Ministry of Education of the Russian Federation
VLADIMIR STATE UNIVERSITY
Department of Ecology
ABSTRACT
in the discipline "Ecology"
on the topic of:
“The flow of energy and the cycle of substances in nature”
Completed:
student gr. ZEVM-107
Bocharov A.V.
Accepted:
Mishchenko T.V.
VLADIMIR 2011
Introduction……………………………………………………….….………….. 3
1. Flow of energy 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 Sulfur cycle…………………………………….…………. 18
3. Factors influencing the cycle of substances in nature………………... 19
4. Human influence on the cycles of substances in nature ………………… 23
Conclusion…………………………………………………………….……………….. 26
List of references used……………….………………… 27
Introduction
The main function of the biosphere is to ensure the cycle of chemical elements, which is expressed in the circulation of substances between the atmosphere, soil, hydrosphere and living organisms.
Ecosystems are communities of organisms connected to the inorganic environment by the closest material and energy connections. Plants can exist only due to the constant supply of carbon dioxide, water, oxygen, and mineral salts. In any given habitat, the reserves of inorganic compounds necessary to support the life 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 the 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 close in a cycle.
Any collection of organisms and inorganic components in which the circulation of substances can occur is called an ecosystem. This term was proposed in 1935 by the English ecologist A. Tansley, who emphasized that with this approach, inorganic and organic factors act as equal components, and we cannot separate organisms from a specific environment. A. Tansley considered ecosystems as the basic units of nature on the surface of the Earth, although they do not have a specific volume and can cover a space of any extent.
Most substances in the earth's crust pass through living organisms and are involved in the biological cycle of substances that created the biosphere and determines its stability. In terms of energy, life in the biosphere is supported by a constant flow 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 quantities of minerals from the surrounding inanimate nature. After the death of organisms, their constituent chemical elements are returned to the environment. This is how the biogenic cycle of substances arises in nature, 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 to disclose the chosen topic.
The topic of my essay is very large. We can talk about her for a long time. But I will only touch on those issues that I consider the most important and closest to the chosen topic.
1. FLOW of energy in the biosphere
The flow of solar energy, 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 during 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 the plant to herbivores, from them to carnivores, etc. The release of energy contained in organic compounds occurs during the process of respiration or fermentation. The destruction of used or dead biomass residues is carried out by a variety of organisms classified as saprophytes (heterotrophic bacteria, fungi, some animals and plants). They decompose the remains of biomass into inorganic components (mineralization), promoting the involvement of compounds and chemical elements in the biological cycle, which ensures regular cycles and the production of organic matter. However, the energy contained in food does not cycle, but is gradually converted into thermal energy. Ultimately, all solar energy absorbed by organisms in the form of chemical bonds returns again 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 only be used once.
The one-way influx of energy as a universal natural phenomenon occurs as a result of the laws of thermodynamics, which relate to the fundamentals of physics. The first law states that energy can change from one form (such as the energy of light) to another (such as the potential energy of food), but it is never created again or destroyed.
The second law of thermodynamics states 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 unavailable thermal energy, and is therefore lost. For this reason, there cannot be transformations, for example, of food substances into the substance that makes up the body of the organism, which occur with 100% efficiency.
The existence of all ecosystems depends on a constant flow of energy, which is necessary for all organisms to maintain their vital functions 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 normal solar flux falling on green plants (that is, producers) is absorbed by photosynthetic elements and only a small fraction of the absorbed energy (from 1/100 to 1/20 of the part) is stored in the form of biochemical energy (food energy).
Thus, most of the solar energy is lost as heat through evaporation. In general, maintaining life requires a constant supply of energy. And wherever living plants and animals are, we will always find a source of their energy here.
2. Biogeochemical cycles
The 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 pathways of circulation of chemicals (to a greater or lesser extent closed), flowing using 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 cycles with reservoirs of inorganic compounds in the atmosphere or oceans (N 2 , O 2 , CO 2 , H 2 O) and sedimentary-type cycles with less extensive reservoirs in the earth's crust (P, Ca, Fe).
The elements necessary for life and dissolved salts are conventionally called biogenic elements (life-giving), or nutrients. Among biogenic elements, two groups are distinguished: macrotrophic substances and microtrophic substances.
The former cover the elements that constitute 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, also necessary for the existence of living systems, but in extremely small quantities. Such substances are often called microelements. These are iron, manganese, copper, zinc, boron, sodium, molybdenum, chlorine, vanadium and cobalt. Although microtrophic elements are necessary for organisms in very small quantities, their deficiency can severely limit productivity, as can the lack of nutrients.
The circulation of nutrients is usually accompanied by their chemical transformations. Nitrate nitrogen, for example, can be converted into protein nitrogen, then converted into urea, converted into ammonia and again synthesized 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 the respiration of plants and animals, as well as through decomposers, 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 undergo erosion and release phosphates into ecosystems. Most of them end up in the sea and some can be returned to land again through marine food chains ending with fish-eating birds (guano formation). The absorption of phosphorus by plants depends on the acidity of the soil solution: as the acidity increases, practically insoluble phosphates in water are converted into highly soluble phosphoric acid.
Unlike energy, nutrients can be used repeatedly: their cycling is a characteristic feature. Another difference with energy is that the supply of nutrients is not constant. The process of sequestering some of them as 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
In the biosphere, water, continuously moving from one state to another, makes small and large cycles. The evaporation of water from the surface of the ocean, the condensation of water vapor in the atmosphere and the precipitation on the surface of the ocean form a small cycle. If water vapor is carried by air currents to land, the cycle becomes much more complicated. In this case, part of the precipitation evaporates and goes back into the atmosphere, the other feeds rivers and reservoirs, but ultimately returns to the ocean again by river and underground runoff, thereby completing the large cycle. An important property of the water cycle is that, interacting with the lithosphere, atmosphere and living matter, it links together all parts of the hydrosphere: the ocean, rivers, soil moisture, groundwater and atmospheric moisture. Water is the most important component of all living things. Groundwater, penetrating through plant tissue during the process of transpiration, introduces mineral salts necessary for the life of the plants themselves.
The slowest part of the water cycle is the activity of polar glaciers, which reflects the slow movement and rapid melting of glacial masses. After atmospheric moisture, river waters are characterized by the greatest exchange activity, which changes on average every 11 days. The extremely rapid renewability of the main sources of fresh water and the desalination of water in the process of the cycle are a reflection of the global process of water dynamics on the globe.
- Oxygen cycle
In addition to the oxygen cycle described above in an unbound form, this element also completes the most important cycle, being part of water.
- Carbon cycle
Carbon is of exceptional importance for living matter (living matter in geology is the totality of all organisms inhabiting the Earth). Millions of organic compounds are created from carbon in the biosphere. Carbon dioxide from the atmosphere is assimilated and converted into a variety of organic plant compounds during the process of photosynthesis carried out by green plants. Plant organisms, especially lower microorganisms and marine phytoplankton, due to their exceptional reproduction rate, produce about 1.5 * 10 11 per year
etc.................
It is known that all substances in the biosphere of planet Earth are in the process of biochemical circulation.
There are two main cycles: large (geological) and small (biotic).
The Great Cycle lasts millions of years. Rocks are continuously destroyed, weathered, dissolved and carried by streams of water into the World Ocean. Thick marine strata are formed here. In this case, some of the chemical compounds dissolve in water or are consumed by the biocenosis.
Processes associated with the subsidence of continents and the rise of the seabed, the movement of seas and oceans over a long period of time, called geoctonic, lead to the return of marine strata to the land, and this action begins again.
The small cycle, being part of the large one, occurs at the level of biogeocenosis and consists in the fact that nutrients contained in the soil, water and atmosphere accumulate in plants and are spent on creating their mass and life processes in them. The small cycle lasts hundreds of years. Here, under the influence of bacteria, organic substances decompose, disintegrate and break down into mineral components available for nutrition by other plants. Thus, they are again involved in the circular flow of substances in nature (biosphere).
The return of chemicals from the inorganic environment through plant and animal organisms back to the inorganic environment using solar energy and chemical reactions is called the biochemical cycle. Three groups of organisms participate in this cycle of substances: producers, consumers and decomposers.
Producers(producers) - autotrophic organisms and plants that, using solar energy, create the primary production of living matter. They consume carbon dioxide CO 2, water H 2 O, salts and release oxygen O 2. Some bacteria (chemoseptics) capable of creating organic matter also belong to this group.
Consumers(consumers) - heterotrophic organisms that feed on autotrophic organisms and each other. In turn, they are divided into consumers of the first (herbivores), second (predators), third and fourth (superparasites) order.
Decomposers(reducing agents) - organisms that feed on other (dead) organisms, bacteria and fungi. Here, the role of microorganisms is especially great, completely destroying organic residues and converting them into final products: mineral salts, carbon dioxide, water, simple organic substances that enter the soil and are again consumed by plants.
It should be noted that as a result of photosynthesis on the earth's land, from 1.5 to 5.5 billion tons of plant biomass are formed annually, which contains about 4.6 10 18 kJ of solar energy. The entire increase in living matter on Earth is about 88 billion tons per year. Moreover, the total mass of living matter includes about 500 thousand different plant species and about 2 million animal species.
The rate of formation of a biological substance (biomass), or the formation of the mass of a substance per unit time, is called productivity ecosystems. The biological productivity of land and ocean is approximately equal, since the ocean biomass consists mainly of unicellular algae, which are renewed annually. Land biomass is renewed within 15 years.
The cycle of energy on Earth is connected with the cycle of substances. At the level of chemical elements and their contents, the cycle of carbon C is most clearly manifested in the biosphere as the most active chemical element, the compounds of which are continuously formed, changed and destroyed. The main pathway of carbon is from carbon dioxide to living matter and back to gas.
Part of the carbon leaves the cycle, settling in sedimentary rocks of the ocean or in fossil combustible substances of organic origin (peat, coal, oil, flammable gases), where the bulk of it has already been accumulated. And then this carbon takes part in the slow geological cycle. The exchange of carbon dioxide also occurs between the atmosphere and the ocean. A large amount of carbon dioxide is dissolved in the upper layers of the ocean, which is in equilibrium with the atmosphere. In total, the hydrosphere contains about 13 10 13 tons of dissolved carbon dioxide, and the atmosphere contains 60 times less.
The nitrogen cycle plays an important role in biosphere processes. Only nitrogen, which is part of certain chemical compounds, participates in them. The total turnover time of nitrogen in the great cycle is estimated at more than 100 years.
The fixation of nitrogen in chemical compounds occurs during volcanic activity, during lightning discharges in the atmosphere, during the process of its ionization, and during the combustion of materials. Microorganisms play a decisive role in its fixation.
Nitrogen compounds (nitrates, nitrites) in solutions enter plants, participating in the formation of organic matter (amino acids, complex proteins). Some nitrogen compounds are carried into rivers and seas and penetrate into groundwater. From compounds dissolved in sea water, nitrogen is absorbed by aquatic organisms, and after they die, it is returned to the ocean waters. Therefore, the concentration of nitrogen in the upper layers of the ocean increases markedly.
One of the most important elements of the biosphere is phosphorus F, which is part of nucleic acids, cell membranes, and bone tissue. Phosphorus also participates in the small and large cycles and is absorbed by plants. Sodium and calcium phosphates are poorly soluble in water, and in an alkaline environment they are practically insoluble.
The key element of the biosphere is water H 2 O. The water cycle occurs by evaporating it from the surface of reservoirs and land into the atmosphere, and then transported by air masses, condenses and falls as precipitation (Fig. 1).
The average duration of the general cycle of exchange of carbon, nitrogen and water involved in the biological cycle is 300-400 years. According to this rate, mineral compounds associated with the biomass are released.
It is known that different substances have different rates of exchange in the biosphere. Mobile substances include chlorine, sulfur, bromine, and fluorine. Passive ones include silicon, potassium, phosphorus, copper, nickel, aluminum and iron. The circulation of all biogenic elements occurs at the level of biogeocenosis. The productivity of the biogeocenosis depends on how regularly and completely the cycle of chemical elements occurs.
The rate of biovaluable elements in the small cycle is quite high. For example, the turnover time of atmospheric carbon in the small cycle is about 8 years, and in the large cycle - 400 years.
ecosystem biosphere energy cycle
Introduction
Concept and structure of ecosystems
1 Concept of ecosystems
2 Classification of ecosystems
3 Zoning of macroecosystems
4 Ecosystem structure
Factors that ensure the integrity of ecosystems
1 Substance cycles
2 Energy flow in ecosystems
3 Dynamic processes that ensure integrity and sustainability in ecosystems
4 The biosphere as a global ecosystem that ensures the integrity and sustainability of ecosystems
Conclusion
Introduction
An ecosystem is any collection of organisms and inorganic components in which the circulation of substances can occur. According to N.F. Reimers (1990), an ecosystem is any community of living beings and its habitat, united into a single functional whole, arising on the basis of interdependence and cause-and-effect relationships that exist between individual environmental components. A. Tansley (1935) proposed the following relationship:
There are microecosystems, mesoecosystems, macroecosystems and the global biosphere. Large terrestrial ecosystems are called biomes. Ecosystems are not scattered in disorder; on the contrary, they are grouped in fairly regular zones, both horizontally (in latitude) and vertically (in height).
From the equator to the poles, a certain symmetry is visible in the distribution of biomes of different hemispheres: tropical rain forests, deserts, steppes, temperate forests, coniferous forests, taiga.
Every ecosystem has two main components: organisms and factors from their nonliving environment. The totality of organisms (plants, animals, microbes) is called the biota of an ecosystem. From the point of view of the trophic structure (from the Greek trophe - nutrition), the ecosystem can be divided into two tiers: upper, lower.
The following components are distinguished as part of an ecosystem: inorganic, organic compounds, air, water and substrate environments, producers, autotrophic organisms, consumers, or phagotrophs, decomposers and detritivores.
Solar energy on Earth causes two cycles of substances: large, or geological, and small, biological (biotic).
In an ecosystem there are cycles of substances. The most studied are: the cycles of carbon, oxygen, nitrogen, phosphorus, sulfur, etc.
The maintenance of the vital activity of organisms and the circulation of matter in ecosystems, i.e. the existence of ecosystems, depends on the constant influx of solar energy.
In ecosystems, changes constantly occur in the state and vital activity of their members and in the ratio of populations. The diverse changes occurring in any community fall into two main types: cyclical and progressive.
A global ecosystem is a biosphere characterized by the integrity and stability of ecosystems.
1. Concept and structure of ecosystems
1 Concept of ecosystems
Living organisms and their nonliving (abiotic) environment are inseparably connected with each other and are in constant interaction. Any unit (biosystem) of an ecosystem is an ecological system. An ecological system, or ecosystem, is the basic functional unit in ecology, since it includes organisms and the inanimate environment - components that mutually influence each other’s properties and the necessary conditions for maintaining life in the form that exists on Earth. The term "ecosystem" was first proposed in 1935 by the English ecologist A. Tansley. Currently, the following definition of ecosystem is widely used. An ecosystem is any collection of organisms and inorganic components in which the circulation of substances can occur. According to N.F. Reimers (1990), an ecosystem is any community of living beings and its habitat, united into a single functional whole, arising on the basis of interdependence and cause-and-effect relationships that exist between individual environmental components. It should be emphasized that the combination of a specific physicochemical environment (biotope) with a community of living organisms (biocenosis) forms an ecosystem. A. Tansley (1935) proposed the following relationship:
Ecosystem = Biotope + Biocenosis
According to the definition of V.N. Sukachev, biogeocenosis is “a set of homogeneous natural phenomena (atmosphere, rock, soil and hydrological conditions) over a certain extent of the earth’s surface, which has its own special specificity of interactions of these components that make it up and a certain type of exchange of matter and energy between themselves and other natural phenomena and representing an internally contradictory dialectical unity, in constant movement and development."
In addition to the concepts of ecosystem A. Tansley and biogeocenosis V.N. Sukachev formulated the rule of F. Evans (1956), who proposed using the term “ecosystem” absolutely “dimensionlessly” to designate any supraorganismal living system interacting with the environment. However, many authors gave the term “ecosystem” the meaning of biogeocenosis, i.e. elementary ecosystem, and at the same time higher in the hierarchy of supra-biogeocoenotic formations up to the biosphere ecosystem.
2 Classification of ecosystems
The ecosystems existing on Earth are diverse. There are microecosystems (for example, the trunk of a rotting tree), mesoecosystems (forest, pond, etc.), macroecosystems (continent, ocean, etc.) and the global biosphere.
Large terrestrial ecosystems are called biomes. Each biome contains a number of smaller, interconnected ecosystems. There are several classifications of ecosystems:
Evergreen tropical rain forest
Desert: Grass and shrub Chaparral - areas with rainy winters and dry summers
Tropical Graslenz and Savannah
Temperate steppe
Temperate deciduous forest
Boreal coniferous forests
Tundra: arctic and alpine
Types of freshwater ecosystems:
Ribbon (still waters): lakes, ponds, etc.
Lotic (flowing waters): rivers, streams, etc.
Wetlands: swamps and swampy forests
Types of Marine Ecosystems
Open ocean (pelagic)
Continental shelf waters (coastal waters)
Upwelling areas (fertile areas with productive fisheries)
Estuaries (coastal bays, straits, river mouths, salt marshes, etc.). Terrestrial biomes are distinguished here by natural or original vegetation features, and types of aquatic ecosystems are distinguished by geological and physical features. The listed main types of ecosystems represent the environment in which human civilization developed and represent the main biotic communities that support life on Earth.
3 Zoning of macroecosystems
The study of the geographical distribution of ecosystems can only be undertaken at the level of large ecological units - macroecosystems, which are considered on a continental scale. Ecosystems are not scattered in disorder; on the contrary, they are grouped in fairly regular zones, both horizontally (in latitude) and vertically (in height). This is confirmed by the periodic law of geographical zonation of A.A. Grigorieva - M.I. Budyko: with the change of physical-geographical zones of the Earth, similar landscape zones and some of their general properties periodically repeat. This was also discussed when considering the ground-air environment of life. The periodicity established by law is manifested in the fact that the values of the dryness index vary in different zones from 0 to 4-5, three times between the poles and the equator they are close to unity. These values correspond to the highest biological productivity of landscapes.
The periodic repetition of properties in a series of systems of one hierarchical level is probably a general law of the universe, formulated as the law of periodicity in the structure of systemic aggregates, or a system-periodic law - specific natural systems of one level (sublevel) of organization constitute a periodic or repeating series of morphologically similar structures within upper and lower system space-time boundaries, beyond which the existence of systems at a given level becomes impossible. They go into an unstable state or turn into another system structure, including another level of organization.
Temperature and precipitation determine the location of the main terrestrial biomes on the earth's surface. The pattern of temperature and precipitation in a certain area over a fairly long period of time is what we call climate. The climate in different regions of the globe is different. The annual precipitation varies from 0 to 2500 mm or more. Temperature and precipitation regimes combine with each other in very different ways.
The specifics of climatic conditions, in turn, determine the development of a particular biome.
From the equator to the poles, a certain symmetry is visible in the distribution of biomes of different hemispheres:
Tropical rainforests (northern South America, Central America, western and central parts of equatorial Africa, Southeast Asia, coastal areas of northwestern Australia, islands of the Indian and Pacific Oceans). The climate is without a change of seasons (proximity to the equator), the average annual temperature is above 17°C (usually 28°C), the average annual precipitation exceeds 2400 mm.
Vegetation: forests dominate. Some types of trees are up to 60 m high. On their trunks and branches there are epiphytic plants, the roots of which do not reach the soil, and woody vines that take root in the soil and climb the trees to their tops. All this forms a thick canopy.
Fauna: the species composition is richer than in all other biomes combined. Particularly numerous are amphibians, reptiles and birds (frogs, lizards, snakes, parrots), monkeys and other small mammals, exotic insects with bright colors, and brightly colored fish in reservoirs.
Features: soils are often thin and poor, most of the nutrients are contained in the surface biomass of rooted vegetation.
2. Savannas (subequatorial Africa, South America, a significant part of southern India). The climate is dry and hot most of the year. Heavy rainfall during the wet season. Temperature: average annual-high. Precipitation is 750-1650 mm/year, mainly during the rainy season. Vegetation - bluegrass (cereal) plants with rare deciduous trees. Fauna: large herbivorous mammals, such as antelopes, zebras, giraffes, rhinoceroses, predators - lions, leopards, cheetahs.
Deserts (some areas of Africa, for example the Sahara; the Middle East and Central Asia, the Great Basin and the southwestern United States and northern Mexico, etc.). The climate is very dry. Temperature - hot days and cold nights. Precipitation is less than 250 mm/year. Vegetation: sparse shrubs, often thorny, sometimes cacti and low grasses, quickly covering the ground with a flowering carpet after rare rains. Plants have extensive surface root systems that intercept moisture from rare precipitation, as well as tap roots that penetrate the ground to the groundwater level (30 m and deeper). Fauna: various rodents (kangaroo rat, etc.), toads, lizards, snakes and other reptiles, owls, eagles, vultures, small birds and insects in large quantities.
4. Steppes (center of North America, Russia, certain areas of Africa and Australia, southeast of South America). The climate is seasonal. Temperatures - summer temperatures range from moderately warm to hot, winter temperatures below 0°C. Precipitation - 750-2000 mm/year. Vegetation: dominated by bluegrass (cereals) up to 2 m and higher in height in some prairies of North America or up to 50 cm, for example, in the Russian steppes, with isolated trees and shrubs in wet areas. Fauna: large herbivorous mammals - bison, pronghorn antelope (North America), wild horses (Eurasia), kangaroos (Australia), giraffes, zebras, white rhinoceroses, antelopes (Africa); Predators include coyotes, lions, leopards, cheetahs, hyenas, a variety of birds and small burrowing mammals such as rabbits, ground squirrels, and aardvarks.
5. Temperate forests (Western Europe, East Asia, eastern USA). Climate - seasonal with winter temperatures below 0 0C. Precipitation - 750-2000 mm/year. Vegetation: dominated by forests of broad-leaved deciduous trees up to 35-45 m high (oak, hickory, maple), shrubby undergrowth, mosses, lichens. Fauna: mammals (white-tailed deer, porcupine, raccoon, opossum, squirrel, rabbit, shrews), birds (warblers, woodpeckers, blackbirds, owls, falcons), snakes, frogs, salamanders, fish (trout, perch, catfish, etc. ), abundant soil microfauna (Fig. 12.3). The biota is adapted to the seasonal climate: hibernation, migration, dormancy in the winter months. 6. Coniferous forests, taiga (northern regions of North America, Europe and Asia). The climate is long and cold winters, with some precipitation falling in the form of snow. Vegetation: evergreen coniferous forests predominate, mostly spruce, pine, and fir. Fauna: large herbivorous ungulates (mule deer, reindeer), small herbivorous mammals (hare, squirrel, rodents), wolf, lynx, fox, black bear, grizzly bear, wolverine, mink and other predators, numerous blood-sucking insects in short summer time. The climate is very cold with polar days and polar nights. The average annual temperature is below - 5°C. In a few weeks of short summer, the ground thaws no more than one meter deep. Precipitation is less than 250 mm/year. Vegetation: dominated by slowly growing lichens, mosses, grasses and sedges, and dwarf shrubs. Fauna: large herbivorous ungulates (reindeer, musk ox), small burrowing mammals (all year round, for example, lemmings), predators that acquire a camouflage white color in winter (Arctic fox, lynx, ermine, snowy owl). In the short summer, a large number of migratory birds nest in the tundra, among them there are especially many waterfowl, which feed on the insects and freshwater invertebrates that are abundant here. The vertical altitudinal zonation of land ecosystems, especially in places with pronounced relief, is also very clear. Humidity is the main factor that determines the type of biome. With sufficiently large amounts of precipitation, forest vegetation develops. The temperature determines the type of forest. The situation is exactly the same in the steppe and desert biomes. Changes in vegetation types in cold regions occur with lower annual precipitation amounts, since at low temperatures less water is lost to evaporation. Temperature becomes a major factor only in very cold conditions with permafrost. Thus, the composition of ecosystems largely depends on their functional “purpose” and vice versa. According to N.F. Reimers (1994), this is reflected in the principle of ecological complementarity (complementarity): no functional part of the ecosystem (ecological component, element, etc.) can exist without other functionally complementary parts. Close to it and expanding it is the principle of ecological congruence (correspondence):. functionally complementing each other, the living components of the ecosystem develop appropriate adaptations for this, coordinated with the conditions of the abiotic environment, which is largely transformed by the same organisms (bioclimate, etc.), i.e. there is a double series of correspondence - between organisms and their habitat - external and created by the cenosis. 4 Ecosystem structure From the point of view of the trophic structure (from the Greek trophe - nutrition), the ecosystem can be divided into two tiers: The upper - autotrophic (self-feeding) tier, or "green belt", including plants or their parts containing chlorophyll, where the fixation of counting energy and the use of simple inorganic compounds predominate. The lower one is the heterotrophic (fed by others) layer, or the “brown belt” of soils and sediments, decaying matter, roots, etc., in which the use, transformation and decomposition of complex compounds predominate. From a biological point of view, the following components are distinguished as part of an ecosystem: In an ecosystem, food and energy connections between categories are always unambiguous and go in the direction of: autotrophs - heterotrophs or in a more complete form; autotrophs -> consumers -> decomposers (destructors). The primary source of energy for ecosystems is the Sun. The energy flow (according to T.A. Akimova, V.V. Khaskin, 1994) sent by the sun to planet Earth exceeds 20 million EJ per year. Only a quarter of this flow approaches the boundary of the atmosphere. Of this, about 70% is reflected, absorbed by the atmosphere, and emitted in the form of long-wave infrared radiation. Solar radiation falling on the Earth's surface is 1.54 million EJ per year. This huge amount of energy is 5000 times the entire energy supply of humanity at the end of the 20th century and 5.5 times the energy of all available fossil fuel resources of organic origin, accumulated over at least 100 million years. Most of the solar energy that reaches the planet's surface is converted directly into heat, warming water or soil, which in turn warms the air. This heat serves as the driving force behind the water cycle, air currents and ocean currents that determine the weather, and is gradually released into outer space, where it is lost. To determine the place of ecosystems in this natural flow of energy, it is important to realize that no matter how extensive and complex they are, they use only a small part of it. This implies one of the basic principles of the functioning of ecosystems: they exist due to non-polluting and almost eternal solar energy, the amount of which is relatively constant and abundant. Let us give in more detail each of the listed characteristics of solar energy: 2. Factors that ensure the integrity of ecosystems 1 Substance cycles Both cycles are mutually connected and represent, as it were, a single process. It is estimated that all the oxygen contained in the atmosphere is cycled through organisms (combined during respiration and released during photosynthesis) in 2000 years, the carbon dioxide in the atmosphere cycles in the opposite direction in 300 years, and all the water on Earth is decomposed and recreated through photosynthesis and respiration in 2,000,000 years. The interaction of abiotic factors and living organisms of the ecosystem is accompanied by a continuous circulation of matter between the biotope and the biocenosis in the form of alternating organic and mineral compounds. The exchange of chemical elements between living organisms and the inorganic environment, the various stages of which occur within an ecosystem, is called biogeochemical circulation, or biogeochemical cycle. The water cycle. The most significant cycle on Earth in terms of transferred masses and energy consumption is the planetary hydrological cycle - the water cycle. Every second, 16.5 million m3 of water are involved in it and more than 40 billion MW of solar energy is spent on this, (according to T.A. Akimova V.V. Haskin, (1994)). But this cycle is not only the transfer of water masses. These are phase transformations, the formation of solutions and suspensions, precipitation, crystallization, photosynthesis processes, as well as various chemical reactions. Life arose and continues in this environment. Water is the basic element necessary for life. Quantitatively, it is the most common inorganic component of living matter. In humans, water makes up 63% of body weight, in mushrooms - 80%, in plants - 80-90%, and in some jellyfish - 98% Water, as we will see a little later, participates in the biological cycle and serves as a source of hydrogen and oxygen, making up only a small part of its total volume. In liquid, solid and vapor states, water is present in all three main components of the biosphere: the atmosphere, the hydrosphere, and the lithosphere. All waters are united by the common concept of “hydrosphere”. The components of the hydrosphere are interconnected by constant exchange and interaction. Water, continuously moving from one state to another, makes small and large cycles. The evaporation of water from the surface of the ocean, the condensation of water vapor in the atmosphere and the precipitation on the surface of the ocean form a small cycle. When water vapor is carried by air currents to land, the cycle becomes much more complex. In this case, part of the precipitation evaporates and goes back into the atmosphere, the other feeds rivers and reservoirs, but ultimately returns to the ocean through river and underground runoff, thereby completing the large cycle. Biotic (biological) cycle. The biotic (biological) cycle refers to the circulation of substances between soil, plants, animals and microorganisms. The biotic (biological) cycle is the flow of chemical elements from the soil, water and atmosphere into living organisms, the transformation of incoming elements into new complex compounds and their return back in the process of life with the annual fall of part of the organic matter or with completely dead organisms included in ecosystem composition. Now we will present the biotic cycle in a cyclic form. The central biotic cycle (according to T.A. Akimova, V.V., Khaskhin) consisted of primitive unicellular producers (P) and decomposers-destructors (D). Microorganisms are able to quickly multiply and adapt to different conditions, for example, use all kinds of substrates - carbon sources - in their diet. Higher organisms do not have such abilities. In complete ecosystems, they can exist in the form of a structure on the foundation of microorganisms. First, multicellular plants (P) develop - higher producers. Together with unicellular organisms, they create organic matter through the process of photosynthesis, using the energy of solar radiation. Subsequently, primary consumers are connected - herbivorous animals (T), and then carnivorous consumers. We examined the biotic cycle of land. This fully applies to the biotic cycle of aquatic ecosystems, for example, the ocean. All organisms occupy a certain place in the biotic cycle and perform their functions of transforming the branches of energy flow that they receive and transferring biomass. A system of single-celled decomposers (destructors) unites everyone, depersonalizes their substances and closes the general circle. They return to the abiotic environment of the biosphere all the elements necessary for new and new revolutions. The most important features of the biotic cycle should be emphasized. Photosynthesis is a powerful natural process that annually involves huge masses of biosphere matter in the cycle and determines its high oxygen potential. Due to carbon dioxide and water, organic matter is synthesized and free oxygen is released. The direct products of photosynthesis are various organic compounds, and in general the process of photosynthesis is quite complex. In addition to photosynthesis with the participation of oxygen, the so-called oxygenic photosynthesis, we should also focus on oxygen-free photosynthesis, or chemosynthesis. Chemosynthetic organisms include nitrifiers, carboxydobacteria, sulfur bacteria, thionic iron bacteria, and hydrogen bacteria. They are named after their oxidation substrates, which can be NH3, NO2, CO, H2S, S, Fe2+, H2. Some species are obligate chemolithoautotrophs, others are facultative. The latter include carboxydobacteria and hydrogen bacteria. Chemosynthesis is characteristic of deep-sea hydrothermal vents. Photosynthesis occurs, with few exceptions, on the entire surface of the Earth, creates a huge geochemical effect and can be expressed as the amount of the entire mass of carbon involved annually in the construction of organic - living matter of the entire biosphere. The general cycle of matter associated with the construction of organic matter through photosynthesis also involves chemical elements such as N, P, S, as well as metals - K, Ca, Mg, Na, Al. When an organism dies, the reverse process occurs - the decomposition of organic matter through oxidation, decay, etc. with the formation of final decomposition products. In the Earth's biosphere, this process leads to the fact that the amount of biomass of living matter tends to be somewhat constant. Biomass of the ecosphere (2 10|2t) is seven orders of magnitude less than the mass of the earth's crust (2 .10|9t). Plants of the Earth annually produce organic matter equal to 1.6.10"% or 8% of the biomass of the ecosphere. Destructors, constituting less than 1% of the total biomass of the planet's organisms, process a mass of organic matter that is 10 times greater than their own biomass. On average, the period of biomass renewal is 12.5 years. Let us assume that the mass of living matter and the productivity of the biosphere were the same from the Cambrian to the present (530 million years), then the total amount of organic matter that passed through the global biotic cycle and was used by life on the planet will be 2.10 " 2-5,ZL08/12.5=8.5L0|9t, which is 4 times the mass of the earth’s crust. Regarding these calculations N.S. Pechurkin (1988) wrote: “We can say that the atoms that make up our bodies were in ancient bacteria, and in dinosaurs, and in mammoths.” Law of biogenic migration of atoms V.I. Vernadsky states: “The migration of chemical elements on the earth’s surface and in the biosphere as a whole occurs either with the direct participation of living matter (biogenic migration), or it occurs in an environment whose geochemical features (O2, CO2, H2, etc.) are determined living matter, both that which currently inhabits the biosphere and that which has acted on the Earth throughout geological history." IN AND. Vernadsky in 1928-1930 in his deep generalizations regarding processes in the biosphere, he gave an idea of the five main biogeochemical functions of living matter. The first function is gas. The second function is concentration. The third function is redox. The fourth function is biochemical. The fifth function is the biogeochemical activity of mankind, covering an ever-increasing amount of matter in the earth's crust for the needs of industry, transport, and agriculture. The biological cycle varies in different natural zones and is classified according to a set of indicators: plant biomass, litter, litter, the amount of elements fixed in the biomass, etc. The total biomass is highest in the forest zone, and the proportion of underground organs in forests is the lowest. This is confirmed by the biological cycle intensity index - the ratio of the mass of the litter to the part of the litter that forms it. Carbon cycle. Of all the biogeochemical cycles, the carbon cycle is without a doubt the most intense. Carbon circulates at high rates between various inorganic means and through food webs within communities of living organisms. CO and CO2 play a certain role in the carbon cycle. Often in the Earth's biosphere, carbon is represented by the most mobile form of CO2. The source of primary carbon dioxide in the biosphere is volcanic activity associated with secular degassing of the mantle and lower horizons of the earth's crust. Migration of CO2 in the biosphere occurs in two ways. The first way is to absorb it during photosynthesis with the formation of glucose and other organic substances from which all plant tissues are built. They are subsequently transported through food chains and form the tissues of all other living beings in the ecosystem. With the death of plants and animals on the surface, oxidation of organic substances occurs with the formation of CO2. Carbon atoms are also returned to the atmosphere when organic matter is burned. An important and interesting feature of the carbon cycle is that in distant geological epochs, hundreds of millions of years ago, a significant part of the organic matter created in the processes of photosynthesis was not used by either consumers or decomposers, but accumulated in the lithosphere in the form of fossil fuels: oil, coal , oil shale, peat, etc. These fossil fuels are mined in huge quantities to meet the energy needs of our industrial society. By burning it, we, in a sense, complete the carbon cycle. In the second way, carbon migration is carried out by creating a carbonate system in various reservoirs, where CO2 transforms into H2CO3, HCO, CO3. With the help of calcium (or magnesium) dissolved in water, carbonates (CaCO3) are precipitated through biogenic and abiogenic pathways. Thick layers of limestone are formed. According to A.B. Ronov, the ratio of buried carbon in photosynthetic products to carbon in carbonate rocks is 1:4. Along with the large carbon cycle, there are also a number of small carbon cycles on the land surface and in the ocean. In general, without anthropogenic intervention, the carbon content in biogeochemical reservoirs: the biosphere (biomass + soil and detritus), sedimentary rocks, atmosphere and hydrosphere, is maintained with a high degree of constancy (according to T.A. Akimova, V.V. Haskin (1994) ). The constant exchange of carbon, on the one hand, between the biosphere, and on the other, between the atmosphere and the hydrosphere, is determined by the gas function of living matter - the processes of photosynthesis, respiration and destruction, and amounts to about 6-1010 tons/year. There is a flow of carbon into the atmosphere and hydrosphere and during volcanic activity an average of 4.5 106 t/year. The total mass of carbon in fossil fuels (oil, gas, coal, etc.) is estimated at 3.2*1015 tons, which corresponds to an average accumulation rate of 7 million tons/year. This amount is insignificant compared to the mass of circulating carbon and, as it were, fell out of the cycle and was lost in it. Hence, the degree of openness (imperfection) of the cycle is 10"4, or 0.01%, and, accordingly, the degree of closure is 99.99%. This means, on the one hand, that each carbon atom took part in the cycle tens of thousands of times before falling out from the cycle, ended up in the depths. On the other hand, the flows of synthesis and decay of organic substances in the biosphere are adjusted to each other with very high precision. 0.2% of the mobile carbon stock is in constant circulation. Biomass carbon is renewed in 12 years, in the atmosphere - in 8 years. Oxygen cycle. Oxygen (O2) plays an important role in the life of most living organisms on our planet. In quantitative terms, this is the main component of living matter. For example, if we take into account the water contained in tissues, the human body contains 62.8% oxygen and 19.4% carbon. In general, in the biosphere this element, compared to carbon and hydrogen, is the main one among simple substances. Within the biosphere, there is a rapid exchange of oxygen with living organisms or their remains after death. Plants, as a rule, produce free oxygen, and animals consume it through respiration. Being the most widespread and mobile element on Earth, oxygen does not limit the existence and functions of the ecosphere, although the availability of oxygen for aquatic organisms may be temporarily limited. The oxygen cycle in the biosphere is extremely complex, since a large number of organic and inorganic substances react with it. As a result, many epicycles occur, occurring between the lithosphere and the atmosphere or between the hydrosphere and these two environments. The oxygen cycle is in some ways similar to the reverse carbon dioxide cycle. The movement of one occurs in the direction opposite to the movement of the other. The consumption of atmospheric oxygen and its replacement by primary producers occurs relatively quickly. Thus, it takes 2000 years to completely renew all atmospheric oxygen. Nowadays, oxygen accumulation in the atmosphere does not occur, and its content (20.946%) remains constant. In the upper layers of the atmosphere, when ultraviolet radiation acts on oxygen, ozone - O3 - is formed. About 5% of the solar energy reaching the Earth is spent on the formation of ozone - about 8.6 * 1015 W. The reactions are easily reversible. When ozone decays, this energy is released, which maintains high temperatures in the upper atmosphere. The average ozone concentration in the atmosphere is about 106 vol. %; the maximum O3 concentration - up to 4-10 "* vol.% - is achieved at altitudes of 20-25 km (T.A. Akimova, V.V. Haskin, 1998). Ozone serves as a kind of UV filter: it blocks a significant portion of hard ultraviolet rays. Probably, the formation of the ozone layer was one of the conditions for life to emerge from the ocean and colonize land. Most of the oxygen produced during geological epochs did not remain in the atmosphere, but was fixed by the lithosphere in the form of carbonates, sulfates, iron oxides, etc. This mass is 590 * 1014 tons versus 39 * 1014 tons of oxygen, which circulates in the biosphere in the form of gas or sulfates dissolved in continental and oceanic waters. Nitrogen cycle. Nitrogen is an essential biogenic element, as it is part of proteins and nucleic acids. The nitrogen cycle is one of the most complex, since it includes both gas and mineral phases, and at the same time the most ideal cycles. The nitrogen cycle is closely related to the carbon cycle. As a rule, nitrogen follows carbon, together with which it participates in the formation of all protein substances. Atmospheric air, containing 78% nitrogen, is an inexhaustible reservoir. However, the majority of living organisms cannot directly use this nitrogen. For nitrogen to be absorbed by plants, it must be part of ammonium (NH*) or nitrate (NO3) ions. Nitrogen gas is continuously released into the atmosphere as a result of the work of denitrifying bacteria, and fixing bacteria, together with blue-green algae (cyanophytes), constantly absorb it, converting it into nitrates. The nitrogen cycle is clearly visible at the level of destructors. Proteins and other forms of organic nitrogen contained in plants and animals after their death are exposed to heterotrophic bacteria, actinomycetes, fungi (bioreducing microorganisms), which produce the energy they need by reducing this organic nitrogen, converting it into ammonia. In soils, the process of nitrification occurs, consisting of a chain of reactions, where, with the participation of microorganisms, the oxidation of ammonium ion (NH4+) to nitrite (NO~) or nitrite to nitrate (N0~) occurs. The reduction of nitrites and nitrates to the gaseous compounds molecular nitrogen (N2) or nitrous oxide (N20) is the essence of the denitrification process. The formation of nitrates inorganically in small quantities constantly occurs in the atmosphere by binding atmospheric nitrogen with oxygen during electrical discharges during thunderstorms, and then falling with rain onto the soil surface. Another source of atmospheric nitrogen is volcanoes, which compensate for the loss of nitrogen excluded from the cycle during sedimentation or deposition to the bottom of the oceans. In general, the average supply of nitrate nitrogen of abiotic origin during deposition from the atmosphere into the soil does not exceed 10 kg (year/ha), free bacteria produce 25 kg (year/ha), while the symbiosis of Rhizobium with leguminous plants produces an average of 200 kg (year/ha). The predominant part of the fixed nitrogen is processed by denitrifying bacteria into N2 and returned to the atmosphere. Only about 10% of ammonified and nitrified nitrogen is absorbed from the soil by higher plants and ends up at the disposal of multicellular representatives of biocenoses Phosphorus cycle. The phosphorus cycle in the biosphere is associated with metabolic processes in plants and animals. This important and necessary element of protoplasm, contained in terrestrial plants and algae 0.01-0.1%, animals from 0.1% to several percent, circulates, gradually turning from organic compounds into phosphates, which can again be used by plants. However, phosphorus, unlike other biophilic elements, does not form a gas form during migration. The reservoir of phosphorus is not the atmosphere, like nitrogen, but the mineral part of the lithosphere. The main sources of inorganic phosphorus are igneous rocks (apatites) or sedimentary rocks (phosphorites). From rocks, inorganic phosphorus is involved in circulation by leaching and dissolution in continental waters. Getting into terrestrial ecosystems and soil, phosphorus is absorbed by plants from an aqueous solution in the form of inorganic phosphate ion and is included in various organic compounds, where it appears in the form of organic phosphate. Phosphorus moves through food chains from plants to other organisms in the ecosystem. Phosphorus is transported into aquatic ecosystems by flowing waters. Rivers continuously enrich the oceans with phosphates. Where phosphorus becomes part of phytoplankton. Some phosphorus compounds migrate within shallow depths, being consumed by organisms, while the other part is lost at greater depths. Dead remains of organisms lead to the accumulation of phosphorus at different depths. Sulfur cycle. There are numerous gaseous sulfur compounds, such as hydrogen sulfide H2S and sulfur dioxide SO2. However, the predominant part of the cycle of this element is sedimentary in nature and occurs in soil and water. The availability of inorganic sulfur in the ecosystem is facilitated by the good solubility of many sulfates in water. Plants, absorbing sulfates, reduce them and produce sulfur-containing amino acids (methionine, cysteine, cystine) that play an important role in the development of the tertiary structure of proteins during the formation of disulfide bridges between different zones of the polypeptide chain. Many basic features of the biogeochemical cycle are clearly visible: S -> S -> SO2 - colorless, green and purple sulfur bacteria; - "H2S (anaerobic reduction of sulfate) - Desulfovibno; H2S - "SO2" (aerobic oxidation of sulfide) - thiobacillus; organic S in SO and H2S. - aerobic and anaerobic heterotrophic microorganisms, respectively. Primary production ensures the incorporation of sulfate into organic matter, and excretion by animals serves as a way to return sulfate to the cycle. In general, the ecosystem requires less sulfur compared to nitrogen and phosphorus. Hence, sulfur is less often a limiting factor for plants and animals. At the same time, the sulfur cycle is a key one in the overall process of biomass production and decomposition. For example, when iron sulfides form in sediments, phosphorus is transferred from an insoluble form to a soluble form and becomes available to organisms. This is a confirmation of how one cycle is regulated by another. 2 Energy flow in ecosystems Unlike substances that continuously circulate through different blocks of the ecosystem, which can always be reused and enter the cycle, energy can be used once, i.e. there is a linear flow of energy through the ecosystem. The one-way influx of energy as a universal natural phenomenon occurs as a result of the laws of thermodynamics. The first law states that energy can be converted from one form (such as light) to another (such as the potential energy of food), but cannot be created or destroyed. The second law states that there cannot be a single process associated with the transformation of energy without losing some of it. A certain amount of energy in such transformations is dissipated into inaccessible thermal energy and is therefore lost. Hence: there cannot be transformations, for example, of food substances into the substance that makes up the body of the organism, occurring with 100% efficiency. Thus, living organisms are energy converters. And every time energy is converted, part of it is lost in the form of heat. Ultimately, all the energy entering the biotic cycle of an ecosystem is dissipated as heat. Living organisms do not actually use heat as an energy source to do work - they use light and chemical energy. Food chains and networks, trophic levels. Within an ecosystem, energy-containing substances are created by autotrophic organisms and serve as food for heterotrophs. Food connections are mechanisms for transferring energy from one organism to another. A typical example: an animal eats plants. This animal, in turn, can be eaten by another animal. In this way, energy can be transferred through a number of organisms - each subsequent one feeds on the previous one, which supplies it with raw materials and energy. This sequence of energy transfer is called a food (trophic) chain, or food chain. The location of each link in the food chain is a trophic level. The first trophic level, as noted earlier, is occupied by autotrophs, or so-called primary producers. Organisms of the second trophic level are called primary consumers, the third - secondary consumers, etc. There are generally three types of food chains. The carnivore food chain starts with plants and moves from small organisms to increasingly larger organisms. On land, food chains consist of three to four links. One of the simplest food chains looks like: plant -> hare -> wolf producer -" herbivore -> -> carnivore The following food chains are also widespread: Plant material (eg nectar) - "fly -" -" spider -> shrew -> owl. Rosebush sap -> aphid -> -> ladybug -> -> spider - "insectivorous bird -> bird of prey. In aquatic and, in particular, marine ecosystems, predator food chains tend to be longer than in terrestrial ones. The third type of food chains, starting with dead plant remains, carcasses and animal excrement, are referred to as detrital (saprophytic) food chains or detrital decomposition chains. Deciduous forests play an important role in the detrital food chains of terrestrial ecosystems, most of the foliage of which is not consumed by herbivores and is part of the litter of fallen leaves. The leaves are crushed by numerous detritivores - fungi, bacteria, insects (for example, collembola), etc., and then ingested by earthworms, which uniformly distribute humus in the surface layer of the earth, forming the so-called mull. At this level, mushrooms develop mycelium. The decomposing microorganisms that complete the chain produce the final mineralization of dead organic matter. In general, typical detrital food chains of our forests can be represented as follows: Leaf litter -> earthworm -> blackbird - sparrowhawk; Dead animal - "larvae of carrion flies -" grass frog -> common grass snake. In the food chain diagrams discussed, each organism is represented as feeding on other organisms of one type. The actual food connections in an ecosystem are much more complex, since an animal can feed on organisms of different types from the same food chain or from different food chains, for example, predators of the upper trophic levels. Animals often feed on both plants and other animals. They are called omnivores. Food webs in ecosystems are very complex, and we can conclude that the energy entering them takes a long time to migrate from one organism to another. Ecological pyramids. Within each ecosystem, food webs have a well-defined structure, which is characterized by the nature and number of organisms represented at each level of the various food chains. To study the relationships between organisms in an ecosystem and to depict them graphically, they usually use ecological pyramids rather than food web diagrams. Ecological pyramids express the trophic structure of an ecosystem in geometric form. They are constructed in the form of rectangles of the same width, but the length of the rectangles must be proportional to the value of the object being measured. From here you can get pyramids of numbers, biomass and energy. Ecological pyramids reflect the fundamental characteristics of any biocenosis when they show its trophic structure. Pyramids of numbers. They represent the simplest approximation to the study of the trophic structure of an ecosystem. 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. Pyramid of energy. The most fundamental way to display connections between organisms at different trophic levels is through energy pyramids. They represent the energy conversion efficiency and productivity of food chains and are constructed by counting the amount of energy (kcal) accumulated per unit surface area per unit time and used by organisms at each trophic level. The solar energy received by the plant is only partially used in the process of photosynthesis. The energy fixed in carbohydrates represents the gross production of the ecosystem. Carbohydrates are used to build protoplasm and plant growth. Part of their energy is spent on breathing. Second-order consumers (predators) do not destroy the entire biomass of their victims. Moreover, of the amount that they destroy, only a part is used to create biomass of their own trophic level. The rest is mainly spent on breathing energy and is excreted with excrement and excrement. In 1942, R. Lindeman first formulated the law of the pyramid of energies, which in textbooks is often called the “law of 10%”. According to this law, on average, no more than 10% of energy moves from one trophic level of the ecological pyramid to another level. Only 10-20% of the initial energy is transferred to subsequent heterotrophs. Using the law of the energy pyramid, it is easy to calculate that the amount of energy reaching tertiary carnivores (trophic level V) is about 0.0001 of the energy absorbed by producers. It follows that the transfer of energy from one level to another occurs with very low efficiency. This explains the limited number of links in the food chain, regardless of a particular biocenosis. E. Odum (1959) in an extremely simplified food chain - alfalfa -> calf - "the child assessed the transformation of energy, illustrated the magnitude of its losses. Let's say, he reasoned, there is alfalfa crops on an area of 4 hectares. Calves feed on this field (it is assumed that they eat only alfalfa), and a 12-year-old boy eats exclusively veal. The results of calculations, presented in the form of three pyramids: numbers, biomass and energy, indicate that alfalfa uses only 0.24% of all solar energy falling on the field; the calf absorbs 8. % of this product and only 0.7% of the calf's biomass ensures the development of the child during the year. E. Odum, thus, showed that only one millionth of the incident solar energy is converted into carnivore biomass, in this case contributing to an increase in the child’s weight, and the rest is lost and dissipated in a degraded form in the environment. The above example clearly illustrates the very low ecological efficiency of ecosystems and the low efficiency of transformation in food chains. We can state the following: if 1000 kcal (day m 2) recorded by producers, then 10 kcal (day m 2) goes into the biomass of herbivores and only 1 kcal (day m 2) - into the biomass of carnivores. Since a certain amount of a substance can be used by each biocenosis repeatedly, and a portion of energy once, it is more expedient to say that a cascade transfer of energy occurs in the ecosystem. Consumers serve as a managing and stabilizing link in the ecosystem. Consumers generate a spectrum of diversity in the cenosis, preventing the monopoly of dominants. The rule of the controlling value of consumers can rightfully be considered quite fundamental. According to cybernetic views, the control system should be more complex in structure than the controlled one, then the reason for the multiplicity of types of instruments becomes clear. The controlling significance of consumers also has an energetic basis. The flow of energy through one or another trophic level cannot be absolutely determined by the availability of food in the underlying trophic level. As is known, there is always a sufficient “reserve” left, since the complete destruction of food would lead to the death of consumers. These general patterns are observed within the framework of population processes, communities, levels of the ecological pyramid, and biocenoses as a whole. 3 Dynamic processes that ensure integrity and sustainability in ecosystems Cyclic changes in communities reflect the daily, seasonal and long-term periodicity of external conditions and the manifestation of endogenous rhythms of organisms. The daily dynamics of ecosystems is associated mainly with the rhythm of natural phenomena and is strictly periodic in nature. We have already considered that in each biocenosis there are groups of organisms whose life activity occurs at different times of the day. Some are active during the day, others at night. Hence, periodic changes occur in the composition and ratio of individual types of biocenosis of a particular ecosystem, as individual organisms are switched off from it for a certain time. The daily dynamics of the biocenosis are provided by both animals and plants. As is known, the intensity and nature of physiological processes in plants change during the day - photosynthesis does not occur at night, often flowers in plants open only at night and are pollinated by nocturnal animals, others are adapted to pollination during the day. Daily dynamics in biocenoses, as a rule, are more pronounced, the greater the difference in temperature, humidity and other environmental factors between day and night. More significant deviations in biocenoses are observed with seasonal dynamics. This is due to the biological cycles of organisms, which depend on the seasonal cyclicity of natural phenomena. Thus, the change of season has a significant impact on the life activity of animals and plants (hibernation, winter sleep, diapause and migration in animals; periods of flowering, fruiting, active growth, leaf fall and winter dormancy in plants). The tiered structure of the biocenosis is often subject to seasonal variability. Individual layers of plants may completely disappear in the appropriate seasons of the year, for example, a herbaceous layer consisting of annuals. The duration of biological seasons varies at different latitudes. In this regard, the seasonal dynamics of biocenoses in the Arctic, temperate and tropical zones are different. It is most clearly expressed in temperate climate ecosystems and northern latitudes. Long-term variability is normal in the life of any biocenosis. Thus, the amount of precipitation falling in the Barabinsk forest-steppe fluctuates sharply from year to year; a number of dry years alternate with long-term periods of abundant precipitation. This has a significant impact on plants and animals. In this case, the development of ecological niches occurs - functional demarcation in the emerging set or its addition with little diversity. Long-term changes in the composition of biocenoses are also repeated in connection with periodic changes in the general circulation of the atmosphere, which in turn is caused by an increase or decrease in solar activity. In the process of daily and seasonal dynamics, the integrity of biocenoses is usually not violated. The biocenosis experiences only periodic fluctuations in qualitative and quantitative characteristics. Progressive changes in the ecosystem ultimately lead to the replacement of one biocenosis by another, with a different set of dominant species. The reasons for such changes may be factors external to the biocenosis that act for a long time in one direction, for example, increasing pollution of water bodies, increasing drying out of swamp soils as a result of reclamation, increased grazing, etc. These changes from one biocenosis to another are called exogenetic. In the case when the increasing influence of a factor leads to a gradual simplification of the structure of the biocenosis, depletion of their composition, and a decrease in productivity, such shifts are called digressive or digressive. Endogenetic changes arise as a result of processes that occur within the biocenosis itself. The successive replacement of one biocenosis by another is called ecological succession (from Lat. - succession - sequence, change). Succession is a process of self-development of ecosystems. Succession is based on the incompleteness of the biological cycle in a given biocenosis. It is known that living organisms, as a result of their vital activity, change the environment around them, removing some substances from it and saturating it with metabolic products. When populations exist for a relatively long time, they change their environment in an unfavorable direction and, as a result, find themselves displaced by populations of other species, for which the resulting environmental transformations turn out to be ecologically beneficial. In a biocenosis, a change of dominant species thus occurs. The rule (principle) of ecological duplication is clearly visible here. The long-term existence of a biocenosis is possible only if changes in the environment caused by the activity of some living organisms are favorable for others with opposite requirements. Based on competitive interactions of species during succession, more stable combinations are gradually formed that correspond to specific abiotic environmental conditions. An example of succession leading to the replacement of one community by another is the overgrowing of a small lake followed by the appearance of a swamp and then a forest in its place. First, a floating carpet is formed along the edges of the lake - a floating carpet of sedges, mosses and other plants. The lake is constantly filled with dead plant remains - peat. A swamp is formed, gradually overgrown with forest. A successive series of communities gradually and naturally replacing each other in succession is called a succession series. Successions in nature are extremely varied in scale. They can be observed in banks with cultures, which are planktonic communities - various types of floating algae and their consumers - rotifers, flagellates in puddles and ponds, swamps, meadows, forests, abandoned arable lands, weathered rocks, etc. There is a hierarchy in the organization of ecosystems It also manifests itself in succession processes - larger transformations of biocenoses are made up of smaller ones. In stable ecosystems with a regulated cycle of substances, local successional changes are also constantly taking place, supporting the complex internal structure of communities. Types of successional changes. There are two main types of successional changes: 1 - with the participation of autotrophic and heterotrophic populations; 2 - with the participation of only heterotrophs. Succession of the second type occurs only in conditions where a preliminary supply or constant supply of organic compounds is created, due to which the community exists: in heaps or piles of manure, in decomposing plant matter, in reservoirs polluted with organic substances, etc. Succession process. According to F. Clements (1916), the process of succession consists of the following stages: Succession with a change of vegetation can be primary and secondary. Primary succession is the process of development and change of ecosystems in previously uninhabited areas, beginning with their colonization. A classic example is the constant fouling of bare rocks with the eventual development of forests on them. Thus, in the primary successions occurring on the rocks of the Ural Mountains, the following stages are distinguished: Secondary succession is the restoration of an ecosystem that once existed in a given area. It begins when the established relationships of organisms in an established biocenosis are disrupted as a result of a volcanic eruption, fire, felling, plowing, etc. Shifts leading to the restoration of the previous biocenosis are called demutational in geobotany. An example is the dynamics of species diversity on the island of Krakatoa after the complete destruction of native flora and fauna by a volcano. Another example is the secondary succession of the Siberian dark coniferous forest (fir-cedar taiga) after a devastating forest fire. In more scorched areas, pioneer mosses appear from spores blown by the wind: 3-5 years after a fire, the most abundant “fire moss” is Funaria hygrometrica, Geratodon purpureus, etc. Among higher plants, fireweed (Chamaenerion angustifolium) very quickly colonizes burnt areas ), which already after 2-3 months blooms profusely in the fire, as well as ground reed grass (Calamagrostis epigeios) and other species. Further succession phases are observed: the reed meadow gives way to shrubs, then birch or aspen forest, mixed pine-leaved forest, pine forest, pine-cedar forest, and finally, after 250 years, the restoration of the cedar-fir forest occurs. Secondary successions, as a rule, occur faster and easier than primary ones, since in the disturbed habitat the soil profile, seeds, primordia and part of the previous population and previous connections are preserved. Demutation is not a repetition of any stage of primary succession. Climax ecosystem. Succession ends with a stage when all species of the ecosystem, while reproducing, maintain a relatively constant number and no further change in its composition occurs. This equilibrium state is called climax, and the ecosystem is called climax. Under different abiotic conditions, different climax ecosystems are formed. In a hot and humid climate it will be a tropical rainforest, in a dry and hot climate it will be a desert. The main biomes of the earth are the climax ecosystems of their respective geographic areas. Changes in the ecosystem during succession. Productivity and biomass. As already noted, succession is a natural, directed process and the changes that occur at one or another stage are characteristic of any community and do not depend on its species composition or geographic location. There are four main types of successional changes: It should also be noted that the change of succession phases occurs in accordance with certain rules. Each phase prepares the environment for the emergence of the next one. The law of the sequence of passage of development phases operates here; the phases of development of a natural system can follow only in an evolutionarily fixed (historically, environmentally determined) order, usually from relatively simple to complex, as a rule, without the loss of intermediate stages, but possibly with their very rapid passage or evolutionarily fixed absence. When an ecosystem approaches a state of menopause, in it, as in all equilibrium systems, all development processes slow down. This situation is reflected in the law of successional slowdown: processes occurring in mature equilibrium ecosystems that are in a stable state, as a rule, tend to slow down. In this case, the restorative type of succession changes to their secular course, i.e. self-development occurs within the limits of menopause or nodal development. The empirical law of successional slowdown is a consequence of the rule of G. Odum and R. Pinkerton, or the rule of maximum energy for maintaining a mature system: succession proceeds in the direction of a fundamental shift in the flow of energy towards increasing its quantity, aimed at maintaining the system. The rule of G. Odum and R. Pinkerton, in turn, is based on the rule of maximum energy in biological systems, formulated by A. Lotka. This question was later well developed by R. Margalef, Y. Odum and is known as proof of the principle of “zero maximum”, or minimal growth in a mature ecosystem: an ecosystem in successional development tends to form the greatest biomass with the least biological productivity. Lindeman (1942) experimentally proved that succession is accompanied by an increase in productivity up to the climax community, in which energy conversion occurs most efficiently. Data from studies of the succession of oak and oak-ash forests show that in the later stages their productivity actually increases. However, during the transition to a climax community, there is usually a decrease in overall productivity. Thus, productivity in old forests is lower than in young forests, which in turn may be less productive than the more species-rich herbaceous layers that precede them. Similar declines in productivity have been observed in some aquatic systems. There are several reasons for this. One of them is that the accumulation of nutrients in growing forest biomass can lead to a decrease in their cycling. The decline in overall productivity could simply be the result of decreased vitality of individuals as their average age in the community increases. As succession progresses, an increasing proportion of available nutrients accumulates in the biomass of the community, and accordingly their content in the abiotic component of the ecosystem (in soil or water) decreases. The amount of detritus produced also increases. The main primary consumers are not herbivores, but detritivorous organisms. Corresponding changes also occur in trophic networks. Detritus becomes the main source of nutrients. During succession, the closedness of biogeochemical cycles of substances increases. Approximately 10 years from the moment the restoration of vegetation cover begins, the openness of the cycles decreases from 100 to 10%, and then it decreases even more, reaching a minimum in the climax phase. The rule of increasing closedness of the biogeochemical cycle of substances during succession, it can be stated with all confidence, is violated by the anthropogenic transformation of vegetation and natural ecosystems in general. Undoubtedly, this leads to a long series of anomalies in the biosphere and its divisions. A decrease in species diversity during menopause does not mean its low ecological significance. The diversity of species shapes succession, its direction, and ensures that real space is filled with life. An insufficient number of species making up the complex could not form a succession series, and gradually, with the destruction of climax ecosystems, complete desertification of the planet would occur. The value of diversity is functional both statically and dynamically. It should be noted that where the diversity of species is not enough to form the biosphere, which serves as the basis for the normal natural course of the succession process, and the environment itself is sharply disturbed, succession does not reach the climax phase, but ends with a nodal community - a paraclimax, a long-term or short-term derived community. The deeper the disturbance of the environment of a particular space, the earlier phases succession ends. When one or a group of species is lost as a result of their destruction (anthropogenic disappearance of habitats, less often extinction), the achievement of menopause is not a complete restoration of the natural environment. In fact, this is a new ecosystem, because new connections have arisen in it, many old ones have been lost, and a different “fraying” of species has developed. The ecosystem cannot return to its old state, since a lost species cannot be restored. When any abiotic or biotic factor changes, for example, with sustained cooling, or the introduction of a new species, a species that is poorly adapted to new conditions will face one of three paths. The law of evolutionary-ecological irreversibility states that an ecosystem that has lost part of its elements or has been replaced by another as a result of an imbalance of ecological components cannot return to its original state during succession if, during the changes, evolutionary (microevolutionary) changes have occurred in ecological elements (preserved or temporarily lost ). In the case when some species are lost in intermediate phases of succession, this loss can be functionally compensated, but not completely. When diversity decreases beyond a critical level, the course of succession is distorted, and in fact, a climax identical to the past cannot be achieved. To assess the nature of restored ecosystems, the law of evolutionary-ecological irreversibility is important. With the loss of elements, these are, in fact, completely new ecological natural formations with newly formed patterns and connections. Thus, the transfer in the past of a species that dropped out of the ecosystem during its reacclimatization does not mean its mechanical return. This is actually the introduction of a new species into a renewed ecosystem. The law of evolutionary-ecological irreversibility emphasizes the direction of evolution not only at the level of biosystems, but also at all other hierarchical levels of the biota. 4 The biosphere as a global ecosystem that ensures the integrity and sustainability of ecosystems The biosphere is a global ecosystem. As noted earlier, the biosphere is divided into geobiosphere, hydrobiosphere and aerobiosphere (Fig. 2.4). The geobiosphere has divisions in accordance with the main environment-forming factors: terrabiosphere and lithobiosphere - within the geobiosphere, marinobiosphere (oceanobiosphere) and aquabiosphere - within the hydrobiosphere. These formations are called subspheres. The leading environment-forming factor in their formation is the physical phase of the living environment: air-water in the aerobiosphere, water - freshwater and saltwater in the hydrobiosphere, solid-air in the terrabiosphere and solid water in the lithobiosphere. In turn, they all fall into layers: the aerobiosphere - into the tropobiosphere and altobiosphere; hydrobiosphere - into photosphere, disphotosphere and aphotosphere. The structure-forming factors here, in addition to the physical environment, energy (light and heat), special conditions for the formation and evolution of life - the evolutionary directions of penetration of biota onto land, into its depths, into the spaces above the earth, the abyss of the ocean, are undoubtedly different. Together with the apobiosphere, parabiosphere and other sub- and supra-biosphere layers, they constitute the so-called “layer cake of life” and the geosphere (ecosphere) of its existence within the boundaries of the megabiosphere. In a systemic sense, the listed formations are large functional parts of virtually universal or subplanetary dimensions. Scientists believe that in the biosphere there are at least 8-9 levels of relatively independent cycles of substances within the interconnection of 7 main material-energy ecological components and the 8th - informational. Global, regional and local cycles of substances are not closed and partially “intersect” within the ecosystem hierarchy. This material-energy, and partly informational “coupling” ensures the integrity of ecological supersystems up to the biosphere as a whole. Integrity and sustainability of ecosystems. The biosphere is formed to a greater extent not by external factors, but by internal patterns. The most important property of the biosphere is the interaction of living and nonliving things, which is reflected in the law of biogenic migration of atoms by V. I. Vernadsky. The law of biogenic migration of atoms makes it possible for humanity to consciously control biogeochemical processes both on Earth as a whole and in its regions. The amount of living matter in the biosphere, as is known, is not subject to noticeable changes. This pattern was formulated in the form of the law of constancy of the amount of living matter by V.I. Vernadsky: the amount of living matter in the biosphere for a given geological period is a constant. In practice, this law is a quantitative consequence of the law of internal dynamic equilibrium for the global ecosystem - the biosphere. Since living matter, in accordance with the law of biogenic migration of atoms, is an energy intermediary between the Sun and the Earth, its quantity either must be constant, or its energy characteristics must change. The law of physical and chemical unity of living matter (all living matter of the Earth is physical and chemically united and excludes significant changes in the latter property. Hence, quantitative stability is inevitable for the living matter of the planet. It is fully characteristic of the number of species. Living matter, as an accumulator of solar energy, must simultaneously respond to both external (cosmic) influences and internal changes. A decrease or increase in the amount of living matter in one place of the biosphere should lead to a process exactly the opposite in another place, because the released nutrients can be assimilated by the rest of the living matter or their deficiency will be observed. Here we must take into account the speed of the process, which in the case of anthropogenic change is much lower than direct disturbance of nature by man. In addition to the constancy and constancy of the amount of living matter, which is reflected in the law of physical and chemical unity of living matter, in living nature there is a constant preservation of the informational and somatic structure, despite the fact that it changes somewhat with the course of evolution. This property was noted by Yu. Goldsmith (1981) and was called the law of conservation of the structure of the biosphere - informational and somatic, or the first law of ecodynamics. To preserve the structure of the biosphere, living things strive to achieve a state of maturity or ecological balance. The law of the desire for menopause - the second law of ecodynamics by Yu. Goldsmith, applies to the biosphere and other levels of ecological systems, although there are specifics - the biosphere is a more closed system than its subdivisions. The unity of the living matter of the biosphere and the homology of the structure of its subsystems lead to the fact that the living elements of different geological ages and original geographical origins that arose on it are intricately intertwined evolutionarily. The interweaving of elements of different spatio-temporal genesis at all ecological levels of the biosphere reflects the rule or principle of heterogenesis of living matter. This addition is not chaotic, but is subject to the principles of ecological complementarity, ecological conformity (congruence) and other laws. Within the framework of the ecodynamics of Yu. Goldsmith, this is its third law - the principle of ecological order, or ecological mutualism, indicating a global property due to the influence of the whole on its parts, the reverse influence of differentiated parts on the development of the whole, etc., which in total leads to the conservation stability of the biosphere as a whole. Mutual assistance within the framework of the ecological order, or systemic mutualism, is affirmed by the law of orderliness of filling space and spatio-temporal certainty: the filling of space within a natural system, due to the interaction between its subsystems, is ordered in such a way that allows the homeostatic properties of the system to be realized with minimal contradictions between the parts within it. From this law it follows that the long-term existence of accidents “unnecessary” to nature, including human creations alien to it, is impossible. The rules of the mutualistic system order in the biosphere also include the principle of system complementarity, which states that the subsystems of one natural system in their development provide a prerequisite for the successful development and self-regulation of other subsystems included in the same system. The fourth law of ecodynamics by Yu. Goldsmith includes the law of self-control and self-regulation of living things: living systems and systems under the controlling influence of living things are capable of self-control and self-regulation in the process of their adaptation to changes in the environment. In the biosphere, self-control and self-regulation occur during cascade and chain processes of general interaction - during the struggle for the existence of natural selection (in the broadest sense of this concept), adaptation of systems and subsystems, broad co-evolution, etc. Moreover, all these processes lead to positive results “from the point of view” of nature - the preservation and development of ecosystems of the biosphere and it as a whole. The connecting link between generalizations of a structural and evolutionary nature is the rule of automatic maintenance of the global habitat: living matter, in the course of self-regulation and interaction with abiotic factors, autodynamically maintains a life environment suitable for its development. This process is limited by changes in the cosmic and global ecosphere scale and occurs in all ecosystems and biosystems of the planet, as a cascade of self-regulation reaching a global scale. The rule of automatic maintenance of the global habitat follows from the biogeochemical principles of V.I. Vernadsky, the rules for preserving species habitats, relative internal consistency and serves as a constant for the presence of conservative mechanisms in the biosphere and at the same time confirms the rule of system-dynamic complementarity. The cosmic impact on the biosphere is evidenced by the law of refraction of cosmic impacts: cosmic factors, having an impact on the biosphere and especially its subdivisions, are subject to change by the ecosphere of the planet and therefore, in terms of strength and time, manifestations can be weakened and shifted or even completely lose their effect. The generalization here is important due to the fact that there is often a flow of synchronous effects of solar activity and other cosmic factors on the Earth’s ecosystems and the organisms inhabiting it. It should be noted that many processes on Earth and in its biosphere, although subject to the influence of space, cycles of solar activity are assumed with intervals of 1850, 600, 400, 178, 169, 88, 83, 33, 22, 16, 11, 5 (11 ,1), 6.5 and 4.3 years, the biosphere itself and its divisions do not necessarily have to react with the same cyclicity in all cases. The cosmic influences of the biosphere system can be blocked completely or partially. Conclusion Ecosystems are the basic functional unit in ecology, since they include organisms and the inanimate environment - components that mutually influence each other's properties and the necessary conditions for maintaining life in the form that exists on Earth. The combination of a specific physicochemical environment (biotope) with a community of living organisms (biocenosis) forms an ecosystem. There are microecosystems, mesoecosystems, and the global ecosystem - the biosphere. Ecosystems are not scattered in disorder; on the contrary, they are grouped in fairly regular zones, both horizontally (in latitude) and vertically (in height). The primary source of energy for ecosystems is the Sun. Solar radiation falling on the Earth's surface is 1.54 million EJ per year. Most of the solar energy that reaches the planet's surface is converted directly into heat, warming water or soil, which in turn warms the air. Ecosystems exist due to non-polluting and almost eternal solar energy, the amount of which is relatively constant and abundant. Solar energy on Earth causes two cycles of substances: large, or geological, and small, biological (biotic). Both cycles are mutually connected and represent, as it were, a single process. The existence of biogeochemical cycles, or biogeochemical cycles, creates the opportunity for self-regulation (homeostasis) of the system, which gives the ecosystem stability: an amazing constancy of the percentage content of various elements. There are quite a lot of cycles of substances. The most significant cycle on Earth in terms of transferred masses and energy consumption is the planetary hydrological cycle or water cycle. The biotic (biological) cycle refers to the circulation of substances between soil, plants, animals and microorganisms. Of all the biogeochemical cycles, the carbon cycle is without a doubt the most intense. Most of the oxygen produced during geological epochs did not remain in the atmosphere, but was fixed by the lithosphere in the form of carbonates, sulfates, iron oxides, etc. This mass is 590x1014 tons versus 39x1014 tons of oxygen, which circulates in the biosphere in the form of gas or sulfates dissolved in continental and oceanic waters. Nitrogen is an essential biogenic element, as it is part of proteins and nucleic acids. The nitrogen cycle is one of the most complex, since it includes both gas and mineral phases, and at the same time the most ideal cycles. The phosphorus cycle in the biosphere is associated with metabolic processes in plants and animals. This important and necessary element of protoplasm, contained in terrestrial plants and algae 0.01-0.1%, animals from 0.1% to several percent, circulates, gradually turning from organic compounds into phosphates, which can again be used by plants. There are numerous gaseous sulfur compounds, such as hydrogen sulfide H2S and sulfur dioxide SO2. Maintaining the vital activity of organisms and the circulation of matter in ecosystems, i.e., the existence of ecosystems, depends on the constant flow of energy necessary for all organisms for their vital functions and self-reproduction. Unlike substances that continuously circulate through different blocks of the ecosystem, which can always be reused and enter the cycle, energy can be used once, i.e., there is a linear flow of energy through the ecosystem. Within an ecosystem, energy-containing substances are created by autotrophic organisms and serve as food for heterotrophs. Food connections are mechanisms for transferring energy from one organism to another. Within each ecosystem, food webs have a well-defined structure, which is characterized by the nature and number of organisms represented at each level of the various food chains. The formation of ecosystems is a dynamic process. In ecosystems, changes constantly occur in the state and vital activity of their members and in the ratio of populations. The diverse changes occurring in any community fall into two main types: cyclical and progressive. Succession is a natural, directed process and the changes that occur at one or another stage are characteristic of any community and do not depend on its species composition or geographic location. The global ecosystem is the biosphere. As noted earlier, the biosphere is divided into geobiosphere, hydrobiosphere and aerobiosphere. The biosphere is formed to a greater extent not by external factors, but by internal patterns. The most important property of the biosphere is the interaction of living and nonliving things, which is reflected in the law of biogenic migration of atoms by V.I. Vernadsky. The ecosystems existing on Earth are diverse. There are microecosystems (for example, the trunk of a rotting tree), mesoecosystems (forest, pond, etc.), macroecosystems (continent, ocean, etc.) and the global biosphere. Large terrestrial ecosystems are called biomes. Each biome contains a number of smaller, interconnected ecosystems. There are several classifications of ecosystems: evergreen tropical rain forest; desert: grassy and shrubby; tropical grasslens and savanna; temperate steppe; temperate deciduous forest: boreal coniferous forests. Tundra: arctic and alpine. Types of freshwater ecosystems: ribbon (still water): lakes, ponds, etc.; lotic (flowing waters): rivers, streams, etc.; wetlands: swamps and swampy forests; Types of marine ecosystems: open ocean (pelagic); waters of the continental shelf (coastal waters); upwelling areas (fertile areas with productive fisheries); estuaries (coastal bays, straits, river mouths, salt marshes, etc.). Every ecosystem has two main components: organisms and factors from their nonliving environment. The totality of organisms (plants, animals, microbes) is called the biota of an ecosystem. The ways of interaction between different categories of organisms are its biotic structure. Solar energy on Earth causes two cycles of substances: a large, or geological, most clearly manifested in the water cycle and atmospheric circulation, and a small, biological (biotic), developing on the basis of a large one and consisting of a continuous, cyclical, but uneven in time and space, and accompanied by more or less significant losses in the natural redistribution of matter, energy and information within ecological systems of various levels of organization. Both cycles are mutually connected and represent, as it were, a single process. The interaction of abiotic factors and living organisms of the ecosystem is accompanied by a continuous circulation of matter between the biotope and the biocenosis in the form of alternating organic and mineral compounds. The exchange of chemical elements between living organisms and the inorganic environment, the various stages of which occur within an ecosystem, is called the biogeochemical cycle, or biogeochemical cycle. The existence of such cycles creates the opportunity for self-regulation (homeostasis) of the system, which gives the ecosystem stability: an amazing constancy of the percentage of various elements. The principle of the functioning of ecosystems applies here: the acquisition of resources and disposal of waste occur within the framework of the cycle of all elements. List of used literature 1.Bigon M.I. Ecology, individuals, populations and communities. M.: 1989. - 290 p. 2.Beysenova A.S., Shildebaev Zh.B., Sautbaeva G.Z. Ecology. Almaty: "Gylym, 2001. - 201 p. 3.Akimova T.A., Khaskin V.V. Ecology. M.: UNITY Publishing House, 1998. - 233 p. .Gorelov A.A. Ecology. Lecture course. M.: "Center" 1997. - 280 p. .Stadnitsky G.V., Rodionov A.I. Ecology. M.: UNITY Publishing House, 1996. - 272 p. .Sadanov A.K., Svanbaeva Z.S., Ecology. Almaty: "Agrouniversity", 1999. - 197 p. .Shilov I.A. Ecology. M.: Higher School, 2000. - 348 p. .Reimers N.F. Ecology (Theory, laws, rules, principles and hypotheses). M.: "Young Russia", 1994. - 260 p. .Tsvetkova L.I., Alekseev M.I., Usenov B.P. and others. Ecology. Textbook for technical universities. M.; ASV, St. Petersburg: Khimizdat, 1999, 185 p. .Girusov E.V. Ecology and economics of environmental management. M.: Law and Law, UNITY. 1998 - 232 p. .Vronsky V.A. Applied ecology: Proc. Benefit. Rostov-on-Don: 1995. - 197 p. .Budyko M.I. Global ecology. M.: Mysl, 1977.-248 p. .Alekseenko V.A. Environmental geochemistry. Textbook. M.: Logos, 2000 - 410 p. .Petrov K.M. General ecology of S-P. Tutorial. "Chemistry", 1997. - 218 p. .Andersen J.M. Ecology and environmental science. Biosphere, ecosystem, man. L., 1985. 376 p. .Girenok F.I. Ecology. Civilization. Noosphere.M.: 191987. - 281 p. .In search of balance: ecology in the system of social political priorities M.: 1992. - 427 p. .History of interaction between society and nature: Factors and concept. M.: ANSSSR 1990. .Stepanovskikh A.S. Applied ecology: Environmental protection. Textbook for universities. M.: UNITY DANA. 2003. 751 p. Similar works to - Cycle of substances and energy flows in ecosystems
Maintaining the vital activity of organisms and the circulation of matter in ecosystems, i.e., the existence of ecosystems, depends on the constant flow of energy necessary for all organisms for their vital functions and self-reproduction.
Unlike substances that continuously circulate through different blocks of the ecosystem, which can always be reused and enter the cycle, energy can be used only once, i.e., there is a linear flow of energy through the ecosystem.
The one-way influx of energy as a universal natural phenomenon occurs as a result of the laws of thermodynamics. First Law states that energy can be converted from one form (such as light) to another (such as the potential energy of food), but cannot be created or destroyed. Second Law states that there cannot be a single process associated with the transformation of energy without losing some of it. A certain amount of energy in such transformations is dissipated into inaccessible thermal energy and is therefore lost. Hence, there cannot be transformations of, for example, food substances into the substance that makes up the body of the organism, which occur with 100% efficiency.
Thus, living organisms are energy converters. And every time energy is converted, part of it is lost in the form of heat. Ultimately, all the energy entering the biotic cycle of an ecosystem is dissipated as heat. Living organisms do not actually use heat as an energy source to do work - they use light and chemical energy.
Ecological pyramids. Within each ecosystem, food webs have a well-defined structure, which is characterized by the nature and number of organisms represented at each level of the various food chains. To study the relationships between organisms in an ecosystem and to depict them graphically, they usually use ecological pyramids rather than food web diagrams. Ecological pyramids express the trophic structure of an ecosystem in geometric form. They are constructed in the form of rectangles of the same width, but the length of the rectangles must be proportional to the value of the object being measured. From here you can get pyramids of numbers, biomass and energy.
Ecological pyramids reflect the fundamental characteristics of any biocenosis when they show its trophic structure:
Their height is proportional to the length of the food chain in question, i.e., the number of trophic levels it contains;
Their shape more or less reflects the efficiency of energy transformations during the transition from one level to another.
Pyramids of numbers. They represent the simplest approximation to the study of the trophic structure of an ecosystem. In this case, the number of organisms in a given territory is first counted, grouped by trophic levels and presented in the form of 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). A basic rule has been established that in any environment there are more plants than animals, more herbivores than carnivores, more insects than birds, etc.
Population pyramids reflect the density of organisms at each trophic level. There is great diversity in the construction of various population pyramids. Often they are upside down.
For example, in a forest there are significantly fewer trees (primary producers) than insects (herbivores).
Biomass pyramid. Reflects more fully the food relationships in the ecosystem, since it takes into account the total mass of organisms (biomass) each trophic level. The rectangles in the biomass pyramids represent the mass of organisms at each trophic level per unit area or volume. The shape of the biomass pyramid is often similar to the shape of the population pyramid. A decrease in biomass at each successive trophic level is characteristic.
Pyramids of biomass, as well as numbers, can be not only straight, but also inverted. Inverted pyramids of biomass are characteristic of aquatic ecosystems, in which primary producers, such as phytoplanktonic algae, divide very quickly, and their consumers - zooplanktonic crustaceans - are much larger but have a long reproduction cycle. In particular, this applies to freshwater environments, where primary productivity is provided by microscopic organisms whose metabolic rates are increased, i.e., biomass is low, productivity is high.
Pyramid of energy. The most fundamental way to display connections between organisms at different trophic levels is through energy pyramids. They represent the energy conversion efficiency and productivity of food chains and are constructed by counting the amount of energy (kcal) accumulated per unit surface area per unit time and used by organisms at each trophic level. Thus, it is relatively easy to determine the amount of energy stored in biomass, but it is more difficult to estimate the total amount of energy absorbed at each trophic level. Having constructed a graph (Fig. 12.28), we can state that destructors, the importance of which seems small in the biomass pyramid, and vice versa in the population pyramid; receive a significant portion of the energy passing through the ecosystem. Moreover, only part of all this energy remains in organisms at each trophic level of the ecosystem and is stored in biomass; the rest is used to satisfy the metabolic needs of living beings: maintaining existence, growth, reproduction. Animals also expend a significant amount of energy for muscular work.
R. Lindeman in 1942 first formulated energy pyramid law, which in textbooks is often called the “law of 10%”. According to this law, from one trophic level of the ecological pyramid On average, no more than 10% of energy passes to another level.
Consumers serve as a managing and stabilizing link in the ecosystem. Consumers generate a spectrum of diversity in the cenosis, preventing the monopoly of dominants. Rule of control value of consumers can rightfully be considered quite fundamental. According to cybernetic views, the control system should be more complex in structure than the controlled one, then the reason for the multiplicity of consumer types becomes clear. The controlling significance of consumers also has an energetic basis. The flow of energy through one or another trophic level cannot be absolutely determined by the availability of food in the underlying trophic level. As is known, there is always a sufficient “reserve” left, since the complete destruction of food would lead to the death of consumers. These general patterns are observed within the framework of population processes, communities, levels of the ecological pyramid, and biocenoses as a whole.
To trace the relationship between living and inanimate nature, it is necessary to understand how the cycle of substances occurs in the biosphere.
Meaning
The cycle of substances is the repeated participation of the same substances in processes occurring in the lithosphere, hydrosphere and atmosphere.
There are two types of substance cycles:
- geological(great cycle);
- biological(small cycle).
The driving force of the geological circulation of substances is external (solar radiation, gravity) and internal (energy of the Earth's interior, temperature, pressure) geological processes, biological processes - the activity of living beings.
The Great Cycle occurs 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, and movement of the earth's crust, valleys, mountains, rivers, hills are formed, and geological layers are formed.
Rice. 1. Geological cycle.
The biological circulation of substances in the biosphere occurs with the participation of living organisms that convert and transmit 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 approximately 40 chemical elements;
- presence of solar energy;
- interaction of living organisms.
Rice. 2. Biological cycle.
The cycle of substances has no specific starting point. The process is continuous and one stage invariably flows into another. You can start considering the cycle from any point, the essence will remain the same.
The general cycle of substances includes the following processes:
- photosynthesis;
- metabolism;
- decomposition.
Plants, which are producers in the food chain, convert solar energy into organic substances, which enter the body of decomposer animals with food. After death, decomposition of plants and animals occurs with the help of consumers - bacteria, fungi, worms.
Rice. 3. Food chain.
Cycle of substances
Depending on the location of substances in nature, they are distinguished 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 matter and energy in the biosphere is described in the table using the example of several elements.
|
Substance |
Cycle |
Meaning |
|
Big circle. Evaporates from the surface of the ocean or land, lingers in the atmosphere, falls as precipitation, returning to water bodies and to the surface of the Earth. |
Shapes the natural and climatic conditions of the planet |
|
|
On land there is a small cycle of substances. They are received by producers and passed on to decomposers and consumers. Returns as carbon dioxide. There is a big cycle in the ocean. Retained as sediment |
Is the basis of all organic substances |
|
|
Nitrogen-fixing bacteria found in the roots of plants fix free nitrogen from the atmosphere and fix it in plants in the form of plant protein, which is passed further along the food chain. |
Contains proteins and nitrogenous bases |
|
|
Oxygen |
Small cycle - enters the atmosphere during photosynthesis and is consumed by aerobic organisms. Great Gyre - formed from water and ozone under the influence of ultraviolet radiation |
Participates in oxidation and respiration processes |
|
Found in the atmosphere and soil. Absorbed by bacteria and plants. Some settle on the seabed |
Necessary for building amino acids |
|
|
Large and small gyres. Contained in rocks, consumed by plants from the soil and transmitted through the food chain. After the organisms decompose, it returns to the soil. In the reservoir it is absorbed by phytoplankton and transmitted to fish. After the fish die, some remain in the skeleton and settle to the bottom |
Contains proteins and nucleic acids |
Stopping the cycle of substances in nature means disrupting the course of life. For life to continue, energy must go through cycle after cycle.
What have we learned?
From the lesson we 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 examined the cycle of water, carbon, nitrogen, oxygen, sulfur and phosphorus.
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Average rating: 4.5. Total ratings received: 129.