Biogeocenoses as important biological processes. §44. The main properties of biogeocenoses. Change of biogeocenoses

In any confined space usually inhabited by many species, between which permanent and complex relationships have been established. In other words, various types of organisms that exist in a certain space with a complex of physico-chemical conditions form complex system more or less long lasting in nature. In ecology, they are called ecosystems (A. Tensley, 1935) or biogeocenoses (V. N. Sukachev, 1940).

Biogeocenosis is a historical community of organisms different types (biocenosis), closely connected with each other and with the surrounding inanimate nature (biotope) metabolism and energy (Fig. 1 and 2).

Fig.1. The main components of the ecosystem. The light arrows show the flow of energy, the black arrows show the cycle nutrients

Rice. 2.Energy flows from the Sun through green plants to animals

Biogeocenosis is spatially limited and relatively homogeneous both in terms of the species composition of living beings and in terms of a complex of abiotic factors.

The constant supply of solar energy determines its existence as an integral system.

The leading active role in the processes of interaction between the components of the ecosystem belongs to living beings, i.e., biocenosis. Functionally, they are divided into three groups - producers, consumers and decomposers, which are in close interaction with each other and with inanimate nature (biotope) and united by food ties.

Producers constitute a group of autotrophic organisms that, consuming minerals from the biotope and energy sunlight, create primary organic matter. This group includes plants and some bacteria.

decomposers- these are organisms that decompose the remains of dying organisms, break down organic substances into inorganic ones and thereby return mineral substances that were "withdrawn" by producers to the biotope. For example, these are some types of bacteria and unicellular fungi.

Rice. 3.A small freshwater pond as an example of an ecosystem: 1 - basic mineral and organic compounds; 2 - plants with roots, and phytoplankton - producers; 3 - zooplankton and benthic forms (herbivores), primary consumers; 4 - carnivores, secondary consumers; 5 - secondary carnivores, tertiary consumers; 6 - bacteria and fungi, destroyers

This is how the circulation of substances occurs in the biogeocenosis (see Fig. 1), the constancy of which is the key to the long existence of the ecosystem, despite the limited supply of minerals in it.

Rice. 4.Scheme of food relations between organisms of meadow biogeocenosis

Each natural natural biogeocenosis is a system that has developed over many thousands and millions of years. All its elements are "lapped" to each other, which ensures resistance to changes. environment. However, the "strength" of ecological systems is not unlimited: abrupt and profound changes natural conditions, a decrease in the number of certain species of organisms (for example, as a result of an unlimited catch of commercial species) can upset the balance in the biogeocenosis and lead to its destruction.

On the territories of our planet used by man for agricultural purposes (sowing, planting cultivated plants), special communities of organisms are formed - agrobiocenoses. Unlike natural biogeocenoses, producers (plants) here are represented by one type of culture grown by man, as well as a certain number of weed species. The vegetation cover determines the species composition of herbivorous animals (insects, birds, rodents, etc.) that are able to feed on these plants and stay in the conditions of their cultivation. These conditions determine the existence of other species of plants, animals, fungi and microorganisms.

Agrobiocenosis depends on human activities (mechanical tillage, fertilization, pesticide treatment, irrigation, etc.) and is characterized by poor stability - without human intervention, it will collapse very quickly. This is partly due to the fact that cultivated plants are much more whimsical than wild ones, and will not withstand competition with them.

Of particular interest are another kind of anthropogenic ecosystems - urban biogeocenoses, such as parks. As well as for agrobiocenoses, the main environmental factors they are anthropogenic. A person determines the species composition of plants in plantings, constantly carries out their processing and care. Changes are most pronounced in cities external environment- increase in temperature (by 2–7 °C), features of the atmospheric and soil composition, a peculiar mode of illumination, humidity, and wind action. All this forms urban biogeocenoses.

The concept of biogeocenosis first appeared in the works of the Soviet biologist V. Sukachev in 1942. This term today means a system located in a certain part of space and including all living organisms living in this area, and a combination of factors inanimate nature affecting their existence. Parts of animate and inanimate nature are connected by a constant cycle of energy metabolism and metabolism, thanks to which the system acquires the ability to self-regulate.

One of the main distinguishing features of the existing biogeocenosis is its homogeneity in terms of the species of living beings and the abiotic factors present. The energy component, as a rule, is based on the receipt, its absorption and transformation.

Components of biogeocenosis

The decisive role in the existence of biogeocenosis belongs to living organisms, which in biology are divided into three main types:

— producers- living organisms that consume nutrients for their life activity directly from inanimate nature. These include most plant species and some bacteria;

With the help of these three components, the cycle of nutrients and energy of biogeocenosis is carried out. Producers absorb inorganic substances from the soil and solar energy, thanks to which they have the opportunity to build their cells and increase the volume of organic substances. Consumers actively eat producers and each other, including the organic substances produced by them in their biochemical and energy metabolism. The function of decomposers is to decompose organic matter remaining after the death of living organisms and thereby return nutritious minerals back to the soil.

The structure of biogeocenoses

Various biogeocenoses are formed under different conditions according to the degree of daylight, climatic conditions, soil composition, etc. It is not surprising that their species composition, the amount of biomass and the number of interspecific relationships are completely different in different ecosystems. Scientists consider the spatial, species, trophic and ecological structuring of biogeocenosis.


species structure- this is the diversity of species included in the biogeocenosis, and the ratio of the biomass or the number of all its constituent populations. Biogeocenoses can be rich in species composition if the biotope conditions are favorable for most species of living beings, or poor - living in not very favorable conditions (in deserts, tundra, etc.).

Spatial structure is determined primarily by the plant components of the biogeocenosis, which are most often structured vertically. Each of the plant layers has its own composition of plant and animal inhabitants, as well as insects and microorganisms.

ecological structure biogeocenosis is a set environmental groups living beings, the ratio of which varies depending on the prevailing abiotic factors.

Trophic structure- this is the number and composition of food chains formed by the totality of species of living beings living in the biogeocenosis.


As a rule, biogeocenosis develops over many hundreds, and sometimes thousands of years. From time to time, new components are introduced into its composition, which either take their place in its structures, or are gradually removed due to existing system self-regulation.

The concept of biogeocenosis was introduced into scientific use in 1942 by Academician Vladimir Nikolaevich Sukachev (1880-1967). According to his ideas, biogeocenosis is a set over a known extent earth's surface homogeneous natural phenomena ( , rock, flora, fauna and the world of microorganisms, soil and hydrological conditions), which has the specifics of the interaction of these constituent components and a certain type of exchange of matter and energy between themselves and other natural phenomena.

Biogeocenosis - an open bio-inert (i.e., consisting of living and non-living matter) system, the main external source for which is energy solar radiation. This system consists of two main blocks. The first block, ecotope, combines all factors of inanimate nature (abiotic environment). This inert part of the system is formed by an aerotop - a set of factors of the aboveground environment (heat, light, humidity, etc.) and an edaphotop - a set of physical and chemical properties soil environment. The second block, biocenosis, is a collection of all types of organisms. AT functionally biocenosis consists of autotrophs - organisms capable of using energy sun rays to create organic matter from inorganic, and heterotrophs - organisms that use organic matter created by autotrophs as a source of matter and energy.

A very important functional group is diazotrophs - prokaryotic nitrogen-fixing organisms. They determine the sufficient autonomy of most natural biogeocenoses in providing plants with available nitrogen compounds. This includes both autotrophic and heterotrophic bacteria, cyanobacteria and actinomycetes.

In the literature, especially foreign literature, instead of the term biogeocenosis or along with it, they use the concept proposed by the English geobotanist Arthur Tansley and the German hydrobiologist Voltereck. The ecosystem and biogeocenosis are essentially identical representations. However, the ecosystem is understood as a dimensionless formation. As an ecosystem, for example, they consider a rotting stump in a forest, individual trees, a forest phytocenosis in which these trees and a stump are located; forest area, which includes a number of phytocenoses; the forest zone, etc. Biogeocenosis is always understood as a chorological (topographic) unit that has certain boundaries outlined by the boundaries of its constituent phytocenosis. “Biogeocenosis is an ecosystem within the boundaries of a phytocenosis” - an aphorism of one of the like-minded people V. N. Sukachev. Ecosystem is a broader concept than biogeocenosis. An ecosystem can be not only a biogeocenosis, but also bio-inert systems dependent on biogeocenoses, in which organisms are represented only by heterotrophs, as well as such human-made bio-inert systems as a granary, an aquarium, a ship with organisms inhabiting it, etc.

Consortia as structural and functional units of biocenoses

The idea of ​​consortia in the modern sense of them as structural and functional biocenoses was formed in the early 1950s. domestic scientists - zoologist Vladimir Nikolaevich Beklemishev and geobotanist Leonty Grigoryevich Ramensky.

Consortium populations of some plant species may consist of many tens or even hundreds of plant, animal, fungal, and prokaryotic species. More than 900 species of organisms are known in the composition of the first three concentrations in the consortium of warty birch (Betula verrucosa).

General characteristics of natural communities and their structure

Basic unit natural communities is a biocenosis. Biocenosis - a community of plants, animals, fungi and other organisms inhabiting the same territory, mutually connected in the food chain and exerting a certain influence on each other.

Biocenosis consists of a plant community and organisms that accompany this community.

A plant community is a set of plants growing in a given area that form the basis of a particular biocenosis.

The plant community is formed by autotrophic photosynthetic organisms, which are a source of nutrition for heterotrophic organisms (phytophages and detritophages).

Based on the ecological role, the organisms that form the biocenosis are divided into producers, consumers, decomposers and detritophages of various orders.

The concept of "biogeocenosis" is closely related to the concept of "biocenosis". The existence of an organism is impossible without its habitat, therefore, the composition of the flora and fauna of a given community of organisms big influence renders the substrate (its composition), climate, relief features of a given particular area, etc. All this makes it necessary to introduce the concept of "biogeocenosis".

Biogeocenosis is a stable self-regulating ecological system located in a given specific territory, in which organic components are closely and inextricably linked with inorganic ones.

Biogeocenoses are diverse, they are interconnected in a certain way, they can be stable for a long time, but under the influence of changing external conditions or as a result of human activity, they can change, die, be replaced by other communities of organisms.

Biogeocenosis consists of two constituent parts: biota and biotope.

Biotope - a space relatively homogeneous in terms of abiotic factors, occupied by a biogeocenosis (biota) (sometimes a biotope is understood as the habitat of a species or its individual population).

Biota - a set of various organisms that inhabit a given territory and are part of a given biogeocenosis. It is formed by two groups of organisms that differ in the way they feed - autotrophs and heterotrophs.

Autotrophic organisms (autotrophs) are those organisms that are able to absorb energy coming from outside in the form of separate portions (quanta) with the help of chlorophyll or other substances, while these organisms synthesize organic substances from inorganic compounds.

Among autotrophs, phototrophs and chemotrophs are distinguished: the first include plants, the second - chemosynthetic bacteria, such as Serobacter.

Heterotrophic organisms (heterotrophs) are organisms that feed on ready-made organic substances, while the latter are both a source of energy (it is released during their oxidation) and a source of chemical compounds for the synthesis of their own organic substances.

The essence of the concepts of ecosystem, biogeocenosis

In biology, three concepts that are close in meaning are used:

Biogeocenosis(Greek "bios" - life, "geo" - earth, "cenos" - general) - structural and functional elementary unit of the biosphere. It is a sustainable self-regulating ecological system in which organic components (animals, plants) are inextricably linked with inorganic ones (water, soil). For example, a lake, a pine forest, a mountain valley (Fig. 8.1). The doctrine of biogeocenosis was developed by academician Vladimir Sukachev (Fig. 8.10) in 1940.

Biogeocenosis- biocenosis, which is considered in interaction with abiotic factors that affect it and, in turn, change under its influence. Biocenosis has a synonym community, he is also close to the concept ecosystem.

Ecosystem- a group of organisms of different species, interconnected by the circulation of substances.

Each biogeocenosis is an ecosystem, but not every ecosystem is a biogeocenosis. To characterize biogeocenosis, two close concepts are used: biotope and ecotope (factors of inanimate nature: climate, soil). Biotope- this is the territory occupied by biogeocenosis. Ecotop- this is a biotope that is affected by organisms from other biogeocenoses. An ecotope also consists of climate (climatotope) in all its diverse manifestations and the geological environment (soils and soils), called edaphotop. edaphotop- this is where the biocenosis draws its livelihood and where it releases waste products.

Properties of biogeocenosis:

natural, historically developed system;

a system capable of self-regulation and maintaining its composition at a certain constant level;

the circulation of substances is characteristic;

an open system for the input and output of energy, the main source of which is the Sun.

Fig. 8.1 Tropical forest biocenosis

Fig. 8.1a Pond biocenosis

The main indicators of biogeocenosis:

species composition- the number of species living in the biogeocenosis.

Species diversity- the number of species living in biogeocenosis per unit area or volume.

In most cases, the species composition and species diversity do not quantitatively coincide, and the species diversity directly depends on the area under study.

Biomass- the number of organisms of biogeocenosis, expressed in units of mass. Most often, biomass is divided into (Fig. 8.2):

producer biomass;

consumer biomass;

decomposer biomass

Fig. 8.2 The concept of consumers and producers

Mechanisms of stability of biogeocenoses

One of the properties of biogeocenoses is the ability to self-regulate, that is, to maintain their composition at a certain stable level. This is achieved through a stable circulation of matter and energy. The stability of the cycle itself is provided by several mechanisms:

sufficiency of living space, that is, such a volume or area that provides one organism with all the resources it needs.

species richness. The richer it is, the more stable the food chain and, consequently, the circulation of substances.

a variety of species interactions that also maintain the strength of trophic relationships.

environment-forming properties of species, that is, the participation of species in the synthesis or oxidation of substances.

direction of anthropogenic impact.

Thus, the mechanisms ensure the existence of unchanging biogeocenoses, which are called stable. A stable biogeocenosis that has existed for a long time is called climax. There are few stable biogeocenoses in nature, more often there are stable - changing biogeocenoses, but capable, thanks to self-regulation, to return to their original, initial position.

Biogeocenosis- a system that includes a society of living organisms and a closely related set of abiotic causes of the environment within the boundaries of one locality, interconnected by the circulation of substances and the flow of energy. It is a stable self-regulating ecological system in which organic components (animals, plants) are inextricably linked with inorganic (water, soil).

Examples: pine forest, mountain plain.

The doctrine of biogeocenosis was created by Vladimir Sukachev in 1940. In foreign literature - little used. Previously, it was also widely used in German scientific literature.

Biogeocenosis and ecosystem

A concept that is close in meaning is an ecosystem - a system consisting of interconnected communities of organisms. various kinds and their habitats. Ecosystem is a broader concept that refers to any similar system. Biogeocenosis, in turn, is a class of ecosystems, an ecosystem that occupies a certain area of ​​\u200b\u200bland and includes the main components of the environment - soil, subsoil, vegetation cover, and the surface layer of the atmosphere. Aquatic ecosystems are not biogeocenoses, most of artificial ecosystems. Therefore, every biogeocenosis is an ecosystem, but not every ecosystem is a biogeocenosis. For the property of biogeocenosis, two close concepts are used: biotope and ecotope(causes of inanimate nature: climate, soil). A biotope is a set of abiotic causes within the boundaries of the area occupied by the biogeocenosis. An ecotope is a biotope that is affected by organisms from other biogeocenoses.

Characteristics of biogeocenosis

The main indicator of biogeocenosis

Almost always, the species composition and species abundance do not quantitatively coincide, and the species abundance directly depends on the area under study.

Spatial properties

The transition of the 1st biogeocenosis to another in space or time is accompanied by a change in the states and parameters of all its components and, as it follows, a change in the nature of biogeocenotic metabolism. The boundaries of biogeocenosis can be traced on many of its components, but more often they coincide with the boundaries of plant communities (phytocenoses). The thickness of the biogeocenosis is not homogeneous either in the composition and state of its components, or in terms of the conditions and results of their biogeocenotic activity. It is differentiated into aboveground, underground, underwater parts, which in turn are divided into simple vertical structures - bio-geohorizons, very specific in composition, structure and state of living and inert components. To denote horizontal heterogeneity, or mosaicity of biogeocenosis, the concept of biogeocenotic parcels has been introduced. Like biogeocenosis as a whole, this concept is all-encompassing, because the composition of the parcel, as participants in the metabolism and energy, includes vegetation, animals, the smallest organisms, soil, atmosphere.

Mechanisms of resistance of biogeocenoses

One of the parameters of biogeocenoses is the ability to self-regulate, in other words, to maintain their own composition at a certain measured level. This is achieved through a stable circulation of matter and energy. The stability of the cycle itself is provided by several mechanisms:

Consequently, the mechanisms ensure the existence of unchanging biogeocenoses, which are called measured. Measured biogeocenosis, available long time, is called climax. Measured biogeocenoses in nature are not enough, more often there are stable - changing biogeocenoses, however, capable, thanks to self-regulation, to return to their original, initial position.

Forms of existing relationships between organisms in biogeocenoses

The joint life of organisms in biogeocenoses proceeds in the form of 6 main types of relationships:

1. mutually beneficial

2. useful neutral (commensalism)

3. beneficial

4. mutually harmful

5. Neutral harmful

6. Neutral (neutralism)