How agroecosystems differ from natural ecosystems: concepts and comparative characteristics. Ecosystems: natural and artificial

Natural and artificial ecosystems

In the biosphere, in addition to natural biogeocenoses and ecosystems, there are communities artificially created by human economic activity - anthropogenic ecosystems.

natural ecosystems are characterized by considerable species diversity, there are long time, they are capable of self-regulation, have great stability, stability. The biomass and nutrients created in them remain and are used within the biocenoses, enriching their resources.

artificial ecosystems- agrocenoses (fields of wheat, potatoes, vegetable gardens, farms with adjacent pastures, fish ponds, etc.) make up a small part of the land surface, but provide about 90% of food energy.

Development Agriculture since ancient times, it has been accompanied by the complete destruction of the vegetation cover over large areas in order to make room for a small number of human-selected species that are most suitable for food.

However, initially human activity in an agricultural society fit into the biochemical cycle and did not change the flow of energy in the biosphere. In modern agricultural production, the use of synthesized energy in the mechanical processing of the land, the use of fertilizers and pesticides has increased dramatically. This disrupts the overall energy balance of the biosphere, which can lead to unpredictable consequences.

Comparison of natural and simplified anthropogenic ecosystems

(according to Miller, 1993)

Ecosystems are very diverse. Distinguished by origin the following types ecosystems:

1)Natural (natural) ecosystems These are ecosystems in which the biological cycle proceeds without direct human participation. e.g. swamps, seas, forests,

2) Anthropogenic (artificial) ecosystems- ecosystems created by man, which can only exist with the support of man.

For example, agroecosystems (rpech. agros- field) - artificial ecosystems resulting from human agricultural activities; technoecosystems - artificial ecosystems resulting from human industrial activity; urbanecosystems (lat. urban) - ecosystems resulting from the creation of human settlements. There are also transitional types of ecosystems between natural and anthropogenic, for example, ecosystems of natural pastures used by humans for grazing farm animals.

According to the source of energy that ensures their vital activity, ecosystems are divided into the following types:

1) Autotrophic ecosystems- These are ecosystems that provide themselves with energy received from the Sun, due to own photos or chemotrophic organisms. Most natural ecosystems and some anthropogenic ones belong to this type. This also includes natural ecosystems capable of producing surplus organic matter, which can be accumulated or removed to other ecosystems.

In agricultural ecosystems, a person contributes energy, which is called anthropogenic (fertilizers, fuel for tractors, etc.). But its role is insignificant compared to the solar energy used by the ecosystem.

Distinguish natural(natural) and anthropogenic(artificial) ecosystems. For example, a meadow formed under the influence of natural factors represents a natural ecosystem. A meadow created as a result of the destruction of a natural community (for example, by draining a swamp) and replacing it with a grass mixture is an anthropogenic ecosystem.

Ecosystems can be ground(forests, steppes, deserts) and water(swamps, lakes, ponds, rivers, seas). in different ecological systems completely different species are included, but necessarily some of them perform the function of producers, the second - consumers, and the third - decomposers. For example, forest and pond ecosystems differ in habitat and species composition, but contain all three functional groups. In the forest, the producers are trees, shrubs, herbs, mosses, and in the pond - aquatic plants, algae, blue-green. Forest consumers include animals, birds, invertebrates that inhabit the forest floor and soil. In the pond, consumers are fish, amphibians, crustaceans, and insects. Decomposers in the forest are represented by terrestrial forms, and in the pond - by water.

Nature is multifaceted and beautiful. We can say that this is a whole system that includes both living and inanimate nature. Inside it there are many other different systems that are inferior to it in scale. But not all of them are completely created by nature. In some of them, a person contributes. The anthropogenic factor can radically change the natural landscape and its orientation.

Agroecosystem - resulting from anthropogenic activity. People can plow the land, plant the territory with trees, but no matter what we do, we have always been surrounded and will be surrounded by nature. This is some of its peculiarity. How are agroecosystems different from natural ecosystems? This is worth looking into.

generally

In general, an ecological system is any combination of organic and inorganic components in which there is a circulation of substances.

Whether natural or man-made, it is still an ecological system. But still, how do agroecosystems differ from natural ecosystems? About everything in order.

natural ecosystem

A natural system, or, as it is also called, biogeocenosis, is a combination of organic and inorganic components on a plot of the earth's surface with homogeneous natural phenomena: atmosphere, rocks, hydrological conditions, soils, plants, animals and the world of microorganisms.

The natural system has its own structure, which includes the following components. Producers, or, as they are also called, autotrophs, are all those plants capable of producing organic matter, that is, capable of photosynthesis. Consumers are those who eat plants. It is worth noting that they belong to the first order. In addition, there are consumers and other orders. And, finally, another group is the group of decomposers. It is customary to include various kinds of bacteria, fungi.

The structure of the natural ecosystem

In any ecosystem, food chains, food webs, and trophic levels are distinguished. The food chain is the sequential transfer of energy. A food web is all chains that are interconnected. Trophic levels are the places that organisms occupy in food chains. Producers belong to the very first level, consumers of the first order belong to the second, consumers of the second order to the third, and so on.

A saprophytic chain, or otherwise detrital, begins with dead remains and ends with some kind of animal. There is an omnivorous food chain. Grazing grazing) in any case begins with photosynthetic organisms.

This is all about biogeocenosis. How are agroecosystems different from natural ecosystems?

Agroecosystem

An agroecosystem is an ecosystem created by man. This includes gardens, arable land, vineyards, parks.

Like the previous one, the agroecosystem includes the following blocks: producers, consumers, decomposers. The first ones are cultivated plants, weeds, plants of pastures, gardens and forest belts. Consumers are all farm animals and humans. The decomposer block is a complex of soil organisms.

Types of agroecosystems

The creation of anthropogenic landscapes includes several types:

• agricultural landscapes: arable lands, pastures, irrigated lands, gardens and others;
• forest: forest parks, shelterbelts;
• water: ponds, reservoirs, canals;
• urban: cities, towns;
• industrial: mines, quarries.

There is another classification of agroecosystems.

Types of agroecosystems

Depending on the level of economic use, the systems are divided into:

• agrosphere (global ecosystem),
• agricultural Landscape,
• agroecosystem,
• agrocenosis.

Depending on the energy natural areas division takes place:

• tropical;
• subtropical;
• moderate;
• arctic types.

The first is characterized by high heat supply, continuous vegetation and the predominance of perennial crops. The second - two periods of vegetation, namely summer and winter. The third type has only one growing season, as well as a long dormant period. As for the fourth type, here the cultivation of crops is very difficult due to low temperatures, as well as cold spells for a long time.

Variety of signs

All cultivated plants must have certain properties. Firstly, high ecological plasticity, that is, the ability to produce crops in a wide range of fluctuations in climatic conditions.

Secondly, the heterogeneity of populations, that is, in each of them there should be plants that differ in such characteristics as flowering time, drought resistance, and frost resistance.

Thirdly, precocity - the ability for rapid development, which will outstrip the development of weeds.

Fourth, resistance to fungal and other diseases.

Fifth, resistance to harmful insects.

Comparative and agroecosystems

In addition, as mentioned above, these ecosystems are very different in a number of other features. Unlike natural, in the agroecosystem, the main consumer is the person himself. It is he who seeks to maximize the receipt of primary production (crop) and secondary (livestock). The second consumer are farm animals.

The second difference is that the agroecosystem is formed and regulated by man. Many people ask why an agroecosystem is less resilient than an ecosystem. The thing is that they have a weakly expressed ability for self-regulation and self-renewal. Without human intervention, they exist only for a short time.

The next difference is selection. The stability of the natural ecosystem is ensured by natural selection. In the agroecosystem, it is artificial, provided by man and aimed at obtaining the maximum possible production. The energy received by the agricultural system includes the sun and everything that a person gives: irrigation, fertilizers, and so on.

Natural biogeocenosis feeds only on natural energy. As a rule, plants grown by man include several species, while the natural ecosystem is very diverse.

Different nutritional balance is another difference. The products of plants in a natural ecosystem are used in many food chains, but still return to the system. It turns out the circulation of substances.

How are agroecosystems different from natural ecosystems?

Natural and agroecosystems differ from each other in many ways: plants, consumption, vitality, resistance to pests and diseases, species diversity, type of selection, and many other traits.

A human-made ecosystem has both advantages and disadvantages. The natural system, in turn, cannot have any disadvantages. Everything is beautiful and harmonious in it.

When creating artificial systems, a person must carefully treat nature so as not to disturb this harmony.

ecological communities. Species and spatial structure of ecosystems.

Ecosystem - a biological system consisting of a community of living organisms (biocenosis), their habitat (biotope), a system of connections that exchange matter and energy between them.
Biocenosis is an organized group of interconnected populations of plants, animals, fungi and microorganisms living together in the same environmental conditions.
Biosphere - the shell of the Earth, inhabited by living organisms, under their influence and occupied by the products of their vital activity; "film of life"; global ecosystem of the Earth.

2. Fill in the table.

Ecological communities

3. What features underlie the classification of ecosystems?
When classifying terrestrial ecosystems, signs of plant communities (which form the basis of ecosystems) and climatic (zonal) signs are usually used. So, certain types of ecosystems are distinguished, for example, lichen tundra, moss tundra, coniferous forest (spruce, pine), deciduous forest (birch forest), rain forest (tropical), steppe, shrubs (willow forest), grassy swamp, sphagnum swamp. Often, the classification of natural ecosystems is based on characteristic ecological signs habitats, highlighting communities of sea coasts or shelves, lakes or ponds, floodplain or upland meadows, rocky or sandy deserts, mountain forests, estuaries (mouths of large rivers), etc.

4. Fill in the table.

Comparative characteristics of natural and artificial ecosystems

5. What is the importance of agrobiocenoses in human life?
Agrobiocenoses provide humanity with about 90% of food energy.

6. List the main activities undertaken to improve the state of the ecological systems of cities.
Landscaping of the city: the creation of parks, squares, green areas, flower beds, flower beds, green areas around industrial enterprises. Compliance with the principles of uniformity and continuity in the placement of green spaces.

7. What is meant by community structure?
This is the ratio of various groups of organisms that differ in their systematic position, in the role they play in the processes of energy and matter transfer, in the place occupied in space, in the food or trophic web, or in another sign that is essential for understanding the patterns of functioning of natural ecosystems. .

8. Fill in the table.

Community structure

Food connections, matter cycling and energy conversion in ecosystems

1. Define the concepts.
Food chain - a series of species of plants, animals, fungi and microorganisms that are related to each other by relationships: food - consumer (a sequence of organisms in which a phased transfer of matter and energy from source to consumer occurs).
A food web is a diagram of all food (trophic) links between species in a community.
Trophic level- This is a set of organisms that, depending on the way they eat and the type of food, make up a certain link in the food chain.

2. How do grazing chains differ from detrital chains?
In the grazing chain, energy flows from plants through herbivores to carnivores. The flow of energy coming from dead organic matter and passing through the system of decomposers is called the detritus chain.

3. Fill in the table.

Trophic levels of the ecosystem

4. What is the essence of the cycle of substances in an ecosystem?
Energy cannot be transferred in a vicious circle, it is spent, turning into the energy of chemical bonds and heat. The substance can be transmitted in closed cycles, repeatedly circulating between living organisms and the environment.

5. Do the practical work.
1. Drawing up schemes for the transfer of substances and energy (food chain)
Name the organisms that should be in the missing places in the following food chains.

2. From the proposed list of organisms, make up detritus and pasture food webs: grass, berry bush, fly, titmouse, snake, hare, wolf, decay bacteria, mosquito, grasshopper.

6. What limits the length of each food chain in an ecosystem?
Living organisms, eating representatives of the previous level, receive the energy stored in its cells and tissues. A significant part of this energy (up to 90%) is spent on movement, breathing, body heating, etc. and only 10% accumulates in its body the form of proteins (muscles), fats (adipose tissue). Thus, only 10% of the energy accumulated by the previous level is transferred to the next level. That is why food chains cannot be very long.

7. What is meant by ecological pyramids? What types distinguish them?
It is a way of graphically displaying the ratio of different trophic levels in an ecosystem. Can be of three types:
1) the pyramid of numbers - reflects the number of organisms at each trophic level;
2) biomass pyramid - reflects the biomass of each trophic level;
3) pyramid of energy - shows the amount of energy that has passed through each trophic level during a certain period of time.

8. Can ecological pyramid be upside down? Support your answer with a specific example.
If the reproduction rate of the prey population is high, then even with a low biomass, such a population can be a sufficient food source for predators with a higher biomass, but a low reproduction rate. For this reason, the pyramids of abundance or biomass may be inverted, i.e. low trophic levels may have less density and biomass than higher ones.
For instance:
1) Many insects can live and feed on one tree.
2) An inverted pyramid of biomass is characteristic of marine ecosystems, where primary producers (phytoplankton algae) divide very quickly, and their consumers (zooplankton crustaceans) are much larger, but multiply much more slowly. Marine vertebrates have an even greater mass and a long reproduction cycle.

9. Solve environmental problems.
Task 1. Calculate the amount of plankton (in kg) required for a 350 kg dolphin to grow in the sea.

Solution. The dolphin, eating predatory fish, has accumulated in its body only 10% of the total mass of food, knowing that it weighs 350 kg, let's make up the proportion.
350kg - 10%,
X - 100%.
Let's find what X is equal to. X \u003d 3500 kg. (predatory fish). This weight is only 10% of the mass of non-predatory fish that they ate. Let's do the proportion again.
3500kg - 10%
X - 100%
Х=35 000 kg (mass of non-predatory fish)
How much plankton did they have to eat in order to have that weight? Let's make a proportion.
35 000 kg - 10%
X \u003d 100%
X = 350,000 kg
Answer: In order for a 350 kg dolphin to grow, 350,000 kg of plankton are needed.

Task 2. As a result of the study, it turned out that after the extermination of birds of prey, the number of game birds, which they had previously destroyed, first grows rapidly, but then falls rapidly. How can this pattern be explained?

Answer: To answer this question, it is necessary to take into account the following provisions: an “uncontrolled” increase in the number of game birds leads to depletion of the food supply, weakening the resistance of bird organisms to diseases, rapid spread of infection, degeneration, reduced fertility and mass death of birds from diseases.

Task 3. Daphnia feeding on planktonic algae were placed in a vessel. Thereafter, algae numbers declined, but algal biomass production (measured by cell division rate) increased. What are the possible explanations for this phenomenon?

Answer: As a result of metabolism, Daphnia secrete substances that accelerate the growth of algae (their food base), thereby achieving an eco-balance.

Causes of sustainability and ecosystem change

1. Define the concepts.
Succession is a natural and consistent process of changing communities in a certain area, caused by the interaction of living organisms with each other and their abiotic environment.
Community breath- in ecology, the total energy costs, i.e., the total production of autotrophs in energy terms, exactly corresponds to the energy costs that go to ensure the vital activity of its constituent organisms.

2. What is meant by equilibrium in a community, and what significance does it have for its existence as a whole?
The biomass of organisms in an ideal succession remains constant, and the system itself is in equilibrium. If the "total respiration" is less than the gross primary production, the accumulation of organic matter will occur in the ecosystem, if more - its decrease. Both will lead to changes in the community. With an excess of a resource, there will always be species that can master it, with a shortage of it, some of the species will die out. Such changes constitute the essence of ecological succession. main feature of this process lies in the fact that changes in the community always occur in the direction of an equilibrium state. Each stage of succession is a community with a predominance of certain species and life forms. They replace each other until a state of stable equilibrium occurs.

3. Fill in the table.

Types of successions

4. What determines the duration of succession?
The duration of succession is largely determined by the structure of the community.
Secondary successions proceed much faster. This is explained by the fact that the primary community leaves behind a sufficient amount of nutrients, developed soil, which creates conditions for accelerated growth and development of new settlers.

5. What are the advantages of a mature community over a young community?
A mature community, with its high diversity and abundance of organisms, developed trophic structure, and balanced energy flows, is able to withstand changes in physical factors (eg temperature, humidity) and even some types of chemical pollution to a much greater extent than a young community.

6. What is the importance of being able to manage the processes taking place in the community?
A person can reap a rich harvest in the form of pure products, artificially supporting early stages succession community. On the other hand, the stability of a mature community, its ability to withstand the impact of physical factors (and even manage them) is a very important and highly desirable property. At the same time, various disturbances of mature ecosystems can lead to various ecological disturbances. The transformation of the biosphere into one vast carpet of arable land is fraught with great danger. Therefore, it is necessary to learn how to properly manage the processes in the community in order to prevent an ecological catastrophe.

Ecosystems are unified natural complexes that are formed by a combination of living organisms and their habitats. The science of ecology is engaged in the study of these formations.

The term "ecosystem" appeared in 1935. The English ecologist A. Tensley suggested using it. A natural or natural-anthropogenic complex, in which both living and indirect components are in close relationship through the metabolism and distribution of energy flow - all this is included in the concept of "ecosystem". The types of ecosystems are different. These basic functional units of the biosphere are divided into separate groups and studied by environmental science.

Origin Classification

There are various ecosystems on our planet. Types of ecosystems are classified in a certain way. However, it is impossible to link together the diversity of these units of the biosphere. That is why there are several classifications of ecological systems. For example, they distinguish them by origin. This:

1. Natural (natural) ecosystems. These include those complexes in which the circulation of substances is carried out without any human intervention.
2. Artificial (anthropogenic) ecosystems. They are created by man and can only exist with his direct support.

natural ecosystems

Natural complexes that exist without human intervention have their own internal classification. There are the following types of natural ecosystems on the basis of energy:

Completely dependent on solar radiation;

Receiving energy not only from the heavenly body, but also from other natural sources.

The first of these two types of ecosystems is unproductive. Nevertheless, such natural complexes are extremely important for our planet, since they exist over vast areas and influence climate formation, purify large volumes of the atmosphere, etc.

Natural complexes that receive energy from several sources are the most productive.

Artificial units of the biosphere

Anthropogenic ecosystems are also different. The types of ecosystems included in this group include:

Agro-ecosystems that appear as a result of human agriculture;

Technoecosystems resulting from the development of industry;

Urban ecosystems resulting from the creation of settlements.

All these are types of anthropogenic ecosystems created with the direct participation of man.

Diversity of natural components of the biosphere

Types and types of ecosystems of natural origin are different. Moreover, environmentalists distinguish them based on the climatic and natural conditions of their existence. Thus, there are three groups whole line various units of the biosphere.

The main types of ecosystems of natural origin:

ground;

freshwater;

Marine.

Ground natural complexes

The variety of types of terrestrial ecosystems includes:

Arctic and Alpine tundra;

Coniferous boreal forests;

Deciduous massifs of the temperate zone;

Savannas and tropical grasslands;

Chaparrals, which are areas with dry summers and rainy winters;

Deserts (both shrub and grassy);

Semi-evergreen tropical forests located in areas with pronounced dry and wet seasons;

Tropical evergreen rain forests.

In addition to the main types of ecosystems, there are also transitional ones. These are forest-tundras, semi-deserts, etc.

Reasons for the existence of various types of natural complexes

By what principle are various natural ecosystems located on our planet? Types of ecosystems of natural origin are in one or another zone depending on the amount of precipitation and air temperature. It is known that the climate in different parts of the world has significant differences. At the same time, the annual amount of precipitation is not the same. It can range from 0 to 250 or more millimeters. In this case, precipitation either falls evenly throughout all seasons, or falls in the main share for a certain wet period. The average annual temperature also varies on our planet. It can have values ​​​​from negative values ​​\u200b\u200band reach thirty-eight degrees Celsius. The constancy of heating of air masses is also different. It may either not have significant differences during the year, as, for example, near the equator, or it may constantly change.

Characteristics of natural complexes

The variety of types of natural ecosystems of the terrestrial group leads to the fact that each of them has its own distinctive features. So, in the tundra, which are located north of the taiga, there is a very cold climate. This area is characterized by a negative average annual temperature and a change of polar day and night. Summer in these parts lasts only a few weeks. At the same time, the earth has time to thaw to a small meter depth. Precipitation in the tundra is less than 200-300 millimeters during the year. Due to such climatic conditions, these lands are poor in vegetation, represented by slow-growing lichens, moss, as well as dwarf or creeping lingonberry and blueberry bushes. At times you can meet

The animal world is not rich either. It is represented by reindeer, small burrowing mammals, and predators such as ermine, arctic fox and weasel. The world of birds is represented by a snowy owl, a snow bunting and a plover. Insects in the tundra are mostly Diptera species. The tundra ecosystem is very vulnerable due to poor resilience.

The taiga, located in the northern regions of America and Eurasia, is very diverse. This ecosystem is characterized by cold and long winter and lots of snowfall. The flora is represented by evergreen coniferous forests, in which fir and spruce, pine and larch grow. Representatives of the animal world - moose and badgers, bears and squirrels, sables and wolverines, wolves and lynxes, foxes and minks. The taiga is characterized by the presence of many lakes and swamps.

The following ecosystems are represented by broad-leaved forests. Ecosystem types of this type are found in the eastern United States, in East Asia and in Western Europe. This is a seasonal climate zone where temperatures drop below zero mark, and during the year falls from 750 to 1500 mm of precipitation. The flora of such an ecosystem is represented by such broad-leaved trees as beech and oak, ash and linden. There are bushes and a thick grassy layer here. The fauna is represented by bears and elks, foxes and lynxes, squirrels and shrews. Owls and woodpeckers, thrushes and falcons live in such an ecosystem.

The steppe temperate zones are found in Eurasia and North America. Their counterparts are Tussoks in New Zealand, as well as pampas in South America. The climate in these areas is seasonal. In summer, the air heats up from moderately warm to very high values. Winter temperatures are negative. During the year there is from 250 to 750 millimeters of precipitation. The flora of the steppes is represented mainly by turf grasses. Among the animals there are bison and antelopes, saigas and ground squirrels, rabbits and marmots, wolves and hyenas.

Chaparrals are located in the Mediterranean, as well as in California, Georgia, Mexico and on the southern coast of Australia. These are soft zones. temperate climate, where 500 to 700 millimeters of precipitation falls during the year. From the vegetation there are shrubs and trees with evergreen hard leaves, such as wild pistachio, laurel, etc.

Ecological systems such as savannahs are located in East and Central Africa, South America and Australia. Most of them are in South India. These are zones of hot and dry climate, where from 250 to 750 mm of precipitation falls during the year. The vegetation is mainly grassy, ​​only in some places there are rare deciduous trees (palms, baobabs and acacias). The fauna is represented by zebras and antelopes, rhinos and giraffes, leopards and lions, vultures, etc. There are many blood-sucking insects in these parts, such as tsetse flies.

Deserts are found in some areas of Africa, in northern Mexico, etc. The climate is dry, with less than 250 mm of precipitation per year. Days in deserts are hot and nights are cold. The vegetation is represented by cacti and sparse shrubs with extensive root systems. Ground squirrels and jerboas, antelopes and wolves are common among representatives of the animal world. This is a fragile ecosystem, easily destroyed by water and wind erosion.

Semi-evergreen tropical deciduous forests are found in Central America and Asia. In these zones, there is a change of dry and wet seasons. The average annual rainfall is from 800 to 1300 mm. Tropical forests are inhabited by rich wildlife.

Rainforest tropical evergreen forests are found in many parts of our planet. They are in Central America, in the north South America, in the central and western part of equatorial Africa, in the coastal regions of northwestern Australia, as well as on the islands of the Pacific and Indian Oceans. Warm climatic conditions in these parts do not differ seasonally. Heavy rainfall exceeds the limit of 2500 mm throughout the year. This system is distinguished by a huge variety of flora and fauna.

Existing natural complexes, as a rule, do not have any clear boundaries. There must be a transition zone between them. It not only involves the interaction of populations different types ecosystems, but also there are special types of living organisms. Thus, the transition zone includes a greater variety of representatives of fauna and flora than the territories adjacent to it.

Water natural complexes

These units of the biosphere can exist in fresh water bodies and seas. The first of these include such ecosystems as:

Lentic are reservoirs, that is, stagnant waters;

Lotic, represented by streams, rivers, springs;

Upwelling areas where productive fishing takes place;

Straits, bays, estuaries, which are estuaries;

Deep water reef zones.

An example of a natural complex

Ecologists distinguish a wide variety of types of natural ecosystems. Nevertheless, the existence of each of them occurs according to the same pattern. In order to most deeply understand the interaction of all living and non-living beings in a unit of the biosphere, consider the species All microorganisms and animals living here have a direct impact on the chemical composition of air and soil.

The meadow is a balanced system that includes various elements. Some of them are macro-producers, which are herbaceous vegetation, create organic products of this terrestrial community. Further, the life of the natural complex is carried out at the expense of the biological food chain. Plant animals or primary consumers feed on meadow grasses and their parts. These are such representatives of the fauna as large herbivores and insects, rodents and many species of invertebrates (gopher and hare, partridge, etc.).

Primary consumers are eaten by secondary ones, which include carnivorous birds and mammals (wolf, owl, hawk, fox, etc.). Further reducers are connected to work. Impossible without them Full description ecosystems. Species of many fungi and bacteria are these elements in the natural complex. Reducers decompose organic products to a mineral state. If temperature conditions favorable, then plant remains and dead animals quickly disintegrate into simple connections. Some of these components contain batteries that are leached out and reused. The more stable part of organic residues (humus, cellulose, etc.) decomposes more slowly, nourishing the plant world.

Anthropogenic ecosystems

The natural complexes considered above are able to exist without any human intervention. The situation is quite different in anthropogenic ecosystems. Their connections work only with the direct participation of a person. For example, the agroecosystem. The main condition for its existence is not only the use of solar energy, but also the receipt of "subsidies" in the form of a kind of fuel.

In part, this system is similar to the natural one. Similarity with the natural complex is observed during the growth and development of plants, which occurs due to the energy of the Sun. However, agriculture is impossible without soil preparation and harvesting. And these processes require the energy subsidies of the human society.

What type of ecosystem does the city belong to? This is an anthropogenic complex, in which fuel energy is of great importance. Its consumption compared to the flow of sunlight is two to three times higher. The city can be compared to deep-sea or cave ecosystems. After all, the existence of these particular biogeocenoses largely depends on the supply of substances and energy from the outside.

Urban ecosystems have emerged as a result of historical process called urbanization. Under his influence, the population of countries left countryside creating large settlements. Gradually, cities increasingly strengthened their role in the development of society. At the same time, to improve life, man himself created a complex urban system. This led to some detachment of cities from nature and disruption of existing natural complexes. The settlement system can be called urbanistic. However, as the industry developed, things changed somewhat. What type of ecosystems does the city in which the plant or factory operates belong to? Rather, it can be called industrial-urban. This complex consists of residential areas and territories on which facilities are located that produce a variety of products. The ecosystem of the city differs from the natural one in a more abundant and, moreover, toxic stream of various wastes.

In order to improve their environment, people create so-called green belts around their settlements. They consist of grassy lawns and shrubs, trees and ponds. These small natural ecosystems create organic products that do not play a special role in urban life. For existence, people need food, fuel, water and electricity from outside.

The process of urbanization has significantly changed the life of our planet. The impact of the artificially created anthropogenic system has changed nature to a large extent in vast areas of the Earth. At the same time, the city affects not only those zones where the architectural and construction objects themselves are located. It affects vast territories and beyond. For example, with an increase in demand for products of the woodworking industry, a person cuts down forests.

During the functioning of the city, many different substances enter the atmosphere. They pollute the air and change climate conditions. Cities have higher cloud cover and less sunshine, more fog and drizzle, and are slightly warmer than nearby rural areas.

Lecture number 5. artificial ecosystems

5.1 Natural and artificial ecosystems

In the biosphere, in addition to natural biogeocenoses and ecosystems, there are communities artificially created by human economic activity - anthropogenic ecosystems.

Natural ecosystems are distinguished by a significant species diversity, they exist for a long time, they are capable of self-regulation, they have great stability and resilience. The biomass and nutrients created in them remain and are used within the biocenoses, enriching their resources.

Artificial ecosystems - agrocenoses (fields of wheat, potatoes, vegetable gardens, farms with adjacent pastures, fish ponds, etc.) make up a small part of the land surface, but provide about 90% of food energy.

The development of agriculture since ancient times has been accompanied by the complete destruction of the vegetation cover over large areas in order to make room for a small number of human-selected species that are most suitable for food.

However, initially human activity in an agricultural society fit into the biochemical cycle and did not change the flow of energy in the biosphere. In modern agricultural production, the use of synthesized energy in the mechanical processing of the land, the use of fertilizers and pesticides has increased dramatically. This disrupts the overall energy balance of the biosphere, which can lead to unpredictable consequences.

Comparison of natural and simplified anthropogenic ecosystems

(according to Miller, 1993)

5.2 Artificial ecosystems

5.2.1 Agroecosystems

Agroecosystem(from the Greek agros - field) - a biotic community created and regularly maintained by man in order to obtain agricultural products. Usually includes the totality of organisms that live on agricultural land.

Agroecosystems include fields, orchards, vegetable gardens, vineyards, large livestock complexes with adjacent artificial pastures.

A characteristic feature of agroecosystems is low ecological reliability, but high productivity of one (several) species or varieties of cultivated plants or animals. Their main difference from natural ecosystems is their simplified structure and depleted species composition.

Agroecosystems are different from natural ecosystems a number of features:

1. The variety of living organisms in them is sharply reduced to obtain the highest possible production.

On a rye or wheat field, in addition to a cereal monoculture, only a few types of weeds can be found. In a natural meadow, biological diversity is much higher, but biological productivity is many times inferior to a sown field.

Artificial regulation of pest numbers - for the most part necessary condition maintaining agroecosystems. Therefore, in agricultural practice, powerful means are used to suppress the number of undesirable species: pesticides, herbicides, etc. Environmental consequences these actions lead, however, to a number of undesirable effects, in addition to those for which they are applied.

2. Species of agricultural plants and animals in agroecosystems are obtained as a result of artificial rather than natural selection, and cannot withstand the struggle for existence with wild species without human support.

As a result, there is a sharp narrowing of the genetic base of agricultural crops, which are extremely sensitive to the mass reproduction of pests and diseases.

3. Agro-ecosystems are more open, matter and energy are withdrawn from them with crops, livestock products, and also as a result of soil destruction.

In natural biocenoses, the primary production of plants is consumed in numerous food chains and again returned to the biological cycle in the form of carbon dioxide, water and mineral nutrients.

Due to the constant harvesting and disruption of soil formation processes, with long-term cultivation of monoculture on cultivated lands, soil fertility gradually decreases. This position in ecology is called law of diminishing returns .

Thus, for prudent and rational agriculture, it is necessary to take into account the depletion of soil resources and preserve soil fertility with the help of improved agricultural technology, rational crop rotation and other methods.

The change of vegetation cover in agroecosystems does not occur naturally, but at the will of man, which is not always well reflected in the quality of abiotic factors included in it. This is especially true for soil fertility.

Main difference agroecosystems from natural ecosystems - getting extra energy for normal operation.

Supplementary refers to any type of energy that is added to agroecosystems. It can be the muscular strength of a person or animals, different kinds fuel for the operation of agricultural machines, fertilizers, pesticides, pesticides, additional lighting, etc. The concept of "additional energy" also includes new breeds of domestic animals and varieties of cultivated plants introduced into the structure of agroecosystems.

It should be noted that agroecosystems - highly unstable communities. They are not capable of self-healing and self-regulation, they are subject to the threat of death from the mass reproduction of pests or diseases.

The reason for the instability is that agrocenoses are composed of one (monoculture) or less often a maximum of 2–3 species. That is why any disease, any pest can destroy the agrocenosis. However, a person consciously goes to simplify the structure of agrocenosis in order to obtain the maximum yield. Agrocenoses, to a much greater extent than natural cenoses (forest, meadow, pastures), are subject to erosion, leaching, salinization and pest invasion. Without human participation, agrocenoses of grain and vegetable crops exist for no more than a year, berry plants - 3-4, fruit crops - 20-30 years. Then they disintegrate or die.

The advantage of agrocenoses Before natural ecosystems is the production of food necessary for humans and great opportunities to increase productivity. However, they are realized only with constant concern for the fertility of the earth, providing plants with moisture, protecting cultural populations, varieties and breeds of plants and animals from the adverse effects of natural flora and fauna.

All agro-ecosystems of fields, gardens, pasture meadows, gardens, greenhouses artificially created in agricultural practice are human-supported systems.

In relation to the communities that take shape in agroecosystems, the emphasis is gradually changing in connection with the general development of ecological knowledge. The idea of ​​fragmentation, fragmentation of coenotic connections and the ultimate simplification of agrocenoses is being replaced by an understanding of their complex systemic organization, where a person significantly affects only individual links, and the whole system continues to develop according to natural, natural laws.

From an ecological point of view, it is extremely dangerous to simplify the natural environment of a person, turning the entire landscape into an agricultural one. The main strategy for creating a highly productive and sustainable landscape should be to preserve and increase its diversity.

Along with the maintenance of highly productive fields, special care should be taken to preserve protected areas that are not subject to anthropogenic impact. Reserves with a rich species diversity are a source of species for communities recovering in successional series.

Comparative characteristics of natural ecosystems and agroecosystems

5.2.2 Industrial-urban ecosystems

The situation is quite different in ecosystems, which include industrial-urban systems - here the fuel energy completely replaces solar energy. Compared to the flow of energy in natural ecosystems, here its consumption is two to three orders of magnitude higher.

In connection with the above, it should be noted that artificial ecosystems cannot exist without natural systems, while natural ecosystems can exist without anthropogenic ones.

urban systems

Urban system (urbosystem)- "an unstable natural-anthropogenic system consisting of architectural and construction objects and sharply disturbed natural ecosystems" (Reimers, 1990).

As the city develops, its functional zones become more and more differentiated. industrial, residential, forest park.

industrial zones- these are the territories of concentration of industrial facilities of various industries (metallurgical, chemical, machine-building, electronic, etc.). They are the main sources of pollution environment.

residential areas- these are the territories of concentration of residential buildings, administrative buildings, objects of culture, education, etc.

Forest park - this is a green area around the city, cultivated by man, that is, adapted for mass recreation, sports, and entertainment. Its sections are also possible inside cities, but usually here city ​​parks- tree plantations in the city, occupying quite extensive territories and also serving the citizens for recreation. Unlike natural forests and even forest parks, city parks and similar smaller plantings in the city (squares, boulevards) are not self-supporting and self-regulating systems.

The forest park zone, city parks and other areas of the territory allotted and specially adapted for people's recreation are called recreational zones (territories, sites, etc.).

The deepening of urbanization processes leads to the complexity of the city's infrastructure. A significant place begins to occupy transport and transport facilities(car roads, gas stations, garages, service stations, railways with their complex infrastructure, including underground ones - the subway; airfields with a service complex, etc.). Transport systems cross all functional areas of the city and have an impact on the entire urban environment (urban environment).

Human environment under these conditions, it is a combination of abiotic and social environments that jointly and directly influence people and their economy. At the same time, according to N.F. Reimers (1990), it can be divided into natural environment and human-transformed natural environment(anthropogenic landscapes up to the artificial environment of people - buildings, asphalt roads, artificial lighting, etc., i.e. up to artificial environment).

In general, the urban environment and urban-type settlements are part of technosphere, i.e., the biosphere, radically transformed by man into technical and man-made objects.

In addition to the terrestrial part of the landscape, its lithogenic base, i.e., the surface part of the lithosphere, which is commonly called the geological environment, also falls into the orbit of human economic activity (E. M. Sergeev, 1979).

Geological environment- these are rocks, groundwater, which are affected by human activities (Fig. 10.2).

In urban areas, in urban ecosystems, a group of systems can be distinguished, reflecting the complexity of the interaction of buildings and structures with the environment, which are called natural and technical systems(Trofimov, Epishin, 1985) (Fig. 10.2). They are closely connected with anthropogenic landscapes, with their geological structure and relief.

Thus, urban systems are the focus of the population, residential and industrial buildings and structures. The existence of urban systems depends on the energy of fossil fuels and nuclear energy raw materials, is artificially regulated and maintained by man.

The environment of urban systems, both its geographical and geological parts, has been most strongly changed and, in fact, has become artificial, here there are problems of utilization and reutilization of natural resources involved in circulation, pollution and purification of the environment, here there is an increasing isolation of economic and production cycles from natural metabolism (biogeochemical turnovers) and the flow of energy in natural ecosystems. And, finally, it is here that the population density and the built environment are highest, which threaten not only human health, but also the survival of all mankind. Human health is an indicator of the quality of this environment.