The circulation of substances and the flow of energy in nature. The cycle of substances and the flow of energy in nature presentation for the lesson in biology (grade 10)

ESSAY
in the discipline "Ecology"
on the topic:
"The flow of energy and the circulation of substances in nature"

Completed:
student gr. ZEVM-107
Bocharov A.V.

Accepted:
Mishchenko T.V.

VLADIMIR 2011

Introduction ……………………………………………………….…. ………… .. 3
1. Energy flow in the biosphere ………………………………… .. ……………. 5
2. Biogeochemical cycles …………………………….…. ……… ... 7
2.1 Water cycle ………………………………………….…. …… 9
2.2 Oxygen cycle ……………………………………. …… ... 11
2.3 Carbon cycle …………………………. ………………… 12
2.4 Nitrogen cycle …………………………………………. ……… 14
2.5 Phosphorus cycle ………………………. ……………. ……… .. 17
2.6 The sulfur cycle ………………………………………. …………. eighteen
3.Factors affecting the cycle of substances in nature ..................... 19
4. Human influence on the circulation of substances in nature ………………… 23
Conclusion …………………………………………………. ……………… .. 26
List of used literature sources ………………. …………… 27

Introduction
The main function of the biosphere is to ensure the circulation of chemical elements, which is expressed in the circulation of substances between the atmosphere, soil, hydrosphere and living organisms.
Ecosystems are communities of organisms associated with the inorganic environment by the closest material and energy ties. Plants can exist only due to the constant supply of carbon dioxide, water, oxygen, and mineral salts. In any particular habitat, the reserves of inorganic compounds necessary to maintain the vital activity of the organisms inhabiting it would not last long if these reserves were not renewed. The return of nutrients to the environment occurs both during the life of organisms (as a result of respiration, excretion, defecation), and after their death, as a result of decomposition of corpses and plant debris. Thus, the community acquires a certain system with the inorganic environment, in which the flow of atoms, caused by the vital activity of organisms, tends to be closed in a cycle.
Any set of organisms and inorganic components in which the circulation of substances can take place is called an ecosystem. This term was proposed in 1935 by the English ecologist A. Tensley, who emphasized that with this approach, inorganic and organic factors act as equal components, and we cannot separate organisms from a specific environment. A. Tensley considered ecosystems as the basic units of nature on the surface of the Earth, although they do not have a certain volume and can cover a space of any length.
Most of the substances in the earth's crust pass through living organisms and are involved in the biological cycle of substances, which created the biosphere and determines its stability. Energetically, life in the biosphere is supported by a constant influx of energy from the Sun and its use in the processes of photosynthesis. The activity of living organisms is accompanied by the extraction of large amounts of mineral substances from the inanimate nature surrounding them. After the death of organisms, their constituent chemical elements return to the environment. This is how the biogenic circulation of substances in nature arises, that is, the circulation of substances between the atmosphere, hydrosphere, lithosphere and living organisms.
The purpose of this essay is to study the circulation of the flow of energy and substances in nature, and the disclosure of the selected topic.
The topic of my essay is very long. You can talk about it for a long time. But I will touch upon only those issues that I consider the most important and close to the chosen topic.

1. FLOW of energy in the biosphere
The flow of solar energy, being perceived by the molecules of living cells, is converted into the energy of chemical bonds. In the process of photosynthesis, plants use the radiant energy of sunlight to convert substances with low energy content (CO 2 and H 2 O) into more complex organic compounds, where part of the solar energy is stored in the form of chemical bonds.
Organic substances formed in the process of photosynthesis can serve as a source of energy for the plant itself or are transferred in the process of eating and subsequent assimilation from one organism to another: from a plant to herbivorous animals, from them to carnivores, etc. The release of the energy contained in organic compounds occurs during the process of breathing or fermentation. The destruction of used or dead biomass residues is carried out by various organisms belonging to the number of saprophytes (heterotrophic bacteria, fungi, some animals and plants). They decompose the remains of biomass into inorganic constituents (mineralization), contributing to the involvement of compounds and chemical elements in the biological cycle, which ensures the next cycles and production of organic matter. However, the energy contained in food does not make a cycle, but gradually turns into heat energy. Ultimately, all the solar energy absorbed by organisms in the form of chemical bonds returns to space in the form of thermal radiation, so the biosphere needs an influx of energy from the outside.
Unlike substances that continuously circulate through different blocks of the ecosystem and can always re-enter the cycle, energy can be used only once.
A one-way inflow of energy as a universal phenomenon of nature occurs as a result of the action of the laws of thermodynamics related to the foundations of physics. The first law states that energy can pass from one form (for example, the energy of light) to another (for example, the potential energy of food), but it is never created again or disappears.
The second law of thermodynamics says that there cannot be a single process associated with the transformation of energy without losing some of it. In such transformations, a certain amount of energy is dissipated into inaccessible thermal energy, and, therefore, is lost. For this reason, there can be no transformations, for example, of nutrients into a substance that makes up the body of the body, going with 100 percent efficiency.
The existence of all ecosystems depends on a constant flow of energy, which is necessary for all organisms to maintain their life and self-reproduction.
The sun is practically the only source of all energy on Earth. However, not all the energy of solar radiation can be absorbed and used by organisms. Only about half of the usual solar flux falling on green plants (that is, on producers) is absorbed by photosynthetic elements, and only a small fraction of the absorbed energy (from 1/100 to 1/20 of a part) is stored in the form of biochemical energy (food energy).
Thus, most of the solar energy is lost as heat for evaporation. In general, maintaining life requires a constant supply of energy. And wherever there are living plants and animals, we will always find here the source of their energy.

2. Biogeochemical cycles
Chemical elements that make up living things usually circulate in the biosphere along characteristic paths: from the external environment to organisms and again to the external environment. Biogenic migration is characterized by the accumulation of chemical elements in organisms (accumulation) and their release as a result of the mineralization of dead biomass (detritus). Such paths of circulation of chemicals (more or less closed), flowing with the use of solar energy through plant and animal organisms, are called biogeochemical cycles ( bio refers to living organisms, and geo- to soil, air, water on the earth's surface).
There are gas-type gyres with reservoirs of inorganic compounds in the atmosphere or oceans (N 2, O 2, CO 2, H 2 O) and sedimentary-type gyres with less extensive reservoirs in the earth's crust (P, Ca, Fe).
Elements necessary for life and dissolved salts are conventionally called biogenic elements (giving life), or nutrients. Among biogenic elements, two groups are distinguished: macrotrophic substances and microtrophic substances.
The first covers the elements that make up the chemical basis of the tissues of living organisms. These include: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur.
The latter include elements and their compounds, which are also necessary for the existence of living systems, but in extremely small quantities. Such substances are often referred to as trace elements. These are iron, manganese, copper, zinc, boron, sodium, molybdenum, chlorine, vanadium and cobalt. Although microtrophic elements are essential for organisms in very small quantities, their deficiency can severely limit productivity, as can nutrient deficiencies.
The circulation of biogenic elements is usually accompanied by their chemical transformations. Nitrate nitrogen, for example, can be converted into protein, then converted into urea, converted into ammonia and synthesized again into the nitrate form under the influence of microorganisms. Various mechanisms, both biological and chemical, are involved in the processes of denitrification and nitrogen fixation.
Carbon contained in the atmosphere in the form of CO 2 is one of the initial components for photosynthesis, and then, together with organic matter, is consumed by consumers. During respiration of plants and animals, as well as due to reducers, carbon in the form of CO 2 is returned to the atmosphere.
Unlike nitrogen and carbon, the reservoir of phosphorus is found in rocks that are eroded and release phosphates into ecosystems. Most of them end up in the sea and partly can be returned to land through marine food chains ending in fish-eating birds (guano formation). The assimilation of phosphorus by plants depends on the acidity of the soil solution: as the acidity increases, phosphates that are practically insoluble in water are converted into readily soluble phosphoric acid.
Unlike energy, biogenic elements can be used repeatedly: the cycle is their characteristic feature. Another difference from energy is that the supply of nutrients is not constant. The process of binding some of them in the form of living biomass reduces the amount remaining in the ecosystem environment.
Let us consider in more detail the biogeochemical cycles of some substances.

The water cycle

Oxygen cycle

The carbon cycle

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The cycle of substances and energy in nature

The circulation of substances is the repetitive processes of transformation and movement of matter in nature, which are more or less cyclical. All substances on our planet are in the process of circulation. In nature, there are two main cycles Large (geological) Small (biogeochemical)

The Great Cycle of Substances The Great Cycle lasts for millions of years, due to the interaction of solar energy with the deep energy of the Earth. It is associated with geological processes, the formation and destruction of rocks and the subsequent movement of destruction products.

Small cycle of substances Small cycle (biogeochemical) occurs within the biosphere, at the level of biocenosis. Its essence is in the formation of living matter from inorganic compounds in the process of photosynthesis and in the transformation of organic matter during decomposition into inorganic compounds. Biogeochemical cycles - Vernadsky V.I.

Water cycle Tr runoff inf Water evaporation Vapor condensation Precipitation runoff Transpiration infiltration

Transpiration is the process of movement of water through the plant and its evaporation through the external organs of the plant, such as leaves, stems and flowers. Water is essential for the life of the plant, but only a small part of the water entering through the roots is used directly for the needs of growth and metabolism.

The water cycle

The water cycle Most of the water is concentrated in the oceans. Water evaporates from their surface to supply natural and artificial terrestrial ecosystems. The closer the area is to the ocean, the more precipitation falls there. The land constantly returns water to the ocean: part of the moisture evaporates, most actively in the forests, part is collected by rivers: rain and melt water enter them. The exchange of moisture between the ocean and land requires very high energy costs: it consumes about 30% of the solar energy supplied to the Earth.

Human influence on the water cycle The water cycle in the biosphere before the development of civilization was equilibrium, i.e. the ocean received as much water from the rivers as it consumed in evaporation. With the development of civilization, this cycle began to be disrupted. Forests, in particular, evaporate less and less water. their area is shrinking, and the surface of the soil, on the contrary, is more and more, because the area of ​​agricultural irrigated is increasing. land. The rivers of the southern regions have become shallow. Water evaporates worse from the surface of the ocean, because a significant part of it is covered with a film of oil. All this deteriorates the water supply to the biosphere.

Droughts are becoming more frequent, and hotbeds of ecological disasters appear. For example, a catastrophic drought has lasted for more than 35 years in Africa, in the Sahel zone - a semi-desert region separating the Sahara from the northern countries of the continent. Freshwater that returns to the ocean and other bodies of water from land is often contaminated. The water of many rivers in Russia has become practically unsuitable for drinking. The share of fresh water available to living organisms is quite small, so it must be used sparingly and not polluted! Every fourth inhabitant of the planet lacks clean drinking water. In many parts of the world, there is not enough water for industrial production and irrigation.

Different components of the hydrosphere participate in the water cycle in different ways and at different speeds. Full renewal of water in glaciers takes 8000 years, groundwater - 5000 years, ocean - 3000 years, soil - 1 year. Atmospheric vapors and river waters are completely renewed in 10 - 12 days. The water cycle in nature takes about 1 million years.

Oxygen Cycle Oxygen is one of the most abundant elements in the biosphere. The oxygen content in the atmosphere is almost 21%. Oxygen is a part of water molecules, a part of living organisms (proteins, fats, carbohydrates, nucleic acids). Oxygen is produced by producers (green plants). Ozone plays an important role in the oxygen cycle. The ozone layer is located at an altitude of 20-30 km above sea level. The oxygen content in the atmosphere is influenced by 2 main processes: 1) photosynthesis 2) decomposition of organic matter, in which it is consumed.

The oxygen cycle is a slow process. It takes about 2000 years to completely renew all oxygen in the atmosphere. For comparison: a complete renewal of carbon dioxide in the atmosphere takes about 3 years. Oxygen is consumed for the respiration of most living organisms. Oxygen is used in the combustion of fuel in an internal combustion engine, in the furnaces of thermal power plants, in aircraft and missile engines, etc. Additional anthropogenic consumption can disrupt the equilibrium of the oxygen cycle. So far, the biosphere compensates for human intervention: the losses are replenished by green plants. With a further decrease in forest area and the burning of more and more fuel, the oxygen content in the atmosphere will begin to decrease.

IT IS IMPORTANT!!! With a decrease in the oxygen content in the air to 16%, a person's health worsens (in particular, the heart suffers), up to 7% - a person loses consciousness, up to 3% - death occurs.

The carbon cycle

Carbon cycle Carbon is the basis of organic compounds; it is a part of all living organisms in the form of proteins, fats, and carbohydrates. Carbon enters the atmosphere in the form of carbon dioxide. In the atmosphere, where the bulk of carbon dioxide is concentrated, there is a constant exchange: plants absorb carbon dioxide during photosynthesis, and all organisms release it during respiration. Up to 50% of carbon in the form of CO 2 is returned to the atmosphere by decomposers - soil microorganisms. Carbon leaves the cycle in the form of calcium carbonate.

Human influence on the carbon cycle Man-made human activity disrupts the natural balance of the carbon cycle: 1) the combustion of fossil fuel annually releases about 6 billion tons of CO2 into the atmosphere: a) Electricity production at CHP plants b) Exhaust gases from cars 2) destruction of forests. Over the past 100 years, the content of carbon dioxide in the atmosphere has been steadily and rapidly increasing. Carbon dioxide + methane + water vapor + ozone + nitrogen oxides = greenhouse gas. As a result - the greenhouse effect - global warming, which can lead to large-scale natural disasters.

The nitrogen cycle In free form, nitrogen is a constituent part of the air - 78%. Nitrogen is one of the most important elements for the life of organisms. Nitrogen is part of all proteins. The nitrogen molecule is very strong, for this reason, most organisms are not able to assimilate atmospheric nitrogen. Living organisms assimilate nitrogen only in the form of compounds with hydrogen and oxygen. The fixation of nitrogen into chemical compounds occurs as a result of volcanic and thunderstorm activity, but mostly as a result of the activity of microorganisms - nitrogen fixers (nitrogen fixing bacteria and blue-green algae).

Nitrogen enters the roots of plants in the form of nitrates, which are used for the synthesis of organic matter (proteins). Animals consume nitrogen from plant or animal foods. The return of nitrogen to the atmosphere occurs as a result of the destruction of dead organic material. Soil bacteria decompose proteins to inorganic substances - gases - ammonia, nitrogen oxides, which enter the atmosphere. Nitrogen that gets into water bodies also passes through the food chains “plant - animal - microorganisms” and returns to the atmosphere.

Human Impact on the Nitrogen Cycle Man-made human activity disrupts the natural balance of the nitrogen cycle. When plowing land, the activity of microorganisms - nitrogen fixers decreases by almost 5 times, therefore the nitrogen content in the soil decreases, which leads to a decrease in soil fertility. Therefore, a person introduces an excess of nitrates into the soil, which are included in mineral fertilizers. A large amount of nitrogen oxides enters the atmosphere during the combustion and processing of gas, oil, coal and falls in the form of acid rain. The restoration of the natural nitrogen cycle is possible by reducing the production of nitrogen fertilizers, reducing industrial emissions of nitrogen oxides into the atmosphere, etc.

Phosphorus cycle

Unlike the cycles of water, carbon, nitrogen and oxygen, which are closed, the cycle of phosphorus is open. phosphorus does not form volatile compounds that enter the atmosphere. Phosphorus is contained in rocks, from where it enters ecosystems during natural destruction of rocks or when phosphorus fertilizers are applied to fields. Plants absorb inorganic phosphorus compounds, and animals that feed on these plants accumulate phosphorus in their tissues. After the decomposition of dead bodies of animals and plants, not all phosphorus is involved in the circulation. Part of it is washed out of the soil into water bodies (rivers, lakes, seas) and settles to the bottom. Phosphorus returns to land in small quantities with fish caught by humans.

Human Impact on Phosphorus Cycle The transfer of phosphorus from land to the ocean has increased markedly under the influence of man. With the destruction of forests, plowing of soils, the volume of surface water flow increases, and in addition, phosphorus fertilizers are supplied to rivers and lakes from the fields. Since the reserves of phosphorus on land are limited, and its return from the ocean is difficult, in the future there may be a lack of phosphorus in agriculture, which will cause a decrease in yields (primarily of grain crops).

Any life requires a constant flow of energy and substance. Energy is spent on the implementation of basic life reactions, matter is spent on building the bodies of organisms. The existence of natural ecosystems is accompanied by complex processes of material and energy exchange between living and inanimate nature. The processes depend not only on the composition of biotic substances, but also on the physical environment.

The flows of energy and matter are considered in ecology as the transfer of energy and matter from the outside to autotrophs and further along the food chains from organisms of one trophic level to the next.

The flow of energy in a community is the transfer of energy from organisms of one level to another in the form of chemical bonds of organic compounds.

The flow of a substance is the movement of a substance in the form of chemical elements and their compounds from producers to reducers and then through chemical reactions that take place without the participation of living organisms, back to producers.

The flow of matter occurs in a closed cycle, which is why it is called the cycle.

The flow of matter and the flow of energy- not identical concepts, although different energy equivalents (calories, kilocalories, joules) are often used to measure the flow of matter.

The fundamental difference between the flows of matter and energy in an ecosystem is that biogenic elements (nitrogen, carbon, phosphorus, etc.) that make up organic matter can repeatedly participate in the cycle of matter, while the flow of energy is unidirectional and irreversible.

The existence of all ecosystems depends on a constant flow of energy, which is necessary for all organisms to maintain their life and self-reproduction.

The main channel for energy transfer in a community is the food chain. As you move away from the primary producer, the flow of energy sharply weakens - the amount of energy decreases.

Exercise

Using the 10% rule, calculate the share of energy entering the 4th trophic level, assuming that its total amount at the first level was 100 units.

Circulation of substances and energy conversion- a necessary condition for the existence of any ecosystem. Transport of substances and energy in food chains in an ecosystem.

An ecosystem can ensure the circulation of matter only if it includes the necessary four components: reserves of nutrients, producers, consumers and reducers

Rice. 1. Essential Ecosystem Components

This structure is composed of several groups of organisms, each of which performs a certain work in the cycle of substances. Organisms belonging to one such link form trophic level, and successive connections between trophic levels form power circuits, or trophic chains. The ecosystem includes organisms that are distinguished by the way of feeding - autotrophs and heterotrophs.

Autotrophs(self-nourishing) - organisms that form the organic matter of their body from inorganic substances - mainly from carbon dioxide and water - through the processes of photosynthesis and chemosynthesis. Photosynthesis is carried out by photoautotrophs - all chlorophyll-bearing (green) plants and microorganisms. Chemosynthesis is observed in some soil and water bacteria, which do not use sunlight as an energy source, but enzymatic oxidation of a number of substances - hydrogen, sulfur, hydrogen sulfide, ammonia, and iron.

Heterotrophs(feeding on others) - organisms that consume the finished organic matter of other organisms and their waste products. These are all animals, fungi and most of the bacteria.

Unlike producer autotrophs, heterotrophs act as consumers and destructors (destroyers) of organic substances. Depending on the sources of nutrition and participation in destruction, they are divided into consumers and reducers.

Consumptions - consumers of organic matter of organisms. These include:

Consumers of the 1st order - herbivorous animals (phytophages), eating living plants (aphids, grasshopper, goose, sheep, deer, elephant);

2nd order consumers - carnivores (zoophages), eating other animals - various predators (predatory insects, insectivorous and predatory birds, predatory reptiles and animals), attacking not only phytophages, but also other predators. There are many animals with a mixed diet that consume both plant and animal food - carnivorous, herbivorous and omnivorous. Order I and II consumables occupy the second, third, and sometimes the next trophic levels in the ecosystem, respectively.

Reducers - bacteria and lower fungi - complete the destructive work of consumers and saprophages, bringing the decomposition of organic matter to its complete mineralization and returning molecular nitrogen, mineral elements and the last portions of carbon dioxide to the ecosystem environment.

Ecosystem sustainability. Dependence of the sustainability of ecosystems on the number of species inhabiting them and the length of food chains: the more species, food chains, the more stable the ecosystem from the cycle of substances.

Artificial ecosystem- created as a result of human activity. Examples of artificial ecosystems: park, field, garden, vegetable garden.

Differences between an artificial ecosystem and a natural one:

Few species (eg wheat and some weeds in a wheat field and related animals);

The predominance of organisms of one or more species (wheat in the field);

Short food chains due to the small number of species;

Unclosed circulation of substances due to a significant removal of organic substances and their withdrawal from the circulation in the form of a crop;

Low stability and inability to live independently without human support.

Rice. 14.5... Sulmmar energy flow (dark arrows) and the cycle of matter (light arrows) in the ecosystem.

Thus, the basis of the ecosystem is autotrophic organisms - producers(producers, creators) who, in the process of photosynthesis, create energy-rich food - the primary organic matter. In terrestrial ecosystems, the most important role belongs to higher plants, which, forming organic matter, give rise to all trophic links in the ecosystem, serve as a substrate for many animals, fungi and microorganisms, and actively influence the microclimate of the biotope. In aquatic ecosystems, algae are the main producers of primary organic matter.

Ready organic substances are used to obtain and accumulate energy of heterotrophs, or consumers(consumers). Heterotrophs include herbivorous animals (1st order consumers), carnivores living off herbivorous forms (2nd order consumers), consuming other carnivores (3rd order consumers), etc.

A special group of consumers are reducers(destroyers, or] destructors), decomposing organic residues of producers and consumers to simple inorganic compounds, which are then used by producers. Reducers include mainly microorganisms - bacteria and fungi. In terrestrial ecosystems, soil decomposers are of particular importance, involving organic matter of dead plants in the general circulation (they consume up to 90% of the primary forest production). Thus, each living organism in an ecosystem occupies a certain ecological niche (place) in a complex system of ecological relationships with other organisms and abiotic environmental conditions.

Food chains (webs) and trophic levels. The basis of any ecosystem, its foundation is food (trophic) and associated energy connections. They are constantly transferring Substance and energy, which are contained in food, created mainly by plants.

The transfer of the potential energy of food created by plants through a number of organisms by eating some species by others is called power circuit or food chain, and each of its links - trophic level(fig.14.6).

Rice. 14.6... African savannah food chain.

Rice. 14.7. Power networks in the ecological system.

There are two main types of food chains - grazing (grazing or consumption chains) and detrital (decomposition chains). Pasture chains start with producers: clover -> rabbit -> wolf; phytoplankton (algae) -> zooplankton (protozoa) -> roach -> pike - > osprey.

Detrital chains start from plant and animal residues, animal excrement - detritus; go to microorganisms that feed on them, and then to small animals (detritophages) and their consumers - predators. Detrital chains are most common in forests, where most (more than 90%) of the annual increase in plant biomass is not consumed directly by herbivorous animals, but dies off, undergoing decomposition (saprotrophic organisms) and mineralization. A typical example of a detrital food relationship in our forests is the following: leaf litter - > earthworm -> blackbird > Sparrowhawk. In addition to earthworms, detritus feeders are woodlice, flares, springtails, nematodes, etc.

Ecological pyramids. Food webs within each biogeocenosis have a well-defined structure. It is characterized by the number, 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, reproduction rate and productivity of their biomasses. 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 the form of excrement. In addition, most of the nutrients absorbed by the intestines are consumed for respiration, and only 10-15% is ultimately used to build new cells and tissues of the caterpillar. For this reason, the production of organisms at 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 progressively decreases. This pattern was named ecological pyramid rule(fig.14.8).

Rice, 14.8. Simplified ecological pyramid.

There are three ways of drawing up 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 differ greatly in size, then the pyramid of numbers gives distorted ideas about the true ratios 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 one tree - the producer.

2. 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 first-order consumers is higher 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 or 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 the high rates of reproduction, a small supply of them is sufficient to maintain the rate of regeneration of organic matter. In this regard, the biomass pyramid in the ocean has an inverse relationship, ie, "inverted". At the higher trophic levels, the tendency towards the accumulation of 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 entering the food chains is retained in their body.

3. Energy pyramid reflects the amount of energy flow in the food chain. 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 idea of ​​the functional organization of the community, of all metabolic processes in the ecosystem. If the pyramids of numbers and biomasses reflect the statics of the ecosystem (the number and biomass of organisms at a given moment), then the pyramid of energy is the dynamics of the passage of the mass of food through the food chain. Thus, the base in the pyramids of numbers and biomasses can be greater or less than subsequent trophic levels (depending on the ratio of producers and consumers in different ecosystems). The energy pyramid always narrows upward. 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 respiration of organisms, food chains cannot be long; they usually 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 (agroienoses) are the main source of food supplies for mankind. Accurate calculations of the energy flow and the scale of the productivity of ecosystems make it possible to regulate the cycle of substances in them in such a way as to achieve the highest yield of products necessary for humans.

To trace the relationship between living and inanimate nature, it is necessary to understand how the circulation of substances in the biosphere occurs.

Meaning

The circulation of substances is the repeated participation of the same substances in the processes occurring in the lithosphere, hydrosphere and atmosphere.

There are two types of circulation of substances:

• geological(great circulation);
• biological(small circulation).

The driving force of the geological cycle of substances is external (solar radiation, gravity) and internal (energy of the Earth's interior, temperature, pressure) geological processes, biological - the activity of living beings.

The great circulation takes place without the participation of living organisms. Under the influence of external and internal factors, the relief is formed and smoothed. As a result of earthquakes, weathering, volcanic eruptions, the movement of the earth's crust, valleys, mountains, rivers, hills are formed, and geological layers are formed.

Rice. 1. Geological circulation.

The biological cycle of substances in the biosphere takes place with the participation of living organisms, which transform and transfer energy along the food chain. A stable system of interaction between living (biotic) and nonliving (abiotic) substances is called biogeocenosis.

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For the circulation of substances to occur, several conditions must be met:

• the presence of about 40 chemical elements;
• the presence of solar energy;
• interaction of living organisms.

Rice. 2. Biological circulation.

The cycle of substances has no definite starting point. The process is continuous and one stage invariably flows into another. You can start looking at the cycle from any point, the essence remains the same.

The general circulation of substances includes the following processes:

• photosynthesis;
• metabolism;
• decomposition.

Plants, which are producers in the food chain, convert solar energy into organic matter, which enter the body of decomposing animals with food. After death, plants and animals decompose with the help of consumers - bacteria, fungi, worms.

Rice. 3. Food chain.

The cycle of substances

Depending on the location of substances in nature, they emit two types of circulation:

• gas- occurs in the hydrosphere and atmosphere (oxygen, nitrogen, carbon);
• sedimentary- occurs in the earth's crust (calcium, iron, phosphorus).

The cycle of substances and energy in the biosphere is described in the table using the example of several elements.

Cessation of the circulation of substances in nature means a disruption in the course of life. For life to continue, it is necessary that the energy goes through cycle after cycle.

What have we learned?

From the lesson, they learned about the essence of the large and small cycle of substances in the biosphere, the interaction of inanimate nature with living organisms, and also considered the cycle of water, carbon, nitrogen, oxygen, sulfur and phosphorus.

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