Which scientist introduced the concept of biogeocenosis. How does biogeocenosis differ from an ecosystem
Environments within the same territory, interconnected by the circulation of substances and the flow of energy (natural ecosystem). It is a sustainable self-regulating ecological system in which organic components (animals, plants) are inextricably linked with inorganic ones (water, soil). Examples: pine forest, mountain valley. The doctrine of biogeocenosis was developed by Vladimir Sukachev in 1942. IN foreign literature- unused. Previously, it was also widely used in German scientific literature.
Biogeocenosis and ecosystem
Properties
Main characteristics
- 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:
- producer biomass
- consumer biomass
- decomposer biomass
- Productivity
- Sustainability
- Ability to self-regulate
Spatial characteristics
The transition of one biogeocenosis to another in space or time is accompanied by a change in the states and properties of all its components and, consequently, 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 elementary vertical structures - bio-geohorizons, very specific in composition, structure and state of living and inert components. The concept of biogeocenotic parcels has been introduced to denote horizontal heterogeneity, or mosaicity of biogeocenosis. Like biogeocenosis as a whole, this concept is complex, since the composition of the parcel as participants in the metabolism and energy includes vegetation, animals, microorganisms, soil, atmosphere.
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.
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:
Literature
- Razumovsky S. M. Patterns of the dynamics of biogeocenoses: Fav. works. - M.: KMK Scientific Press, 1999.
- Tsvetkov V.F. Forest biogeocenosis / V. F. Tsvetkov. 2nd ed. Arkhangelsk, 2003. 267 p.
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An excerpt characterizing Biogeocenosis
Natasha knew that she had to leave, but she could not do it: something was squeezing her throat, and she looked impolitely, directly, with open eyes at Prince Andrei."Now? This minute!… No, it can't be!” she thought.
He looked at her again, and this look convinced her that she had not been mistaken. - Yes, now, this very minute her fate was being decided.
“Come, Natasha, I will call you,” said the countess in a whisper.
Natasha looked with frightened, pleading eyes at Prince Andrei and at her mother, and went out.
“I have come, Countess, to ask for the hand of your daughter,” said Prince Andrei. The countess's face flushed, but she said nothing.
“Your suggestion…” the Countess began sedately. He remained silent, looking into her eyes. - Your offer ... (she was embarrassed) we are pleased, and ... I accept your offer, I'm glad. And my husband ... I hope ... but it will depend on her ...
- I will tell her when I have your consent ... do you give it to me? - said Prince Andrew.
“Yes,” said the Countess, and held out her hand to him, and with a mixture of aloofness and tenderness pressed her lips to his forehead as he leaned over her hand. She wanted to love him like a son; but she felt that he was a stranger and a terrible person for her. “I'm sure my husband will agree,” said the countess, “but your father ...
- My father, to whom I informed my plans, made it an indispensable condition for consent that the wedding should not be before a year. And this is what I wanted to tell you, - said Prince Andrei.
- It is true that Natasha is still young, but so long.
“It could not be otherwise,” Prince Andrei said with a sigh.
“I will send it to you,” said the countess, and left the room.
“Lord, have mercy on us,” she repeated, looking for her daughter. Sonya said that Natasha was in the bedroom. Natasha sat on her bed, pale, with dry eyes, looked at the icons and, quickly making the sign of the cross, whispered something. Seeing her mother, she jumped up and rushed to her.
- What? Mom?… What?
- Go, go to him. He asks for your hand, - said the countess coldly, as it seemed to Natasha ... - Go ... go, - the mother said with sadness and reproach after her daughter, who was running away, and sighed heavily.
Natasha did not remember how she entered the living room. When she entered the door and saw him, she stopped. “Is this stranger really become my everything now?” she asked herself and instantly answered: “Yes, everything: he alone is now dearer to me than everything in the world.” Prince Andrei went up to her, lowering his eyes.
“I fell in love with you from the moment I saw you. Can I hope?
He looked at her, and the earnest passion of her countenance struck him. Her face said: “Why ask? Why doubt that which is impossible not to know? Why talk when you can’t express what you feel in words.
She approached him and stopped. He took her hand and kissed it.
– Do you love me?
“Yes, yes,” Natasha said as if with annoyance, sighed loudly, another time, more and more often, and sobbed.
– About what? What's wrong with you?
“Oh, I’m so happy,” she answered, smiled through her tears, leaned closer to him, thought for a second, as if asking herself if it was possible, and kissed him.
Prince Andrei held her hands, looked into her eyes, and did not find in his soul the former love for her. Something suddenly turned in his soul: there was no former poetic and mysterious charm of desire, but there was pity for her feminine and childish weakness, there was fear of her devotion and gullibility, a heavy and at the same time joyful consciousness of the duty that forever connected him with her. The real feeling, although it was not as light and poetic as the former, was more serious and stronger.
“Did maman tell you that it couldn’t be before a year?” - said Prince Andrei, continuing to look into her eyes. “Is it really me, that child girl (everyone said so about me) thought Natasha, is it possible that from now on I am a wife, equal to this stranger, dear, smart person respected even by my father. Is that really true! Is it really true that now it is no longer possible to joke with life, now I am big, now responsibility for all my deeds and words lies on me? Yes, what did he ask me?
“No,” she answered, but she did not understand what he was asking.
“Forgive me,” said Prince Andrei, “but you are so young, and I have already experienced so much life. I'm scared for you. You don't know yourself.
Natasha listened with concentrated attention, trying to understand the meaning of his words, but did not understand.
“No matter how hard this year will be for me, postponing my happiness,” continued Prince Andrei, “during this period you will believe yourself. I ask you to make my happiness in a year; but you are free: our engagement will remain a secret, and if you are convinced that you do not love me, or would love ... - said Prince Andrei with an unnatural smile.
Why are you saying this? Natasha interrupted him. “You know that from the very day you first came to Otradnoye, I fell in love with you,” she said, firmly convinced that she was telling the truth.
- In a year you will recognize yourself ...
- A whole year! - Natasha suddenly said, now only realizing that the wedding was postponed for a year. - Why is it a year? Why a year? ... - Prince Andrei began to explain to her the reasons for this delay. Natasha didn't listen to him.
- And it can not be otherwise? she asked. Prince Andrei did not answer, but his face expressed the impossibility of changing this decision.
- It's horrible! No, it's terrible, terrible! Natasha suddenly spoke up and sobbed again. “I’ll die waiting for a year: it’s impossible, it’s terrible. - She looked into the face of her fiancé and saw on him an expression of compassion and bewilderment.
“No, no, I’ll do everything,” she said, suddenly stopping her tears, “I’m so happy!” The father and mother entered the room and blessed the bride and groom.
All communities of plants, animals, microorganisms, fungi that are in the closest connection with each other, creating an inseparable system of interacting organisms and their populations - biocenosis, which is also called community.
Producers in the forest are trees, shrubs, herbs, mosses.
Consumers - animals, birds, insects.
Reducers - ground.
Producers in the pond - floating plants, algae, blue-green.
Consumers - insects, amphibians, crustaceans, herbivorous and predatory fish.
Decomposers are water forms of fungi and plants.
An example of an ecosystem is a deciduous forest. Deciduous forests include beeches, oaks, hornbeams, lindens, maples, aspens and other trees whose foliage falls in autumn. Several tiers of plants stand out in the forest: high and low woody, shrubs, grasses and moss ground cover. The plants of the upper tiers are more photophilous and are better adapted to fluctuations in temperature and humidity than the plants of the lower tiers. Shrubs, grasses and mosses in the forest are shade-tolerant; in summer they exist in the twilight, which is formed after the trees have fully unfolded their leaves. On the surface of the soil lies a litter consisting of semi-decomposed remains, fallen leaves, twigs of trees and shrubs, and dead grasses.
The fauna of deciduous forests is rich. There are many burrowing rodents, digging insectivores, predators. There are mammals that live in trees. Birds nest in different tiers of the forest: on the ground, in bushes, on trunks or in hollows and on tops of trees. There are many insects that feed on leaves and wood. An enormous number of invertebrates, fungi and bacteria inhabit the litter and upper soil horizons.
Properties of biogeocenoses.
Sustainability.
Resilience is the property of a community and ecosystem to withstand changes created by external influences. The ability of organisms to endure unfavorable conditions and high breeding potential ensure the maintenance of populations in an ecosystem, which guarantees its sustainability.
Self-regulation.
Biogeocenosis (on the example of an oak forest)
1. Oak forest as a natural community (biogeocenosis), characterized by integrity and sustainability
- Considered by us on the excursion, such a type of natural community as an oak forest is one of the most complex among terrestrial biogeocenoses. Well, firstly, what is biogeocenosis? Biogeocenosis is a complex of interconnected species (populations of different species) living in a certain area with more or less uniform conditions of existence. This definition will be needed for later use. Oak forest is a perfect and stable ecological system capable of existing for centuries under constant external conditions. The biogeocenosis of oak forests consists of more than a hundred species of plants and several thousand species of animals. It is clear that with such a variety of species inhabiting the oak forest, it will be difficult to shake the stability of this biogeocenosis by exterminating one or more species of plants or animals. It is difficult, because as a result of the long coexistence of plant and animal species from disparate species, they became a single and perfect biogeocenosis - an oak forest, which, as mentioned above, is capable of existing for centuries under unchanged external conditions.
2. The main components of biogeocenosis and the relationship between them; Plants are the main link in an ecosystem.
- The vast majority of biogeocenosis is based on green plants, which, as you know, are the producer of organic matter (producers). And since in the biogeocenosis there are necessarily herbivorous and carnivorous animals - consumers of living organic matter (consumers) and, finally, destroyers of organic residues - mainly microorganisms that bring the breakdown of organic substances to simple mineral compounds (decomposers), it is not difficult to guess why plants are the main link in the ecosystem. But because in the biogeocenosis everyone consumes organic matter, or compounds formed after the decay of organic matter, and it is clear that if plants, the main source of organic matter, disappear, then life in the biogeocenosis will practically disappear.
3. Circulation of substances in biogeocenosis. Significance in the cycle of plants using solar energy
- The circulation of substances in biogeocenosis is a necessary condition for the existence of life. It arose in the process of the formation of life and became more complicated in the course of the evolution of living nature. On the other hand, in order for the circulation of substances to be possible in the biogeocenosis, it is necessary to have organisms in the ecosystem that create organic substances from inorganic ones and convert the energy of solar radiation, as well as organisms that use these organic substances and again turn them into inorganic compounds. All organisms are divided into two groups according to the method of nutrition - autotrophs and heterotrophs. Autotrophs (mainly plants) use inorganic compounds to synthesize organic substances. environment. Heterotrophs (animals, humans, fungi, bacteria) feed on ready-made organic substances synthesized by autotrophs. Therefore, heterotrophs depend on autotrophs. In any biogeocenosis, all reserves of inorganic compounds would very soon run out if they were not renewed in the course of the life of organisms. As a result of respiration, decomposition of animal corpses and plant residues, organic substances turn into inorganic compounds, which return back to the natural environment and can again be used by autotrophs. Thus, in the biogeocenosis, as a result of the vital activity of organisms, there is a continuous flow of atoms from inanimate nature live and back, closing in a cycle. For the circulation of substances, an influx of energy from the outside is necessary. The source of energy is the Sun. The movement of matter caused by the activity of organisms occurs cyclically, it can be used repeatedly, while the flow of energy in this process is unidirectional. The radiation energy of the Sun in the biogeocenosis is converted into various forms: into the energy of chemical bonds, into mechanical and, finally, into internal. From all that has been said, it is clear that the circulation of substances in biogeocenosis is a necessary condition for the existence of life and plants (autotrophs) in it the most important link.
4. Diversity of species in the biogeocenosis, their adaptability to living together.
- A characteristic feature of the oak forest is the species diversity of vegetation. As mentioned above, the biogeocenosis of oak forests consists of more than a hundred plant species and several thousand animal species. Between plants there is an increased competition for the basic living conditions: space, light, water with minerals dissolved in it. As a result of long-term natural selection, oak forest plants have developed adaptations that allow different species to exist together. This is clearly manifested in the layering characteristic of oak forests. The upper tier forms the most light-loving tree species: oak, ash, linden. Below are the less light-loving trees accompanying them: maple, apple, pear, etc. Even lower is the undergrowth layer formed by various shrubs: hazel, euonymus, buckthorn, viburnum, etc. Finally, a layer of herbaceous plants grows on the soil. The lower the tier, the more shade-tolerant the plants forming it. Layering is also expressed in the location of root systems. The trees of the upper tiers have the deepest root system and can use water and minerals from the deep layers of the soil.
5. Food connections, ecological pyramid.
6. Populations of plants and animals; factors causing changes in numbers; self-regulation in biogeocenosis.
7. Changes in biogeocenosis in spring: in the life of plants and animals.
8. Possible destinations biogeocenosis changes.
- Any biogeocenosis develops and evolves. The leading role in the process of changing terrestrial biogeocenoses belongs to plants, but their activity is inseparable from the activity of the other components of the system, and the biogeocenosis always lives and changes as a whole. The change goes in certain directions, and the duration of the existence of various biogeocenoses is very different. An example of a change in an insufficiently balanced system is the overgrowth of a reservoir. Due to the lack of oxygen in the bottom water layers, part of the organic matter remains unoxidized and is not used in the further circulation. In the coastal zone, the remains of aquatic vegetation accumulate, forming peaty deposits. The pond is shrinking. Coastal aquatic vegetation spreads to the center of the reservoir, peat deposits are formed. The lake gradually turns into a swamp. The surrounding terrestrial vegetation is gradually advancing on the site of the former reservoir. Depending on local conditions, a sedge meadow, a forest, or another type of biogeocenosis may appear here. Oak forest can also turn into a different type of biogeocenosis. For example, after cutting down trees, it can turn into a meadow, a field (agrocenosis) or something else.
9. Influence of human activity on biogeocenosis; measures to be taken to protect it.
- Man has recently become very active in influencing the life of biogeocenosis. The economic activity of people is a powerful factor in the transformation of nature. As a result of this activity, peculiar biogeocenoses are formed. These include, for example, agrocenoses, which are artificial biogeocenoses resulting from agricultural economic activity person. Examples are artificially created meadows, fields, pastures. Artificial biogeocenoses created by man require tireless attention and active intervention in their life. Of course, there are many similarities and differences in artificial and natural biogeocenoses, but we will not dwell on this. A person also influences the life of natural biogeocenoses, but, of course, not as much as on agrocenoses. Forest areas created for planting young trees, as well as for limiting hunting, can serve as an example. Nature reserves and National parks created to protect certain species of plants and animals. Mass societies are also being created that promote the preservation and protection of the environment, such as the "green" society, etc.
10. Conclusion: using the example of an excursion walk through a natural biogeocenosis - an oak forest, they found out and disassembled why the oak forest is integral and stable, what are the main components of a biogeocenosis, what is their role and what connections exist between them, they also disassembled why the circulation of substances in a biogeocenosis is a necessary condition for existence life, also found out how the whole variety of species living in an oak forest does not conflict with each other, allowing each other to develop normally, sorted out what nutritional relationships exist in an oak forest and sorted out such a concept as an ecological pyramid, substantiated the factors causing a change in numbers and such a phenomenon as self-regulation, found out what changes occur in the biogeocenosis in the spring and sorted out the possible directions of evolution of the biogeocenosis, as well as how a person affects life in biogeocenoses. In general, on the example of oak forests, the life of biogeocenoses was completely dismantled
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.
Biogeocenosis 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 has a special specificity of interactions of these constituent components and a certain type of metabolism and energy: among 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.
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 field of knowledge about biogeocenoses is called biogeocenology. To control natural processes, one must know the patterns to which they are subject. These patterns are studied by a number of sciences: 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.
2. Definition of biogeocenosis
"Biogeocenosis- this is a section of the earth's surface on which in close interaction develop: vegetation homogeneous in composition and productivity, a homogeneous complex of animals and microorganisms, soil homogeneous in physical and chemical composition; a homogeneous gas and climatic situation is maintained, the same material and energy exchange is established between all components of the biogeocenosis "(V.N. Sukachev).
3.Component composition of biogeocenosis
Components of biogeocenosis- material bodies (components of biogeocenosis). They are divided into 2 groups:
1. Living (biotic, biocenosis)
2. Inert (abiotic substance, raw materials) - ecotope, biotope.
They include carbon dioxide, water, oxygen, etc.
Biotic components of biogeocenosis:
1.Producers
2.Consumers
3. Reducers (detritivores, destructors of organic substances).
Producers - organisms that produce (synthesize) organic substances from inorganic (green plants).
Consumers- organisms that consume ready-made organic substances. Primary consumers are herbivores. Secondary consumers are carnivores.
decomposers organisms that break down organic matter final products decay (bacteria of decay and fermentation).
In the biogeocenosis is established ecological homeostasis- dynamic balance between all components of biogeocenosis.
Occurs periodically ecological succession- regular change of communities in biogeocenosis.
There are several classifications of biogeocenoses.
I.1. Land, Freshwater, 2. Aquatic, Marine
II. By geographic area:
1. Forest, 2. Marsh, 3. Steppe, 4. Meadow, 5. Tundra, etc.
III. Lobachev in 1978 identified biogeocenoses:
1) Natural 2) Rural (agrocenoses)
3) Urban cenoses (urban, industrial)
4. Borders between biogeocenoses.
The configuration and boundaries of the biogeocenosis are determined, according to Sukachev, by the boundaries of the phytocenosis characteristic of it, 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 (1976), are sharp, especially under conditions of human intervention, but they can also be vague, as if smeared in case of interpenetration of components of neighboring biogeocenoses.
B. A Bykov (1970) distinguishes the following types of boundaries between plant communities and, therefore, between biogeocenoses
a) sharp boundaries are observed with a sharp difference in environmental conditions in adjacent cenoses or in the presence of dominants with powerful environment-forming properties;
b) mosaic boundaries, in contrast to sharp ones, are characterized by the inclusion of their individual fragments in the transitional zone of adjacent cenoses, forming a kind of complexity;
c) bordered borders - when a narrow border of a cenosis develops in the contact zone of adjacent cenoses, which differs from both of them;
d) diffuse boundaries between adjacent cenoses are characterized by a gradual spatial change in the species composition in the contact zone during the transition from one to another
The vertical boundaries of the biogeocenosis, as well as the horizontal ones, are determined by the placement of the living plant biomass of the phytocenosis in space - the upper boundary is determined by the maximum height of the aboveground plant organs - phototrophs - above the soil surface, the lower one by the maximum depth of penetration of the root system into the soil.
At the same time, in tree-shrub biogeocenoses, the vertical boundaries, as T. A. Rabotnov (1974a) writes, do not change during the growing season, while in herbal biogeocenoses (meadow, steppe, etc.) they vary by season, as occurs either an increase in herbage, or a decrease in it, or a complete alienation in hayfields and pastures. only their lower borders are not subject to seasonal changes.
Bibliography
Voronov A.G. Geobotany. Proc. Allowance for high fur boots and ped. in-comrade. Ed. 2nd. M.: Higher. school, 1973. 384 p.
Fundamentals of Forest Biogeocenology / Ed. V.N. Sukacheva and N.V. Dilisa. M.: Nauka, 1964. 574 p.
Stepanovskikh A.S. General ecology: A textbook for universities. M.: UNITI, 2001. 510 p.
Tsvetkov V.F. Forest biogeocenosis. Arkhangelsk, 2003. 2nd ed. 267 p.
Questions
1. The concept of biogeocenosis and biogeocenology.
2. Component composition of biogeocenosis.
3. The essence of biogeocenosis.
4. Properties of biocenoses: self-regulation and self-reproduction. Le Chatelier's principle.
5. Biogeocenosis and ecosystem: differences between these concepts.
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 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 (Fig. 1 and 2).
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That is why special importance has been 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.
The definition of biogeocenosis according to V.N. Sukachev (1964: 23) is considered classical - “... this is a set of homogeneous natural phenomena(atmosphere, rocks, vegetation, wildlife and the world of microorganisms, soil and hydrological conditions), which has a special specificity of interactions of these constituent components and a certain type of exchange of matter and energy: between itself and with other natural phenomena and representing an internal contradictory unity, 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 peaty soils,
- - herb meadow on a high river floodplain on floodplain soddy-gley medium loamy soil,
- - lichen larch forest on Al-Fe-humus-podzolic soils,
- - mixed broad-leaved forest 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. These patterns are studied by a number of sciences: 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
Thus, plants form relatively constant 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 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 reactions oxidation.
Microorganisms (microbes, bacteria, protozoa) important role in the decomposition of dead organic matter to mineral, i.e., 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.
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Biotope- this is an ecotope (see Fig. 5), 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, the closest to the biogenic component of the biogeocenosis is the soil, 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.
3. The essence of biogeocenosis
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Second side essence reflects mobility and versatility biogeocenosis. It can be represented by a combination of radials (R) and laterals (L). Behind these concepts lies the mobile component of biogeocenosis, i.e. bioflows.
Radials mean everything moving in the radial direction - from one tier (biogeohorizon) to another, i.e. vertically.
Laterals symbolize everything moving within the tier (biohorizon) in lateral directions - from one parcel to another, i.e. horizontally. The parameters of the radials and laterals are measured in units that reflect certain processes.
Stations create discreteness (discontinuity) for biogeocenosis, and radials and laterals create smoothness, smoothness), i.e. form a kind of continuum of the circulation of matter and energy within the tiers and parcels of the cenosis.
An example of "threads". In ecosystems with the dominance of vascular plants (forest biogeocenoses, meadows), the largest number Nutrients are involved in internal cycles, representing flows from soil reserves of elements to plants and vice versa - from plants to soil.
Intrasystem parish includes both liquid and dry fallout from the atmosphere, as well as weathering from the underlying rock.
Intrasystem output occurs with the hydrological movement of ions and particles of matter through the soil. In this case, there is a partial loss, which is especially important for the cycles of circulation of some chemical elements(S, N).
The nature and power of intrasystemic, or intrabio-geocenotic, flows determine the overall (integral) production potential and spatial structure of biogeocenosis. This potential is determined both by the biogeocenosis's own characteristics and by the scale and intensity of its external relations - with neighboring (adjacent) biogeocenoses and ecosystems of other, higher ranks.
In nature, there are no completely identical biogeocenoses, even if they have a very similar composition of components, because in different conditions environments, the same components of cenoses may differ in the features of the functions performed, their special production indicators. This is the general law of the universe.
4. Properties of biocenoses: self-regulation and self-reproducibility. Le Chatelier's principle
The main properties of biocenoses that distinguish them from non-living components are ability to produce living matter, possess self-regulation and self-reproducibility. In the biocenosis, individual species, populations and groups of species can be replaced by others, respectively, without much damage to the community, and the system itself exists by balancing the forces of antagonism (competition) between species. It takes time for a biosystem to acquire these properties.
A very important property of biocenoses, like any biological material systems , is an self-regulation- the ability to withstand high negative loads, the ability to return to a state close to the original after significant violations of the components, structure, relationships. Self-regulation reflects Le Chatelier's principle.
According to Le Chatelier's principle, biogeocenosis is able to maintain its state under sharp, unfavorable effects of external factors or disturbances. At the same time, it changes in such a way that it reduces the effect of perturbation and, thus, retains its status quo.
Example. Restoration of the former type of community after a fire, deforestation, windblow, trampling, etc. There is a high activity of growth and a high rate of metabolic processes of plants growing in extreme conditions.
Since the components of the cenosis are in constant interaction with each other - they are connected with each other by flows of matter and energy, then, speaking of the balance of biogeocenosis, one should keep in mind not static, but dynamic balance, first of all, the balance of the flows of matter and energy. If the ecosystem is taken out of the state of dynamic equilibrium, then it tends to return to it, using part of its internal energy and orderliness (orderliness is structural negentropy). If the reserve of internal energy and negentropy is sufficient, then the system returns to a state close to the original. If there are not enough resources of matter and energy, then the system (biogeocenosis) either irrevocably collapses or passes into a new state of dynamic equilibrium, but at a much lower level. energy level. At the same time, they say that the ecosystem has degraded.
EXAMPLE degradation is the plowing and destruction of natural vegetation in large areas in the dry steppe zone. This impact sharply reduces the moisture reserves in the soil, promotes wind erosion of soils, and the ecosystem passes into a new state with very low biological productivity. Steppe ecosystems are replaced by desert ecosystems. Some environmental scientists believe that this is how the Sahara desert formed about 10 thousand years ago on the site of the savannah in North Africa.
One of the most characteristic examples irreversible destruction of biogeocenoses - mountain ranges where mining is carried out in an open way. Forest floodplain biogeocenoses, the most productive and diverse in species composition, are turning into lunar landscapes. The destruction of the heat-insulating layer - the vegetation cover - on soils with permafrost also leads to a violation of the dynamic balance and the phenomenon of thermokarst.
For any biogeocenosis there are limits of tolerance (stability). Some are more tolerant, or resistant, to the effects of external disturbing factors, while others are less. But so far, little is known about the limits of tolerance in natural ecosystems, and there is disagreement among scientists. For example, some say that tundra ecosystems are very unstable and easily vulnerable. Others, on the contrary, believe that the most unstable ecosystems are tropical rainforests, and tundra ecosystems are no less stable than taiga and steppe ecosystems. Tolerance of different ecological systems should be studied as soon as possible, otherwise the most vulnerable ecosystems will be under powerful anthropogenic impact.
This problem is very complex in that different ecosystems are in varying degrees resistant to destructive factors.
FOR EXAMPLE, a track from a tractor on a slope in the taiga zone will overgrow and disappear in 50 years, but the same track in the tundra zone will turn into a ravine up to 20-30 m deep and up to 10-20 m wide in 50 years.
5. Biogeocenosis and ecosystem: differences between these concepts
Somewhat earlier than Sukachev developed the concept of biogeocenosis, in 1935, the English botanist A. Tensley introduced the term "ecosystem".
Ecosystem, according to A. Tensley, - “a set of complexes of organisms with a complex physical factors its environment, i.e., habitat factors in the broadest sense.” Ecosystems are characterized by various kinds of exchange not only between organisms, but also between organisms and their environment, otherwise called the circulation of substances. The same qualities are inherent in biogeocenosis.
The most noticeable changes in the state of the biosphere, violations of the ecological balance occur at the level of biogeocenosis. Therefore, most scientists, in particular Yu. Odum (1975, 1986), do not consider the differences between the concepts of "biogeocenosis" and "ecosystem" significant, put an equal sign between the above concepts, implying an ecosystem as a biocenosis, which together with a biotope (ecotope) forms a biogeocenosis. This is also justified by the fact that the term "ecosystem" is widely used in related sciences, especially in environmental matters.
However, a number of Russian scientists do not share this opinion, seeing certain differences between the biogeocenosis and the ecosystem.
The following types of ecosystems are distinguished by size:
- microecosystems (lichen pillow, etc.);
- mesoecosystems (pond, lake, steppe, etc.);
- macroecosystems (continent, ocean) and, finally,
- global ecosystem, or ecosphere - the totality of all ecosystems of the world (Earth's biosphere).
Biogeocenosis of the above corresponds to the middle position between the micro- and meso-ecosystem. It represents the elementary unit of the biosphere; this is the smallest unit in which the material-energy cycle is carried out in the biosphere. None of the parts of the biogeocenosis is able to fully implement this cycle.
The differences between an ecosystem and a biogeocenosis can be reduced to the following points:
1) biogeocenosis - concept territorial, refers to specific land areas and has certain boundaries that coincide with the boundaries of the phytocenosis. A characteristic feature of biogeocenosis, which N.V. Timofeev-Resovsky, A.N. Tyurukanov (1966) - not a single significant biocenotic, soil-geochemical, geomorphological and microclimatic boundary passes through the territory of biogeocenosis.
- the concept of an ecosystem is broader than the concept of biogeocenosis; it applies to biological systems different complexity and sizes; ecosystems often do not have a certain volume and strict boundaries;
2) in biogeocenosis, organic matter is always produced by plants, therefore the main component of biogeocenosis is phytocenosis ;
In ecosystems, organic matter is not always created by living organisms, it often comes from outside.
(brought in by the current - lake, sea; brought in by man - agricultural land; carried by wind or precipitation - plant remains on eroded mountain slopes).
3) biogeocenosis potentially immortal ;
The existence of an ecosystem can end with the cessation of the arrival of matter or energy into it.
4) an ecosystem can be both terrestrial and aquatic;
Biogeocenosis is always a terrestrial or shallow-water ecosystem.
5) - in the biogeocenosis there should always be a single edificator (edificatory grouping or synusia), which determines the whole life and structure of the system.
There may be several in an ecosystem.
At the early stages of development, the slope ecosystem is the future forest cenosis. It consists of groupings of organisms with different edificators and rather heterogeneous environmental conditions. Only in the future, the same grouping can be influenced not only by its edifier, but also by the edifier of the cenosis. And the second will be the main one.
Thus, not every ecosystem is a biogeocenosis, but each biogeocenosis is an ecosystem, which fully corresponds to Tensley's definition.
Illustrations of biogeocenoses of Primorye
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Biocenosis(or community) is a historically established stable set of populations of organisms of different species inhabiting a relatively homogeneous part of a territory or water area and connected by certain relationships. (K. Möbius, 1877).
Examples of biocenoses: communities on a tree trunk, in a hole, in a forest area, meadow, lake, swamp, pond, etc.
Different populations of the biocenosis must be adapted to living together. It means that:
■ all types of biocenosis should have similar requirements for abiotic environmental conditions (light, temperature, humidity, etc.);
■ there must be regular trophic (food), topical, phoric and factory relationships between organisms of different populations necessary for their nutrition, reproduction, resettlement and protection.
❖ Components of biocenosis:
■ phytocenosis
(sustainable plant community); has easily recognizable character traits and borders, is the main structural component of any biocenosis, determines the species composition of zoo-, myco- and microbial cenoses;
■ zoocenosis
(a set of interrelated animal species);
■ mycocenosis
(community of mushrooms);
■ microbiocenosis
(community of microorganisms).
Ecotop- this primary a complex of abiotic environmental factors and some components of living origin (soil, soil) that were present on the area of the earth's surface (land or water body) occupied by one or another biocenosis, without taking into account the changes introduced by living beings of this biocenosis.
■ All ecotope factors can be divided into climatetop
, edaphotop
And hydrotop
.
climatetop
- a set of climatic factors of the ecotope.
edaphotop
- a set of soil and soil factors.
Hydrotop
- a set of hydrofactors (presence and characteristics of a reservoir, water contained in it, etc.).
Biotope- this is a piece of the environment (land or water body) that has relatively homogeneous living conditions and is occupied by one biocenosis. At the same time, environmental conditions are considered taking into account all the modifications that were introduced into them by the organisms of this biocenosis.
Biogeocenosis and ecosystem
Biogeocenosis(briefly - BGC) is a single natural complex lying within the boundaries of a certain phytocenosis and connected by the mutual exchange of substances and energy, formed by a piece of the earth's surface (land) with certain environmental conditions (biotope) and populations of all types of organisms inhabiting this biotope (biocenosis), see Fig. .
Examples of biogeocenoses: spruce forest, oak forest, sphagnum bog, upland meadow, etc.
Biogeocenosis functions as an integral self-reproducing, self-regulating open system. Populations of organisms receive from the inorganic environment the resources necessary to maintain life, and at the same time release waste products that restore the environment.
ecological system(or ecosystem) - any combination of cohabiting organisms and inorganic components, the interaction of which occurs the cycle of matter and the flow of energy .
Examples of ecosystems; rotting stump, anthill, rainwater puddle, park, aquarium, biosphere, etc.
The difference between an ecosystem and a biogeocenosis. The concept of an ecosystem does not require any restrictions on the territory or water area it occupies and can be applied to any complexes of organisms and their habitats (including water), not only to natural ones, but also to those created by man. Biogeocenosis is a natural ecosystem isolated on land, the boundaries of which are determined by phytocenosis, i.e. plant community. Therefore, an ecosystem is a broader concept than a biogeocenosis: any biogeocenosis is an ecosystem, but not every ecosystem is a biogeocenosis .
❖ Components of biogeocenosis:
■ inorganic substances included in the cycle (compounds of carbon and nitrogen, oxygen, water, mineral salts);
■ climatic factors (temperature, illumination, humidity);
■ organic substances (proteins, nucleic acids, carbohydrates, lipids, etc.);
■ organisms of various functional groups - producers, consumers, decomposers.
Producers- autotrophic organisms (mainly green plants and algae), synthesizing organic substances from inorganic ones. Producers use the energy of the Sun, converting it into the chemical energy of organic substances, available to all other organisms.
decomposers- heterotrophic organisms (bacteria, fungi), which, in the course of their nutrition, destroy the organic matter of dead plants and animals and animal excrement, turning them into simple inorganic compounds suitable for absorption by plants.
Characteristics biogeocenosis (ecosystems): biomass, productivity, species diversity, population density of each species, ratio of species in terms of abundance and population density, spatial and trophic (food) structures, etc.
Biomass is the total mass of all organisms in an ecosystem or its individual trophic levels.
■ Biomass is usually expressed in units of mass of a substance per unit area or volume of an ecosystem (kg/ha, kg/m3, etc.).
■ The biomass of all organisms on Earth is 2.4 10 12 tons of dry matter, 90% of this amount is the biomass of terrestrial plants.
Productivity is the increase in biomass created by ecosystem organisms per unit of time per unit area or volume.
■ Productivity is expressed in units of mass of a substance per unit area or volume for a certain period of time (kg / m 2 per year, etc.).
Ecosystem Primary Productivity- the amount of biomass produced per unit of time by all plants of this ecosystem as a result of photosynthesis.
Ecosystem Secondary Productivity is the amount of biomass produced by all consumers of this ecosystem per unit of time.
■ The total annual production of dry organic matter on Earth is 150-200 billion tons (of which 2/3 come from terrestrial ecosystems, 1/3 from aquatic ecosystems).
■ Most productive ecosystems: tropical rainforest (about 2 kg/m 2 per year) and polar regions of the World Ocean (about 0.25 kg/m 2 per year).
Species structure of biogeocenosis (ecosystems)
Species structure of BGC or ecosystems - the diversity of species of all populations included in the BGC (or ecosystem) and the ratio of these species in terms of abundance (or biomass) and population density.
■ In each ecosystem, there is a natural selection of organisms that are most adapted to given environmental conditions.
■ A distinction is made between ecosystems rich in species (coral reefs, tropical rainforests, etc.) and those poor in them (arctic tundra, deserts, swamps, etc.).
Dominant species- species that dominate in terms of the number of individuals or occupy a large area in a given ecosystem.
Species-edifiers- dominant species (more often plants, sometimes animals), playing leading role in determining the composition, structure and properties of the ecosystem by creating an environment for the entire community (in the spruce forest - spruce, in the birch forest - birch, etc.).
■ For example, in a spruce forest, the illumination is much less, and the air temperature is lower than in a deciduous one; rainwater flowing from the crowns of spruces is acidic, and under the trees a powerful litter is formed from very slowly decomposing needles with a low humus content. As a result, spruce in the course of its life activity changes environmental conditions so much that this biotope becomes unsuitable for the existence of many species of organisms and is populated only by species well adapted to life in such conditions.
The role of rare and scarce species: they increase the diversity of relationships in the community and serve as a reserve for the replacement of dominant species.
■ The more specific environmental conditions, the poorer the species composition and the higher the number of individual species. Conversely, in rich communities, all species are few in number.
■ The higher the species diversity, the more stable the community.
Spatial and ecological structures of biogeocenosis
Spatial structure- distribution of organisms (mainly plants) along rather clearly defined in space (vertically and/or horizontally) elements of the structure - tiers and microgroups .
Tiers characterize vertical division of phytocenoses. They are formed by aboveground vegetative organs of plants and their root systems.
■ The main factor determining the vertical distribution of plants is the amount of light that determines the temperature and humidity regimes at different levels above the soil surface in biogeocenosis. The upper tiers are formed by plants that are light-loving and better adapted to fluctuations in temperature and air humidity; plants that are less demanding of light live in the lower tiers.
■ Layers are well expressed in the forest (arboreal, shrubby, herbaceous, moss, etc.). Animals are also distributed over tiers (inhabitants of shrubs, moss cover, soil, etc.).
■ Underground layering of phytocenoses is weak or absent. As a rule, the total mass of underground organs naturally decreases from top to bottom.
Mosaic- dissection (heterogeneity) of biogeocenosis horizontally, expressed in the presence of various microgroups in it, which differ in species composition, quantitative ratio of different species, productivity and other signs and properties.
Mosaic is due to:
■ heterogeneity of the microrelief;
■ peculiarities of reproduction biology and plant form;
■ activities of plants, animals and humans (the formation of anthills, trampling grass, selective felling of trees, etc.).
The ecological structure of BHC is the ratio of various ecological groups of organisms that make up a given biogeocenosis.
■ The diversity and abundance of representatives of one or another ecological group depend on environmental conditions (in deserts, xerophyte plants and xerophile animals adapted to life in conditions of water deficiency prevail; in aquatic communities, hydrophyte plants and hydrophilic animals, etc.) and add up over time. long time in certain climatic, soil and landscape conditions is strictly natural.
■ This diversity provides a high density of organisms per unit area, their maximum biological productivity and optimal competitive relations.
Communities with a similar ecological structure may have a different species composition, since the same ecological niches can be occupied by different species (example: the marten occupies the same ecological niche in the European taiga, and sable in the Siberian taiga).
Trophic structure of the ecosystem. Cycle of matter and energy flow in ecosystems
All organisms in any ecosystem share the same nutrients and energy needed to sustain life. Necessary condition the existence of an ecosystem is a constant influx of energy from outside. Food is the main mode of movement of matter and energy in an ecosystem.
Trophic level- a set of organisms united by the type of food.
There are the following trophic levels:
■ first level form autotrophic organisms producers ), which create organic substances from inorganic ones due to solar energy;
■ second trophic level form herbivores animals ( consumers of the 1st order: butterfly caterpillars, mice, voles, hares, goats, etc.), consuming organic substances created by producing plants;
■third trophic level constitute carnivores animals ( consumers of the 2nd order: predatory insects, insectivorous birds, etc.), eating small herbivores;
■ fourth trophic level form carnivores animals ( 3rd order consumers : birds of prey and animals), consuming consumers of the 2nd order, etc.
Carnivores can move from the third to the fourth level and back, as well as to higher trophic levels.
Trophic (food) chain(or power circuit) - a number of organisms connected with each other by nutritional relationships (by eating some species by others) and constituting a certain sequence in which the cycle of substances and the flow of energy in the ecosystem are carried out by transferring them from one trophic level to another.
■ Separate links in the trophic chain are organisms belonging to different trophic levels.
Ecosystem food web — complex connection all food chains characteristic of a given ecosystem, in which the links of one chain are components of other chains.
■ The food web reflects trophic structure ecosystems.
❖ Types of food chains:
■pasture chains(chains of eating or consumption ) begin with photosynthetic producing organisms: on the land : plants → insects → insectivorous birds → birds of prey; or plants → herbivorous mammals → carnivorous mammals; in the sea : algae and phytoplankton → lower crustaceans (zooplankton) → fish → mammals (and partially birds). Pasture chains dominate the seas at relatively shallow depths.
■ detrital chains(chains decomposition) begin with dead small remains of plants, corpses and excrement of animals ( detritus): detritus → decomposers that feed on it (bacteria, fungi) → small animals (detritophages: earthworms, wood lice, mites, springtails, nematodes) → predators (birds, mammals). Such chains are most common in forests, where more than 90% of the annual increase in plant biomass dies off, being decomposed by saprotrophic organisms and mineralized.
❖ Main characteristics of the food chain within biogeocenosis: chain length, number, size and biomass of organisms at each trophic level.
■ The food chain usually consists of 3-5 links (trophic levels) due to large energy losses for building new tissues and respiration of organisms.
The productivity of organisms of each subsequent trophic level of the food chain is always less (on average, by 10 times) than the production of the previous one, because:
■ consumers assimilate only part of the food (the rest is excreted in the form of excrement);
■ most of the nutrients absorbed by the intestines are used for respiration and other life processes.
ecological pyramid — graphic image ratios between the numbers of individuals, biomasses or energies of organisms that make up trophic levels in an ecosystem, expressed in number of individuals.
■ In this case, the individual links of the food chain are depicted as rectangles, the area of \u200b\u200bwhich corresponds to the numerical values of the links.
Types of ecological pyramids:
■ the pyramid of numbers graphically displays the ratio of the number of individuals of different trophic levels of the ecosystem;
■ The biomass pyramid graphically shows the amount of biomass (mass of living matter) at each trophic level;
■ The pyramid of energy graphically displays the magnitude of energy flows transferred from one trophic level to another.
❖ Properties of ecological pyramids:
■ the height of the pyramids is determined by the length of the food chain;
■ the biomass and number of individuals of each subsequent link in the food chain progressively decreases - the rule of the ecological pyramid; it operates in most (but not all) terrestrial ecosystems; in such ecosystems, the bases of the pyramids of numbers and biomass are greater than the subsequent levels;
■ in aquatic ecosystems, the bases of the pyramids of numbers and biomass may be smaller than the sizes of the subsequent levels (the pyramids are inverted), which is explained by the small size of the producing organisms (single-celled algae - phytoplankton);
■ The pyramid of energy in terrestrial and aquatic ecosystems always narrows upward, since the energy spent on respiration is not transferred to the next trophic level and leaves the ecosystem.
Self-reproduction. self-regulation and sustainability of ecosystems
Any ecosystem is complex dynamic system, consisting of many hundreds, sometimes thousands of species of organisms, united by trophic, topical and other connections.
self-reproduction- the ability of ecosystems to recreate the flow of energy and ensure the circulation of basic substances and elements between living and non-living components.
■ Living organisms extract resources from the environment and supply it with waste products (plants use light energy, CO 2, H 2 O, replenish the atmosphere O 2; animals absorb O 2 from the atmosphere, release CO 2 into it, etc.).
Self-regulation— the ability of the population of the ecosystem to restore its species and quantitative composition after any deviation, as well as the ability of its various species to exist together, without completely destroying each other, but only limiting the number of individuals of each species to a certain level.
■ Regulatory factors are formed in the ecosystem itself: predators regulate the number of their prey, the activities of herbivores affect plants, and so on.
Ecosystem homeostasis- the property of relative constancy of the species composition and number of individuals of various species in the ecosystem, as well as the relative stability and integrity of the genetic structure of the ecosystem.
■ The specified constancy is observed only on average and reflects the dynamic balance of opposing factors.
Sustainability- the ability of an ecosystem to withstand changes caused by external (natural or anthropogenic) influences, and to restore connections and dynamic balance between its main components, disturbed by external influences.
■ The resilience of each ecosystem has its own limits: if the intensity or time of action of the external influence exceeds a certain threshold, the ecosystem may perish.
♦ Factors that ensure sustainability and longevity of the ecosystem:
■ constant supply of solar energy;
■ the general cycle of substances carried out by producers, consumers and decomposers;
■ ecosystem self-regulation;
■ biological diversity and complexity of the trophic relationships of the organisms that make up it;
■ the ability to switch organisms to feed on another species instead of a species that has become rare (since almost all animal species can use several food sources); at the same time, a small species, freed from the pressure of predation, will gradually restore its numbers;
■ high breeding potential of the main groups of organisms in the ecosystem (an ecosystem is stable if a decrease in precipitation by 50% leads to a decrease in the mass of producers by 25%, herbivorous consumers by 12.5%, predatory consumers by 6.2%, etc.);
■ genetic diversity of individuals in populations; the higher it is, the greater the chance for a population to have organisms with alleles responsible for the appearance of traits and properties that allow them to survive and reproduce in changed conditions of existence and restore their previous numbers;
■ low degree of fluctuations in environmental conditions. For example, tropical ecosystems are highly stable, since the tropics are characterized by relatively constant temperature, humidity, and illumination. On the contrary, the tundra is characterized by sharp fluctuations in temperature, humidity, and illumination; therefore, tundra ecosystems are less stable, and they are characterized by sharp fluctuations in the number of populations of different species.
Based on the knowledge of the laws of ecosystem dynamics, calculations of their productivity and energy flows make it possible to regulate the number of populations and the circulation of substances in ecosystems in such a way as to achieve the greatest yield of products necessary for humans.
Ill-considered human intervention in ecosystems can disrupt natural food chains and lead to uncontrolled growth or decline in the number of individuals of certain populations and to the disruption of natural ecosystems.
Self-development and succession of ecosystems
An absolutely sustainable state of the ecosystem is never achieved due to:
■ volatility of environmental conditions;
■ changes occurring in the ecosystem itself as a result of the vital activity of its organisms.
Ecosystem self-development- its ability to cyclical and progressive changes caused by various reasons.
■ Cyclical changes are usually associated with daily and seasonal changes in external conditions and biological rhythms of organisms.
■ Incremental change is driven by permanent external or internal factors and lead to the change of one biogeocenosis by another (succession).
Succession- a natural, consistent, irreversible and directed change (in a certain territory) of one biogeocenosis to another.
The replacement of one phytocenosis in an ecosystem by another is succession series. In the absence of disturbances, succession ends with the formation of a more stable community that is in relative equilibrium with the abiotic environment (spruce forest, oak forest, feather grass steppes, peat bog, etc.).
❖ Reasons for successions:
■external: permanent external factors: changes in the climate and soil conditions in a given territory (waterlogging, salinization), including as a result of human activities (deforestation, irrigation of land in arid areas, drainage of swamps, fertilization of meadows, plowing, enhanced grazing, etc.);
■ internal: changes that occur in a biotope due to the vital activity of organisms during the long-term existence of populations in one place, due to which the biotope becomes unsuitable for some species, but suitable for others. As a result, another biocenosis, more adapted to the new conditions, develops in this place.
Changing the conditions of the habitat (biotope) inevitably leads to a change (change) in the biocenosis. As a result, a new one arises in place of the former biogeocenosis (ecosystem). The leading role in the process of changing biogeocenoses belongs to plants, although biogeocenoses change as a whole. Along with the change in vegetation, the animal world also changes.
❖ Classification of successions depending on the state and properties of the environment:
■ primary, starting in areas devoid of soil and vegetation (on bare rocks, sand dunes, formed reservoirs, river sediments, frozen lava flows, etc.; they last hundreds and thousands of years. The most important stage of such successions is the formation of soil through the accumulation of dead plant residues or products of their decomposition;
■ secondary occurring at the site of formed communities after their disturbance as a result of erosion, fire, clearing, drought, volcanic eruption, etc. Since rich life resources are usually preserved in such places, these successions proceed quickly (within tens of years).
Agroienosis
Agrocenosis(or agrobiocenosis) is an ecosystem artificially created by man, the structure and functions of which he maintains and controls in his own interests. This is a community of organisms that live on agricultural land, occupied by crops or planting of cultivated plants.
Examples; fields, kitchen gardens, orchards, parks, forest plantations, pastures, greenhouses, aquariums, fish ponds, etc.
The role of man in agrocenosis: he creates an agrocenosis, ensures its high productivity with the help of a complex of special agrotechnical methods, collects and uses the crop.
❖ The role of agrocenoses:
■ they currently occupy 10% of the entire land surface (about 1.2 billion hectares) and annually produce 2.5 billion tons of agricultural products (about 90% of all food energy, necessary for humanity);
■ they have a huge potential for increasing productivity, the realization of which is possible with constant, scientifically based soil care, providing plants with moisture and mineral nutrients, and protecting plants from adverse abiotic and biotic factors.
IN composition of agrocenosis includes cultivated plants, weeds, insects, earthworms, mouse-like rodents, birds, bacteria, fungi and other organisms linked by trophic relationships.
Food chains in agrocenosis the same as in the natural ecosystem: producers (cultivated plants and weeds), consumers (insects, birds, voles, foxes) and decomposers (bacteria, fungi); Man is an essential link in the food chain.
❖ Differences between agrocenoses and natural biogeocenoses:
■ in agrocenoses, it is predominantly not natural, but artificial selection , which is aimed by man mainly at maximizing the yield of crops. This sharply reduces the ecological stability of agrocenoses, which not capable of self-regulation and self-renewal, cannot exist independently (without human support) for a more or less long time (turn into a biogeocenosis) and may die during the mass reproduction of pests or pathogens;
■ in agrocenoses there is no complete cycle of substances and the balance of nutrients is sharply disturbed (their main part is withdrawn by humans during harvesting); to compensate for losses, it is necessary to constantly add various nutrients to the soil in the form of fertilizers;
■ agrocenoses, in addition to solar energy, have an additional source of energy in the form of energy man-made mineral and organic fertilizers, chemical protection against weeds, pests and diseases, energy spent on tillage, irrigation or drainage of land, etc.;
■ change of agrocenoses occurs at the will of a person (in field agrocenoses - crop rotation );
■the productivity of agrocenoses is higher than biogeocenoses.
♦ Methods for increasing the productivity of agrocenoses:
■ drainage and irrigation of soils;
■ erosion control (strengthening of slopes, non-moldboard plowing, grassing of former peatlands);
■ rationed application of fertilizers;
■ metered use of weed, pest and plant disease control agents;
■ application of biological methods of pest control;
■ use of high-performance equipment;
■ development and use of new high-yielding varieties of cultivated plants resistant to diseases and pests;
■ observance of scientifically substantiated crop rotations;
■ use of greenhouses and greenhouses;
■ application of methods of growing vegetables without soil - hydroponics (gravel irrigated with salt solutions is used as a substrate) and aeroponics (there is no substrate, and the roots are periodically sprayed with mineral salt solutions). 
