The species structure of the forest biocenosis is characterized. The concept of biocenosis. Species and trophic structure of biocenoses. Artificial biological systems

What are biocenoses

Groups of co-living and mutually related organisms are calledbiocenoses. The adaptability of members of a biocenosis to living together is expressed in a certain similarity of requirements for the most important abiotic environmental conditions and natural relationships with each other.

The term “biocenosis” is more often used in relation to the population of territorial areas that are distinguished on land by relatively homogeneous vegetation (usually along the boundaries of plant associations), for example, the biocenosis of spruce-sorrel forest, the biocenosis of upland meadow, white moss pine forest, the biocenosis of feather grass steppe, wheat field, etc. ). This refers to the entire set of living beings - plants, animals, microorganisms, adapted to living together in a given territory. In the aquatic environment, biocenoses are distinguished that correspond to the ecological divisions of parts of reservoirs, for example, biocenoses of coastal pebble, sandy or silty soils, and abyssal depths.

STRUCTURE OF BIOCENOSIS

1.Species structure of the biocenosis.

Under species structure biocenosis understand the diversity of species in it and the ratio of their numbers or mass. There are species-poor and species-rich biocenoses. In polar arctic deserts and northern tundras with extreme heat deficiency, in waterless hot deserts, in reservoirs heavily polluted by sewage, wherever one or several environmental factors deviate far from the average optimal level for life, communities are greatly impoverished, since only few species can adapt to such extreme conditions. Wherever abiotic conditions approach the average optimum for life, extremely species-rich communities emerge. Examples of these include tropical forests, coral reefs with their diverse populations, river valleys in arid dry regions, etc.

The species composition of biocenoses, in addition, depends on the duration of their existence. Young, just emerging communities usually include a smaller set of species than long-established, mature ones. Biocenoses created by humans (fields, vegetable gardens, orchards) are also poorer in species than similar natural systems (forest, steppe, meadow. However, even the most impoverished biocenoses include at least several dozen species of organisms belonging to different systematic and ecological groups.

In some conditions, biocenoses are formed in which there are no plants (for example, in caves or reservoirs below the photic zone), and in exceptional cases, consisting only of microorganisms (in an anaerobic environment, at the bottom of a reservoir, in rotting sludge). Species-rich natural communities include thousands and even tens of thousands of species, united by a complex system of relationships.

The influence of a variety of conditions on the diversity of species is manifested, for example, in the so-called "borderline", or edge , effect. It is well known that on the edges the vegetation is usually lush and richer, more species of birds nest, more species of insects, spiders, etc. are found than in the depths of the forest. The conditions of illumination, humidity, and temperature are more varied here. The stronger the differences between two neighboring biotypes, the more heterogeneous the conditions at their boundaries and the stronger the border effect. Species richness increases greatly in places of contact between forest herbaceous, aquatic and land communities, etc.

The species that predominate in numbers are dominants communities. For example, in our spruce forests, spruce dominates among the trees, wood sorrel and other species dominate in the grass cover, wood oxalis and other species dominate in the bird population, kinglets, robin, and chiffchaffs dominate among the mouse-like rodents, bank voles and red-gray voles, etc. However, not all dominant species equally influence the biocenosis. Among them, those stand out that, through their vital activity, to the greatest extent create the environment for the entire community and without which, therefore, the existence of most other species is impossible. Such species are called edifiers. The main edificators of terrestrial biocenoses are certain types of plants: in spruce forests - spruce, in pine forests - pine, in the steppes - turf grasses (feather grass, fescue, etc.). In some cases, animals can also be edificators. For example, in territories occupied by marmot colonies, it is their digging activity that mainly determines the nature of the landscape, microclimate, and plant growth conditions.

In addition to a relatively small number of dominant species, biocenoses include many small and rare forms. They create its species richness, increase the diversity of biocenotic connections and serve as a reserve for the replenishment and replacement of dominants, i.e. give the biocenosis stability and ensure the reliability of its functioning in different conditions. The greater the reserve of such minor species in a community, the greater the likelihood that among them there will be those that can play the role of dominants in the event of any changes in the environment.

The more specific the environmental conditions, the poorer the species composition of the community and the higher the number individual species. In the richest biocenoses, almost all species are small in number.

The diversity of a biocenosis is closely related to its stability: the higher the species diversity, the more stable the biocenosis . Human activity greatly reduces diversity in natural communities.

2. Spatial structure .

The spatial structure of the biocenosis is determined first
in total, the composition of its plant part - phytocenosis, the distribution of above-ground and underground plant masses. Phytocenosis often acquires a clear longline addition : The assimilating above-ground plant organs and their underground parts are arranged in several layers, using and changing the environment in different ways. Layering is especially noticeable in temperate forests. For example, in spruce forests the tree, herb-shrub and moss layers are clearly distinguished. 5-6 tiers can be distinguished in a broad-leaved forest: the first, or upper, tier is formed by trees of the first size (pedunculate oak, cordate linden, sycamore maple, smooth elm, etc.); the second - trees of the second size (common mountain ash, wild apple and pear trees, bird cherry, goat willow, etc.); the third tier is the undergrowth formed by shrubs (common hazel, brittle buckthorn, forest honeysuckle, European euonymus, etc.); the fourth consists of tall grasses (borets, spreading boron, forest chist, etc.); the fifth tier is made up of lower herbs (common sedge, hairy sedge, perennial grass, etc.); in the sixth tier - the lowest grasses, such as European hoofed grass.

In forests there are always inter-tiered (extra-tiered) plants - these are algae and lichens on the trunks and branches of trees, higher spore-bearing and flowering epiphytes, lianas, etc. Layering allows plants to more fully use the light flux: under the canopy tall plants Shade-tolerant, even shade-loving, can exist, intercepting even weak sunlight. Vegetation layers can be of different lengths: the tree layer, for example, is several meters thick, and the grass cover is only a few centimeters thick. Each tier participates in the creation of phytoclimate in its own way and is adapted to a certain set of conditions.

The underground layering of phytocenoses is associated with different rooting depths of the plants included in their composition, with the placement of the active part of the root systems. In forests you can often observe several (up to six) underground tiers.

Dismemberment in the horizontal direction is mosaic. Mosaic due to a number of reasons: heterogeneity of microrelief, soils, environment-forming influence of plants and their environmental features. It can arise as a result of animal activity (formation of soil emissions and their subsequent overgrowing, formation of anthills, trampling and eating of grass by ungulates, etc.) or humans (selective felling, fire pits, etc.), due to tree fallouts during hurricanes, etc. Changes in the environment under the influence of the vital activity of individual plant species create the so-called phytogenic mosaic.

3. Ecological structure of the biocenosis.

Different types of biocenoses are characterized by a certain ratio of ecological groups of organisms, which expresses the ecological stricture of the community. Biocenoses with similar ecological structures may have different species composition, since in them the same ecological niches can be occupied by species that are similar in ecology, but are far from related. Such types that perform the same , functions in similar biocenoses are called vicarious. For example, the same ecological niche - bison on the prairies North America, antelopes in the savannas of Africa, wild horses and kulans in the steppes of Asia. The ecological structure of biocenoses that develop in certain climatic and landscape conditions is strictly natural. For example, in biocenoses of different natural zones the ratio of phytophages and saprophages naturally changes. In steppe, semi-desert and desert areas, animal phytophages predominate over saprophages; in forest communities of the temperate zone, on the contrary, saprophagy is more developed. The main type of feeding of animals in the depths of the ocean is predation , whereas in the illuminated, surface zone of the pelagic there are many filter feeders that consume phytoplankton or species with a mixed feeding pattern.

The ecological structure of communities is also reflected by the ratio of such groups of organisms as hygrophytes, mesophytes and xerophytes among plants or hygrophiles, mesophylls and xerophytes among animals. It is quite natural that in dry arid conditions the vegetation is characterized by a predominance of sclerophytes and succulents, while in highly moist biotopes hygro- and even hydrophytes are more abundant.

The relationship of organisms in the biocenosisX.

The basis for the emergence and existence of biocenoses is the relationship of organisms, their connections into which they enter into each other, inhabiting the same biotope. These connections determine the basic living conditions of species in a community, the possibilities of obtaining food and conquering new space.

1.Trophic connections occur when one species feeds on another gim-either living individuals, or their dead remains, or waste products. Dragonflies that catch other insects in flight, dung beetles that feed on the droppings of large ungulates, and bees that collect plant nectar enter into a direct trophic relationship with species that provide food. In the case of competition between two species over food objects, an indirect trophic relationship arises between them, since the activity of one affects the food supply of the other. Any effect of one species on the eatability of another or the availability of food for it should be regarded as an indirect trophic relationship between them. For example, caterpillars of nun butterflies, eating pine needles, make it easier for bark beetles to gain access to weakened trees.

Topical and trophic connections have highest value in the biocenosis, form the basis of its existence. It is these types of relationships that keep organisms close to each other different types, uniting them into fairly stable communities of different scales.

3. Phoric connections. This is the participation of one species in the spread of another. Animals act as transporters. The transfer of seeds, spores, and plant pollen by animals is called zoochory; the transfer of other smaller animals is called zoochory. phoresia. Animals can capture plant seeds in two ways: passive and active. Passive capture occurs when an animal's body accidentally comes into contact with a plant, the seeds or infructescences of which have special hooks, hooks, and outgrowths (straw, burdock). The active method of capture is eating fruits and berries. Animals excrete seeds that cannot be digested along with their droppings. Animal phoresia is common mainly among small arthropods, especially in various groups of mites. It is one of the methods of passive dispersal and is characteristic of species for which transfer from one biotope to another is vital for preservation or prosperity. Dung beetles sometimes crawl with raised elytra, which they are unable to fold due to mites densely littering their bodies. Among large animals, phoresia is almost never found.

4. Factory connections . This is a type of biocenotic relationship into which a species enters, using excretory products, either dead remains, or even living individuals of another species for its constructions (fabrication). So birds use tree branches, mammal fur, grass, leaves, down and feathers of other bird species, etc. to build nests. The megachila bee places eggs and supplies in cups constructed from the soft leaves of various shrubs (rose hips, lilac, acacia, etc.).

Each biocenosis can be described based on the totality of its constituent species, which make up species structure of the biocenosis. Some biocenoses are composed primarily of animal species, such as the biocenosis of a coral reef. In other biocenoses - forests - the main role is played by plants: the biocenosis of spruce, birch, and oak forests. The number of species (species diversity) in different biocenoses is different and depends on their geographical location. It has been established that it decreases from the tropics towards high latitudes, which is explained by the deterioration of living conditions of organisms.

The most well-known pattern of changes in species diversity is its decrease from the tropics towards high latitudes. Moreover, this applies to all groups of terrestrial and aquatic organisms, ranging from bivalves, ants and flying insects to reptiles, birds, and trees.

For example, in tropical rainforests in Malaysia, on 1 hectare of forest you can count up to 200 species of tree species. The biocenosis of a pine forest in the conditions of Belarus can include a maximum of ten species of trees per 1 hectare, and in the north of the taiga region there are 2-5 species on the same area. The poorest biocenoses in terms of the set of species are alpine and arctic deserts, the richest are tropical forests. True, there are some exceptions. Penguins and seals of the polar regions are the most diverse here. However, in the tropics there are much more such groups of animals that are not found in higher latitudes.

The simplest indicator of the species diversity of a biocenosis is the total number of species - species richness. If any species of plant (or animal) quantitatively predominates in a community (has greater biomass, productivity, number or abundance), then this species is called dominant , or dominant species .

There are dominant species in any biocenosis. In an oak grove, powerful oaks, using the bulk of solar energy, increase the greatest biomass, shade the soil, weaken air movement and create a lot of amenities for the lives of other forest inhabitants.

However, in addition to oak trees, the oak grove is home to a large number of other organisms. For example, the earthworm living here constantly improves the physical and chemical conditions of the soil by passing particles of dead plants and fallen leaves through its digestive system. The oak and the worm make their own special contribution to the life of the biocenosis, however, despite the fact that the role of the worm is important, the role of the oak is decisive, since the entire life of the oak forest is determined by this tree species and the plants associated with it. Therefore, it is the oak that is the dominant species in such a forest.

Species can be distributed differently in space according to their needs and habitat conditions.

This distribution of species that make up the biocenosis in space is called spatial structure of the biocenosis. The problem of determining the spatial structure of a biocenosis boils down in general terms to dividing it into different intracenosis parts and clarifying their nature, their connections and the degree of their dependence on each other and on environmental conditions.

There are vertical and horizontal structures of the biocenosis.

Vertical structure of biocenosis formed by its individual elements, special layers called tiers. Tier- co-growing groups of plant species that differ 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. So, the first tier here is usually formed by tall trees with high-mounted foliage, which is well illuminated by the sun. Unused light can be absorbed by smaller trees that form a second sub-canopy layer. The remaining about 10% of solar radiation is intercepted by the undergrowth layer. These are various shrubs. The remaining light - from 1 to 5% is used by plants of the grass cover (herb-shrub layer). The ground layer of mosses and lichens forms the moss-lichen layer. So, schematically, 5 tiers can be distinguished in the forest biocenosis.

Layering is also characteristic of the underground parts of plants. Such tiers are distinguished by the depth of the suction parts of the roots. Tiering in the underground part of the biocenosis contributes to a more productive use of water and minerals in different soil horizons. Thanks to this, a large number of plants can live in the same area. Underground tiers are not always easy to identify, since the bulk of the roots fall on the topmost layer of soil, up to 20-30 centimeters deep. However, nevertheless, it is often possible to distinguish 2-3, or even more underground tiers.

Similar to the distribution of vegetation by tiers, in biocenoses different species of animals also occupy certain levels.

Soil worms, microorganisms, and digging animals live in the soil. Various centipedes, ground beetles, mites and other small animals live in leaf litter and on the soil surface. Birds nest in the upper canopy of the forest, and some can feed and nest below the upper tier, others in bushes, and others near the ground. Large mammals live in the lower tiers.

Tiers are also inherent in the biocenoses of the ocean and seas. Different types of plankton stay at different depths, depending on the lighting. Also, different types of fish live at different depths, depending on where they find food.

Individuals of living organisms are distributed unevenly in space. Usually they form groups 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 of species that form various kinds of patterning and spotting of each species.

There are many examples of such a distribution. These are numerous herds of zebras, antelopes, elephants in the savannah, colonies of corals on seabed, schools of sea fish, flocks of migratory birds.

The same examples can be given for plants: thickets of reeds and aquatic plants, accumulations of mosses and lichens on the soil in a forest biocenosis, patches of heather or lingonberries in the forest.

The presence of horizontal elements of the biocenosis, mosaic, is quite important for the life of the community. Mosaic allows for more complete use Various types microhabitats. Individuals forming groups are characterized by high survival rates and use food resources most efficiently.

This leads to an increase and diversity of species in the biocenosis, contributes to its stability and vitality.

The elementary units of the horizontal structure of plant communities include such structural units as microcenosis and microgrouping.

Microcenosis(from the Greek “micros” - small and “koinos” - general) - 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.

Microgroup- Condensation of individuals of one or more species within a tier, intra-tier mosaic spots. For example, in the moss layer, various moss patches with dominance of one or several species can be distinguished. In the herb-shrub layer, microgroups of bilberry, bilberry-oxalis, blueberry-sphagnum, etc. can be distinguished.

The presence of mosaics is quite important for the life of the community. Mosaicism allows for more complete use of different types of microhabitats. Individuals forming groups are characterized by high survival rates and use food resources most efficiently. This leads to an increase and diversity of species in the biocenosis, contributing to its stability and viability.

There are concepts of “species richness” and “species diversity” of biocenoses. Species richness is a general set of community species, which is expressed by lists 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 species-poor and species-rich biocenoses. In polar arctic deserts and northern tundras with extreme heat deficiency, in waterless hot deserts, in reservoirs heavily polluted by sewage - wherever one or several environmental factors deviate far from the average optimal level for life, communities are greatly impoverished, since few species can adapt to such extreme conditions. The species spectrum is also small in those biocenoses that are often subject to some catastrophic impacts, for example, annual flooding due to river floods or regular destruction of plant cover during plowing, the use of herbicides and other anthropogenic interventions. Conversely, wherever abiotic conditions approach the average optimum for life, extremely species-rich communities emerge. Examples of these include tropical forests, coral reefs with their diverse populations, river valleys in arid regions, etc.

The species composition of biocenoses, in addition, depends on the duration of their existence and the history of each biocenosis. Young, just emerging communities usually include a smaller set of species than long-established, mature ones. Biocenoses created by humans (fields, gardens, orchards) are also poorer in species than similar natural systems (forests, steppes, meadows). Man maintains the monotony and species poverty of agrocenoses with a special complex system of agrotechnical measures - just remember the fight against weeds and plant pests.

However, even the most impoverished biocenoses include at least hundreds of species of organisms belonging to different systematic and ecological groups. The agrocenosis of a wheat field, in addition to wheat, includes, at least in minimal quantities, various weeds, insect pests of wheat and predators that feed on phytophages, mouse-like rodents, invertebrates - inhabitants of the soil and ground layer, microscopic organisms of the rhizosphere, pathogenic fungi and many others.

Almost all terrestrial and most aquatic biocenoses include microorganisms, plants, and animals. However, in some conditions, biocenoses are formed in which there are no plants (for example, in caves or reservoirs below the photic zone), and in exceptional cases, consisting only of microorganisms (for example, in an anaerobic environment at the bottom of reservoirs, in rotting sludge, hydrogen sulfide springs, etc. . P.).

It is quite difficult to calculate the total number of species in a biocenosis due to methodological difficulties in recording microscopic organisms and the lack of development of taxonomy for many groups. It is clear, however, that species-rich natural communities include thousands and even tens of thousands of species, united by a complex system of diverse relationships.

The complexity of the species composition of communities largely depends on the heterogeneity of the habitat. In such habitats, where species with different ecological requirements can find conditions for themselves, communities richer in flora and fauna are formed. The influence of a variety of conditions on the diversity of species is manifested, for example, in the so-called border, or edge, effect. It is well known that on the edges the vegetation is usually lush and richer, more species of birds nest, more species of insects, spiders, etc. are found than in the depths of the forest. The conditions of illumination, humidity, and temperature are more varied here. The stronger the differences between two neighboring biotopes, the more heterogeneous the conditions at their boundaries and the stronger the border effect. Species richness increases greatly in places of contact between forest and herbaceous, aquatic and land communities, etc. The manifestation of the boundary effect is characteristic of the flora and fauna of intermediate zones between contrasting natural zones (forest-tundra, forest-steppe). The exceptional species richness of the flora of the European forest-steppe V.V. Alekhin (1882–1946) figuratively called the “Kursk floristic anomaly.”

In addition to the number of species included in the biocenosis, to characterize its species structure it is important to determine their quantitative ratio. If we compare, for example, two hypothetical groups, including 100 individuals of five identical species, from a biocenotic point of view they may turn out to be unequal. A group in which 96 out of 100 individuals belong to one species and one individual each belongs to four others looks much more uniform than one in which all 5 species are represented equally - 20 individuals each.

Number of a given group of organisms in biocenoses strongly depends on their size. The smaller the individuals of a species, the higher their numbers in biotopes. So, for example, in soils the abundance of protozoa amounts to many tens of billions per square meter, nematodes - several millions, mites and springtails - tens or hundreds of thousands, earthworms - tens or hundreds of individuals. The number of burrowing vertebrates - mouse-like rodents, moles, shrews is no longer calculated per square meters, but per hectares of area.

Dimension species that make up natural biocenoses vary on a gigantic scale. For example, whales are 5 million times longer than bacteria and 3 × 10 20 in volume. Even within individual systematic groups, such differences are very large: if you compare, for example, giant trees and small grasses in the forest, tiny shrews and large mammals - elk, brown bear, etc. Different-sized groups of organisms live in biocenoses at different spatial scales and time. For example, the life cycles of single-celled organisms can take place within an hour, while the life cycles of large plants and animals extend over tens of years. The living space of an insect such as a gall midge may be limited to a closed gall on one leaf of a plant, while larger insects - bees - collect nectar within a radius of a kilometer or more. Reindeer regularly migrate over hundreds and even more than a thousand kilometers. Some migratory birds live in both hemispheres of the Earth, covering tens of thousands of kilometers annually. On the one hand, natural biocenoses represent the coexistence of different sized worlds, and on the other hand, the closest connections are made in them precisely among organisms of different sizes.

Naturally, in all biocenoses the smallest forms – bacteria and other microorganisms – predominate numerically. Therefore, when comparing species of different sizes, the indicator of dominance in numbers cannot reflect the characteristics of the community. It is calculated not for the community as a whole, but for individual groups, within which the difference in the sizes of individual forms can be neglected. Such groups can be distinguished according to various characteristics: systematic (birds, insects, cereals, asteraceae), ecological-morphological (trees, grasses) or directly according to size (microfauna, mesofauna and macrofauna of soils, microorganisms in general, etc.). By comparing the general characteristics of diversity, quantitative ratios of the most abundant species within different size groups, the abundance of rare forms and other indicators, one can obtain a satisfactory idea of the specifics of the species structure of the compared biocenoses.

Species of the same size class that are part of the same biocenosis vary greatly in abundance (Fig. 76). Some of them are rare, others are so common that they determine the appearance of the biocenosis, for example, feather grass in the feather grass steppe or wood sorrel in a spruce-sorrel forest. In each community, one can distinguish a group of main species, the most numerous in each size class, the connections between which, in essence, are decisive for the functioning of the biocenosis as a whole.

The species that predominate in numbers are dominants communities. For example, in our spruce forests, spruce dominates among the trees, wood sorrel and other species dominate in the grass cover, the kinglet, robin, and chiffchaff dominate the bird population, bank voles and red-gray voles dominate among mouse-like rodents, etc.

Dominants dominate the community and form the “species core” of any biocenosis (Fig. 77). Dominant, or mass, species determine its appearance, maintain the main connections, and have the greatest influence on the habitat. Typically, typical terrestrial biocenoses are named by their dominant plant species: pine-blueberry, birch-sedge, etc. Each of them is dominated by certain species of animals, fungi and microorganisms.

Rice. 76. The relationship between the number of species in a community and the number of individuals per species (according to Yu. Odum, 1975): 1, 2 – different types of communities

Rice. 77. Species structure of the springtail community over 5 years (according to N.A. Kuznetsova, A.B. Babenko, 1985).

The total species richness is 72 species. Dominants: 1 – Isotoma notabilis; 2 – Folsomia fimetarioides; 3 – Sphaeridia pumilis; 4 – Isotomiella minor; 5 – Friesea mirabilis; 6 – Onychiurus absoloni; 7 – other types

However, not all dominant species have the same effect on the biocenosis. Among them, those stand out that, through their vital activity, to the greatest extent create the environment for the entire community and without which, therefore, the existence of most other species is impossible. Such species are called edifiers (literal translation from Latin - builders). Removal of an edificator species from a biocenosis usually causes a change in the physical environment, primarily the microclimate of the biotope.

The main edificators of terrestrial biocenoses are certain types of plants: in spruce forests - spruce, in pine forests - pine, in the steppes - turf grasses (feather grass, fescue, etc.). However, in some cases animals can also be edificators. For example, in territories occupied by marmot colonies, it is their digging activity that mainly determines the nature of the landscape, the microclimate, and the growing conditions of plants. In the seas, typical edificators among animals are reef-forming coral polyps.

In addition to a relatively small number of dominant species, the biocenosis usually includes many small and even rare forms. The most common distribution of species according to their abundance is characterized by the Raunkier curve (Fig. 79). A sharp rise in the left part of the curve indicates the predominance of small and rare species in the community, and a slight rise in the right part indicates the presence of a certain group of dominants, the “species core” of the community.

Rare and small species are also very important for the life of the biocenosis. They create its species richness, increase the diversity of biocenotic connections and serve as a reserve for the replenishment and replacement of dominants, i.e., they give the biocenosis stability and ensure the reliability of its functioning in different conditions. The larger the reserve of such “minor” species in a community, the greater the likelihood that among them there will be those that can play the role of dominants in the event of any changes in the environment.

There is a certain connection between the number of dominant species and the overall species richness of the community. With a decrease in the number of species, the abundance of individual forms usually increases sharply. In such impoverished communities, biocenotic connections are weakened and some of the most competitive species are able to reproduce unhindered.

The more specific the environmental conditions, the poorer the species composition of the community and the higher the number of individual species can be. This pattern is called A. Tineman's rules, named after a German scientist who studied the features of the species structure of communities in the 30s of the last century. In species-poor biocenoses, the number of individual species can be extremely high. Suffice it to recall outbreaks of mass reproduction of lemmings in the tundra or insect pests in agrocenoses (Fig. 80). A similar pattern can be observed in communities of very different sizes. In piles of fresh horse manure, for example, there is an almost anaerobic environment, a lot of ammonia and other toxic gases, high temperature due to the activity of microorganisms, i.e., highly specific living conditions deviating from the normal norm are created for various animals. In such piles, the species composition of invertebrates is initially extremely poor. The larvae of fruit flies develop, and a few species of saprophagous nematodes (family Rhabditidae) and predatory gamasid mites (genus Parasitus) reproduce. But all these species are extremely numerous, there are almost no rare forms. In such cases, the curve describing the distribution of species by their abundance has a strongly smoothed left part (as in Fig. 76). Such communities are unstable and are characterized by sharp fluctuations in the abundance of individual species.

Rice. 80. The structure of dominance in the insect community of cereal stems in the fields (according to N.I. Kulikov, 1988). On the x-axis are species in descending order of abundance.

Gradually, as manure decomposes and environmental conditions soften, the species diversity of invertebrates increases, while the relative and absolute numbers of mass forms noticeably decrease.

In the richest biocenoses, almost all species are small in number. In tropical forests it is rare to find several trees of the same species nearby. In such communities there are no outbreaks of mass reproduction of individual species; biocenoses are highly stable. A curve reflecting the species structure of this type would have in Fig. 76 especially steep left side.

Thus, even the most general analysis of the species structure can provide quite a lot for a holistic characterization of the community. The diversity of a biocenosis is closely related to its stability. Human activity greatly reduces diversity in natural communities. This makes it necessary to anticipate its consequences and take measures to maintain natural systems.

Quantitative characteristics of the species in the biocenosis. To assess the role of an individual species in the species structure of the biocenosis, various indicators based on quantitative accounting are used. Species abundance - this is the number of individuals of a given species per unit area or volume of occupied space, for example, the number of small crustaceans in 1 dm 3 of water in a reservoir or the number of birds nesting in 1 km 2 of a steppe area, etc. Sometimes, to calculate the abundance of a species instead of the number of individuals use the value of their total mass. For plants, projective abundance, or area coverage, is also taken into account. Frequency of occurrence characterizes the uniformity or unevenness of the distribution of the species in the biocenosis. It is calculated as the percentage of the number of samples or survey sites where the species occurs to the total number of such samples or sites. The abundance and occurrence of the species are not directly related. A species may be numerous but low in occurrence or low in abundance but quite common. Dominance degree – an indicator reflecting the ratio of the number of individuals of a given species to the total number of all individuals of the group under consideration. So, for example, if out of 200 birds recorded in a given territory, 80 are finches, the degree of dominance of this species among the bird population is 40%.

To assess the quantitative ratio of species in biocenoses in modern ecological literature, they often use diversity index calculated using Shannon's formula:

H = – ?P i log 2 P i ,

Where? – sum sign, R i– share of each species in the community (by number or mass), a log 2 p i– binary logarithm p i .

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Introduction

1. Biocenosis - general information and concepts

2. Structure of the biocenosis

3. Contemporary issues biocenoses and ways to solve them

Conclusion

Bibliography

Introduction

Biocenosis is a historically established collection of animals, plants, fungi and microorganisms inhabiting a relatively homogeneous living space ( specific area land or water areas), and connected with each other 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 sustainably.

Biocenosis is one of the main objects of ecology research. Problems of stability of biocenoses, decrease in population numbers, 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 environmental task, to which ecologists from all countries of the world, including Russian scientists, have paid and continue to pay great attention.

In this work I will dwell in detail on such issues as the properties and structure of the biocenosis, the conditions for their sustainability, as well as the main modern problems and ways to solve them. It should be noted that in the minds 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 issue of the similarities and differences of these concepts and their interrelations. 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 famous foreign ecologists: Y. 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 kpynt - “general”) is a historically established collection of animals, plants, fungi and microorganisms inhabiting a relatively homogeneous living space (a certain area of land or water area), and interconnected and their environment. Biocenoses arose on the basis of the biogenic cycle and ensure 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 sustainably. The main function of the community is to ensure balance in the ecosystem based on a closed cycle of substances.

Biocenoses can include thousands of species various organisms. But not all of them are equally significant. Removing some of them from the community has no noticeable effect on them, while removing others leads to significant changes.

Some types of biocenosis may be represented by numerous populations, while others may be small. The scale of biocenotic groups of organisms varies greatly - from communities of lichen cushions 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 subordinated to hierarchy. As the scale of communities increases, their complexity and the proportion of indirect, indirect connections 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 develop 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 various types or entire complexes of species) present in the environment. In this way, the way they arise differs from the formation of a separate organism, which occurs through gradual differentiation of the simplest initial state.

2) Community parts are interchangeable. The parts (organs) of any organism are unique.

3) If the whole organism maintains constant coordination and consistency in the activities of its organs, cells and tissues, then the supraorganismal system exists mainly due to the balancing of oppositely directed forces.

4) Communities are based on the quantitative regulation of the numbers 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 factors.

A homogeneous natural living space (part of the abiotic environment) occupied by a biocenosis is called a biotope. This could be a piece of land or a body of water, a seashore or a mountainside. A biotope is an inorganic environment that 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 hummocks in a swamp or a decaying stump to the population of entire landscapes. Thus, on land, one can distinguish the biocenosis of a dry meadow (not flooded with water), the biocenosis of a white moss pine forest, the biocenosis of feather grass steppe, the biocenosis of a wheat field, etc.

There are concepts of “species richness” and “species diversity” of biocenoses. Species richness is the general set of species of a community, 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 species-poor and species-rich biocenoses. The species composition of biocenoses, in addition, depends on the duration of their existence and the history of each biocenosis. Young, just emerging communities usually include a smaller set of species than long-established, mature ones. Biocenoses created by humans (fields, gardens, orchards) are also poorer in species than similar natural systems (forests, steppes, meadows). Man maintains the monotony and species poverty of agrocenoses with a special complex system of agrotechnical measures.

Almost all terrestrial and most aquatic biocenoses include microorganisms, plants, and animals. The stronger the differences between two neighboring biotopes, the more heterogeneous the conditions at their boundaries and the stronger the border effect. The number of a particular group of organisms in biocenoses strongly depends on their size. The smaller the individuals of a species, the higher their numbers in biotopes.

Groups of organisms of different sizes live in biocenoses at different scales of space and time. For example, the life cycles of single-celled organisms can take place within an hour, while the life cycles of large plants and animals extend over tens of years.

Naturally, in all biocenoses the smallest forms - bacteria and other microorganisms - predominate numerically. In each community, one can distinguish a group of main species, the most numerous in each size class, the connections between which are decisive for the functioning of the biocenosis as a whole. Species that are dominant in numbers (productivity) are dominant in 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 the plant - bluegrass, and among the animals grazing there, most of all are cows. This means that bluegrass dominates among producers, and cows dominate among consumers.

The totality of all species in a community constitutes its biodiversity. Typically, a community consists of a few major species with high abundance and many rare species with low abundance.

Biodiversity is responsible for the equilibrium state of the ecosystem, and therefore 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, therefore the output of nutrients from the ecosystem is small, and their constant presence ensures the balance of the ecosystem.

Human activity greatly reduces diversity in natural communities, which requires forecasts and predictions of its consequences, as well as effective measures to maintain natural systems.

1.1 Biocenosis, ecosystem, biosphere

Ecosystem (from the ancient Greek pkpt - dwelling, residence and ueufzmb - system) is 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 creature is surrounded by many different factors influencing it, which together form its habitat - a biotope. Consequently, a biotope is a section of territory that is homogeneous in terms of living conditions for certain species of plants or animals (the slope of a ravine, an urban forest park, a small lake or part of a large one, but with homogeneous conditions - the coastal part, the deep-sea part).

Organisms characteristic of a particular biotope constitute a living 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 an ecological system (ecosystem). An example of natural ecosystems is an anthill, lake, pond, meadow, forest, city, farm. A classic example of an artificial ecosystem is a spaceship. biocenosis species spatial trophic

Close to the concept of ecosystem is the concept of biogeocenosis. Supporters of the ecosystem approach in Zapkada, incl. Yu. Odum, consider these concepts to be synonymous. 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, which regulate the entire energy of biotic communities and the ecosystem as a whole.

Attempts to create a classification of ecosystems globe have been undertaken for a long time, but there is no convenient, universal classification yet. The thing is that due to the huge variety of types of natural ecosystems, due to their lack of rank, it is very difficult to find a single criterion based on which such a classification can be developed.

If a separate ecosystem can be a puddle, a hummock in a swamp, or a sand dune with established vegetation, then, naturally, count everything possible options bumps, puddles, etc. does not seem possible. Therefore, ecologists decided to focus on large combinations of ecosystems - biomes. Biome is a large biological system that is characterized by a dominant type of vegetation or other landscape feature. According to the American ecologist R. Whittaker, the main type of community of 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 land biomes can be distinguished: tundra, taiga, temperate deciduous forest biome, temperate steppe, Mediterranean mud vegetation, desert, tropical savanna and grassland biome, tropical or thorny woodland biome, tropical forest biome .

The main components of ecosystems are:

1) inanimate (abiotic) environment. These are water, minerals, gases, as well as organic matter and humus;

2) biotic components. These include: producers or producers (green plants), consumers or consumers (living beings that feed on producers), and decomposers or decomposers (microorganisms).

The biomass created by organisms (the substance of the bodies of organisms) and the energy they contain 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. 1.

Rice. 1. Food web and direction of flow of matter

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 bottom part atmosphere, that is, inhabits the ecosphere. The biosphere is the totality of all living organisms. It is home to more than 3,000,000 species of plants, animals, fungi and bacteria. Man is also part of the biosphere; his activities surpass many natural processes.

The state of equilibrium in the biosphere is based on the interaction of biotic and abiotic environmental factors, which is maintained through the continuous exchange of matter and energy between all components of ecosystems.

In closed circulations of natural ecosystems, along with others, the participation of two factors is necessary: the presence of decomposers and the constant supply of solar energy. In urban and artificial ecosystems there are few or no decomposers, so liquid, solid and gaseous waste accumulate, polluting the environment.

1.3 History of the study of biocenosis

At the end of the 70s. XIX century German hydrobiologist Karl Möbius studied complexes of bottom animals - accumulations of oysters (oyster banks). He observed that, along with oysters, there were also animals such 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 were called biocenoses by Mobius. The term “biocenosis” (from the Greek bios - life and koinos - general) was introduced by him into the 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 were laid for an important direction in ecology - biocenology (ecology of communities).

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”. However, strictly speaking, the term “community” is not synonymous with the term “biocenosis”. If a biocenosis can be called a multi-species community, then a population (an integral part of the biocenosis) is a single-species community.

2. 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) species;

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 unite into natural systems called populations. Therefore, a biocenosis can also be defined as a set of populations of all types of living organisms inhabiting common habitats.

The composition of the biocenosis includes a set of plants in a certain territory - phytocenosis; the totality of animals living within a phytocenosis is a zoocenosis; microbiocenosis - a collection of microorganisms inhabiting the soil. Sometimes mycocenosis, a collection of fungi, is included as a separate component element 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 bodies of water, where they serve as an important source of food for fish and some other animals. At a young age, they are part of the aquatic biocenosis, and as adults 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 look for food not only in the forest, but also in adjacent meadows or swamps.

2.1 Species structure of the biocenosis

The species structure of a biocenosis is the totality 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 forest.

A simple indicator of the diversity of a biocenosis is the total number of species, or species richness. If any species of plant (or animal) quantitatively predominates in a community (has greater biomass, productivity, number or abundance), then this species is called a dominant, or dominant species (from the Latin dominans - dominant). There are dominant species in any biocenosis. For example, in a spruce forest, spruce trees, using the main share of solar energy, increase the greatest biomass, shade the soil, weaken air movement and create a lot of inconvenience for the lives 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 changes in species diversity is its decrease from the tropics towards high latitudes. The closer to the equator, the richer and more diverse the 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 rain forests of the Amazon basin, on an area of about 1 hectare, you can count up to 400 trees of more than 90 species. In addition, many trees serve as supports 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 tree species per 1 hectare, and in the north of the taiga region there are 2-5 species in the same area.

The poorest biocenoses in terms of the set of species are alpine and arctic deserts, the richest are tropical forests. Panama's rainforests are home to three times more species of mammals and birds than 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 quite difficult to draw a clear boundary between them. Almost everywhere there is a kind of transitional strip of varying width and length, because hard, sharp boundaries in nature are a rare exception. They are characteristic mainly of communities subject to intense anthropogenic impact.

In the early 30s. XX century American naturalist A. Leopold proclaimed the need to take into account the so-called “edge effect” in hunting activities. In this case, the edge was understood not only as the edge of the forest, but also as any border between two biocenoses, even between two tracts of different agricultural crops. On both sides of this conventional line, the relative species diversity of plants and animals increases, feeding and protective conditions for game improve, the disturbance factor is weakened, 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 sharp changes in abiotic environmental factors. For example, such boundaries exist between aquatic 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. This tendency to increase the diversity and density of living organisms at the boundaries of biocenoses is called the edge (edge, boundary) effect. The edge effect is most clearly manifested in zones separating forest from meadow (shrub zone), forest from swamp, etc.

2.2 Spatial structure of the biocenosis

Species can be distributed differently in space according to their needs and habitat conditions. This distribution of the species that make up the biocenosis in space is called the spatial structure of the biocenosis. There are vertical and horizontal structures.

1) The vertical structure of the biocenosis is formed by its individual elements, special layers, which are called tiers. Layer - 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, woody, tier usually consists of tall trees with high-mounted foliage, which is well illuminated by the sun. Unused light can be absorbed by trees forming a second, sub-canopy layer.

Rice. 2. Tiers of forest biocenosis

The undergrowth layer consists of shrubs and shrubby forms of tree species, for example hazel, rowan, buckthorn, willow, forest apple tree, etc. In open areas under normal environmental conditions, many shrubby forms of such species as mountain ash, apple, and pear would have the appearance of trees of the first size. However, under the forest canopy, in conditions of shading and lack of nutrients, they are doomed to exist in the form of low-growing, often non-barking seeds and fruits of trees. As the forest biocenosis develops, such species will never reach the first tier. This is how 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. This includes forest herbs and shrubs: lily of the valley, oxalis, strawberries, lingonberries, blueberries, ferns.

The ground layer of mosses and lichens forms the moss-lichen layer.

So, in the forest biocenosis there are tree stand, undergrowth, undergrowth, grass cover and moss-lichen layer.

Similar to the distribution of vegetation by tiers, in biocenoses different species of animals also occupy certain levels. Soil worms, microorganisms, and digging animals live in the soil. Various centipedes, ground beetles, mites and other small animals live in leaf litter and on the soil surface. Birds nest in the upper canopy of the forest, and some can feed and nest below the upper tier, others in bushes, and still others near the ground. Large mammals live in the lower tiers.

Tiering is inherent in the biocenoses of oceans and seas. Different types of plankton stay at different depths depending on the lighting. Different species of fish live at different depths depending on where they find food.

2) Individuals of living organisms are distributed unevenly in space. Usually they form groups 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 and spotting of each species.

There are many examples of such distribution: these are numerous herds of zebras, antelopes, elephants in the savanna, colonies of corals on the seabed, schools of sea fish, flocks of migratory birds; thickets of reeds and aquatic plants, accumulations of mosses and lichens on the soil in a 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 a community, which includes all tiers. Almost every community includes a complex of microcommunities or microcenoses.

Microgrouping is a concentration of individuals of one or several species within a tier, intra-tier mosaic spots. For example, in the moss layer, various moss patches with dominance of one or several species can be distinguished. In the herbaceous-shrub layer there are blueberry, blueberry-sour sorrel, and blueberry-sphagnum microgroups.

The presence of mosaics is important for the life of the community. Mosaicism allows for more complete use of different types of microhabitats. Individuals forming groups are characterized by high survival rates and use food resources most efficiently. This leads to an increase and diversity of species in the biocenosis, contributing to its stability and viability.

2.3 Trophic structure of the biocenosis

The interaction of organisms occupying 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 Latin producens - producing) - organisms that synthesize from inorganic substances (mainly water and carbon dioxide) all 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.). Typically, producers are understood as green chlorophyll-bearing plants (autotrophs) that provide primary production. The total weight of dry matter of phytomass (plant mass) is estimated at 2.42 x 1012 tons. This constitutes 99% of all living matter on the earth's surface. And only 1% accounts for heterotrophic organisms. Therefore, planet Earth owes its existence to vegetation only to the existence of life on it. It was green plants that created the necessary conditions for the appearance and existence, first, of various prehistoric animals, and then of humans. When plants died, they accumulated energy in sediments coal, peat and even oil.

Producing plants provide humans with food, raw materials for industry, and medicine. They purify the air, trap dust, soften the air temperature, and muffle noise. Thanks to vegetation, there is a huge variety of animal organisms that populate the Earth. Producers constitute the first link in food prices and form the basis of ecological pyramids.

2. Consumers (from the 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 obtain it in finished form by feeding on other organisms. In their organisms, they transform organic matter into specific forms of proteins and other substances, and release waste generated during their life into the environment.

Grasshopper, hare, antelope, deer, elephant, etc. herbivores are consumers of the first order. The toad that grabbed the dragonfly ladybug, feeding on aphids, a wolf hunting a hare - all these are consumers of the second order. 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 the Latin reducens, reducentis - returning, restoring) - organisms that destroy dead organic matter and transform it into inorganic substances, which, in turn, are absorbed by other organisms (producers).

The main decomposers are bacteria, fungi, protozoa, i.e. heterotrophic microorganisms found in the soil. If their activity decreases (for example, when humans use pesticides), the conditions for the production process of plants and consumers worsen. Dead organic remains, be it a tree stump or the corpse of an animal, do not disappear into nowhere. They are rotting. But dead organic matter cannot rot on its own. Reducers (destructors, destroyers) act as “gravediggers”. They oxidize dead organic residues to C0 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 disruption of the stability of biocenoses and poses a threat to the entire biosphere of the planet.

Each species participates in the circulation of substances and maintains dynamic balance in natural ecosystems. Therefore, the loss of any biological species is extremely undesirable for the biosphere.

The loss of species occurred as a result of evolutionary processes. Due to human activity, the planet's biological resources are being lost much faster. Tens of thousands of plant and animal species are at risk of extinction. The reasons for this situation are:

1) loss of habitat: destruction of forests, drainage of swamps and floodplain lakes, plowing of steppes, changes 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 occurring as a result human economic activity;

2) environmental pollution with toxic chemicals and xenobiotics, oil and oil products, salts of heavy metals, solid household waste;

3) the spread of introduced species of plants and animals, actively occupying vast territories and displacing the natural inhabitants of ecosystems. Unintentional, random dispersal of animals has increased with the development of transport;

4) merciless exploitation of natural resources - minerals, soil fertility, aquatic ecosystems, overharvesting of animals, birds and aquatic organisms.

To protect endangered species, it is necessary to take active, sometimes urgent, measures. One of the most effective methods Animal protection is the creation of nature reserves or sanctuaries. There are more than 150 nature reserves in the Russian Federation, where a large number of animals have been preserved. Among them are the Amur tiger, saiga, goral, Bukhara deer, kulan and others. Zoos located throughout the country help breed endangered species.

In order to preserve and increase the number of rare species, states on all continents of the Earth pass laws regarding the protection and use of wildlife. In the Russian Federation, such a law was adopted on June 25, 1980. To record rare species, so-called Red Books are being created both in Russia and in other countries of the world. Endangered animal species around the world require separate registration; for this purpose, the International Red Book was 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 collection of populations of plants, animals and microorganisms. The main function of the biocenosis is to ensure balance in the ecosystem based on a closed cycle of substances. The place occupied by a biocenosis is called a biotope. Types of biocenosis structures: species, spatial (vertical (tiered) and horizontal (mosaic) organization of the biocenosis) and trophic. The species structure of a biocenosis covers all species living in it. The spatial structure includes a vertical structure - tiers and a horizontal structure - 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 a 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 a biocenosis and ecosystem is usually displayed by graphic models in the form of ecological pyramids. There are ecological pyramids of numbers, biomass and energy. The rate of solar energy fixation determines the productivity of biocenoses. The set of environmental factors within which a species lives is called an ecological niche.

Humanity is now faced with the acute problem of the disappearance of species of various living organisms, leading to a violation of the stability of biocenoses and the biosphere as a whole. To prevent population decline 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; restrictions on 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 volumes. T. 1 - M., 1986 - 328 pp.; 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 species structure of the forest biocenosis is characterized. The concept of biocenosis. Species and trophic structure of biocenoses. Artificial biological systems

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Introduction

Introduction

1. Biots Enosis - general information and concepts

Bibliography

1. Korobkin V.I., Peredelsky L.V. Ecology. - R.-on-Don, 2001 - 576 p.

2. Odum Yu. Ecology: in 2 volumes. T. 1 - M., 1986 - 328 pp.; 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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