When building an ecological pyramid, they are located at the base. Ecological pyramid rule

Ecosystems are very diverse in the relative rate of creation and expenditure of both primary production and secondary production at each trophic level. However, all ecosystems, without exception, are characterized by certain quantitative ratios of primary and secondary production, which are called product pyramid rules: at each previous trophic level, the amount of biomass created per unit of time is greater than at the next. Graphically, this rule is expressed in the form of pyramids, tapering upwards and formed by stacked rectangles of equal height, the length of which corresponds to the scale of production at the corresponding trophic levels. The product pyramid reflects the laws of energy expenditure in food chains.

The rate of creation of organic matter does not determine its total reserves, i.e., the total biomass of all organisms of each trophic level. The available biomass of producers or 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 correlate, i.e., how much the formed reserves are consumed. An important role is played by the turnover rate of the generations of the main producers and consumers.

Rice. 150. Pyramids of biomass in some biocenoses (according to F. Dre, 1976): P - producers; RK - herbivorous consumers; PC - carnivorous consumers; F - phytoplankton; 3 - zooplankton

In most terrestrial ecosystems, there is also biomass pyramid rule, i.e., the total mass of plants turns out to be greater than the biomass of all phytophages and herbivores, and the mass of those, in turn, exceeds the mass of all predators (Fig. 150). The ratio of annual vegetation growth to biomass in terrestrial ecosystems is relatively small. In different phytocenoses, where the main producers differ in the duration of the life cycle, size and growth rate, this ratio varies from 2 to 76%. The rates of relative growth of biomass are especially low in forests of different zones, where annual production is only 2-6% of the total mass of plants accumulated in the bodies of long-lived large trees. Even in the most productive tropical rainforests, this value does not exceed 6.5%. In communities dominated by herbaceous forms, the rate of biomass reproduction is much higher: the annual production in the steppes is 41-55%, and in herbal tugai and ephemeral-shrub semi-deserts it even reaches 70-76%.

The ratio of primary production to plant biomass determines the extent of plant mass grazing that is possible in a community without undermining its productivity. The relative share of primary production consumed by animals in herbaceous communities is higher than in forests. Ungulates, rodents, phytophagous insects in the steppes use up to 70% of the annual growth of plants, while in forests, on average, no more than 10%. However, the possible limits of alienation of plant mass by animals in terrestrial communities are not fully realized, and a significant part of the annual production goes to waste.

In the pelagial of the oceans, where the main producers are unicellular algae with a high turnover rate of generations, their annual production can exceed the biomass reserve by tens and even hundreds of times (Fig. 151). All pure primary production is so quickly involved in the food chain that the accumulation of algae biomass is very small, but due to the high reproduction rates, a small supply of them is sufficient to maintain the rate of organic matter reproduction.

Rice. 151. Scheme of the ratio of production and biomass in bacteria (1), phytoplankton (2), zooplankton (3), benthos (4) and fish (5) in the Barents Sea (according to L. A. Zenkevich from S. A. Zernov, 1949)

For the ocean, the biomass pyramid rule is invalid (the pyramid is inverted). At the highest trophic levels, the tendency to accumulate biomass prevails, since the life span of large predators is long, the turnover rate of their generations, on the contrary, is low, and a significant part of the substance that enters the food chains is retained in their bodies.

All three pyramid rules - production, biomass and numbers - ultimately express energy relations in ecosystems, and if the last two are manifested in communities with a certain trophic structure, then the first (production pyramid) has a universal character.

Knowledge of the laws of ecosystem productivity, the ability to quantify the flow of energy are of extreme practical importance. The primary production of agrocenoses and human exploitation of natural communities is the main source of food for mankind. No less important is the secondary products obtained from agricultural and game animals, since animal proteins include a number of amino acids essential for humans, which are not found in plant foods. Accurate calculations of the energy flow and the scale of ecosystem productivity make it possible to regulate the cycle of substances in them in such a way as to achieve the greatest yield of products beneficial to humans. In addition, it is necessary to have a good understanding of the allowable limits for the removal of plant and animal biomass from natural systems in order not to undermine their productivity. Such calculations are usually very complex due to methodological difficulties and are best performed for simpler aquatic ecosystems. An example of energy ratios in a particular community can be the data obtained for the ecosystems of one of the lakes (Table 2). The P/B ratio reflects the growth rate.

table 2

Energy flow in the ecosystem of a eutrophic lake (in kJ / m 2) on average for the growing season (according to G. G. Vinberg, 1969)

In this aquatic community, the biomass pyramid rule applies, since the total mass of producers is higher than that of phytophages, while the proportion of predators, on the contrary, is lower. The highest productivity is characteristic of phyto- and bacterioplankton. In the studied lake, their P/B ratios are quite low, which indicates a relatively weak involvement of primary production in food chains. The biomass of benthos, which is based on large molluscs, is almost twice that of plankton, while the production is many times lower. In zooplankton, the production of non-predatory species is only slightly higher than the diet of their consumers; therefore, plankton food relations are quite tense. The entire production of non-predatory fish is only about 0.5% of the primary production of the reservoir, and, therefore, fish occupy a modest place in the energy flow in the lake ecosystem. However, they consume a significant part of the zooplankton and benthos growth and therefore have a significant influence on the regulation of their production.

The description of the energy flow, therefore, is the foundation of a detailed biological analysis to establish the dependence of final products useful to humans on the functioning of the entire ecological system as a whole.

The trophic structure of an ecosystem can be depicted graphically as an ecological pyramid, which is based on the first level. These pyramids reflect the laws of biomass and energy expenditure 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 accumulated in it.

Food webs that emerge in an ecosystem have a structure that is characterized by a certain number of organisms at each trophic level. It is noticed that the number of organisms decreases in direct proportion when moving from one trophic level to another. This pattern is called "Rule of the Ecological Pyramid". In this case, considered pyramid of numbers . It can be broken if small predators live due to group hunting for large animals.

Each trophic level has its own biomass - the 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 much higher than the biomass of consumers - herbivorous animals (the second trophic level). The biomass of each of the subsequent trophic levels of the food chain also progressively decreases. This pattern has been named biomass pyramids .

A similar pattern can be identified when considering the transfer of energy through trophic levels, that is, in pyramid of energy (production ) . The amount of energy spent on maintaining one's own life activity in the chain of trophic levels is growing, while productivity is falling. Plants absorb only a small part of solar energy during photosynthesis. Herbivorous animals, which make up the second trophic level, assimilate only a certain part (20-60%) of the absorbed food. 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 deposition).

Organisms of the third trophic level (carnivorous animals) when eating 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 supply chains can only be replenished by the supply of new portions of it. Therefore, in an ecosystem there cannot be a cycle of energy, similar to the cycle of substances. Ecosystems are open systems that need an influx of solar energy or ready-made reserves of organic matter, thus. energy transfer in ecosystems occurs according to known the laws of thermodynamics:

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

2. There cannot be a single process associated with the transformation of energy without losing some of it in the form of heat, i.e. there are no energy conversions with 100% efficiency.

It is estimated that only about 10% of energy is transferred from one trophic level to another. This pattern has been named ten percent rule.

Thus, most of the energy in the power chain is lost when moving from one level to another. The next link in the food chain receives only the energy that is contained in the mass of the previous eaten link. Energy losses are about 90% with each transition through the food chain. For example, if the energy of a plant organism is 1000 J, then when it is completely eaten by a herbivore, only 100 J is assimilated in the body of the latter, in the body of a predator 10 J, and if this predator is eaten by another, then 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 running out. Therefore, the food chain cannot include more than 4 - 5 links. The energy lost in the supply chains can only be replenished through the receipt of new portions of it. In ecosystems, there can be no cycle of energy, like the cycle of substances. The life and functioning of any ecological system is possible only with a one-way directed flow of energy in the form of solar radiation or with an influx of ready-made organic matter.

Thus, the pyramid of numbers reflects the number of individuals in each link in the food chain. The biomass pyramid reflects the amount of organic matter formed at 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 the number of individuals. Pyramids of biomass and abundance of organisms for a given biocenosis repeat in general terms the configuration of the productivity pyramid.

Graphically, the ecological pyramid is depicted as several rectangles of the same height but different lengths. The length of the rectangle decreases from the bottom to the top, corresponding to a decrease in productivity at subsequent trophic levels. The lower triangle is the largest in length and corresponds to the first trophic level - producers, the second is approximately 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 has a universal character, while the pyramids of biomass and abundance appear 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 agricultural animals, is also important as a source of animal protein. Knowledge of the laws of distribution of energy, flows of energy and matter in biocenoses, the laws of productivity of plants and animals, understanding the limits of permissible withdrawal of plant and animal biomass from natural systems allow us to correctly build relationships in the "society - nature" system.

There are three ways of compiling ecological pyramids:

1. The pyramid of numbers reflects the numerical ratio of individuals of different trophic levels of the ecosystem. If organisms within the same or different trophic levels vary greatly in size, then the pyramid of numbers gives distorted ideas about the true ratios of trophic levels. For example, in a 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 one tree - the producer.

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 the largest, 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 greater than the biomass of producers. For example, in the oceans, where the main producers are unicellular algae with a high reproduction rate, their annual production can exceed the biomass reserve by tens and even hundreds of times. At the same time, all the products formed by algae are so quickly involved in the food chain that the accumulation of algae biomass is small, but due to high reproduction rates, their small reserve is sufficient to maintain the rate of organic matter reproduction. In this regard, in the ocean, the biomass pyramid has an inverse relationship, i.e., “inverted”. At the highest trophic levels, the tendency to accumulate biomass prevails, since the life span of predators is long, the turnover rate of their generations, on the contrary, is low, and a significant part of the substance that enters the food chains is retained in their body.

3. The pyramid of energy reflects the amount of energy flow in the food chain. The shape of this pyramid is not affected by the size of the individuals, and will always be triangular with a wide base at the bottom, as dictated by the second law of thermodynamics. Therefore, the pyramid of energy gives the most complete and accurate idea of ​​the functional organization of the community, of all metabolic processes in the ecosystem. If the pyramids of numbers and biomass reflect the statics of the ecosystem (the number and biomass of organisms at a given moment), then the pyramid of energy reflects the dynamics of the passage of a mass of food through the food chain. Thus, the base in the pyramids of numbers and biomass can be larger or smaller than the subsequent trophic levels (depending on the ratio of producers and consumers in different ecosystems). The pyramid of energy always narrows upwards. This is due to the fact that the energy spent on respiration 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 abundance 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, food chains cannot be long; usually they consist of 3-5 links (trophic levels).

Knowledge of the laws of ecosystem productivity, the ability to quantify the flow of energy are of great practical importance, since the products of natural and artificial communities (agroenoses) are the main source of food for mankind. Accurate calculations of the energy flow and the scale of ecosystem productivity make it possible to regulate the cycle of substances in them in such a way as to achieve the greatest yield of products necessary for humans.

Successions and their types.

The process by which communities of plant and animal species are replaced over time by other, usually more complex, communities is called ecological succession, or just succession.

Ecological succession usually continues until the community is stable and self-sustaining. Ecologists distinguish two types of ecological succession: primary and secondary.

primary succession- this is the consistent development of communities in areas devoid of soil.

Stage 1 - the emergence of a place devoid of life;

2nd stage - the resettlement of the first plant and animal organisms at this place;

3rd stage - survival of organisms;

4th stage - competition and displacement of species;

5th stage - transformation of habitat by organisms, gradual stabilization of conditions and relationships.

A well-known example of primary succession is the colonization of solidified lava after a volcanic eruption or a slope after an avalanche that destroyed the entire soil profile, areas of open-pit mining from which the topsoil was removed, etc. In such barren areas, primary succession from bare rock to mature forest can take hundreds to thousands of years.

secondary succession- consistent development of communities in an area in which natural vegetation has been eliminated or severely disturbed, but the soil has not been destroyed. Secondary succession begins at the site of the destroyed biocenosis (forest after a fire). Succession is fast because seeds, parts of food links are preserved in the soil, and a biocenosis is formed. If we consider succession on abandoned lands that are not used in agriculture, we can see that the former fields are quickly covered with a variety of annual plants. Seeds of tree species: pine, spruce, birch, aspen, can also get here, sometimes overcoming long distances with the help of wind or animals. In the beginning, change happens quickly. Then, as more slowly growing plants emerge, the rate of succession decreases. Birch seedlings form dense shoots that shade the soil, and even if spruce seeds germinate along with birch, its seedlings, being in very unfavorable conditions, lag far behind birch trees. The birch is called the "pioneer of the forest" as it is almost always the first to settle in disturbed lands and has a wide range of adaptability. Birches at the age of 2-3 years can reach a height of 100-120 cm, while fir-trees at the same age barely reach 10 cm. Changes also affect the animal component of the considered biocenosis. At the first stages, May-bearers, birch moths settle, then numerous birds appear: finches, warblers, warblers. Small mammals settle: shrews, moles, hedgehogs. Changing lighting conditions begin to have a positive effect on young Christmas trees, which accelerate their growth.

The stable stage of succession, when the community (biocenosis) has fully formed and is in balance with the environment is called climax. The climax community is capable of self-regulation and can be in equilibrium for a long time.

Thus, succession occurs, in which at first a birch, then a mixed spruce-birch forest is replaced by a pure spruce forest. The natural process of changing birch forest to spruce forest lasts for more than 100 years. That is why the process of succession is sometimes called secular change.

18. Functions of living matter in the biosphere. living matter - it is the totality of living organisms (biomass of the Earth). It is an open system which is characterized by growth, reproduction, distribution, exchange of matter and energy with the external environment, accumulation of energy and its transfer in food chains. Living matter performs 5 functions:

1. Energy (the ability to absorb solar energy, convert it into the energy of chemical bonds and transfer it through food chains)

2. Gas (the ability to maintain the constancy of the gas composition of the biosphere as a result of the balance of respiration and photosynthesis)

3. Concentration (the ability of living organisms to accumulate certain elements of the environment in their body, due to which the elements were redistributed and minerals were formed)

4. Redox (the ability to change the oxidation state of elements and create a variety of compounds in nature to maintain the diversity of life)

5. Destructive (the ability to decompose dead organic matter, due to which the circulation of substances is carried out)

1. The water function of living matter in the biosphere is associated with the biogenic water cycle, which is of great importance in the water cycle on the planet.

Performing the listed functions, living matter adapts to the environment and adapts it to its biological (and if we are talking about a person, then also social) needs. At the same time, living matter and its habitat develop as a whole, but control over the state of the environment is carried out by living organisms.

In any trophic chain, not all food is used for the growth of an individual, i.e. for the accumulation of its biomass. Part of it is spent to meet the energy costs of the body (breathing, movement, reproduction, maintaining body temperature).

At the same time, the biomass of one link cannot be completely processed by the next, and in each subsequent link of the trophic chain, a decrease in biomass occurs.

On average, it is believed that only about 10% of the biomass and the energy associated with it passes from each trophic level to the next, i.e. the production of organisms of each subsequent trophic level is always less on average 10 times the production of the previous level.

So, for example, on average, 100 kg of biomass of herbivorous animals (consumers of the first order) is formed from 1000 kg of plants. Carnivores (second-order consumers) that eat herbivores can synthesize 10 kg of their biomass from this amount, and predators (third-order consumers) that feed on carnivores synthesize only 1 kg of their biomass.

Thus , the total biomass, the energy contained in it, as well as the number of individuals progressively decrease as one ascends the trophic levels.

This pattern has been named ecological pyramid rules.

This phenomenon was first studied by C. Elton (1927) and named by him pyramid of numbers or Elton's pyramid.

ecological pyramid - this is a graphic representation of the relationship between producers and consumers of different orders, expressed in units of biomass (pyramid of biomass), number of individuals (population pyramid) or the energy contained in the mass of living matter (pyramid of energy) ( Fig.6).

Fig.6. Diagram of the ecological pyramid.

The ecological pyramid expresses the trophic structure of ecosystems in geometric form.

There are three main types of ecological pyramids: the pyramid of numbers (numbers), the pyramid of biomass and the pyramid of energy.

1) pyramids of numbers, based on the count of organisms of each trophic level; 2) biomass pyramids, which use the total mass (usually dry) of organisms at each trophic level; 3) energy pyramids, taking into account the energy intensity of organisms of each trophic level.

energy pyramids are considered the most important, since they directly refer to the basis of nutritional relationships - the flow of energy necessary for the life of any organisms.

Pyramid of numbers (numbers)

The pyramid of numbers (numbers) or Elton's pyramid reflects the number of individual organisms at each trophic level.

The population pyramid is the simplest approximation to the study of the trophic structure of an ecosystem.

At the same time, the number of organisms in a given area is first calculated, grouping them by trophic levels and presenting them as a rectangle, the length (or area) of which is proportional to the number of organisms living in a given area (or in a given volume, if it is an aquatic ecosystem).

The population pyramid can have a regular shape, i.e. taper upwards (correct or straight), and may be an inverted top down (inverted or reversed) Fig.7.

right (straight) inverted (inverted)

(pond, lake, meadow, steppe, pasture, etc.) (temperate forest in summer, etc.)

Fig.7. Pyramid of numbers (1 - correct; 2 - inverted)

The population pyramid has a regular shape, i.e. narrows when moving from the level of producers to higher trophic levels, for aquatic ecosystems (pond, lake, etc.) and terrestrial ecosystems (meadow, steppe, pasture, etc.).

For example:

1,000 phytoplankton in a small pond can feed 100 small crustaceans - first-order consumers, which in turn will feed 10 fish - second-order consumers, which will be enough to feed 1 perch - third-order consumers.

The abundance pyramid for some ecosystems, such as temperate forests, is inverted.

For example:

in the forest of the temperate zone in summer, a small number of large trees - producers supply food to a huge number of small-sized phytophagous insects and birds - consumers of the first order.

However, in ecology, the population pyramid is rarely used, since due to the large number of individuals at each trophic level, it is very difficult to display the structure of the biocenosis on the same scale.

biomass pyramid

The biomass pyramid reflects more fully the nutritional relationships in the ecosystem, since it takes into account the total mass of organisms (biomass) of each trophic level.

Rectangles in biomass pyramids display the mass of organisms of each trophic level, per unit area or volume.

Pyramids of biomass, as well as pyramids of abundance, can be not only regular in shape, but also inverted (reversed) Fig.8.

Consumers of the 3rd order

Consumers of the 2nd order

Consumers of the 1st order

Producers

right (straight) inverted (inverted)

(terrestrial ecosystems: (aquatic ecosystems: lake,

meadow, field, etc.) pond and especially marine

ecosystems)

Fig.7. Pyramid of biomass (1 - correct; 2 - inverted)

For most terrestrial ecosystems (meadow, field, etc.), the total biomass of each subsequent trophic level of the food chain decreases.

This creates a biomass pyramid, where producers significantly predominate, and gradually decreasing trophic levels of consumers are located above them, i.e. the biomass pyramid has a regular shape.

For example:

on average, out of 1000 kg of plants, 100 kg of the body of herbivorous animals are formed - consumers of the first order (phytophages). Carnivorous animals - consumers of the second order, eating herbivores, can synthesize 10 kg of their biomass from this amount. And predators - consumers of the third order, eating carnivores, synthesize only 1 kg of their biomass.

In aquatic ecosystems (lake, pond, etc.), the biomass pyramid can be inverted, where the biomass of consumers prevails over the biomass of producers.

This is explained by the fact that in aquatic ecosystems the producer is microscopic phytoplankton, which rapidly grows and reproduces), which continuously supplies live food in sufficient quantities to consumers who grow and reproduce much more slowly. Zooplankton (or other animals that feed on phytoplankton) accumulate biomass over years and decades, while phytoplankton have an extremely short life span (several days or hours).

Functional relationships, i.e., the trophic structure, can be depicted graphically, in the form of the so-called ecological pyramids. The base of the pyramid is the level of producers, and the subsequent levels of nutrition form the floors and top of the pyramid. There are three main types of ecological pyramids: 1) pyramid of numbers, reflecting the number of organisms at each level (Elton's pyramid); 2) biomass pyramid characterizing the mass of living matter - total dry weight, caloric content, etc.; 3) product pyramid(or energy), which has a universal character, showing the change in primary production (or energy) at successive trophic levels.

The pyramid of numbers reflects a clear pattern discovered by Elton: the number of individuals that make up a series of links from producers to consumers is steadily decreasing (Fig. 5.). This pattern is based, firstly, on the fact that many small bodies are needed to balance the mass of a large body; secondly, the amount of energy is lost from the lower trophic levels to the higher ones (only 10% of the energy reaches the previous one from each level) and, thirdly, the inverse dependence of metabolism on the size of individuals (the smaller the organism, the more intense the metabolism, the higher the growth rate their abundance and biomass).

Rice. 5. Simplified diagram of Elton's pyramid

However, the pyramids of abundance will vary greatly in shape in different ecosystems, so it is better to give the abundance in tabular form, but biomass - in graphical form. It clearly indicates the amount of all living matter at a given trophic level, for example, in units of mass per unit area - g / m 2 or per volume - g / m 3, etc.

In terrestrial ecosystems, the following rule applies biomass pyramids: the total mass of plants exceeds the mass of all herbivores, and their mass exceeds the entire biomass of predators. This rule is observed, and the biomass of the entire chain changes with changes in the value of net production, the ratio of the annual growth of which to the biomass of the ecosystem is small and varies in forests of different geographical zones from 2 to 6%. And only in meadow plant communities it can reach 40-55%, and in some cases, in semi-deserts - 70-75%. On fig. 6 shows the biomass pyramids of some biocenoses. As can be seen from the figure, for the ocean, the above biomass pyramid rule is invalid - it has an inverted (inverted) form.

Rice. 6. Pyramids of biomass of some biocenoses: P - producers; RK - herbivorous consumers; PC - carnivorous consumers; F, phytoplankton; Z - zooplankton

The ocean ecosystem tends to accumulate biomass at high levels, in predators. Predators live for a long time and the turnover rate of their generations is low, but for producers - phytoplankton algae, the turnover rate can be hundreds of times higher than the biomass reserve. This means that their net production here also exceeds the production absorbed by consumers, i.e., more energy passes through the level of producers than through all consumers.

From this it is clear that an even more perfect reflection of the influence of trophic relations on the ecosystem should be the rule of the product (or energy) pyramid: at each previous trophic level, the amount of biomass created per unit of time (or energy) is greater than at the next.

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

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

A striking example is the high seas food chain, represented by plankton and whales. The mass of plankton is dispersed in the ocean water and, with the bioproductivity of the open sea less than 0.5 g/m 2 day -1 , the amount of potential energy in a cubic meter of ocean water is infinitely small compared to the energy of a whale, whose mass can reach several hundred tons. As you know, whale oil is a high-calorie product that was even used for lighting.

In accordance with the last digit, one percent rule: for the stability of the biosphere as a whole, the share of possible final consumption of net primary production in energy terms should not exceed 1%.

Fig.7. Pyramid of energy transfer along the food chain (according to Y. Odum)

In the destruction of organics, a 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% by invertebrates, and less than 1% by vertebrates, which are final cosuments.

Ultimately, all three rules of the pyramids reflect energy relations in the ecosystem, and the pyramid of production (energy) has a universal character.

In nature, in stable systems, biomass changes insignificantly, i.e., nature tends to use the entire gross production. Knowledge of the energy of the ecosystem and its quantitative indicators make it possible to accurately take into account the possibility of removing one or another amount of plant and animal biomass from the natural ecosystem without undermining its productivity.

A person receives a lot of products from natural systems, nevertheless, agriculture is the main source of food for him. Having created agro-ecosystems, a person seeks to get as much pure vegetation production as possible, but he needs to spend half of the plant mass on feeding herbivores, birds, etc., a significant part of the production goes to industry and is lost in garbage, i.e., it is lost about 90% of pure production and only about 10% is directly used for human consumption.

In natural ecosystems, energy flows also change in intensity and nature, but this process is regulated by the action of environmental factors, which is manifested in the dynamics of the ecosystem as a whole.

Based on the food chain as the basis for the functioning of the ecosystem, it is also possible to explain the cases of accumulation in the tissues of certain substances (for example, synthetic poisons), which, as they move along the trophic chain, do not participate in the normal metabolism of organisms. According to biological amplification rules there is an approximately tenfold increase in the concentration of the pollutant when moving to a higher level of the ecological pyramid. In particular, a seemingly insignificant elevated content of radionuclides in river water at the first level of the trophic chain is assimilated by microorganisms and plankton, then it is concentrated in fish tissues and reaches maximum values ​​in gulls. Their eggs have a level of radionuclides 5000 times higher than background pollution.

Types of ecosystems:

There are several classifications of ecosystems. First, ecosystems are subdivided by nature of origin and are divided into natural (swamp, meadow) and artificial (arable land, garden, spaceship).

By size ecosystems are divided into:

1. micro-ecosystems (for example, the trunk of a fallen tree or a clearing in a forest)

2. mesoecosystems (forest or steppe kolok)

3. macroecosystems (taiga, sea)

4. global ecosystems (planet Earth)

Energy is the most convenient basis for classifying ecosystems. There are four fundamental types of ecosystems type of energy source:

1. driven by the sun, little subsidized
2. driven by the Sun, subsidized by other natural sources
3. driven by the sun and subsidized by man
4. driven by fuel.

In most cases, two sources of energy can be used - the Sun and fuel.

Natural ecosystems driven by the Sun, little subsidized- these are open oceans, alpine forests. All of them receive energy practically from only one source - the Sun and have low productivity. The annual energy consumption is estimated at approximately 10 3 -10 4 kcal-m 2 . The organisms living in these ecosystems are adapted to the scarce amounts of energy and other resources and use them efficiently. These ecosystems are very important for the biosphere, as they occupy vast areas. The ocean covers about 70% of the earth's surface. In fact, these are the main life support systems, mechanisms that stabilize and maintain conditions on the "spaceship" - the Earth. Here, huge volumes of air are cleaned daily, water is returned to circulation, climatic conditions are formed, temperature is maintained, and other functions that ensure life are performed. In addition, at no cost to man, some food and other materials are produced here. It should also be said about the aesthetic values ​​​​of these ecosystems that cannot be taken into account.

Natural ecosystems driven by the Sun, subsidized by other natural sources, are ecosystems that are naturally fertile and produce excess organic matter that can accumulate. They receive natural energy subsidies in the form of tidal energy, surf, currents coming from the catchment area with rain and wind of organic and mineral substances, etc. Energy consumption in them ranges from 1 * 10 4 to 4 * 10 4 kcal * m - 2 *year -1 . The coastal part of an estuary such as the Neva Bay is a good example of such ecosystems, which are more fertile than adjacent land areas receiving the same amount of solar energy. Excessive fertility can also be observed in rainforests.

Ecosystems driven by the Sun and subsidized by humans, are terrestrial and aquatic agro-ecosystems that receive energy not only from the Sun, but also from humans in the form of energy subsidies. Their high productivity is supported by muscle energy and fuel energy, which are spent on cultivation, irrigation, fertilization, selection, processing, transportation, etc. Bread, corn, potatoes are "partially made from oil." The most productive agriculture receives about the same amount of energy as the most productive natural ecosystems of the second type. Their production reaches approximately 50,000 kcal*m -2 year -1 . The difference between them lies in the fact that a person directs as much energy as possible to the production of food products of a limited type, while nature distributes them among many types and accumulates energy for a “rainy day”, as if putting it into different pockets. This strategy is referred to as the “diversity-for-survival strategy”.

Fuel-driven industrial-urban ecosystems, - the crown of human achievements. In industrial cities, highly concentrated fuel energy does not supplement, but replaces solar energy. Food - the product of systems driven by the Sun - is brought into the city from outside. A feature of these ecosystems is the huge need for energy in densely populated urban areas - it is two to three orders of magnitude greater than in the first three types of ecosystems. If in non-subsidized ecosystems the energy influx ranges from 10 3 to 10 4 kcal*m -2 year -1 , and in subsidized systems of the second and third type - from 10 4 to 4*10 in large industrial cities, energy consumption reaches several million kilocalories per 1 m 2: New York - 4.8 * 10 6, Tokyo - 3 * 10 6, Moscow - 10 6 kcal * m -2 year -1.

Energy consumption by a person in a city averages more than 80 million kcal*year -1; for food, he needs only about 1 million kcal * year -1, therefore, for all other activities (household, transport, industry, etc.), a person spends 80 times more energy than is required for the physiological functioning of the body. Of course, in developing countries the situation is somewhat different.