The trophic structure of the ecosystem can be depicted graphically in the form of an ecological pyramid, which is based on the first level. These pyramids reflect the laws of biomass and energy consumption in food chains. The numerical value of each step of such a pyramid can be expressed by the number of individuals, their biomass or the energy stored in it.

Food networks that arise in an ecosystem have a structure that is characterized by a certain number of organisms at each trophic level. Noticed that the number of organisms decreases in direct proportion to the transition from one trophic level to another. This pattern is called "The rule of the ecological pyramid."   In this case, considered pyramid of numbers . It can be violated if small predators live due to group hunting for large animals.

Each trophic level is characterized by its own biomass   - total mass of organisms of any group. In food chains, the biomass of organisms at different trophic levels is different: the biomass of producers (the first trophic level) is significantly higher than the biomass of consumers - herbivorous animals (second trophic level). The biomass of each of the subsequent trophic levels of the food chain is also progressively decreasing. This pattern is called biomass pyramids .

A similar pattern can be identified when considering the transfer of energy at trophic levels, that is, in energy pyramid (products ) . The amount of energy spent on maintaining one's own life activity in the chain of trophic levels is growing, and productivity is falling. Plants absorb only a small fraction of solar energy during photosynthesis. The herbivorous animals that make up the second trophic level absorb only a fraction (20-60%) of the absorbed feed. Digested food is used to support the vital processes of animal organisms and growth (for example, to build tissues, reserves in the form of fat deposits).

Organisms of the third trophic level (carnivorous animals) when they eat herbivorous animals again lose most of the energy contained in food. The amount of energy at subsequent trophic levels again progressively decreases. The result of these energy losses is a small number (three to five) of trophic levels in the food chain.

The energy lost in the power circuits can only be replenished by the arrival of new portions of it. Therefore, in the ecosystem there cannot be a cycle of energy, similar to a cycle of substances. Ecosystems are open systems that need an influx of solar energy or ready-made stocks of organic matter, i.e. energy transfer in ecosystems is according to known laws of thermodynamics:

1. Energy can pass from one form to another, but it is never created again and never disappears.

2. There can be no process associated with the conversion of energy without loss of some part of it in the form of heat, ie no energy conversions with 100% efficiency.

It is estimated that only about 10% of the energy is transferred from one trophic level to another. This pattern is called "ten percent rule."

Thus, most of the energy in the power circuit is lost during the transition from one level to another. Only the energy that is contained in the mass of the previous eaten link enters the next link in the food chain. Energy loss is about 90% at each transition through the trophic chain. For example, if the energy of a plant organism is 1000 J, then when it is fully consumed by herbivores in the body of the latter, only 100 J is assimilated in the body of the predator, 10 J, and if this predator is eaten by another, only 1 J of energy is assimilated in its body, then there is 0.1%.

As a result, the energy accumulated by green plants in food chains is rapidly drying up. Therefore, the food chain cannot include more than 4 to 5 links. The energy lost in the power circuits can only be replenished by the arrival of new portions of it. There can be no energy cycle in ecosystems, like a cycle of matter. The life and functioning of any ecological system is possible only with a unilaterally directed flow of energy in the form of solar radiation or with an influx of stocks of finished organic matter.

Thus, the pyramid of numbers reflects the number of individuals in each link of the food chain. The biomass pyramid reflects the amount of organic matter formed on each link - its biomass. The energy pyramid shows the amount of energy at each trophic level.

A decrease in the amount of available energy at each subsequent trophic level is accompanied by a decrease in biomass and number of individuals. The pyramids of biomass and the number of organisms for a given biocenosis in general outline the configuration of the pyramid of productivity.

Graphically, the ecological pyramid is depicted in the form of several rectangles of the same height, but of different lengths. The length of the rectangle decreases from lower to upper according to a decrease in productivity at subsequent trophic levels. The lower triangle is the longest and corresponds to the first trophic level - producers, the second - about 10 times smaller and corresponds to the second trophic level - herbivorous animals, consumers of the first order, etc.

All three rules of the pyramid - productivity, biomass and abundance express energy relations in ecosystems. At the same time, the productivity pyramid is universal, and the pyramids of biomass and abundance are manifested in communities with a certain trophic structure.

Knowledge of the laws of ecosystem productivity, the ability to quantify the flow of energy are of great practical importance. The primary production of agrocenoses and human exploitation of natural communities is the main source of food for humans. The secondary production of biocenoses obtained from industrial and farm animals as a source of animal protein is also important. Knowledge of the laws of energy distribution, energy and substance fluxes in biocenoses, patterns of plant and animal productivity, understanding the limits of permissible removal of plant and animal biomass from natural systems make it possible to correctly build relationships in the society-nature system.

An environmental pyramid is a graphic representation of energy losses in power circuits.

Food chains are stable chains of interrelated species that sequentially extract materials and energy from the original food substance that have developed during the evolution of living organisms and the biosphere as a whole. They make up the trophic structure of any biocenosis, through which the transfer of energy and the cycles of substances are carried out. The food chain consists of a number of trophic levels, the sequence of which corresponds to the flow of energy.

The primary source of energy in power circuits is solar energy. The first trophic level - producers (green plants) - use solar energy in the process of photosynthesis, creating the primary production of any biocenosis. However, only 0.1% of solar energy is used in the process of photosynthesis. The efficiency with which green plants assimilate solar energy is estimated by the value of primary productivity. More than half of the energy associated with photosynthesis is immediately consumed by plants in the process of respiration, the rest of the energy is transferred further along the food chains.

At the same time, an important regularity applies, associated with the efficient use and conversion of energy in the nutrition process. Its essence is as follows: the amount of energy spent on maintaining one's own life activity in food chains grows from one trophic level to another, and productivity decreases.

Phytobiomass is used as a source of energy and material to create biomass of second organisms.

trophic level of consumers of the first order - herbivores. Typically, the productivity of the second trophic level is not more than 5 - 20% (10%) of the previous level. This is reflected in the ratio on the planet of biomass of plant and animal origin. The amount of energy necessary to ensure the vital functions of the body grows with increasing levels of morphofunctional organization. Accordingly, the amount of biomass generated at higher trophic levels is reduced.

Ecosystems are very diverse in terms of the relative speed of creation and expenditure of both net primary production and net secondary production at each trophic level. However, all ecosystems without exception are characterized by certain ratios of primary and secondary products. Always the amount of plant matter that serves as the basis of the food chain is several times (about 10 times) more than the total mass of herbivorous animals, and the mass of each subsequent link in the food chain, respectively, varies proportionally.

A progressive decrease in assimilated energy in a series of trophic levels is reflected in the structure of ecological pyramids.

A decrease in the amount of available energy at each subsequent trophic level is accompanied by a decrease in biomass and number of individuals. The pyramids of biomass and the number of organisms for a given biocenosis in general outline the configuration of the pyramid of productivity.

Graphically, the ecological pyramid is depicted in the form of several rectangles of the same height, but of different lengths. The length of the rectangle decreases from lower to upper according to a decrease in productivity at subsequent trophic levels. The lower triangle is the longest and corresponds to the first trophic level - producers, the second - approximately 10 times smaller and corresponds to the second trophic level - herbivorous animals, consumers of the first order, etc.

The rate of creation of organic matter does not determine its total reserves, i.e. the total mass of organisms of each trophic level. The present biomass of producers and consumers in specific ecosystems depends on how the rates of accumulation of organic matter at a certain trophic level and its transfer to a higher level, i.e. how much is the depletion of the formed stocks. An important role is played by the playback speed of the main generations of producers and consumers.

In most terrestrial ecosystems, as already mentioned, the biomass rule also applies, i.e. the total mass of plants is greater than the biomass of all herbivores, and the mass of herbivores exceeds the mass of all predators.

It is necessary to distinguish quantitatively productivity, namely, annual growth of vegetation, and biomass. The difference between the primary production of the biocenosis and the biomass determines the extent to which the plant mass is consumed. Even for communities with a predominance of grassy forms, the biomass reproduction rate of which is quite high, animals use up to 70% of the annual growth of plants.

In those trophic chains where energy is transferred through the predator – prey bonds, pyramids of the number of individuals are often observed: the total number of individuals participating in the food chains decreases with each link. This is also due to the fact that predators are usually larger than their victims. An exception to the rules of the pyramid of numbers are cases where small predators live off a group hunt for large animals.

All three rules of the pyramid - productivity, biomass and abundance - express energy relations in ecosystems. At the same time, the productivity pyramid is universal, and the pyramids of biomass and abundance are manifested in communities with a certain trophic structure.

Knowledge of the laws of ecosystem productivity, the ability to quantify the flow of energy are of great practical importance. The primary production of agrocenoses and human exploitation of natural communities is the main source of food for humans. The secondary production of biocenoses obtained from industrial and farm animals as a source of animal protein is also important. Knowledge of the laws of energy distribution, energy and substance flows in biocenoses, patterns of plant and animal productivity, understanding the limits of permissible removal of plant and animal biomass from natural systems make it possible to correctly build relationships in the "society - nature" system.

Connections in which some organisms eat other organisms or their remains or excreta (excrement) are called trophic (trophy - nutrition, food, gr.). Moreover, nutritional relationships between ecosystem members are expressed through trophic (food) chains . Examples of such circuits are:

· Reindeer → deer → wolf (tundra ecosystem);

· Grass → cow → man (anthropogenic ecosystem);

· Microscopic algae (phytoplankton) → bugs and daphnia (zooplankton) → roach → pike → gulls (aquatic ecosystem).

The impact on the supply chain in order to optimize them and to obtain greater or better quality products is not always successful. So widely known from literature is the example of the importation of cows to Australia. Prior to this, kangaroos were mainly used in natural pastures, the excrement of which was successfully developed and processed by the Australian dung beetle. Australian beetle excrement was not mastered, resulting in a gradual degradation of pastures. To stop this process, a European dung beetle had to be brought to Australia.

Trophic or food chains may be presented in the form pyramids.   The numerical value of each step of such a pyramid can be expressed by the number of individuals, their biomass, or the energy stored in it.

In accordance with energy pyramid law   R. Lindeman and ten percent rules , from each stage to the next stage, approximately 10% (from 7 to 17%) of the energy or substance in energy terms (Fig. 3.7) passes. Note that at each subsequent level, with a decrease in the amount of energy, its quality increases, i.e. the ability to perform work of a unit of animal biomass is an appropriate number of times higher than the same plant biomass.

A striking example is the trophic chain of the open sea, represented by plankton and whales. The mass of plankton is scattered in ocean water and, with open sea bioproductivity less than 0.5 g / m2 day-1, the amount of potential energy in a cubic meter of ocean water is infinitesimal in comparison with the energy of a whale, whose mass can reach several hundred tons. As you know, whale fat is a high-calorie product that was used even for lighting.

Figure 3.7. Pyramid-transmitting energy along the food chain (according to Yu. Odum)

In the destruction of organics, the corresponding sequence is also observed: for example, about 90% of the energy of pure primary production is released by microorganisms and fungi, less than 10% - invertebrates and less than 1% - vertebrates, which are the final reason. In accordance with the last figure is formulated one percent rule : for the stability of the biosphere as a whole, the share of the possible final consumption of net primary production in energy terms should not exceed 1%.

Relying on the food chain as the basis for the functioning of the ecosystem, one can also explain the cases of accumulation of certain substances in the tissues (for example, synthetic poisons), which, as they move along the trophic chain, do not participate in the normal metabolism of organisms. According to biological reinforcement rules   there is an approximately tenfold increase in the concentration of the pollutant upon transition to a higher level of the ecological pyramid.

In particular, a seemingly insignificant increased content of radionuclides in river water at the first level of the trophic chain is developed by microorganisms and plankton, then it is concentrated in fish tissues and reaches its maximum values \u200b\u200bin gulls. Their eggs have a radionuclide level of 5,000 times greater than background pollution.

The species composition of organisms is usually studied at the level of populations .

Recall that a population is a collection of individuals of the same species inhabiting the same territory, having a common gene pool and the ability to freely interbreed. In the general case, one or another population may be located within a certain ecosystem, but may also spread abroad. For example, the black-capped marmot population of the Tuora-Sis ridge, listed in the Red Book, is known and protected. This population is not limited to this ridge, but extends south to the Verkhoyansk mountains in Yakutia.

The environment in which the studied species is usually found is called its habitat.

As a rule, one ecological species or its population occupies an ecological niche. With the matching requirements for the environment and food resources, two species invariably enter the competition, which usually ends with the crowding out of one of them. A similar situation is known in systems ecology as principle G.F. Gause , which states that two species cannot exist in the same locality if their ecological needs are identical, i.e. if they occupy the same niche. Accordingly, the system of interacting populations differentiated by ecological niches, complementing each other to a greater extent than competing among themselves for the use of space, time and resources, is called a community (cenosis).

A polar bear cannot live in taiga ecosystems, just like a brown bear in polar regions.

Speciation is always adaptive, therefore, according to axiom of C. Darwineach species is adapted to a strictly defined set of conditions of existence specific to it. In this case, organisms multiply with an intensity that ensures their maximum possible number ( rule of maximum "pressure of life" ).

For example, the organisms of oceanic plankton quickly cover a space of thousands of square kilometers in the form of a film. V.I. Vernadsky calculated that the speed of advancement of Fisher bacteria 10-12 cm3 in size by propagation in a straight line would be equal to about 397,200 m / h - the speed of the aircraft! However, excessive reproduction of organisms is limited by limiting factors and correlates with the amount of food resources of their environment.

When species, primarily composed by large individuals, disappear, the material-energy structure of qualifications changes as a result. If the energy flow passing through the ecosystem does not change, then the mechanisms are activated environmental duplication on a principle: an endangered or destroyed species within the framework of one level of the ecological pyramid replaces another functional-coenotic, similar. The replacement of the species follows the pattern: small replaces large, evolutionarily lower organized, more highly organized, more genetically labile, less genetically variable. Since the ecological niche in the biocenosis cannot be empty, environmental duplication is necessary.

The successive change of biocenoses, successively arising in the same territory under the influence of natural factors or human exposure, is called succession (succession - continuity, lat.). For example, after a forest fire, a burner for many years is first populated with grass, then shrubbery, then deciduous trees and ultimately coniferous forest. Moreover, successive communities replacing each other are called series or stages. The end result of succession will be the state of a stabilized ecosystem - menopause (climax - staircase, "mature stage", gr.).

Succession starting on a previously unoccupied area is called primary . These include lichen settlements on stones, which subsequently replace mosses, grasses and shrubs (Fig. 3.8). If a community develops on the site of an existing one (for example, after a fire or uprooting, installation of a pond or reservoir), then secondary   succession. Of course, the succession rate will be different. Primary successions may take hundreds or thousands of years, and secondary ones are faster.

All populations of producers, consumers and heterotrophs closely interact through trophic chains and thus support the structure and integrity of biocenoses, coordinate the flow of energy and substances, and determine the regulation of their environment. The whole set of bodies of living organisms inhabiting the Earth is physically and chemically one, regardless of their systematic affiliation, and is called living matter ( the law of physico-chemical unity of living matter V.I. Vernadsky) The mass of living matter is relatively small and is estimated at 2.4-3.6 * 1012 tons (in dry weight). If you distribute it over the entire surface of the planet, you get a layer of only one and a half centimeters. According to V.I. Vernadsky, this "film of life", comprising less than 10-6 masses of other shells of the Earth, is "one of the most powerful geochemical forces of our planet."

As a result of complex nutritional relationships between different organisms trophic (food) bonds or food chains.The power circuit usually consists of several links:

producers - consumers - reducers.

Ecological pyramid- the amount of plant matter that serves as the basis for nutrition is several times greater than the total mass of herbivorous animals, and the mass of each of the subsequent links of the food chain is less than the previous one (Fig. 54).

Ecological pyramid - graphic representations of the relationship between producers, consumers and reducers in an ecosystem.

Fig. 54. A simplified diagram of the ecological pyramid

or pyramids of numbers (according to Korobkin, 2006)

The graphic model of the pyramid was developed in 1927 by the American zoologist Charles Elton. The basis of the pyramid is the first trophic level - the level of producers, and the next floors of the pyramid are formed by subsequent levels - consumers of various orders. The height of all blocks is the same, and the length is proportional to the number, biomass or energy at the corresponding level. There are three ways to build ecological pyramids.

1. Pyramid of numbers (abundance) reflects the abundance of individual organisms at each level (see Fig. 55). For example, to feed one wolf, you need at least a few rabbits, which he could hunt; To feed these hares, you need a fairly large number of different plants. Sometimes pyramids of numbers can be reversed or inverted. This applies to the food chains of the forest, when the producers are trees, and the primary consumers are insects. In this case, the level of primary consumers is numerically richer than the level of producers (a large number of insects feed on one tree).

2. Biomass Pyramid –   mass ratio of organisms of different trophic levels. Typically, in terrestrial biocenoses, the total mass of producers is greater than each subsequent link. In turn, the total mass of first-order consumers is greater than second-order consumers, etc. If organisms do not vary too much in size, then a graph usually turns out to be a step pyramid with a tapering apex. So, for the formation of 1 kg of beef you need 70–90 kg of fresh grass.

In aquatic ecosystems, you can also get a reversed, or inverted, pyramid of biomass, when the biomass of producers is smaller than consumers, and sometimes reducers. For example, in the ocean, at a relatively high phytoplankton productivity, the total mass at the moment may be less than that of consumer consumers (whales, large fish, mollusks) (Fig. 55).

Fig. 55. Biomass pyramids of some biocenoses (according to Korobkin, 2004):

P - producers; RK - herbivorous consumers; PC - carnivorous consumers;

F - phytoplankton; 3 - zooplankton (the rightmost biomass pyramid is inverted)

Pyramids of numbers and biomass reflect staticssystems, i.e., characterize the number or biomass of organisms in a certain period of time. They do not provide complete information on the trophic structure of the ecosystem, although they make it possible to solve a number of practical problems, especially those related to maintaining ecosystem stability. The pyramid of numbers allows, for example, to calculate the allowable value of fish catch or shooting animals during the hunting period without consequences for their normal reproduction.

3. Energy pyramid reflects the magnitude of the energy flow, the speed of passage of the mass of food through the food chain. The biocenosis structure is more influenced not by the amount of fixed energy, but by the rate of food production (Fig. 56).

It has been established that the maximum amount of energy transferred to the next trophic level can in some cases be 30% of the previous one, and this is in the best case. In many biocenoses, food chains, the amount of transmitted energy can be as little as 1%.

Fig. 56. Pyramid of energy (law 10% or 10: 1),

(according to Tsvetkova, 1999)

In 1942, the American ecologist R. Lindeman formulated energy pyramid law (10 percent law), according to which, on average, about 10% of the energy delivered to the previous level of the ecological pyramid passes from one trophic level through food chains to another trophic level. The rest of the energy is lost in the form of thermal radiation, for movement, etc. Organisms, as a result of metabolic processes, lose about 90% of all energy in each link of the food chain that is spent on maintaining their vital functions.

If the hare ate 10 kg of plant mass, then its own weight may increase by 1 kg. A fox or a wolf, eating 1 kg of hare, increases its weight by only 100 g. For woody plants, this proportion is much lower due to the fact that wood is poorly absorbed by organisms. For herbs and algae, this value is much larger, since they lack hard-to-digest tissues. However, the general pattern of energy transfer remains: through the upper trophic levels it passes much less than through the lower levels.

That is why food chains usually cannot have more than 3-5 (rarely 6) links, and ecological pyramids cannot consist of a large number of floors. To the final link of the food chain, as well as to the upper floor of the ecological pyramid, so little energy will flow that it will not be enough if the number of organisms increases.

The rule of the ecological pyramid

The amount of plant matter that serves as the basis of the food chain is approximately 10 times greater than the mass of herbivorous animals, and each subsequent food level also has a mass 10 times smaller.

Pyramid of numbers (numbers)   reflects the number of individual organisms at each level. For example, in order to feed one wolf, it is necessary at least a few rabbits, which he could hunt; To feed these hares, you need a fairly large number of different plants. Sometimes pyramids of numbers can be reversed or inverted. This applies to the food chains of the forest, when the producers are trees, and the primary consumers are insects. In this case, the level of primary consumers is numerically richer than the level of producers (a large number of insects feed on one tree).

Biomass Pyramid   - the ratio of the masses of organisms of different trophic levels. Typically, in terrestrial biocenoses, the total mass of producers is greater than each subsequent link. In turn, the total mass of first-order consumers is greater than second-order consumers, etc. If organisms do not vary too much in size, then a graph usually turns out to be a step pyramid with a tapering apex. So, for the formation of 1 kg of beef, you need 70-90 kg of fresh grass.

In aquatic ecosystems, you can also get a reversed, or inverted, pyramid of biomass, when the biomass of producers is less than consumers, and sometimes reducers. For example, in the ocean, at a relatively high productivity of phytoplankton, the total mass at the moment may be less than that of consumer consumers (whales, large fish, mollusks).

Pyramids of numbers and biomass reflect the statics of the system, i.e. characterize the number or biomass of organisms in a certain period of time. They do not provide complete information on the trophic structure of the ecosystem, although they make it possible to solve a number of practical problems, especially those related to maintaining ecosystem stability. The pyramid of numbers allows, for example, to calculate the allowable value of fish catch or shooting animals during the hunting period without consequences for their normal reproduction.

Energy pyramid   reflects the magnitude of the energy flow, the speed of passage of the mass of food through the food chain. The structure of the biocenosis to a greater extent is affected not by the amount of fixed energy, but by the rate of food production.

It has been established that the maximum amount of energy transferred to the next trophic level can in some cases be 30% of the previous one, and this is in the best case. In many biocenoses, food chains, the amount of transmitted energy can be as little as 1%.

In 1942, the American ecologist R. Lindeman formulated energy pyramid law (10 percent law), according to which, on average, about 10% of the energy delivered to the previous level of the ecological pyramid passes from one trophic level through food chains to another trophic level. The rest of the energy is lost in the form of thermal radiation, in motion, etc. Organisms as a result of metabolic processes lose about 90% of all energy that is spent on maintaining their vital activity in each link of the food chain.

Food networks within each biogeocenosis have a well-defined structure.

It is characterized by the quantity, size and total mass of organisms - biomass - at each level of the food chain. Pasture food chains are characterized by an increase in population density, breeding rate and productivity of their biomass.

The decrease in biomass during the transition from one food level to another is due to the fact that not all food is assimilated by consumers.

So, for example, in a caterpillar feeding on leaves, only half of the plant material is absorbed in the intestine, the rest is excreted.

In addition, most of the nutrients absorbed by the intestine are spent on respiration and only 10-15% are ultimately used to build new caterpillar cells and tissues. For this reason, the production of organisms of each subsequent trophic level is always less (on average 10 times) than the production of the previous one, i.e., the mass of each subsequent link in the food chain is progressively decreasing. This pattern is called the rule of the ecological pyramid.

There are three ways to compile ecological pyramids:

• 1. The pyramid of numbers reflects the numerical ratio of individuals of different trophic levels of the ecosystem. If organisms within one or different trophic levels vary greatly in size, then the pyramid of numbers gives distorted ideas about the true relationships of trophic levels. For example, in the plankton community, the number of producers is tens and hundreds of times greater than the number of consumers, and in the forest hundreds of thousands of consumers can feed on the organs of a single producer tree;
• 2. The biomass pyramid shows the amount of living matter, or biomass, at each trophic level. In most terrestrial ecosystems, the biomass of producers, i.e., the total mass of plants is greatest, and the biomass of organisms of each subsequent trophic level is less than the previous one. However, in some communities the biomass of consumers of the first order is more biomass producers. For example, in the oceans, where the main producers are unicellular algae with a high reproduction rate, their annual production may be tens or even hundreds of times greater than the biomass supply. At the same time, all products formed by algae are so quickly involved in the food chain that the accumulation of algae biomass is small, but due to the high reproduction rates, their small supply is sufficient to maintain the rate of organic matter regeneration. In this regard, in the ocean, the biomass pyramid has an inverse relationship, that is, it is “inverted”. At higher trophic levels, the biomass accumulation trend prevails, since the life span of predators is long, the rate of turnover of their generations, on the contrary, is small, and a significant part of the substance entering the food chains is retained in their body;
• 3. The energy pyramid reflects the magnitude of the energy flow in the power circuit. The shape of this pyramid is not affected by the size of individuals, and it will always have a triangular shape with a wide base at the bottom, as dictated by the second law of thermodynamics. Therefore, the energy pyramid gives the most complete and accurate picture of the functional organization of the community, of all metabolic processes in the ecosystem. If the pyramids of numbers and biomass reflect the ecosystem statics (the number and biomass of organisms at the moment), then the energy pyramid is the dynamics of the passage of food masses through the food chain. Thus, the base in the pyramids of numbers and biomass can be more or less than subsequent trophic levels (depending on the ratio of producers and consumers in different ecosystems). The pyramid of energy always tapers up. This is due to the fact that the energy spent on breathing is not transferred to the next trophic level and leaves the ecosystem. Therefore, each subsequent level will always be less than the previous one. In terrestrial ecosystems, a decrease in the amount of available energy is usually accompanied by a decrease in the number and biomass of individuals at each trophic level. Due to such large losses of energy for the construction of new tissues and the respiration of organisms, the food chains cannot be long, they usually consist of 3-5 links (trophic levels).