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Consumers, their role in the functioning of the ecosystem. Biology at the Lyceum Can plants act as consumers?

Consumers are heterotrophic organisms (mostly animals) that consume organic matter from other organisms - plants (herbivores - phytophages) and animals (carnivores - zoophages).[...]

Consumers (consume - consume), or heterotrophic organisms (heteros - other, trophe - food), carry out the process of decomposition of organic substances. These organisms use organic matter as nutritional material and energy source. Heterotrophic organisms are divided into phagotrophs (phaqos - devouring) and saprotrophs (sapros - rotten).[...]

Consumers partially use wheat to support life processes (“breathing costs”), and partially build their own body on its basis, thus carrying out the first, fundamental stage of transformation of organic matter synthesized by producers. The process of creation and accumulation of biomass at the level of consumers is designated as secondary production.[...]

Consumers are heterotrophic animals that consume ready-made organic substances. First order consumers can use organic matter from plants (herbivores). Heterotrophs that use animal food are divided into consumers of orders II, III, etc. (carnivores). All of them use the energy of chemical bonds stored in organic substances by producers.[...]

CONSUMERS - organisms that consume ready-made organic substances, but do not decompose these substances to simple mineral components (cf. decomposers). The totality of K. forms trophic chains (levels), in which K. of the first order (herbivores) and K. of the second, third and subsequent orders (predators) are distinguished.[...]

Consumers are organisms, which include all animals that consume ready-made organic substances created by photosynthetic or chemosynthetic species - producers. Unlike destructors, they do not bring organic substances to complete decomposition into simple mineral components. [...]

There are no consumers who live in isolation: they are all influenced by other consumers. The most obvious example is competition; many consumers face exploitative competition for limited food resources when consumer densities are high and food quantities are low; in this case, as the density of consumers increases, the rate of food consumption by each individual decreases. However, even if food supplies are not limited, the rate of food consumption per individual can decrease with increasing consumer density due to a number of interactions, which are generally called mutual interference. For example, many consumers interact with other individuals in a population on a behavioral basis; This leaves less time for food consumption and the rate of food consumption generally decreases.[...]

If the consumer quickly leaves the feeding patch, then this period will be short (/r + 5cr. in Fig. 9.21.5). But at the same time, he will receive correspondingly little energy (Ecr). The rate of energy production (for the entire period £¿ + 5) will be given by the slope of the segment OB [i.e. e. £Kr./(+ 5Kr.)]. At the same time, if the consumer stays in the spot for a long time (5DL), then he will receive much more energy (£DL); but in general, the rate of production (slope of the segment Ob) will change little. In order to maximize the rate of energy production over the period ¿/ + 5, it is necessary to achieve the maximum value of the slope of the segment connecting point O with the consumption curve. This is achieved simply by drawing a tangent to the curve (line OP in Fig. 9.21, B). It is impossible to draw a straight line from point O even steeper and so that it intersects the curve, and therefore the dwell time obtained using the tangent is optimal (50Pm).[...]

The reactions of consumers to food spots often have not only a spatial, but also a temporal component. In such cases, the behavior of the main characters resembles a “game of hide and seek.”[...]

P - producers C, - primary consumers. D. Soil arthropods - according to Engeliann (1968).[...]

All living components of an ecosystem - producers, consumers and decomposers - make up the total biomass (“live weight”) of the community as a whole or its individual parts, certain groups of organisms. Biomass is usually expressed in terms of wet and dry weight, but can also be expressed in energy units - calories, joules, etc., which makes it possible to identify the relationship between the amount of incoming energy and, for example, the average biomass.[...]

A person, eating cow meat, is a secondary consumer at the third trophic level, and eating plants, he is a primary consumer at the second trophic level. Each person requires about 1 million kcal of energy received through food per year for the physiological functioning of the body. Humanity produces about 810 5 kcal (with a population of over 6 billion people), but this energy is distributed extremely unevenly. For example, in the city energy consumption per person reaches 80 million kcal per year, i.e. For all types of activities (transport, household, industry), a person spends 80 times more energy than is necessary for his body.[...]

At the same time, it cannot be expected that the birth rate, growth rate and survival rate of consumers will increase indefinitely as food availability increases. Consumers reach a state of satiation, and the rate of food consumption gradually reaches a constant level, at which it does not depend on the amount of available food (Fig. 8.7); therefore, the gain received by the consumer also reaches a constant level. Thus, there is a limit to the amount of food that a given consumer population can eat, a limit to the harmful effects on its prey population, and a limit to which the consumer population can increase in size. [...]

In an ecosystem, food and energy connections go in the direction: producers -> consumers -> decomposers.[...]

Each biocenosis includes the following functional components: producers, consumers of orders I-III, as well as decomposers that form food chains of different types (pasture and detritus). This structure of the ecosystem ensures the transfer of energy from link (trophic level) to link. In real conditions, food chains can have a different number of links; in addition, trophic chains can intersect, forming food networks. Almost all species of animals, with the exception of those that are very specialized in food terms, use not just one food source, but several. If one member of the biocenosis drops out of the community, the entire system is not disrupted, since other food sources are used. The greater the species diversity in a biocenosis, the more stable it is. For example, in the plant-hare-fox food chain there are only three links. But the fox feeds not only on hares, but also on rodents and birds. The hare also has alternative types of food - green parts of plants, dry stems (“hay”), twigs of trees and shrubs, etc.[...]

A third of the groups of organisms participating in the cycle of matter in the biosphere are consumers - organisms that feed on living or dead organic matter. The difference between consumers and decomposers, who also feed on organic matter, is that for their life activity they use only part of the energy (on average about 90%) contained in the organic matter of food, and not all organic matter of food is converted into inorganic compounds. [...]

In the case of pasture forest food chains, when trees are producers and insects are primary consumers, the level of primary consumers is numerically richer in individuals of the producer level. Thus, pyramids of numbers can be reversed. For example in Fig. Figure 9.7 shows pyramids of numbers for ecosystems of the steppe and forests of the temperate zone.[...]

Biological resources are all living environment-forming components of the biosphere: producers, consumers and decomposers with genetic material contained in them (Reimers, 1990). They are sources for people to receive material and spiritual benefits. These include commercial objects, cultivated plants, domestic animals, picturesque landscapes, microorganisms, i.e. plant resources, animal resources, etc. Genetic resources are of particular importance.[...]

In addition, the modeling results become different when it is taken into account that consumer populations are influenced by food resources, and those do not depend on the influence of consumers (¡3,/X), 3(/ = 0: the so-called “donor-regulated system” ), In this type of food web, stability is either independent of complexity or increases with it (DeAngelis, 1975). In practice, the only group of organisms that usually satisfies this condition are detritivores.[...]

Man is part of the biotic component of the biosphere, where he is connected by food chains with producers, is a consumer of the first and second (sometimes third) order, a heterotroph, uses ready-made organic matter and nutrients, is included in the cycle of substances in the biosphere and obeys the law of physical and chemical unity of matter B .AND. Vernadsky - living matter is physico-chemically united.[...]

The above example shows how the same resource (raspberry plant) can be used by a wide variety of consumers; It also shows how many seemingly unrelated consumers can nevertheless interact through a common resource (see Chapter 7).[...]

The trophic level is the location of each link in the food chain. The first trophic level is producers, all the rest are consumers.[...]

The biotic communities of each of these zones, except for the euphotic, are divided into benthic and pelagic. In them, the primary consumers include zooplankton; insects in the sea are ecologically replaced by crustaceans. The overwhelming majority of large animals are predators. The sea is characterized by a very important group of animals called sessile (attached). They are not found in freshwater systems. Many of them resemble plants and hence their names, for example, crinoids. Mutualism and commensalism are widely developed here. All benthic animals in their life cycle pass through the pelagic stage in the form of larvae.[...]

But still, without a doubt, a more general rule is a decrease in the rate of food consumption by an individual as the population density of consumers increases. This decline is likely to have negative effects on fertility, growth, and the likelihood of individual mortality, and this negative effect will increase as density increases. Thus, density-dependent control is exercised in the consumer population and, consequently, mutual interference stabilizes the dynamics of the predator population and the dynamics of the interacting populations of predator and prey.[...]

The organic mass created by plants per unit of time is called the primary production of the community, and the production of animals or other consumers is called secondary. Obviously, secondary production cannot be greater than primary production or even equal to it. Products are expressed quantitatively in the wet or dry mass of plants or in energy units - the equivalent number of joules. [...]

Energy is transferred from organism to organism, creating a food or trophic chain: from autotrophs, producers (creators) to heterotrophs, consumers (eaters) and so on 4-6 times from one trophic level to another.[...]

In an agrocenosis, as in any biocenosis, food chains develop. An obligatory link in these chains is a person, and here he acts as a consumer of the first order, and the food chain is interrupted at him. Agrocenoses are very unstable and exist without human intervention from 1 year (cereals, vegetables) to 20-25 years (fruits and berries).[...]

COMMUNITY is a collection of interconnected individuals, interconnected species within a certain space.[...]

Ranked preference prevails when food items can be classified based on a single indicator. A mixed diet is preferable for various reasons.[...]

Biocenosis (“bios” - life, “cenosis” - community, Karl Moebius, 1877) is the entire complex of species living together and interconnected with each other. Biocenoses, like populations, are a supraorganismal level of organization of LIFE.[...]

Predators that feed on herbivores and “superpredators” that feed on both the same herbivores and smaller predators constitute the levels of 2nd and 3rd order consumers. Part of the organic matter created by producers does not reach the level of consumers as food, but, together with organic residues of all levels, is processed by organisms that feed on dead organic residues, destructors, and is finally destroyed by fungi and microorganisms, which are called decomposers. Many authors, however, combine these two groups of organisms into one under either of the two names. Analysis of the functioning of systems of connections between different levels, the role of individual species and groups of species in the processing of matter and energy in trophic networks, and they are always much more complex than a generalized “pyramid” scheme, constitutes the main content of environmental research.[...]

It is not difficult to notice that the shorter the food chain of a population, the greater the amount of energy available for its life activity. Therefore, for a given output of primary production of the ecosystem, the transition to each next level of the food chain sharply reduces the number of consumers (up to 10 times) that can feed themselves.[...]

The beneficial effect of food on individual predators is not difficult to imagine. An increase in the amount of food eaten, generally speaking, leads to an increase in the rate of growth, development and reproduction and a decrease in mortality. However, there are a number of situations in which the relationship between the rate of food consumption and the gain received by the predator turns out to be more complex than it seems at first glance.[...]

In terrestrial ecosystems, flowering plants typically dominate not only their trophic level, but also the entire community, since they provide shelter for the vast majority of organisms in the community and, in addition, have a variety of influences on the abiotic environment. Consumers can also play a regulatory role in the entire community. Where plants are small in size, animals have a fairly large influence on the physical environment.[...]

All animals first require some amount of food simply to survive (Figure 8.6), and unless this threshold is exceeded the animal will not be able to grow and reproduce and thus will not be able to produce offspring. In other words, a low rate of food consumption does not simply give the consumer too little gain, but rather affects the rate at which he approaches death from starvation. [...]

They create biomass, which contains the potential energy of chemical bonds. Therefore, they are called producers - producers. The rate of energy accumulation at cone levels is called secondary productivity.[...]

In the vicinity of the plant, a mole colony was found at a distance of 16 km from the emission center, voles were captured no closer than 7–8 km, and shrews were captured at 3–4 km. Moreover, at these distances from the plant, animals do not live permanently, but only come in temporarily. This means that the biogeocenosis, with an increase in anthropogenic load, is simplified primarily due to the loss or sharp reduction of consumers (see Fig. 4) and the circuit of carbon (and other elements) circulation becomes two-part: producers and receptors.[...]

An ecosystem is a collection of organisms and inorganic components in which the circulation of matter can be maintained. Any ecosystem includes a living part - a biocenosis and its physical environment. Smaller ecosystems are part of increasingly larger ones, up to the overall ecosystem of the Earth - the biosphere. An ecosystem can ensure the circulation of matter only if there are four components: reserves of nutrients, producers, consumers and decomposers.[...]

One of the reasons for the lack of paleontological data on the Archean and Proterozoic is the lack of skeletons, external or internal, that could be preserved as fossils. One of the assumptions on this matter, which is closest to the ecological view of evolution, is that for a long time the level of production of organic matter by photosynthetics, represented mainly by phytoplankton, microscopic algae floating in the upper layers of water, was sufficient or even excessive to support life a variety of consumers that fed on living or dead algae and evolved to improve mechanisms for filtering water or collecting silt. A significant part of modern marine organisms have retained their diet from filtered tiny organic particles (sponges, many mollusks, crustaceans, larval chordates and many others) or from silt collected from the bottom. This type of biosphere, whose ecosystems probably consisted of only three levels - producers, consumers and decomposers, microorganisms that finally decompose organic matter, existed on Earth for quite a long time.[...]

In addition to illustrating the potential importance of predator satiation, the yield example highlights another issue related to the time scale of interactions. Seed consumers are unable to make maximum profit (or cause maximum damage) from a bountiful harvest because their generation time is too long. A hypothetical seed consumer, which could produce several generations over the course of a season, would be able, on abundant food, to exponentially increase its population and destroy the crop. -Generally speaking, consumers with relatively short generation times tend to repeat fluctuations in the abundance of their prey, whereas consumers with relatively long generation times require a longer period to respond to increases in prey abundance and to recover from declines in prey abundance.

IN biocenoses Living organisms are closely connected not only with each other, but also with inanimate nature. This connection is expressed through matter and energy.

Metabolism, as you know, is one of the main manifestations of life. In modern terms, organisms are open biological systems because they are connected to their environment by a constant flow of matter and energy passing through their bodies. The material dependence of living beings on the environment was recognized back in Ancient Greece. The philosopher Heraclitus figuratively expressed this phenomenon in the following words: “Our bodies flow like streams, and matter is constantly renewed in them, like water in a stream.” The substance-energy connection of an organism with its environment can be measured.

The flow of food, water, and oxygen into living organisms are flows of matter from environment. Food contains the energy necessary for the functioning of cells and organs. Plants directly absorb the energy of sunlight, store it in the chemical bonds of organic compounds, and then it is redistributed through food relationships in biocenoses.

V. N. Sukachev
(1880 – 1967)

Prominent Russian botanist, academician
Founder of biogeocenology - the science of natural ecosystems

The flows of matter and energy through living organisms in metabolic processes are extremely large. A person, for example, consumes tens of tons of food and drink during his life, and many millions of liters of air through his lungs. Many organisms interact with their environment even more intensely. To create each gram of their mass, plants spend from 200 to 800 or more grams of water, which they extract from the soil and evaporate into the atmosphere. Substances necessary for photosynthesis, plants obtain from soil, water and air.

With such an intensity of flows of matter from inorganic nature into living bodies, the reserves of compounds necessary for life are nutrients– would have been exhausted on Earth long ago. However, life does not stop, because nutrients are constantly returned to the environment surrounding organisms. This happens in biocenoses, where, as a result of nutritional relationships between species, synthesized by plants organic matter are eventually destroyed again into compounds that can be used again by plants. This is how it arises biological cycle of substances.

Thus, the biocenosis is part of an even more complex system, which, in addition to living organisms, also includes their inanimate environment, containing the matter and energy necessary for life. A biocenosis cannot exist without material and energy connections with the environment. As a result, the biocenosis represents a certain unity with it.

A. Tansley
(1871 – 1955)

English botanist, introduced the concept of “ecosystem” into science

Any collection of organisms and inorganic components in which the cycle of matter can be maintained is called ecological system, or ecosystem.

Natural ecosystems can be of different volumes and lengths: a small puddle with its inhabitants, a pond, an ocean, a meadow, a grove, a taiga, a steppe - all these are examples of ecosystems of different scales. Any ecosystem includes a living part - a biocenosis and its physical environment. Smaller ecosystems are part of increasingly larger ones, up to the overall ecosystem of the Earth. The general biological cycle of matter on our planet also consists of the interaction of many more private cycles. An ecosystem can ensure the circulation of matter only if it includes the four components necessary for this: reserves of nutrients, producers, consumers And decomposers(Fig. 1).

Rice. 1. Essential Ecosystem Components

Producers- these are green plants that create organic matter from biogenic elements, i.e. biological products, using solar energy flows.

Consumers– consumers of this organic substance, processing it into new forms. Animals usually act as consumers. There are first-order consumers - herbivorous species and second-order - carnivorous animals.

Decomposers- organisms that completely destroy organic compounds to mineral ones. The role of decomposers in biocenoses is performed mainly by fungi and bacteria, as well as other small organisms that process the dead remains of plants and animals (Fig. 2).

Rice. 2. Destroyers of dead wood (bronze beetle and its larva; stag beetle and its larva; large oak longhorned beetle and its larva; odoriferous woodworm butterfly and its caterpillar; red flat beetle; nodule centipede; black ant; woodlice; earthworm)

Life on Earth has been going on for about 4 billion years, without interruption precisely because it occurs in the system of biological cycles of matter. The basis for this is plant photosynthesis and food connections between organisms in biocenoses. However, the biological cycle of matter requires constant energy expenditure. Unlike chemical elements that are repeatedly involved in living bodies, the energy of sunlight retained by green plants cannot be used by organisms indefinitely.

According to the first law of thermodynamics, energy does not disappear without a trace; it is preserved in the world around us, but passes from one form to another. According to the second law of thermodynamics, any transformation of energy is accompanied by the transition of part of it to a state where it can no longer be used for work. In the cells of living beings, the energy that provides chemical reactions is partially converted into heat during each reaction, and the heat is dissipated by the body in the surrounding space. The complex work of cells and organs is thus accompanied by loss of energy from the body. Each cycle of the circulation of substances, depending on the activity of the members of the biocenosis, requires more and more new supplies of energy.

Thus, life on our planet is carried out as a permanent cycle of substances, supported flow of solar energy. Life is organized not only into biocenoses, but also into ecosystems, in which there is a close connection between living and nonliving components of nature.

The diversity of ecosystems on Earth is associated both with the diversity of living organisms and with the conditions of the physical and geographical environment. Tundra, forest, steppe, desert or tropical communities have their own characteristics of biological cycles and connections with the environment. Aquatic ecosystems are also extremely diverse. Ecosystems differ in the speed of biological cycles and in the total amount of substance involved in these cycles.

The basic principle of the sustainability of ecosystems - the cycle of matter supported by the flow of energy - essentially ensures the endless existence of life on Earth.

Based on this principle, sustainable artificial ecosystems and production technologies that save water or other resources can be organized. Violation of the coordinated activity of organisms in biocenoses usually entails serious changes in the cycles of matter in ecosystems. This is the main reason for such environmental disasters, such as a decline in soil fertility, a decrease in plant yield, growth and productivity of animals, and the gradual destruction of the natural environment.

Establish a correspondence between the characteristics and names of the functions of living matter in the biosphere (according to V.I. Vernadsky): for each position given in the first column, select the corresponding position from the second column.

Write down the selected numbers in the table under the corresponding letters.

A	B	IN	G	D

Explanation.

1) redox: B) the formation of water and carbon dioxide during the respiration of aerobes;

D) reduction of carbon dioxide during photosynthesis

2) gas: A) release methane into the atmosphere as a result of the activity of denitrifying bacteria

3) concentration: B) accumulation of silicon salts in horsetail cells; D) formation of limestone

Answer: 21313

Note.

Functions of living matter.

According to Vernadsky - nine: gas, oxygen, oxidation, calcium, reduction, concentration, the function of destruction of organic compounds, the function of reductive decomposition, the function of metabolism and respiration of organisms. Currently, taking into account new research, the following functions are distinguished.

Biogeochemical the function of humanity is the creation and transformation of substances by humanity.

Energy function. Absorption of solar energy during photosynthesis and chemical energy during the decomposition of energy-saturated substances, energy transfer through food chains (used by heterotrophs). The absorbed energy is distributed within the ecosystem among living organisms in the form of food. Part of the energy is dissipated in the form of heat, and part of it accumulates in dead organic matter and turns into a fossil state. This is how deposits of peat, coal, oil and other combustible minerals were formed.

Destructive function. This function consists of decomposition, mineralization of dead organic matter, chemical decomposition of rocks, involvement of the resulting minerals in the biotic cycle, i.e. causes the transformation of living matter into inert matter. As a result, biogenic and bioinert matter of the biosphere is also formed. On the rocks - bacteria, blue-green algae, fungi and lichens - have a strong chemical effect on the rocks with solutions of a whole complex of acids - carbonic, nitric, sulfuric and various organic ones. By decomposing certain minerals with their help, organisms selectively extract and include in the biotic cycle the most important nutritional elements - calcium, potassium, sodium, phosphorus, silicon, and microelements.

Concentration function. This is the name for the selective accumulation during the life of certain types of substances for building the body of the organism or those removed from it during metabolism. As a result of the concentration function, living organisms extract and accumulate biogenic elements of the environment. The composition of living matter is dominated by atoms of light elements: hydrogen, carbon, nitrogen, oxygen, sodium, magnesium, silicon, sulfur, chlorine, potassium, calcium, iron, aluminum. Carbon: limestone, chalk, coal, oil, bitumen, peat, oil shale (sapropel + humus), sapropel (centuries-old bottom sediments of freshwater bodies - silt). Certain species are specific concentrators of certain elements: seaweed (kelp) - iodine, buttercups - lithium, duckweed - radium, diatoms and cereals - silicon, mollusks and crustaceans - copper, vertebrates - iron, bacteria - manganese, etc.

Along with the concentration function of a living organism, a substance is released that is opposite to it according to the results - scattering. It manifests itself through the trophic and transport activities of organisms. For example, the dispersion of matter when organisms excrete excrement, the death of organisms during various types of movements in space, or changes in integument. Iron in blood hemoglobin is dispersed, for example, through blood-sucking insects.

Environment-forming function. Transformation of physical and chemical parameters of the environment (lithosphere, hydrosphere, atmosphere) as a result of vital processes in conditions favorable for the existence of organisms.

This function is a joint result of the functions of living matter discussed above: the energy function provides energy to all links of the biological cycle; destructive and concentration contribute to the extraction from the natural environment and the accumulation of scattered, but vital for living organisms, elements. It is very important to note that as a result of the environment-forming function, the following important events occurred in the geographic shell: the gas composition of the primary atmosphere was transformed, the chemical composition of the waters of the primary ocean changed, a layer of sedimentary rocks was formed in the lithosphere, and a fertile soil cover appeared on the land surface.

The four functions of living matter considered are the main, determining functions. Some other functions of living matter can be distinguished, for example:

Gas function determines the migration of gases and their transformations, ensures the gas composition of the biosphere.

The predominant mass of gases on Earth is of biogenic origin. During the functioning of living matter, the main gases are created: nitrogen, oxygen, carbon dioxide, hydrogen sulfide, methane, etc. CO 2 violation => greenhouse effect.

Redox function consists in the chemical transformation mainly of those substances that contain atoms with a variable oxidation state (compounds of iron, manganese, nitrogen, etc.). At the same time, biogenic processes of oxidation and reduction predominate on the Earth's surface.

Transport function- transfer of matter against gravity and in the horizontal direction. Since the time of Newton, it has been known that the movement of matter flows on our planet is determined by the force of gravity. Nonliving matter itself moves along an inclined plane exclusively from top to bottom. Only in this direction do rivers, glaciers, avalanches, and screes move. Living matter is the only factor that determines the reverse movement of matter - from bottom to top, from the ocean - to the continents.

Due to active movement, living organisms can move various substances or atoms in the horizontal direction, for example, through various types of migrations. Vernadsky called the movement, or migration, of chemical substances by living matter biogenic migration of atoms or matter.

Answer: 21313

Living organisms are closely connected not only with each other, but also with inanimate nature. This connection is expressed through matter and energy.

Metabolism, as you know, is one of the main manifestations of life. In modern terms, organisms are open biological systems because they are connected to their environment by a constant flow of matter and energy passing through their bodies. The material dependence of living beings on the environment was recognized back in Ancient Greece. Philosopher Heraclitus figuratively expressed this phenomenon in the following words: “Our bodies flow like streams, and matter is constantly renewed in them, like water in a stream.” The substance-energy connection of an organism with its environment can be measured.

The flow of food, water, and oxygen into living organisms are flows of matter from the environment. Food contains the energy necessary for the functioning of cells and organs. Plants directly absorb the energy of sunlight, store it in the chemical bonds of organic compounds, and then it is redistributed through food relationships in biocenoses.

With such an intensity of flows of matter from inorganic nature into living bodies, the reserves of compounds necessary for life - biogenic elements - would have long been exhausted on Earth. However, life does not stop, because nutrients are constantly returned to the environment surrounding organisms. It occurs in biocenoses where, as a result of nutritional relationships between species, organic substances synthesized by plants are eventually destroyed again into compounds that can be used again by plants. This is how the biological cycle of substances arises.

Any collection of organisms and inorganic components in which the cycle of matter can be maintained is called an ecological system or ecosystem.

Natural ecosystems can be of different volumes and extents: a small puddle with its inhabitants, a pond, an ocean, a meadow, a grove, a taiga, a steppe - all these are examples of ecosystems of different scales. Any ecosystem includes a living part - a biocenosis and its physical environment. Smaller ecosystems are part of increasingly larger ones, up to the overall ecosystem of the Earth. The general biological cycle of matter on our planet also consists of the interaction of many more private cycles.

An ecosystem can ensure the circulation of matter only if it includes the four components necessary for this: reserves of nutrients, producers, consumers and decomposers (Fig. 67).

Producers - these are green plants that create organic matter from biogenic elements, i.e. biological products, using solar energy flows.

Consumers - consumers of this organic substance, processing it into new forms. Animals usually act as consumers. There are first-order consumers - herbivorous species and second-order - carnivorous animals.

Decomposers - organisms that completely destroy organic compounds to mineral ones. The role of decomposers in biocenoses is performed mainly by fungi and bacteria, as well as other small organisms that process the dead remains of plants and animals (Fig. 68).

However, the biological cycle of matter requires constant energy expenditure.

Unlike chemical elements that are repeatedly involved in living bodies, the energy of sunlight retained by green plants cannot be used by organisms indefinitely.

Thus, life on our planet occurs as a constant cycle of substances, supported by the flow of solar energy. Life is organized not only into biocenoses, but also into ecosystems, in which there is a close connection between living and nonliving components of nature.

The diversity of ecosystems on Earth is associated both with the diversity of living organisms and with the conditions of the physical and geographical environment. Tundra, forest, steppe, desert or tropical communities have their own characteristics of biological cycles and connections with the environment. Aquatic ecosystems are also extremely diverse. Ecosystems differ in the speed of biological cycles and in the total amount of substance involved in these cycles.

The basic principle of the sustainability of ecosystems - the cycle of matter supported by the flow of energy - essentially ensures the endless existence of life on Earth.

Based on this principle, sustainable artificial ecosystems and production technologies that save water or other resources can be organized. Violation of the coordinated activity of organisms in biocenoses usually entails serious changes in the cycles of matter in ecosystems. This is the main cause of such environmental disasters as a decline in soil fertility, a decrease in plant yields, growth and productivity of animals, and the gradual destruction of the natural environment.

Examples and additional information

1. In forests, all herbivorous organisms (first-order consumers) on average use about 10-12% of the annual growth of plants. The rest is processed by decomposers after the foliage and wood die off. In steppe ecosystems, the role of consumers greatly increases. Herbivores can eat up to 70% of the total aboveground mass of plants without significantly undermining the rate of their renewal. A significant part of the eaten substance returns to the ecosystem in the form of excrement, which is actively decomposed by microorganisms and small animals. Thus, the activity of consumers greatly accelerates the circulation of substances in the steppes. The accumulation of dead plant litter in ecosystems is an indicator of a slowdown in the rate of biological turnover.

2. In terrestrial ecosystems, soil plays primarily the role of a storage and reserve of those resources that are necessary for the life of the biocenosis. Ecosystems that do not have soils - aquatic, rocky, on shallows and dumps - are very unstable. The circulation of substances in them is easily interrupted and difficult to resume.

In soils, the most valuable part is humus - a complex substance that is formed from dead organic matter as a result of the activity of numerous organisms. Humus provides long-term and reliable nutrition for plants, as it decomposes very slowly and gradually, releasing nutrients. Soils with a large supply of humus are characterized by high fertility, and ecosystems are stable.

3. Unstable ecosystems in which the cycle of matter is not balanced can be easily observed by the example of overgrowing of ponds or small lakes. In such reservoirs, especially if fertilizers are washed away from surrounding fields, both coastal vegetation and various algae rapidly develop. Plants do not have time to be processed by aquatic inhabitants and, dying, form layers of peat at the bottom. The lake becomes shallow and gradually ceases to exist, turning first into a swamp and then into a damp meadow. If the reservoir is small, such changes can occur quite quickly, over several years.

4. The seas are also gigantic complex ecosystems. Despite the enormous depth, they are populated with life to the very bottom. In the seas there is a constant circulation of water masses, currents arise, and ebbs and flows occur near the coast. Sunlight penetrates only into the surface layers of water; below 200 m, photosynthesis of algae is impossible. Therefore, only heterotrophic organisms live at depths - animals and bacteria. Thus, the activities of producers and the bulk of decomposers and consumers are strongly separated in space. Dead organic matter eventually sinks to the bottom, but the released mineral elements return to the upper layers only in places where there are strong updrafts. In the central part of the oceans, the reproduction of algae is sharply limited by the lack of nutrients, and the “productivity” of the ocean in these areas is as low as in the driest deserts.

Questions.

1. List as fully as possible the composition of decomposers in the forest ecosystem.
2. How does the cycle of substances manifest itself in an aquarium? How closed is he? How to make it more sustainable?
3. In the steppe reserve, in an area completely fenced off from herbivorous mammals, the grass yield was 5.2 c/ha, and in the grazing area - 5.9. Why is the elimination of consumers lower?
lo plant products?
4. Why is the fertility of the Earth’s soil decreasing if substances removed by humans in the form of crops from fields still sooner or later return to the environment in processed form?

Exercise.

Compare the annual increase in green mass and stocks of dead plant residues (litter in forests, rags in steppes) in different ecosystems. Determine in which ecosystems the cycle of substances is more intense.

Topics for discussion.

1. In the vicinity of smoky industrial enterprises, litter began to accumulate in the forests. Why is this happening and what predictions can be made about the future of this forest?

2. Is it possible for ecosystems to exist in which the living part is represented by only two groups - producers and decomposers?

3. In past eras, large reserves of coal arose in a number of regions of the Earth. What can be said about the main features of the ecosystems in which this happened?

4. In complex tropical rainforest ecosystems, the soil is very poor in nutrients. How to explain this? Why don't tropical forests come back to their original form if they are cleared?

5. What should the spacecraft ecosystem be like for long-term missions?

Chernova N. M., Fundamentals of Ecology: Textbook. days 10 (11) grade. general education textbook institutions/ N. M. Chernova, V. M. Galushin, V. M. Konstantinov; Ed. N. M. Chernova. - 6th ed., stereotype. - M.: Bustard, 2002. - 304 p.

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Producers, consumers and decomposers in the structure of biological communities

According to the functional classification of living organisms, they are divided into three main groups:

producers,
consumers,
decomposers.

The first produce organic substances from inorganic ones, the second ones subject them to various transformations, migration, concentration, etc., and the third ones destroy them during the process of mineralization to form the simplest inorganic compounds. Let us consider the role of these groups of organisms in the cycle of substances in more detail.

Producers

The group of producers includes autotrophs(phototrophs are mainly plants, and chemotrophs are mainly some bacteria). In terrestrial ecosystems, producers are dominant in terms of mass, numbers (not always) and energy role in ecosystems. In aquatic ecosystems they may not dominate in terms of biomass, but they remain dominant in terms of numbers and role in the community.

The result of the activities of producers in ecosystems is gross biological production - the total or total production of individuals, communities, ecosystems or the biosphere as a whole, including respiration costs. If we exclude the energy consumption to ensure the life activity of the producers themselves, then pure primary production remains. Throughout the land area it is 110-120 billion tons of dry matter, and in the sea it is 50-60 billion tons. Primary gross production is twice as large.

The amount of gross (and net) primary production of ecosystems and the biosphere as a whole is determined by the projective coverage of the territory by producers (maximum - up to 100% in forests, and even more, since there is a layering, and some producers are under the canopy of others), and the efficiency of photosynthesis, which is very low. To form biomass, only about 1% of the solar energy received on the surface of the plant organism is used, usually significantly less.

Consumers

Food for consumers are producers (for consumers of the first order) or other consumers (for consumers of the second and subsequent orders). The division of consumers into orders sometimes encounters certain difficulties when, for example, the composition of food of any type includes both plant food and animal food, and the consumers they produce may themselves belong to different orders. However, at any given moment in time, any consumer belongs to a very specific order.

In different ecosystems, consumers account for different amounts of processed primary products. Thus, in forest communities, consumers consume a total of 1% to 10% of net primary plant production, rarely more. The rest of the organic matter falls into decay due to the death of plants and their parts (for example, fallen leaves), and is also partially consumed by consumers (detrital food chain), and partially processed by decomposers. In open herbaceous communities (meadows, steppes, pastures), consumers can consume up to 50% of the biomass of living plants (usually significantly less). Similar indicators are typical for coastal communities of the oceans (where macrophyte algae serve as producers) and freshwater ecosystems. In pelagic ocean communities based on phytoplankton, consumers consume up to 90% of the biomass formed by producers.

Note 1

The assimilated production of consumers is the food eaten minus the organic matter of excrement. In turn, the net product of a consumer at any level is the assimilated net product minus the cost of breathing.

Decomposers

Decomposers (reducers) are an integral part of any ecosystem. They destroy high-molecular organic substances of dead organisms and use the energy released in this process for their own life activity, while mineral substances are returned to the biotic cycle, which are then reused by producers. As a rule, decomposers are small in size. Sometimes a group of so-called macro-reducers is distinguished, including all relatively large consumers of dead organic matter that are part of the detrital food chain. With this understanding, many invertebrates - insects, worms, etc. - are considered decomposers.

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