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Introduction
1. Biocenosis - general information and concepts
2. The structure of the biocenosis
3. Modern problems of biocenoses and ways to solve them
Conclusion
Bibliography
Introduction
Biocenosis is a historically established set of animals, plants, fungi and microorganisms that inhabit a relatively homogeneous living space (a certain area of \u200b\u200bland or water), and are interconnected and their environment. The concept of "biocenosis" is one of the most important in ecology, since it follows from it that living beings form complexly organized systems on Earth, outside of which they cannot exist stably.
Biocenosis is one of the main objects of ecology research. Problems of sustainability of biocenoses, a decrease in the number of populations, the disappearance of entire species of living organisms are acute problems facing humanity today. Therefore, the study of biocenoses, their structure and conditions of sustainability is an important ecological task, which has been and continues to be given great attention by ecologists from all over the world, including Russian scientists.
In this work, I will dwell in detail on such issues as the properties and structure of the biocenosis, the conditions for their stability, as well as the main modern problems and ways to solve them. It should be noted that in the mind of a person who is not a specialist in the field of ecology, there is confusion in the concepts of "biocenosis", "ecosystem", "biogeocenosis", "biosphere", so I will briefly dwell on the similarities and differences of these concepts and their relationships. Biocenosis is one of the main objects of ecology research. Ecologists from all over the world, including Russian scientists, have paid and continue to pay great attention to the study of biocenoses. In the process of working on the abstract, I used textbooks written by well-known foreign ecologists: Yu. Odum, V. Tishler; and Russian authors: Korobkin V.I., Peredelsky L.V., as well as modern electronic resources indicated in the list of references.
1. Biots enosis - general information and concepts
Biocenosis (from the Greek vyapt - “life” and kpint - “general”) is a historically established set of animals, plants, fungi and microorganisms that inhabit a relatively homogeneous living space (a certain area of \u200b\u200bland or water area), and interconnected and their environment. Biocenoses arose on the basis of the biogenic cycle and provide it in specific natural conditions. Biocenosis is a dynamic system capable of self-regulation, the components of which (producers, consumers, decomposers) are interconnected.
The most important quantitative indicators of biocenoses are biodiversity (the total number of species in it) and biomass (the total mass of all types of living organisms in a given biocenosis).
The concept of "biocenosis" is one of the most important in ecology, since it follows from it that living beings form complexly organized systems on Earth, outside of which they cannot exist stably. The main function of the community is to ensure balance in the ecosystem based on a closed cycle of substances.
The composition of biocenoses can include thousands of species of various organisms. But not all of them are equally significant. The removal of some of them from the community does not have a noticeable effect on them, while the removal of others leads to significant changes.
Some types of biocenosis can be represented by numerous populations, while others are small. The scales of biocenotic groupings of organisms are very different - from communities of lichen pillows on tree trunks or a decaying stump to the population of entire landscapes: forests, steppes, deserts, etc.
The organization of life at the biocenotic level is subject to hierarchy. With an increase in the scale of communities, their complexity and the proportion of indirect, indirect relationships between species increase.
Natural associations of living beings have their own laws of functioning and development, i.e. are natural systems.
Thus, being, like organisms, structural units of living nature, biocenoses, nevertheless, are formed and maintain their stability on the basis of other principles. They are systems of the so-called frame type - without special control and coordinating centers, and are also built on numerous and complex internal connections.
The most important features of systems related to the supraorganismal level of life organization, for example, according to the classification of the German ecologist W. Tischler, are the following:
1) Communities always arise, are made up of ready-made parts (representatives of various species or entire complexes of species) that are present in the environment. In this way their origin differs from the formation of a separate organism, which occurs through the gradual differentiation of the simplest initial state.
2) Parts of the community are interchangeable. Parts (organs) of any organism are unique.
3) If constant coordination and consistency of the activity of its organs, cells and tissues is maintained in the whole organism, then the supraorganismal system exists mainly due to the balancing of oppositely directed forces.
4) Communities are based on the quantitative regulation of the number of some species by others.
5) The maximum size of an organism is limited by its internal hereditary program. The dimensions of supraorganismal systems are determined by external causes.
A homogeneous natural living space (part of the abiotic environment) occupied by a biocenosis is called a biotope. It can be a piece of land or a reservoir, a seashore or a mountainside. Biotope is an inorganic environment, which is a necessary condition for the existence of a biocenosis. Biocenosis and biotope closely interact with each other.
The scale of biocenoses can be different - from communities of lichens on tree trunks, moss tussocks in a swamp or a decaying stump to the population of entire landscapes. So, on land, one can distinguish the biocenosis of the upland (not flooded with water) meadow, the biocenosis of the white moss pine forest, the biocenosis of the feather grass steppe, the biocenosis of the wheat field, etc.
There are concepts of "species richness" and "species diversity" of biocenoses. Species richness is a common set of community species, which is expressed by a list of representatives of different groups of organisms. Species diversity is an indicator that reflects not only the qualitative composition of the biocenosis, but also the quantitative relationships of species.
There are poor and species-rich biocenoses. The species composition of biocenoses, in addition, depends on the duration of their existence, the history of each biocenosis. Young, just emerging communities usually include a smaller set of species than long-established, mature ones. Biocenoses created by man (fields, gardens, orchards) are also poorer in species than natural systems similar to them (forest, steppe, meadow). The monotony and species poverty of agrocenoses is supported by a special complex system of agrotechnical measures.
Almost all terrestrial and most aquatic biocenoses include microorganisms, plants, and animals in their composition. The stronger the differences between two neighboring biotopes, the more heterogeneous the conditions at their boundaries and the stronger the boundary effect. The number of one or another group of organisms in biocenoses strongly depends on their size. The smaller the individuals of species, the higher their abundance in biotopes.
Groups of organisms of different sizes live in a biocenosis at different scales of space and time. For example, the life cycles of unicellular organisms can take place within an hour, while the life cycles of large plants and animals stretch for decades.
Naturally, in all biocenoses, the smallest forms - bacteria and other microorganisms - predominate numerically. In each community, it is possible to single out a group of main, most numerous species in each size class, the relationships between which are decisive for the functioning of the biocenosis as a whole. Species that prevail in terms of numbers (productivity) are the dominants of the community. Dominants dominate the community and constitute the "species core" of any biocenosis.
For example, when studying a pasture, it was found that the maximum area in it is occupied by a plant - bluegrass, and among the animals grazing there, there are most of all cows. This means that bluegrass dominates among producers, and cows dominate among consumers.
In the richest biocenoses, almost all species are few in number. In tropical forests, it is rare to find several trees of the same species side by side. In such communities, outbreaks of mass reproduction of individual species do not occur; biocenoses are highly stable.
The totality of all types of a community constitutes its biodiversity. Typically, the community includes several major species with high abundance and many rare species with low abundance.
Biodiversity is responsible for the equilibrium state of the ecosystem, and, consequently, for its stability. A closed cycle of nutrients (biogens) occurs only due to biological diversity.
Substances that are not assimilated by some organisms are assimilated by others, so the output of biogens from the ecosystem is small, and their constant presence ensures the balance of the ecosystem.
Human activity greatly reduces the diversity in natural communities, which requires forecasts and foresight of its consequences, as well as effective measures to maintain natural systems.
1.1 Biocenosis, ecosystem, biosphere
Ecosystem (from other Greek pkpt - dwelling, location and ueufzmb - system) - a biological system consisting of a community of living organisms (biocenosis), their habitat (biotope), a system of connections that exchanges matter and energy between them. Thus, the biocenosis is the main component of the ecosystem, its biotic component.
The basis of the ecological view of the world is the idea that every living being is surrounded by many different factors that affect it, forming in a complex its habitat - a biotope. Consequently, a biotope is a piece of territory that is homogeneous in terms of living conditions for certain types of plants or animals (the slope of a ravine, an urban forest park, a small lake or part of a large one, but with uniform conditions - the coastal part, the deep-water part).
Organisms characteristic of a particular biotope constitute a life community, or biocenosis (animals, plants and microorganisms of a lake, meadow, coastal strip).
The biocenosis forms a single whole with its biotope, which is called the ecological system (ecosystem). An anthill, a lake, a pond, a meadow, a forest, a city, a farm can serve as an example of natural ecosystems. A classic example of an artificial ecosystem is a spaceship. biocenosis species spatial trophic
Close to the concept of an ecosystem is the concept of biogeocenosis. Supporters of the ecosystem approach in the West, incl. Y.Odum consider these concepts to be synonyms. However, a number of Russian scientists do not share this opinion, seeing a number of differences. Of particular importance for the identification of ecosystems are the trophic relationships of organisms that regulate the entire energy of biotic communities and the ecosystem as a whole.
Attempts to create a classification of the ecosystems of the globe have been made for a long time, but there is no convenient, universal classification yet. The thing is that because of the huge variety of types of natural ecosystems, because of their lack of rank, it is very difficult to find a single criterion based on which such a classification can be developed.
If a puddle, a hummock in a swamp, and a sand dune with established vegetation can be a separate ecosystem, then, naturally, all possible variants of hummocks, puddles, etc. can be calculated. does not seem possible. Therefore, ecologists decided to focus on large combinations of ecosystems - biomes. A biome is a large biosystem that is characterized by some dominant type of vegetation or other landscape feature. According to the American ecologist R. Whittaker, the main type of community on any continent, distinguished by the physiognomic characteristics of vegetation, is the biome. Moving from the north of the planet to the equator, nine main types of terrestrial biomes can be distinguished: tundra, taiga, temperate deciduous forest biome, temperate steppe, Mediterranean mud vegetation, desert, tropical savanna and grassland biome, tropical or spiny woodland, tropical forest biome .
The main components of ecosystems are:
1) non-living (abiotic) environment. These are water, minerals, gases, as well as organic substances and humus;
2) biotic components. These include: producers or producers (green plants), consumers, or consumers (living creatures that feed on producers), and decomposers, or decomposers (microorganisms).
The biomass created by organisms (the substance of the bodies of organisms) and the energy contained in them are transferred to other members of the ecosystem: animals eat plants, these animals are eaten by other animals. This process is called the food or trophic chain. In nature, food chains often intersect to form a food web. Examples of food chains: plant - herbivore - predator; cereal - field mouse - fox, etc. and the food web are shown in fig. one.
Rice. 1. Food web and direction of matter flow
The biosphere is the shell of the Earth, inhabited by living organisms, under their influence and occupied by the products of their vital activity. The biosphere is the global ecosystem of the Earth. It penetrates the entire hydrosphere, the upper part of the lithosphere and the lower part of the atmosphere, that is, it inhabits the ecosphere. The biosphere is the totality of all living organisms. It is home to over 3,000,000 species of plants, animals, fungi and bacteria. Man is also a part of the biosphere, his activity surpasses many natural processes.
The state of equilibrium in the biosphere is based on the interaction of biotic and abiotic environmental factors, which is maintained due to the continuous exchange of matter and energy between all components of ecosystems.
In closed cycles of natural ecosystems, along with others, the participation of two factors is mandatory: the presence of decomposers and the constant supply of solar energy. There are few or no decomposers in urban and artificial ecosystems, so liquid, solid and gaseous wastes accumulate, polluting the environment.
1.3 History of the study of biocenosis
At the end of the 70s. 19th century the German hydrobiologist Karl Möbius studied the complexes of benthic animals - clusters of oysters (oyster banks). He observed that together with oysters there were also such animals as starfish, echinoderms, bryozoans, worms, ascidians, sponges, etc. The scientist concluded that these animals live together, in the same habitat, not by chance. They need the same conditions as oysters. Such groupings appear due to similar requirements for environmental factors. Complexes of living organisms that constantly meet together at different points of the same water basin under the same conditions of existence, Möbius called biocenoses. The term "biocenosis" (from the Greek bios - life and koinos - general) was introduced by him into scientific literature in 1877 in the book "Die Auster und die Austernwirthschaft" to describe all organisms that inhabit a certain territory (biotope), and their relationships.
The merit of Möbius is that he not only established the existence of organic communities and proposed a name for them, but also managed to reveal many patterns of their formation and development. Thus, the foundations of an important direction in ecology, biocenology (ecology of communities), were laid.
It should be noted that the term "biocenosis" has become widespread in the scientific literature in German and Russian, and in English-speaking countries it corresponds to the term "community" (community). However, strictly speaking, the term "community" is not synonymous with the term "biocenosis". If the biocenosis can be called a multi-species community, then the population (an integral part of the biocenosis) is a single-species community.
2. The structure of the biocenosis
The structure of the biocenosis is multifaceted, and when studying it, various aspects are distinguished. Based on this, the structures of the biocenosis are divided into the following types:
1) specific;
2) spatial, in turn subdivided into vertical (tiered) and horizontal (mosaic) organization of the biocenosis;
3) trophic.
Each biocenosis consists of a certain set of living organisms belonging to different species. But it is known that individuals of the same species are combined into natural systems, which are called populations. Therefore, a biocenosis can also be defined as a set of populations of all types of living organisms that inhabit common habitats.
The composition of the biocenosis includes a set of plants in a certain area - phytocenosis; the totality of animals living within a phytocenosis is a zoocenosis; microbiocenosis - a set of microorganisms that inhabit the soil. Sometimes, as a separate constituent element, mycocenosis, a collection of fungi, is included in the biocenosis. Examples of biocenoses are deciduous, spruce, pine or mixed forest, meadow, swamp, etc.
A specific biocenosis includes not only organisms that permanently inhabit a certain territory, but also those that have a significant impact on it. For example, many insects breed in water bodies, where they serve as an important food source for fish and some other animals. At a young age, they are part of the aquatic biocenosis, and in adulthood they lead a terrestrial lifestyle, i.e. act as elements of land biocenoses. Hares can eat in the meadow, and live in the forest. The same applies to many species of forest birds that seek food not only in the forest, but also in adjacent meadows or swamps.
2.1 Species structure of biocenosis
The species structure of a biocenosis is a set of its constituent species. In some biocenoses, animal species may predominate (for example, the biocenosis of a coral reef), in other biocenoses, plants play the main role: the biocenosis of a floodplain meadow, feather grass steppe, spruce, birch, and oak forests.
A simple indicator of biocenosis diversity is the total number of species, or species richness. If any kind of plant (or animal) quantitatively prevails in the community (has a large biomass, productivity, abundance or abundance), then this species is called a dominant, or dominant species (from Latin dominans - dominant). There are dominant species in any biocenosis. For example, in a spruce forest, spruce, using the bulk of solar energy, increase the largest biomass, shade the soil, weaken air movement and create a lot of inconvenience for the life of other forest inhabitants.
The number of species (species diversity) in different biocenoses is different and depends on their geographical location. The most well-known pattern of change in species diversity is its decrease from the tropics towards high latitudes. The closer to the equator, the richer and more diverse flora and fauna. This applies to all forms of life, from algae and lichens to flowering plants, from insects to birds and mammals.
In the rainforests of the Amazon Basin, on an area of about 1 hectare, up to 400 trees of more than 90 species can be counted. In addition, many trees serve as a support for other plants. Up to 80 species of epiphytic plants grow on the branches and trunk of each tree.
Unlike the tropics, the biocenosis of a pine forest in the temperate zone of Europe can include a maximum of 8-10 species of trees per 1 ha, and in the north of the taiga region, 2-5 species are present in the same area.
Alpine and Arctic deserts are the poorest biocenoses in terms of species, and tropical forests are the richest. Panama's rainforests are home to three times as many species of mammals and birds as Alaska.
Biocenoses are not isolated from each other. Although it is visually possible to distinguish one plant community from another, for example, the biocenosis of a dry forest from the biocenosis of a moist meadow, which is replaced by a swamp, it is rather difficult to draw a clear boundary between them. Almost everywhere there is a kind of transitional strip of various widths and lengths, because rigid, sharp boundaries in nature are a rare exception. They are typical mainly for communities subject to intense anthropogenic impact.
In the early 30s. 20th century the American naturalist A. Leopold proclaimed the need to take into account the so-called "edge effect" in the activities of the hunting economy. In this case, the edge was understood not only as the outskirts of the forest, but also as any border between two biocenoses, even between two arrays of different agricultural crops. On both sides of this conditional line, the relative species diversity of plants and animals increases, fodder and protective conditions for game improve, the disturbance factor weakens, and most importantly, this zone has increased productivity. Such a transitional strip (or zone) between adjacent physiognomically distinct communities is called an ecotone.
More or less sharp boundaries between biocenoses can be observed only in cases of a sharp change in the factors of the abiotic environment. For example, such boundaries exist between water and terrestrial biocenoses, in places where there is a sharp change in the mineral composition of the soil, etc. Often the number of species in an ecotone exceeds their number in each of the adjacent biocenoses. Such a tendency to increase the diversity and density of living organisms at the boundaries of biocenoses is called the marginal (edge, boundary) effect. The edge effect is most clearly manifested in the zones separating the forest from the meadow (the zone of shrubs), the forest from the swamp, and so on.
2.2 Spatial structure of the biocenosis
Species can be distributed in different ways in space according to their needs and habitat conditions. Such a distribution of the species that make up the biocenosis in space is called the spatial structure of the biocenosis. Distinguish between vertical and horizontal structures.
1) The vertical structure of the biocenosis is formed by its individual elements, special layers, which are called tiers. Tier - co-growing groups of plant species, differing in height and position in the biocenosis of assimilating organs (leaves, stems, underground organs - tubers, rhizomes, bulbs, etc.). As a rule, different tiers are formed by different life forms (trees, shrubs, shrubs, herbs, mosses). The layering is most clearly expressed in forest biocenoses (Fig. 2).
The first, arboreal, tier usually consists of tall trees with high-lying foliage, which is well lit by the sun. Unused light can be absorbed by the trees forming the second, substory, tier.
Rice. 2. Layers of forest biocenosis
The undergrowth layer is made up of shrubs and shrubby forms of tree species, for example, hazel, mountain ash, buckthorn, willow, forest apple, etc. In open areas, under normal ecological conditions, many shrub forms of such species as mountain ash, apple, pear, would have the appearance of trees of the first magnitude. However, under the forest canopy, in conditions of shading and lack of nutrients, they are doomed to exist in the form of undersized, often non-barking seeds and fruits of trees. As the forest biocenosis develops, such species will never enter the first tier. In this they differ from the next tier of the forest biocenosis.
The undergrowth layer includes young low (from 1 to 5 m) trees, which in the future will be able to enter the first layer. These are the so-called forest-forming species - spruce, pine, oak, hornbeam, birch, aspen, ash, black alder, etc. These species can reach the first tier and form biocenoses with their dominance (forests).
Under the canopy of trees and shrubs, there is a grass-shrub layer. These include forest herbs and shrubs: lily of the valley, oxalis, strawberries, lingonberries, blueberries, ferns.
The ground layer of mosses and lichens forms a moss-lichen layer.
So, in the forest biocenosis stand out tree stand, undergrowth, undergrowth, grass cover and moss-lichen layer.
Like the distribution of vegetation over tiers, in biocenoses, different animal species also occupy certain levels. Soil worms, microorganisms, diggers live in the soil. In leaf litter, on the surface of the soil, various centipedes, ground beetles, mites and other small animals live. Birds nest in the upper canopy of the forest, and some can feed and nest below the upper tier, others in the bushes, and still others near the ground itself. Large mammals live in the lower tiers.
Layering is inherent in biocenoses of oceans and seas. Different types of plankton stay at different depths depending on the lighting. Different types of fish live at different depths depending on where they find their food.
2) Individuals of living organisms are unevenly distributed in space. Usually they make up groupings of organisms, which is an adaptive factor in their life. Such groupings of organisms determine the horizontal structure of the biocenosis - the horizontal distribution of individuals that form various kinds of patterning, spotting of each species.
There are many examples of such a distribution: these are numerous herds of zebras, antelopes, elephants in the savannah, coral colonies on the seabed, schools of marine fish, flocks of migratory birds; thickets of reeds and aquatic plants, accumulations of mosses and lichens on the soil in the forest biocenosis, patches of heather or lingonberries in the forest.
The elementary (structural) units of the horizontal structure of plant communities include microcenosis and microgrouping.
Microcenosis is the smallest structural unit of the horizontal division of the community, which includes all tiers. Almost every community includes a complex of microcommunities or microcenoses.
Micro-grouping - concentration of individuals of one or several species within a tier, intratier mosaic spots. For example, in the moss layer, various patches of mosses can be distinguished with the dominance of one or several species. Blueberry, blueberry-sour, blueberry-sphagnum microgroups occur in the grass-shrub layer.
The presence of mosaics is essential to the life of the community. Mosaic allows more complete use of various types of microhabitats. Individuals forming groups are characterized by high survival rate, they use food resources most efficiently. This leads to an increase and diversity of species in the biocenosis, contributes to its stability and viability.
2.3 Trophic structure of biocenosis
The interaction of organisms that occupy a certain place in the biological cycle is called the trophic structure of the biocenosis.
In the biocenosis, three groups of organisms are distinguished.
1. Producers (from lat. producens - producing) - organisms that synthesize from inorganic substances (mainly water and carbon dioxide) all the organic substances necessary for life using solar energy (green plants, cyanobacteria and some other bacteria) or energy oxidation of inorganic substances (sulfur bacteria, iron bacteria, etc.). Usually, producers are green chlorophyll-bearing plants (autotrophs) that provide primary production. The total dry matter weight of phytomass (plant mass) is estimated at 2.42 x 1012 tons. This is 99% of the total living matter of the earth's surface. And only 1% falls on the share of heterotrophic organisms. Therefore, only the vegetation of the planet Earth is obliged to the existence of life on it. It was green plants that created the necessary conditions for the appearance and existence of various prehistoric animals, and then humans. Dying, the plants accumulated energy in deposits of coal, peat and even oil.
Producing plants provide man with food, raw materials for industry, medicines. They purify the air, trap dust, soften the temperature regime of the air, muffle the noise. Thanks to vegetation, there is a huge variety of animal organisms that inhabit the Earth. Producers make up the first link in the food price and underlie the ecological pyramids.
2. Consumers (from Latin consumo - I consume), or consumers, are heterotrophic organisms that feed on ready-made organic matter. Consumers themselves cannot build organic matter from inorganic matter and get it ready-made by feeding on other organisms. In their organisms, they convert organic matter into specific forms of proteins and other substances, and they emit waste generated during their life activity into the environment.
Grasshopper, hare, antelope, deer, elephant, i.e. herbivorous animals are consumers of the first order. A toad that seizes a dragonfly, a ladybug that feeds on aphids, a wolf that hunts a hare - all these are second-order consumers. A stork eating a frog, a kite carrying a chicken into the sky, a snake swallowing a swallow are consumers of the third order.
3. Reducers (from lat. reducens, reducentis - returning, restoring) - organisms that destroy dead organic matter and turn it into inorganic substances, and they, in turn, are absorbed by other organisms (producers).
The main decomposers are bacteria, fungi, protozoa, i.e. soil heterotrophic microorganisms. If their activity decreases (for example, when pesticides are used by humans), the conditions for the production process of plants and consumers worsen. Dead organic remains, whether it be a tree stump or the corpse of an animal, do not disappear into nowhere. They are subject to decay. But dead organics cannot rot on their own. Reducers (destructors, destroyers) act as "gravediggers". They oxidize dead organic residues to CO 2 , H 2 0 and simple salts, i.e. to inorganic components, which can again be involved in the cycle of substances, thereby closing it.
3. Modern problems and ways to solve them
The most acute problem of biocenoses is the reduction of populations of various living organisms up to the disappearance of entire species of animals, plants and microorganisms. This leads to a violation of the stability of biocenoses and poses a threat to the entire biosphere of the planet.
Each species participates in the circulation of substances, maintains a dynamic balance in natural ecosystems. Therefore, the loss of any biological species is highly undesirable for the biosphere.
The loss of species occurred as a result of evolutionary processes. Due to human activity, the biological resources of the planet are being lost much faster. Tens of thousands of plant and animal species are under threat of extinction. The reasons for this situation are:
1) loss of habitat: destruction of forests, drainage of swamps and floodplain lakes, plowing of steppes, change and shallowing of river beds, reduction in the area of sea estuaries suitable for nesting, molting and wintering of waterfowl, road construction, urbanization and other changes resulting from human economic activity;
2) environmental pollution with toxic chemicals and xenobiotics, oil and oil products, salts of heavy metals, municipal solid waste;
3) the spread of introduced species of plants and animals, actively capturing vast territories and displacing the natural inhabitants of ecosystems. The unintentional, accidental dispersal of animals intensified with the development of transport;
4) ruthless exploitation of natural resources - minerals, soil fertility, aquatic ecosystems, overfishing of animals, birds and hydrobionts.
To protect endangered species, it is necessary to take active, sometimes urgent measures. One of the most effective methods of animal protection is the creation of reserves or sanctuaries. On the territory of the Russian Federation, there are more than 150 reserves in which a large number of animals have been saved. Among them are the Amur tiger, saiga, goral, Bukhara deer, kulan and others. Zoos located throughout the country help to breed endangered species of animals.
In order to preserve and increase the number of rare species, states on all continents of the Earth adopt laws regarding the protection and use of wildlife. In the Russian Federation, such a law was adopted on June 25, 1980. To account for rare species, both in Russia and in other countries of the world, the so-called Red Books are being created. Endangered species of animals around the world need a separate account; for this, the International Red Book has been created.
It is necessary to rationally use natural resources, including in agriculture. Limit deforestation, as well as hunting and fishing, and completely ban rare and endangered species.
Conclusion
Biocenosis is one of the main objects of ecology research. Biocenosis is a set of populations of plants, animals and microorganisms. The main function of the biocenosis is to ensure balance in the ecosystem based on a closed circulation of substances. The place occupied by a biocenosis is called a biotope. Types of structures of the biocenosis: species, spatial (vertical (tiered) and horizontal (mosaic) organization of the biocenosis) and trophic. The species structure of the biocenosis covers all the species living in it. The spatial structure includes a vertical structure - tiers and a horizontal one - microcenoses and microassociations. The trophic structure of the biocenosis is represented by producers, consumers and decomposers. The transfer of energy from one species to another by eating them is called the food (trophic) chain. The place of an organism in the food chain, associated with its food specialization, is called the trophic level. The trophic structure of the biocenosis and ecosystem is usually displayed by graphical models in the form of ecological pyramids. There are ecological pyramids of numbers, biomass and energy. The rate of fixation of solar energy determines the productivity of biocenoses. The set of environmental factors within which a species lives is called an ecological niche.
Humanity is now facing the acute problem of the extinction of species of various living organisms, leading to a violation of the stability of biocenoses and the biosphere as a whole. To prevent the decline in populations and the extinction of entire species, it is necessary to take urgent and active measures: listing endangered species in the Red Books; creation of nature reserves and national parks; restriction of hunting, fishing and deforestation; rational use of all natural resources.
Bibliography
1. Korobkin V.I., Peredelsky L.V. Ecology. - R.-on-Don, 2001 - 576 p.
2. Odum Yu. Ecology: in 2 vols. T. 1 - M., 1986 - 328 p.; T. 2 - M., 1986 - 376 p.
3. Articles from the electronic resource "Wikipedia": Biocenosis, Biosphere, Ecosystem
4. Tishler V. Agricultural ecology. - M., 1971 - 455 p.
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The concept of "productivity of ecosystems", its types, classification of ecosystems by productivity. The four successive steps (or stages) of the organic matter production process. Species composition and saturation of the biocenosis. Ecological standardization.
test, added 09/27/2009
The concept of trophic structure as the totality of all food dependencies in an ecosystem. Community activity factors. Types of nutrition of living organisms. Distribution of ranges of the solar spectrum. Scheme of the cycle of matter and the flow of energy in the ecosystem.
presentation, added 02/08/2016
History of development of ecology. Species and spatial structure of the biocenosis. Natural resources of the earth. Types of pollution of the hydrosphere and biosphere by production and consumption waste. The role of biotechnology and government agencies in environmental protection.
test, added 06/02/2010
Acquaintance with the interpretation of the concept of biocenosis; identification of its constituent parts and main participants. Description of the nature and methods of environmental risk management, familiarization with its anthropogenic, natural and man-made factors of occurrence.
test, added 04/27/2011
Consideration of the principles of the theory of Bari Commoner, the laws of minimum, necessity, pyramid of energy, the concept of succession (consistent change of communities under the influence of time), biocenosis, tolerance, environmental resistance, sustainability of the natural community.
The concept of biocenosis includes such terms as ecology: biology, ecosystem, biocenosis, biotope, biogeocenosis. What do all these terms mean? It turns out that it's not all that difficult. It is only necessary to translate these words from the Greek language.
All these concepts are based on the same words.: "bio" - life, "eco" - dwelling, "geo" - earth, "logos" - to study, "cenos" - general, "top" - place. Now, having put together understandable words, “complex” scientific terms will no longer frighten. Two of them stand for sciences. This is "ecology", which studies the interaction of living organisms with each other and the environment. And "biology", the system of sciences about living beings in all the variety of their forms, time of existence and distribution on Earth.Scientists from different countries and nationalities contributed to the creation and development of these sciences, and they chose the Greek language as a common and convenient language for communication.
The rapid development of these sciences falls on the beginning of the 19th century. The term "biology" is proposed simultaneously by Friedrich Burdach, Gottfried Reinhold Treviranus and Jean Baptiste Lemarck. The term "ecology" in 1866 was reflected in the book by Ernst Heinrich Haeckel "General Morphology of Organisms".
Carl August Mobius continued the development of science and in 1877 introduced the term "biocenosis" to describe living organisms inhabiting a certain territory. With the introduction of the term biocenosis, the biotope received its definition. It was first designated by the same Ernst Heinrich Haeckel, and developed and introduced in 1908 by the professor of the Berlin Zoological Museum F. Dahl.
The term biocenosis has found its application in the literature in Russian and German. In English-speaking countries, the concept of "community" is used, which is not quite the same thing.
In 1942, Professor Sukachev developed the doctrine of biogeocenosis. Biogeocenosis and biocenosis essentially mean the same thing, however, the term is rarely used in world scientific literature, but is sometimes found in German-language publications.
Definition of terms
Now let's say what the above terms mean.
What is a biocenosis in biology? Let's give the first definition. Biocenosis- these are all animals, plants and microorganisms that exist over a long period of time, in a certain space and under the influence of the natural environment.
A biotope is understood as a certain relatively homogeneous space. That is, an area of land, sea or inland water with a stable environmental impact and climatic conditions. These factors determine the species composition of the animal, plant life and microorganisms living on it.
The totality of the biocenosis and the biotope is already an ecosystem, which consists of the entire number of species of living organisms, their habitat and the connections that arise between them, the impact on each other and the exchange of energy.
Thus, the ecosystem, biocenosis and biotope are concepts where each subsequent one is an integral and integral part of the previous one.
Pictures of the biocenosis characterize these concepts in the best possible way.
Separation of biocenosis by type and saturation
According to its structure, the biocenosis can be divided into: species, spatial or vertical and mosaic or horizontal.
First of all, species characterizes the quantitative diversity of species of living organisms living in it, and their total mass. In other words, biodiversity and biomass.
The variety of species of animals and birds, fish and shellfish, plants and microorganisms, as well as their number, speaks of his wealth or poverty. It also depends on the time when it was formed.
Species diversity or richness decreases as one approaches the Earth's poles. The richest flora and fauna is near the equator.
Biocenoses created by man are incomparably poorer than natural ones and require constant additional measures to maintain them. That is, there are natural and artificial biocenoses.
Another interesting fact is that the smaller the size of a living organism, the greater the number of these individuals.
You can distinguish by the scale of the biocenosis or the area it occupies. It can be a forest or a single tree, even a stump, a small meadow or a whole desert, a small lake or ocean.
A particular "biocenosis" includes not only living organisms that constantly exist in it, but also those that are there for some, even a short time. For example, migratory birds, fish that come to spawn, insects that breed in the water, and so on.
Examples characteristic of biocenosis can be given.
On one hectare of land in the Amazon rainforests, up to 400 trees of more than 90 species can grow. While in the temperate zone of the European continent there will be no more than 10 of them, and even less in the taiga - up to 5.
The same is the case with the animal world. In Alaska, species of animals and birds are many times less than in Panama Colombia.
Separation by spatial factor
In space, the biocenosis should be divided into vertical and horizontal.
The first is characterized by layering, that is, how high above the ground the habitat of living organisms is. For vegetation, it is subdivided into tree, shrub, grass and moss-lichen. For insects, the tiers are distributed in the same way as for the inhabitants of the soil: the surface layer of the earth, mosses, herbage and high tier. For animals and birds, the layering is not so clearly demarcated. In the horizontal plane, it has the character of heterogeneity and resembles a mosaic.
The size of the biocenosis and its conditionality
What determines the size of the biocenosis. It can be imagined that these dimensions can be chosen arbitrarily. But do not forget that it is characterized by stability and self-regulation. This indicates the existence of a closed biological chain, which begins with the synthesis of organic matter from inorganic, and ends with the same.
In other words, the plant synthesizes organic matter from solar energy and soil minerals. Animals eat them. Herbivores are eaten by predators, and all the dead are processed by worms and bacteria. re-forming inorganic compounds. The circuit is closed.
This eating of one living organism by another is called a trophic chain.
But there is one extraneous factor involved. - abiotic. The word is again of Greek origin. The prefix "a" in it carries the character of negation. That is, a non-biological factor or, more precisely, a complex of factors and conditions of the inorganic environment that affects a living organism. These are sunlight, temperature, wind, air, precipitation and pressure.
Some of them can be specified. For example: daylight hours and intensity of solar radiation, contamination of soil or water with chemical or toxic substances, droughts or dust storms, underwater depths or atmospheric rarefaction of high mountains, abnormally high or low temperatures.
Such an abiotic environment underlies the creation of a homogeneous space - a biotope, which is occupied by a biocenosis. And, nevertheless, there are no clear boundaries between them, and they pass one into another. In such border zones, the diversity and density of living organisms is much greater. This effect is called edge.
The set of abiotic factors in which a particular biological species lives is called an ecological niche.
Stability and adaptability
The biocenosis has a certain stability, but under the influence of various factors it also adapts and adapts well.
Its stability can be illustrated by the fact that even in the richest of them, all species are few. This also applies to flora and fauna.
Our concept of biocenosis is formed on the basis of its characteristics according to various factors: spatial, temporal, qualitative, quantitative, geographical and origin. But one thing is invariable - it is stable, capable of self-regulation and self-healing.
There is only one "but" if a person does not intervene. Need examples? You are welcome. Agrarian and urban biocenosis. They are artificially created by man, based only on his needs. For the successful cultivation of selected and unusual for this natural zone, plant species, soils are mechanically processed, fertilizers and pesticides are applied, and artificial irrigation is used. If these events cease to be carried out, then it will not be able to exist on its own and will die.
Watch the video: BIOCENOSIS AS A COMMUNITY OF LIVING ORGANISMS.
Biocenosis(from the Greek words bios - life and koinos - general) - a set of plants, animals, fungi, microorganisms that inhabit a certain area of \u200b\u200bland or water - a biotope.
1. The number of individuals of one species, located on the unit the area occupied by the population called...
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2. The desire of the individual individuals animals to freedom of movement on a certain minimum area within the territory, occupied given population called...
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3. Total special territory occupied by the population is called ...
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4. Quantity individuals populations per unit area or volume is called _______ population.
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Biocenosis. Structural organization of biocenosis
Biocenosis, or community, is a historically established set of populations of plants, animals, fungi and microorganisms adapted to cohabitation in a homogeneous area. The adaptability of members of the biocenosis to living together is expressed in a certain similarity of requirements for the most important abiotic environmental conditions (light, temperature, soil acidity, mineral nutrition, etc.) and regular relationships with each other. Communication with other organisms is a necessary condition for nutrition and reproduction, the possibility of protection, mitigation of adverse environmental conditions, etc. An example of a biocenosis is the totality of all living organisms in an oak forest, pine or birch forest, meadow, lake, swamp or pond.
The components of the biocenosis are phytocenosis (a stable community of plant organisms), zoocenosis (a set of interrelated animal species) and microbiocenosis (a community of microorganisms).
An area of the earth's surface (land or water body) with homogeneous living conditions (soil, climate, moisture content, etc.), occupied by one or another biocenosis, is called a biotope (from Gr. topos - place). Biocenosis and biotope together constitute a biogeocenosis. In spatial terms, the biotope corresponds to the biocenosis. The boundaries of the biocenosis are established by the phytocenosis, which has easily recognizable features. For example, pine forests are easy to distinguish from spruce forests, an upland swamp from a lowland one, and so on. In addition, phytocenosis is the main structural component of the biocenosis, since it determines the species composition of zoo- and microbial cenoses.
The formation of a community is carried out due to interspecific relationships that determine the structure, i.e., the orderliness of the structure of the biocenosis. There are species, spatial and trophic structure of the biocenosis.
The species structure of a biocenosis is understood as the diversity of species in it and the ratio of the abundance or biomass of all its constituent populations. The species of organisms have different requirements for the environment, therefore, in different environmental conditions, an unequal species composition is formed. If the biological features of a species differ sharply from the ecology of other species, then this species, due to competition for means of subsistence, falls out of the community and enters another biocenosis corresponding to it. In other words, in each biocenosis there is a natural selection of organisms most adapted to given environmental conditions.
There are poor and species-rich biocenoses. In polar ice and tundra with extreme heat deficiency, in waterless hot deserts, in reservoirs heavily polluted with sewage, communities are extremely poor in species, since only a few of them can adapt to such unfavorable conditions. Conversely, in those biotopes where the conditions of the abiotic environment are close to optimal for life, communities that are extremely rich in species appear. Examples of them are tropical rainforests, complex oak forests, floodplain meadows. Species-rich natural communities include thousands and even tens of thousands of species.
The species composition of biocenoses also depends on the duration of their existence. Young emerging communities usually include a smaller number of species than long-established, mature ones.
Species that prevail in the biocenosis in terms of numbers are called dominant. However, not all dominant species equally affect the biocenosis. Among them are those that, by their vital activity, to the greatest extent create an environment for the entire community. Such species are called edificators (creators, community builders). The main edificators of terrestrial biocenoses are certain types of plants: in forests - spruce, oak; in the steppes - feather grass, fescue; in lowland swamps - sedges; on raised bogs - sphagnum moss. In some cases, animals can also be edificators. For example, in territories occupied by marmot colonies, it is their activity that mainly determines the nature of the landscape, the microclimate, and the conditions for the growth of grasses.
In addition to a relatively small number of dominant species, the biocenosis usually includes many small and even rare forms that are very important for the life of any community. They create its species richness, increase the diversity of biocenotic relationships and serve as a reserve for replenishment and replacement of dominants, that is, they give stability to the biocenosis and ensure its functioning in different conditions. Therefore, the higher the species diversity, the more stable the biocenosis.
To assess the role of an individual species in the species structure of the biocenosis, indicators such as abundance, projection coverage, occurrence, biomass, etc. are used. Abundance is the number of individuals of each species per unit area or volume of occupied space.
What is a biocenosis is in biology: classification and types
It is expressed in units/m2, units/ha or in points. Sometimes the value of biomass is used to calculate the abundance of a species. The frequency of occurrence characterizes the uniformity of the species distribution in the biocenosis. It is calculated as a percentage of the number of samples or census sites where the species occurs to the total number of such samples or sites. The number and occurrence of the species are not directly related. A species can be numerous, but with low occurrence, or small, but occurring quite often. For phytocenoses, a very important analytical feature is the projection coverage - the absolute or relative area of the projection of the terrestrial parts of plants onto the soil; expressed as a percentage.
Spatial structure of biocenosis determined primarily by the addition of phytocenosis. As a rule, phytocenoses are divided into fairly well delimited in space (vertically and horizontally), and sometimes in time, structural elements, or price elements. The main price elements include tiers and microgroups (microcenoses, parcels, etc.). The former characterize the vertical, the latter - the horizontal division of phytocenoses. The main factor that determines the vertical distribution of plants in ground layers is the amount of light. Plants of the upper tiers are more photophilous than undersized ones, they are better adapted to fluctuations in temperature and air humidity; the lower tiers are formed by plants that are less demanding of light. In turn, the herbaceous cover of the forest, as a result of the death of leaves, stems, roots, is involved in the process of soil formation and thereby affects the plants of the upper tier.
Layers are especially visible in temperate forests. For example, in a broad-leaved forest, 5-6 tiers can be distinguished: the first (upper) tier is formed by trees of the first size (pedunculate oak, heart-shaped linden, smooth elm, etc.); the second - trees of the second size (common mountain ash, wild apple and pear, bird cherry, etc.); the third tier is undergrowth formed by shrubs (common hazel, brittle buckthorn, European spindle tree, etc.); the fourth consists of tall grasses (forest chistets, nettle, common gout) and shrubs (blueberries); the fifth tier is composed of low grasses (hairy sedge, European hoof); in the sixth tier - mosses and lichens.
This shows that in the lower tier, where only 7-10% of the light penetrates, only shade-tolerant shrubs and grasses can grow. Many of them are characterized by such an adaptive morphological feature of "shadow" plants as a wide and thin leaf blade, which allows plants to increase the illuminated surface and thereby to some extent compensate for the lack of light. The internal structure of the leaves also serves the same purpose: they do not have a dense columnar parenchyma, the cells are located loosely, with large intercellular spaces; all this facilitates the penetration of light into the sheet.
The dark color of the leaves, associated with a high content of chlorophyll in shade-tolerant plants, helps to increase the absorption of light. Thus, the chloroplasts of hoof, goutweed, lungwort and other plants contain 5-10 times more green pigments than herbaceous plants in open areas.
The life process of forest grasses is also facilitated by a peculiar seasonal rhythm of photosynthesis: the main photosynthetic work is done in them at the beginning of the growing season, in the early spring period, when the leaves on the trees are just beginning to bloom and it is still quite light in the forest, there are large moisture reserves in the soil, and the temperature background is already quite summer. During this period, ephemera and ephemeroids, respectively, annual and perennial plants with a short growing season (30-50 days) form the main reserves of organic matter in underground organs, due to which they then live the rest of the year. Such are the species of the genus Corydalis, bear's onion (ramson), chistyak, ranunculus anemone, etc. Therefore, this spring peak of the photosynthetic activity of forest grasses is a seasonal adaptation that ensures their shade tolerance, the possibility of growth in the most shaded parts of the forest.
Animals are also predominantly confined to one or another layer of vegetation. For example, among birds there are species that nest only on the ground (pheasants, black grouse, wagtails, pipits, buntings), in the shrub layer (thrushes, warblers, bullfinches) or in tree crowns (finches, goldfinches, kinglets, large predators, etc.) .
Underground layering of phytocenoses, as a rule, is absent. Determined that. with very rare exceptions, the total mass of underground organs naturally decreases from top to bottom. Especially significant is the decrease in the number of small sucking roots, the bulk of which is confined to the upper soil horizon. Such a distribution of the active part of the roots is associated with the formation in the surface horizons of the soil of the largest number of forms of mineral nutrients available to plants, and primarily nitrogen. In a number of cases, deterioration (from top to bottom) of aeration conditions plays a role. Therefore, even deep-rooted plants use the surface horizon of the soil in which they form permanent or temporary roots. The proof of the absence of underground layers is the confinement to the same soil horizon of the assimilating roots of the superficially rooting common oxalis and the more deeply rooted spruce.
Dissection (heterogeneity) in the horizontal direction - mosaic - is characteristic of almost all biocenoses. Mosaic is expressed by the presence of various microgroups in the composition of the biocenosis, which differ in species composition, quantitative ratio of different species, density, productivity and other properties.
The uneven distribution of species of living organisms within the biocenosis and the mosaicism associated with this are due to a number of reasons: the peculiarities of the biology of reproduction and the form of plant growth, the heterogeneity of soil conditions (the presence of depressions and elevations), the environment-forming influence of plants, etc. Mosaicism can arise as a result of animal activity ( formation of anthills, trampling of the grass stand by ungulates, etc.) or a person (selective logging, campfires, etc.).
basis trophic (food) structure of biocenosis make up intertwining trophic chains, or food chains.
The term "Biocenosis" was proposed by the German biologist K. Möbius (1877). Biocenosis is a dialectically developing unity that changes as a result of the activity of its components, as a result of which a natural change and change of Biocenosis (succession) occur, which can lead to the restoration of sharply disturbed Biocenoses (for example, forests after a fire, etc.) In the biogenic cycle of substances in the biocenosis, three groups of organisms are distinguished. 1) Producers (manufacturers) - autotrophic organisms that create organic substances from inorganic ones; the main producers in all biocenoses are green plants (see.
§ 5. Biocenosis. Diversity of biocenoses General biology: Textbook for grade 11
Biocenosis is characterized by division into smaller subordinate units - merocenoses, i.e. regularly formed complexes that depend on the biocenosis as a whole (for example, a complex of inhabitants of rotting oak stumps in an oak forest). If the energy source of the Biocenosis is not autotrophs, but animals (for example, bats in the Biocenosis of caves), then such Biocenoses depend on the influx of energy from the outside and are inferior, representing in essence merocenoses. In the Biocenosis, other subordinate groups of organisms can be distinguished, for example, sinusia. Biocenosis is also characterized by a division into vertical groupings of organisms (tiers Biocenosis). In the annual cycle in the Biocenosis, the abundance, stages of development and activity of individual species change, regular seasonal aspects are created Biocenosis
The study of biocenosis is important for the rational development of lands and water spaces, because Only a correct understanding of the regulatory processes in the Biocenosis allows a person to withdraw part of the Biocenosis production without disturbing and destroying it.
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Global environmental problems, causes and consequences
In this essay, we will consider one of the most relevant and exciting topics today. The problem of pollution of the natural environment is becoming so acute as due to the volume of …
Melting in plasma-arc furnaces with a ceramic crucible Essence of ecological expertise. Types of environmental control BIOCENOSIS, a set of organisms - populations of plants, animals, fungi, microorganisms that inhabit a homogeneous area of \u200b\u200bland or water and are characterized by certain relationships (food chains, symbiosis, etc.) and adaptability to environmental conditions. Each group of organisms occupies a certain stage of the ecological pyramid in the biocenosis (producers, consumers and decomposers). Examples of biocenoses can serve as a set of organisms of a pond, oak forest, pine or birch forest, etc. In many cases, the boundaries of biocenoses are blurred and conditional: for example, oak forest, pine or birch forest gradually pass through the edge, respectively, into a dry meadow, mixed pine-spruce forest, swamp. Biocenoses, developing, either self-renew (a new generation of pine trees grows in a pine forest), or grow old and are replaced by other biocenoses (pine is replaced by a spruce forest, a pond becomes swampy, etc.), as a result, some changes may occur in the abiotic environment (illumination, humidity , heat, etc.). The most complex and stable are biocenoses with a high biological diversity of organisms. In the ocean, these are biocenoses of coral reefs and algal shallow waters. On land - tropical forest biocenoses and temperate forest biocenoses. Thus, an oak forest can be formed by more than 100 species of plants, several thousand animal species, hundreds of species of fungi and microorganisms, which together give a population density of tens and hundreds of thousands of organisms per 1 m. At the same time, the dry biomass of an oak forest is 4–5 kg / m , and biological productivity - 1.5 kg / m per year. Biocenosis is a functional part of a more complex system - biogeocenosis. The most important quantitative indicators of biocenoses are biodiversity (the total number of species in it) and biomass (the total mass of all types of living organisms in a given biocenosis). Biodiversity is responsible for the equilibrium state of the ecosystem, and, consequently, for its sustainability. A closed cycle of nutrients (biogens) occurs only due to biological diversity. Substances that are not assimilated by some organisms are assimilated by others, so the output of biogens from the ecosystem is small, and their constant presence ensures the balance of the ecosystem. The term (German Biocönose) was introduced by Karl Möbius in the 1877 book "Die Auster und die Austernwirthschaft" to describe all organisms that inhabit a certain area (biotope) and their relationships. Types of structures of the biocenosis: species, spatial (vertical (tiered) and horizontal (mosaic) organization of the biocenosis) and trophic. Groups of organisms of different sizes live in a biocenosis at different scales of space and time. For example, the life cycles of unicellular organisms can take place within an hour, while the life cycles of large plants and animals stretch for decades. Biotopes are characterized by a certain species diversity - a set of populations that make up it. The number of species depends on the duration of existence, climate resistance, productivity of the type of biocenosis (desert, tropical forest). The number of individuals of different species varies, etc. The most numerous species of biotopes are called dominant. When studying large biotopes, it is impossible to determine the entire species diversity. For study, the number of species from a certain territory (area) is determined - species richness. The species diversity of different biocenoses is compared in terms of species richness from the same area. The species structure gives an idea of the qualitative composition of the biocenosis. When two species exist together in a homogeneous environment under constant conditions, one of them is completely replaced by the other. There are competitive relationships. On the basis of such observations, the principle of competitive exclusion, or the Gause principle, was formulated. Human activity greatly reduces the diversity in natural communities, which requires forecasts and foresight of its consequences, as well as effective measures to maintain natural systems. Biocenosis is an organized group of interconnected populations of plants, animals, fungi and microorganisms living together in the same environmental conditions. In the biocenosis, autotrophic and heterotrophic components can be distinguished. The concept of "biocenosis" was proposed by the German zoologist Möbius in 1877. Studying oyster banks, he came to the conclusion that each of them is a community of closely interconnected living organisms that respond to environmental changes. A biocenosis cannot exist independently of the environment, therefore certain complexes of living and non-living components, mutually adapted, are formed in nature. The space inhabited by one or another community of organisms (biocenosis), with more or less homogeneous conditions, is called a biotope. The main characteristics of the biocenosis: List of species - species diversity; Diversity is the number of species per unit area; Evenness - characterizes which species is represented as (extreme evenness - each species is represented by the same number of individuals); Under more favorable conditions, diversity increases, but the representation of each species decreases and vice versa. The abundance of a species is the number of individuals of a species per unit area or volume. For example, the Drude scale (eye assessment), scoring - from complete absence to great abundance. Constancy - is determined by the occurrence of the species in different samples. If the species occurs in more than 50% of the samples - permanent; if in 25-50% - an additional view; less than 25% - random. Permanent species determine the structure of the biocenosis. Dominance. The dominant species is the species that determines the entire life of the biocenosis, the leader. The principle of dominance was formed by Ramensky in geobotany. He showed that there are species that determine the entire life of the community. The basis of the biocenosis is interspecific relationships. They determine the entire life of the community, the fate of the species in the structure of other species. The adaptability of the members of the biocenosis to living together is expressed in a certain similarity of their requirements for the most important abiotic environmental conditions (illumination, the nature of soil and air moisture, thermal conditions, etc.) and in regular relationships with each other. Communication between organisms is necessary for their nutrition, reproduction, resettlement, protection, etc. However, it also contains a certain threat and even a danger to the existence of one or another individual. Biotic environmental factors, on the one hand, weaken the organism, on the other hand, they form the basis of natural selection, the most important factor in speciation. The scales of biocenotic groupings of organisms (biocenoses) are different - from communities on a tree trunk, in a hole or on a swamp tussock (they are called microcommunities) to the population of an oak forest, pine or spruce forest, meadow, lake, swamp or pond. There is no fundamental difference between biocenoses of different scales, since small communities are an integral part of larger ones, which are characterized by an increase in complexity and the proportion of indirect relationships between species. The components of the biocenosis are phytocenosis (a stable community of plants), zoocenosis (a set of interrelated animal species), mycocenosis (a community of fungi) and microbiocenosis (a community of microorganisms). Biogeocenosis and ecosystem are similar concepts, but not identical. The concept of "ecosystem" has no rank and dimension, therefore it is applicable both to simple (anthill, rotting stump) and artificial (aquarium, reservoir, park), and to complex natural complexes of organisms with their habitat. Biogeocenosis, according to the Russian scientist V.N. Sukachev, differs from the ecosystem in the certainty of volume. If an ecosystem can cover a space of any length. - from a drop of pond water with microorganisms contained in it to the biosphere as a whole, then biogeocenosis is an ecosystem whose boundaries are determined by the nature of the vegetation cover, i.e. a certain phytocenosis. Therefore, any biogeocenosis is an ecosystem, but not every ecosystem is a biogeocenosis.
Melting in Plasma Arc Furnaces - Furnaces of this type are, with respect to their design, a modification of conventional arc steel furnaces.
The basis of the Russian system of environmental assessment is environmental expertise and environmental impact assessment (EIA), as well as the harmonization of applied approaches with international …Biocenosis
The meaning of the word "biocenosis"
