The community becomes more complex, it becomes more and more ramified. The variety of relationships that exist between organisms increases. More and more community uses the resources of the environment. So 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 take place before the eyes of just one generation of people. For example, this is the overgrowth of small reservoirs.
So, we talked about what biogeocenosis is. The examples with descriptions presented above give a visual representation 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 picture of them.
1. The concept of biogeocenosis and biogeocenology
A person in his everyday life constantly has to deal with specific areas of the natural complexes surrounding him: areas of a field, meadow, swamp, reservoir. Any part of the earth's surface, or natural complex, should be considered as a certain natural unity, where all vegetation, fauna and microorganisms, soil and atmosphere are closely interconnected and interact with each other. These relationships must be taken into account in any economic use of natural resources (plant, animal, soil, etc.).
Natural complexes in which vegetation is fully formed, and which can exist on their own, without human intervention, and if a person or something else violates them, they will be restored, moreover, according to certain laws. Such natural complexes are biogeocenoses.
The most complex and important natural biogeocenoses are forest ones. In no natural complex, in any type of vegetation, these relationships are expressed so sharply and so many-sidedly as in the forest.
Forest represents the most powerful "film of life". Forests play a dominant role in the composition of the vegetation cover of the Earth. They cover almost a third of the planet's land area - 3.9 billion hectares. If we take into account that deserts, semi-deserts and tundras occupy about 3.8 billion hectares, and more than 1 billion hectares are waste, built-up and other unproductive lands, then it becomes obvious how important the forests are in the formation of natural complexes and the function they perform. living matter on earth. The mass of organic matter concentrated in forests is 1017–1018 tons, which is 5–10 times the mass of all herbaceous vegetation.
That is why special importance was attached and is attached to biogeocenological studies of forest systems and the term "biogeocenosis" was proposed by Academician V.N. Sukachev in the late 30s. 20th century in relation to forest ecosystems. But it is valid in relation to any natural ecosystem in any geographic region of the Earth.
Definition of biogeocenosis according to V.N. Sukachev (1964: 23) is considered classical - “... this is a set of homogeneous natural phenomena (atmosphere, rocks, vegetation, fauna and the world of microorganisms, soil and hydrological conditions) over a known extent of the earth's surface, which has a special specificity of interactions of these constituent components and a certain type of metabolism and energy: between themselves and with other natural phenomena and representing an internal contradictory unity, which is in constant motion and development ... ".
This definition reflects all the essence of biogeocenosis, features and characteristics inherent only to it:
biogeocenosis must be homogeneous in all respects: living and non-living matter: vegetation, wildlife, soil population, relief, parent rock, soil properties, depth and groundwater regimes;
each biogeocenosis is characterized by the presence of a special, only inherent type of metabolism and energy,
all components of biogeocenosis are characterized by the unity of life and its environment, i.e. the features and patterns of life activity of biogeocenosis are determined by its habitat, thus, biogeocenosis is a geographical concept.
In addition, each specific biogeocenosis should:
Be homogeneous in its history;
To be a sufficiently long-term established formation;
Clearly differ in vegetation from neighboring biogeocenoses, and these differences should be natural and ecologically explicable.
Examples of biogeocenoses:
Forb oak forest at the foot of the deluvial slope of southern exposure on mountain brown-forest medium loamy soil;
Cereal meadow in a hollow on loamy peat soils,
Forb meadow on a high river floodplain on floodplain soddy-gley medium loamy soil,
Lichen larch on Al-Fe-humus-podzolic soils,
Forest mixed broad-leaved with liana vegetation on the northern slope on brown forest soils, etc.
A simpler definition:"Biogeocenosis is the whole set of species and the whole set of components of inanimate nature that determine the existence of a given ecosystem, taking into account the inevitable anthropogenic impact." The last addition, taking into account the inevitable anthropogenic impact, is a tribute to modernity. At the time of V.N. Sukachev, there was no need to attribute the anthropogenic factor to the main environmental factors, which it is now.
The field of knowledge about biogeocenoses is called biogeocenology. To control natural processes, one must know the patterns to which they are subject. A number of sciences study these patterns: meteorology, climatology, geology, soil science, hydrology, various departments of botany and zoology, microbiology, etc. Biogeocenology, on the other hand, generalizes, synthesizes the results of the listed sciences from a certain angle, focusing on the interactions of the components of biogeocenoses with each other and revealing general patterns that govern these interactions.
The object of study of biogeocenology is biogeocenosis.
The subject of study of biogeocenology is the interaction of the components of biogeocenoses with each other and the general laws that govern these interactions.
2. Component composition of biogeocenoses
The components of biogeocenosis do not just exist side by side, but actively interact with each other. The main and mandatory components are biocenosis and ecotope.
Biocenosis, or biological community - a set of three components living together: vegetation (phytocenosis), animals (zoocenosis) and microorganisms (microbocenosis).
Each of the components is represented by many individuals of different species. The role of all components: plants, animals and microorganisms in the biocenosis is different.
Thus, plants form a relatively permanent structure of the biocenosis due to their immobility, while animals cannot serve as the structural basis of the community. Microorganisms, although most of them are not attached to the substrate, move at a low speed; water and air carry them passively over considerable distances.
Animals depend on plants because they cannot build organic matter from inorganic matter. Some microorganisms (both all green and a number of non-green ones) are autonomous in this respect, as they are capable of building organic matter from inorganic matter using the energy of sunlight or the energy released during chemical oxidation reactions.
Microorganisms (microbes, bacteria, protozoa) play an important role in the decomposition of dead organic matter into minerals, that is, in a process without which the normal existence of biocenoses would be impossible. Soil microorganisms can play a significant role in the structure of terrestrial biocenoses.
The differences (biomorphological, ecological, functional, etc.) in the characteristics of the organisms that make up these three groups are so great that the methods of their study differ markedly. Therefore, the existence of three branches of knowledge - phytocenology, zoocenology and microbiocenology, studying phytocenoses, zoocenoses and microbial cenoses, respectively, is quite legitimate.
Ecotop- a place of life or habitat of a biocenosis, a kind of "geographical" space. It is formed on the one hand by soil with a characteristic subsoil, with forest litter, and also with one or another amount of humus (humus); on the other hand, an atmosphere with a certain amount of solar radiation, with one or another amount of free moisture, with a characteristic content of carbon dioxide in the air, various impurities, aerosols, etc., in aquatic biogeocenoses, instead of the atmosphere, water. The role of the environment in the evolution and existence of organisms is beyond doubt. Its individual parts (air, water, etc.) and factors (temperature, solar radiation, altitude gradients, etc.) are called abiotic, or inanimate, components, in contrast to the biotic components represented by living matter. V.N. Sukachev did not attribute physical factors to components, while other authors do (Fig. 5).
Biotope- this is an ecotope transformed by the biocenosis for "itself". Biocenosis and biotope function in continuous unity. The dimensions of the biocenosis always coincide with the boundaries of the biotope, therefore, with the boundaries of the biogeocenosis as a whole.
Of all the components of the biotope, soil is closest to the biogenic component of the biogeocenosis, since its origin is directly related to living matter. Organic matter in the soil is a product of the vital activity of the biocenosis at different stages of transformation.
The community of organisms is limited by the biotope (in the case of oysters, by the boundaries of the shoal) from the very beginning of existence.
c) V. Dokuchaev;
d) K. Timiryazev;
e) K. Möbius.
(Answer: b.)
2. The scientist who introduced the concept of "ecosystem" into science:
a) A. Tensley;
b) V. Dokuchaev;
c) K. Möbius;
d) V. Johansen.
(Answer: A . )
3. Fill in the gaps with the names of the functional groups of the ecosystem and the kingdoms of living beings.
Organisms that consume organic matter and process it into new forms are called. They are represented mainly by species belonging to the world. Organisms that consume organic matter and completely decompose it into mineral compounds are called. They are represented by species related to ki. Organisms that consume mineral compounds and, using external energy, synthesize organic substances are called. They are represented mainly by species belonging to the world.
(Answers(successively): consumers, animals, decomposers, fungi and bacteria, producers, plants.)
4. All living beings on Earth exist thanks to organic matter, mainly produced by:
a) mushrooms
b) bacteria;
c) animals;
d) plants.
(Answer: G.)
5. Fill in the missing words.
A community of organisms of different species, closely interconnected and inhabiting a more or less homogeneous area, is called. It consists of: plants, animals. The totality of organisms and components of inanimate nature, united by the circulation of substances and the flow of energy into a single natural complex, is called, or.
(Answers(successively): biocenosis, fungi and bacteria, ecosystem, or biogeocenosis.)
6. Of these organisms, producers include:
a) a cow
b) white mushroom;
c) red clover;
d) a person.
(Answer: c.)
7. Select from the list the names of animals that can be attributed to consumers of the second order: gray rat, elephant, tiger, dysentery amoeba, scorpion, spider, wolf, rabbit, mouse, locust, hawk, guinea pig, crocodile, goose, fox, perch , antelope, cobra, steppe tortoise, grape snail, dolphin, Colorado potato beetle, bull tapeworm, kangaroo, ladybug, polar bear, honey bee, blood-sucking mosquito, dragonfly, codling moth, aphid, gray shark.
(Answer: gray rat, tiger, dysentery amoeba, scorpion, spider, wolf, hawk, crocodile, fox, perch, cobra, dolphin, tapeworm, ladybug, polar bear, blood-sucking mosquito, dragonfly, gray shark.)
8. From the listed names of organisms, select producers, consumers and decomposers: bear, bull, oak, squirrel, boletus, wild rose, mackerel, toad, tapeworm, putrefactive bacteria, baobab, cabbage, cactus, penicillium, yeast.
(Answer: producers - oak, wild rose, baobab, cabbage, cactus; consumers - bear, bull, squirrel, mackerel, toad, tapeworm; decomposers - boletus, putrefactive bacteria, penicillium, yeast.)
9. In an ecosystem, the main flow of matter and energy is transferred:
(Answer: V . )
10. Explain why the existence of life on Earth would be impossible without bacteria and fungi.
(Answer: fungi and bacteria are the main decomposers in the Earth's ecosystems. They decompose dead organic matter into inorganic matter, which is then consumed by green plants. Thus, fungi and bacteria support the cycle of elements in nature, and hence life itself.)
11. Explain why it is economically profitable to keep herbivorous fish in cooling ponds at thermal power plants.
(Answer: these ponds are heavily overgrown with aquatic vegetation, as a result, the water in them stagnates, which disrupts the cooling of the waste water. Fish eat all vegetation and grow well.)
12. Name the organisms that are producers, but do not belong to the Plant Kingdom.
(Answer: photosynthetic flagellate protozoa (for example, green euglena), chemosynthetic bacteria, cyanobacteria.
13. Organisms that are not absolutely necessary in maintaining a closed cycle of biogenic elements (nitrogen, carbon, oxygen, etc.):
a) producers;
b) consumers;
c) reducers.
The concept of ecosystems. The doctrine of biogeocenoses
Communities of organisms are connected with the inorganic environment by the closest material and energy ties. Plants can only exist due to the constant supply of carbon dioxide, water, oxygen, and mineral salts. Heterotrophs live off autotrophs, but need inorganic compounds such as oxygen and water. In any particular habitat, the reserves of inorganic compounds necessary to maintain the vital activity of the organisms inhabiting it would suffice for a short time if these reserves were not renewed. The return of biogenic elements to the environment occurs both during the life of organisms (as a result of respiration, excretion, defecation) and after their death, as a result of the decomposition of corpses and plant residues. Thus, the community forms a certain system with the inorganic medium, in which the flow of atoms, caused by the vital activity of organisms, tends to be closed in a cycle.
The concept of ecosystems. Any set of organisms and inorganic components in which the circulation of substances can take place is called ecosystem. The term was proposed in 1935 by the English ecologist A. Tansley, who emphasized that with this approach, inorganic and organic factors act as equal components and we cannot separate organisms from their specific environment. A. Tansley considered ecosystems as the basic units of nature on the surface of the Earth, although they do not have a certain volume and can cover space of any length.
To maintain the circulation of substances in the system, it is necessary to have a stock of inorganic molecules in an assimilated form and three functionally different ecological groups of organisms: producers, consumers, and decomposers.
Producers autotrophic organisms are capable of building their bodies at the expense of inorganic compounds. Consumers - These are heterotrophic organisms that consume the organic matter of producers or other consumers and transform it into new forms. decomposers live at the expense of dead organic matter, translating it again into inorganic compounds. This classification is relative, since both consumers and producers themselves act partially as decomposers, releasing mineral metabolic products into the environment during their life.
In principle, the circulation of atoms can be maintained in the system without an intermediate link - consumers, due to the activity of two other groups. However, such ecosystems are found rather as exceptions, for example, in those areas where communities formed only from microorganisms function. The role of consumers in nature is performed mainly by animals, their activity in maintaining and accelerating the cyclic migration of atoms in ecosystems is complex and diverse.
The scale of the ecosystem in nature is extremely different. The degree of closure of the cycles of matter maintained in them is also not the same, that is, the multiple involvement of the same atoms in cycles. As separate ecosystems, one can consider, for example, a pillow of lichens on a tree trunk, and a collapsing stump with its population, and a small temporary reservoir, meadow, forest, steppe, desert, the entire ocean and, finally, the entire surface of the Earth occupied by life.
In some types of ecosystems, the removal of matter outside their boundaries is so great that their stability is maintained mainly due to the influx of the same amount of matter from outside, while the internal circulation is ineffective. These are flowing reservoirs, rivers, streams, areas on the steep slopes of mountains. Other ecosystems have a much more complete circulation of substances and are relatively autonomous (forests, meadows, steppes in upland areas, lakes, etc.). However, not a single, even the largest, ecosystem of the Earth has a completely closed cycle. The continents intensively exchange matter with the oceans, and the atmosphere plays an important role in these processes, and our entire planet receives some of the matter from outer space, and gives some to space.
In accordance with the hierarchy of communities, life on Earth is also manifested in the hierarchy of the corresponding ecosystems. Ecosystem organization of life is one of the necessary conditions for its existence. The reserves of biogenic elements, from which the bodies of living organisms are built, on the Earth as a whole and in each specific area on its surface are not unlimited. Only a system of cycles could give these reserves the property of infinity, necessary for the continuation of life. Only functionally different groups of organisms can support and carry out the cycle. Thus, the functional and ecological diversity of living beings and the organization of the flow of substances extracted from the environment into cycles are the most ancient property of life.
The doctrine of biogeocenoses. In parallel with the development of the concept of ecosystems, the doctrine of biogeocenoses is successfully developing, the author of which was Academician V.N. Sukachev (1942).
"Biogeocenosis- this is a set of homogeneous natural phenomena (atmosphere, rocks, vegetation, wildlife and the world of microorganisms, soil and hydrological conditions) over a known extent of the earth's surface, which have their own specifics of the interaction of these terms of its components and a certain type of exchange of substances and energy between themselves and others natural phenomena and representing an internally contradictory unity, which is in constant motion, development ”(V. N. Sukachev, 1964).
“Ecosystem” and “biogeocenosis” are essentially close concepts, but if the first of them is applicable to refer to systems that provide cycles of any rank, then “biogeocenosis” is a territorial concept, referring to such land areas that are occupied by certain units of vegetation cover - phytocenoses . The science of biogeocenoses - biogeocenology - grew out of geobotany and is aimed at studying the functioning of ecosystems in specific landscape conditions, depending on the properties of the soil, relief, the nature of the environment of the biogeocenosis and its primary components - rocks, animals, plants, microorganisms.
In the biogeocenosis, V.N. Sukachev distinguished two blocks: ecotope - set of conditions of the abiotic environment and biocenosis is the totality of all living organisms.
Ecotop often considered as an abiotic environment, not transformed by plants (the primary complex of factors of the physical and geographical environment), but biotope- as a set of elements of the abiotic environment, modified by the environment-forming activity of living organisms. In the internal composition of the biogeocenosis, such structural and functional units as parcels are distinguished (the term was proposed by N.V. Dylis). Biogeocenotic parcels include plants, animal population, microorganisms, dead organic matter, soil and atmosphere throughout the entire vertical thickness of the biogeocenosis, creating its internal mosaic. Biogeocenotic parcels differ visually in terms of vegetation: height and density of layers, species composition, life status and age range of populations of dominant species. Sometimes they are well demarcated by the composition, structure, and thickness of the forest litter. They are usually named after the plants that dominate in different tiers. For example, in a hairy-sedge oak-spruce forest, one can distinguish such parcels as spruce-hairy-sedge, spruce-oxalis, large-fern in the windows of the tree layer, oak-sweet, oak-aspen-lungwort, birch-spruce-death cover, aspen-snotweed, etc.
Each parcel has its own phytoclimate. In spring, snow stays longer in shady spruce parcels than in areas under deciduous trees or in windows. Therefore, active life in parcels in spring occurs at different times, and detritus processing also proceeds at different rates. The boundaries between parcels can be either relatively clear or blurry. The relationship is carried out both as a result of the conditioning of environmental conditions (heat exchange, changes in lighting, redistribution of precipitation, etc.), and as a result of material and energy exchange. There is a scattering of plant litter, the transfer of pollen, spores, seeds and fruits by air currents and animals, the movement of animals, the surface runoff of precipitation and melt water, moving mineral and organic substances. All this supports biogeocenosis as a single, internally heterogeneous ecosystem.
The role of different parcels in the structure and functioning of biogeocenoses is not the same; the largest parcels, occupying large spaces and volumes, are called basic. There are few of them. They determine the appearance and structure of biogeocenosis. Small parcels are called complementary. Their number is always greater. Some parcels are more stable, others are subject to significant and rapid changes. As plants mature and age, parcels can greatly change the composition and structure, rhythms of seasonal development, and participate in the cycle of substances in different ways.
Rice. 145. Windows of renewal of the main species in the forest biogeocenosis (according to O. V. Smirnova, 1998)
The mosaic nature of forest biogeocenoses and the emergence of new parcels are often associated with the formation of windows in the forests, i.e., the violation of the tree layer due to the fall of old trees, outbreaks of mass pests - insects, fungal attack, and the activity of large ungulates. The creation of such a mosaic is absolutely necessary for the sustainable existence of the forest and the renewal of the dominant tree species, the undergrowth of which often cannot develop under the parent crowns, since it requires different lighting conditions and mineral nutrition. Resume windows for different breeds should have sufficient spatial extent (Fig. 145). In Eastern European broad-leaved forests, not a single species can proceed to fruiting in windows commensurate with the crown projections of one or two mature trees. Even the most shade-tolerant of them - beeches, maples - require illuminated parcels of 400–600 m 2, and full ontogeny of light-loving species - oak, ash, aspen can be completed only in large windows of at least 1500–2000 m 2.
Based on a detailed study of the structure and functioning of biogeocenoses in ecology, a the concept of mosaic-cyclic organization of ecosystems. From this point of view, the sustainable existence of many species in an ecosystem is achieved through natural habitat disturbances that constantly occur in it, allowing new generations to occupy the newly vacated space.
Biogeocenology considers the Earth's surface as a network of neighboring biogeocenoses, interconnected through the migration of substances, but nevertheless, albeit to varying degrees, autonomous and specific in their cycles. The specific properties of the site occupied by biogeocenosis give it originality, distinguishing it from others, initial by type.
Both concepts - ecosystems and biogeocenoses - complement and enrich each other, allowing us to consider the functional relationships of communities and their inorganic environment in different aspects and from different points of view.
