Biocenosis and agrocenosis comparative table. Natural and artificial ecosystems

Ecosystems are one of the key concepts of ecology, which is a system that includes several components: a community of animals, plants and microorganisms, a characteristic habitat, a whole system of relationships through which the interchange of substances and energies is carried out.

In science, there are several classifications of ecosystems. One of them divides all known ecosystems into two large classes: natural, created by nature, and artificial, those created by man. Let's look at each of these classes in more detail.

natural ecosystems

As noted above, natural, natural ecosystems were formed as a result of the action of the forces of nature. They are characterized by:

• Close relationship between organic and inorganic substances
• A complete, vicious circle of the circulation of substances: starting from the appearance of organic matter and ending with its decay and decomposition into inorganic components.
• Resilience and ability to self-heal.

All natural ecosystems are defined by the following features:

• 1. species structure: the number of each species of animal or plant is regulated by natural conditions.
  2. Spatial structure: all organisms are arranged in a strict horizontal or vertical hierarchy. For example, in a forest ecosystem, tiers are clearly distinguished, in an aquatic ecosystem, the distribution of organisms depends on the depth of the water.
  3. Biotic and abiotic substances. The organisms that make up an ecosystem are divided into inorganic (abiotic: light, air, soil, wind, humidity, pressure) and organic (biotic - animals, plants).
  4. In turn, the biotic component is divided into producers, consumers and destroyers. Producers include plants and bacteria, which, with the help of sunlight and energy, create organic matter from inorganic substances. Consumers are animals and carnivorous plants that feed on this organic matter. Destroyers (fungi, bacteria, some microorganisms) are the crown of the food chain, as they produce the reverse process: organics are converted into inorganic substances.

The spatial boundaries of each natural ecosystem are very conditional. In science, it is customary to define these boundaries by the natural contours of the relief: for example, a swamp, lake, mountains, rivers. But in the aggregate, all the ecosystems that make up the bioenvelope of our planet are considered open, as they interact with the environment and space. In the most general view, the picture looks like this: living organisms receive energy, cosmic and terrestrial substances from the environment, and at the output - sedimentary rocks and gases, which eventually go into space.

All components of the natural ecosystem are closely interconnected. The principles of this connection are formed over the years, sometimes centuries. But that is why they become so stable, since these connections and climatic conditions determine the types of animals and plants that live in this area. Any imbalance in the natural ecosystem can lead to its disappearance or attenuation. Such a violation can be, for example, deforestation, extermination of a population of a particular species of animals. In this case, the food chain is immediately disrupted, and the ecosystem begins to "fail".

By the way, the introduction of additional elements into ecosystems can also disrupt it. For example, if a person starts breeding animals in the selected ecosystem that were not there initially. A vivid confirmation of this is the breeding of rabbits in Australia. At first it was profitable, because in such a fertile environment and excellent climatic conditions for breeding, rabbits began to multiply with incredible speed. But in the end it all came crashing down. Countless hordes of rabbits devastated pastures where sheep used to graze. The number of sheep began to decline. A person receives much more food from one sheep than from 10 rabbits. This case even entered the proverb: "Rabbits ate Australia." It took an incredible effort of scientists and great expenses before they managed to get rid of the rabbit population. It was not possible to completely exterminate their population in Australia, but their numbers declined and no longer threatened the ecosystem.

artificial ecosystems

Artificial ecosystems are communities of animals and plants that live in conditions created for them by man. They are also called noobiogeocenoses or socioecosystems. Examples: field, pasture, city, society, spaceship, zoo, garden, artificial pond, reservoir.

The simplest example of an artificial ecosystem is an aquarium. Here, the habitat is limited by the walls of the aquarium, the influx of energy, light and nutrients is carried out by man, he also regulates the temperature and composition of the water. The number of inhabitants is also initially determined.

First feature: all artificial ecosystems are heterotrophic, i.e. consuming prepared food. Take, for example, a city, one of the largest man-made ecosystems. The influx of artificially created energy (gas pipeline, electricity, food) plays a huge role here. At the same time, such ecosystems are characterized by a high yield of toxic substances. That is, those substances that in the natural ecosystem later serve for the production of organic matter often become unusable in artificial ones.

Another distinctive feature of artificial ecosystems is the open cycle of metabolism. Take, for example, agro-ecosystems - the most important for humans. These include fields, orchards, vegetable gardens, pastures, farms and other agricultural lands on which a person creates conditions for the removal of consumer products. A part of the food chain in such ecosystems is taken out by a person (in the form of a crop), and therefore the food chain becomes destroyed.

The third difference between artificial ecosystems and natural ones is their species scarcity.. Indeed, a person creates an ecosystem for the sake of breeding one (rarely several) species of plants or animals. For example, in a wheat field, all pests and weeds are destroyed, only wheat is cultivated. This makes it possible to get the best harvest. But at the same time, the destruction of organisms "unprofitable" for humans makes the ecosystem unstable.

Comparative characteristics of natural and artificial ecosystems

It is more convenient to present a comparison of natural ecosystems and socio-ecosystems in the form of a table:

Agricultural ecosystems (agroecosystems)

The main goal of the created agricultural systems is the rational use of those biological resources, which are directly involved in the sphere of human activity - sources of food products, technological raw materials, medicines. This also includes species specially cultivated by humans that are objects of agricultural production: fish farming, fur farming, special cultivation of forest crops, as well as species used for industrial technologies.

Agroecosystems are created by man to obtain a high yield - pure production of autotrophs. Summarizing everything that has already been said above about agroecosystems, we emphasize the following main differences from natural ones (Table 10.2):

1. The diversity of species is sharply reduced in them: a decrease in the species of cultivated plants also reduces the species diversity of the animal population of the biocenosis; the species diversity of animals bred by man is negligible compared to the natural one; Cultivated pastures (with undersowing of grasses) are similar in species diversity to agricultural fields.

2. Plant and animal species cultivated by man "evolve" through artificial selection and are not competitive in the fight against wild species without human support.

3. Agro-ecosystems receive additional energy subsidized by man, in addition to solar energy.

4. Pure products (crop) are removed from the ecosystem and do not enter the food chains of the biocenosis, and its partial use by pests, losses during harvesting, which can also fall into natural trophic chains, are suppressed in every possible way by humans.

5. Ecosystems of fields, orchards, pastures, vegetable gardens and other agrocenoses are simplified systems supported by man in the early stages of succession, and they are just as unstable and incapable of self-regulation as natural pioneer communities, and therefore cannot exist without human support.

Table 10.2

In agrocenoses, an excessive increase in individual species occurs much more often, called by Ch. Elton an "ecological explosion". Such, for example, “environmental explosions” are known from history: in the last century, the phytophthora fungus destroyed potatoes in France and caused famine, and the Colorado potato beetle spread in America to the Atlantic Ocean and at the beginning of the 20th century . penetrated into Western Europe, in the 40s. in the European part of Russia. In the difficult post-war period, this beetle literally "cleared" our fields, because we were not ready for its invasion.

To avoid such phenomena, artificial regulation of the number of pests is necessary with the rapid suppression of those that are only trying to get out of control. At the same time, often the opinion of a person does not coincide with the "opinion" of nature about the excess number of a particular pest. Thus, from the point of view of natural selection, stabilization of the number of the apple codling moth at a certain level does not harm the existence of the apple tree as a species, but a person needs much more high-quality fruits for nutrition. Therefore, in agricultural practice, he uses such means to suppress the number of pests and in such a quantity that they act many times stronger than natural abiotic and biotic regulators.

Simplification of the human natural environment, from an ecological point of view, is very dangerous. Therefore, it is impossible to turn the entire landscape into an agricultural one, it is necessary to preserve and increase its diversity, leaving untouched protected areas that could be a source of species for communities recovering in succession series.

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: the 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 former include 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 features of natural zones, the division occurs into:

• 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.

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 the number of pests is, for the most part, a necessary condition for maintaining agroecosystems. Therefore, in agricultural practice, powerful means are used to suppress the number of undesirable species: pesticides, herbicides, etc. The environmental consequences of 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. This can be the muscular strength of a person or animals, various types of 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 environmental pollution.

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(highways, gas stations, garages, service stations, railways with their own 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.

The components of biogeocenosis and agrocenosis are the same components of the environment. In both systems, living organisms are united by territorial and food ties. But in each case, you can notice its own characteristics.

Definition

Biogeocenosis is an independently developed ecosystem in which representatives of the living world are closely connected with the inorganic components that make up their habitat. Examples: coniferous forest, flower meadow.

Agrocenosis is a system that appears when a person intervenes in the space of the natural environment. Like biogeocenosis, it includes organic and inorganic parts. Examples: home garden, cornfield.

Comparison

Comparing the systems under consideration, one should first of all pay attention to their species composition. Biogeocenosis in this respect is characterized by greater diversity. The agrocenosis is dominated by one or more crops chosen by man for cultivation (for example, potatoes planted on the site), and, accordingly, the number of animal species and lower organisms (bacteria, fungi) is also limited.

In this regard, the power chains in artificially created systems are shorter and simpler. However, in the territory where there are many plants of the same species, all conditions are created for the vital activity of harmful organisms that can coexist with just such crops. Without experiencing biological competition, they can multiply intensively and destroy crops or cause diseases in plants. As a result, the entire system is often in danger of death. Biogeocenosis in this respect is much more stable.

The difference between biogeocenosis and agrocenosis also lies in the way in which the circulation of substances is carried out in each case. In a natural natural community, it is closed. Everything produced by plants (as well as their remains) is consumed by representatives of numerous food chains and returned to the soil, enriching it. At the same time, agrocenosis is created precisely for the purpose of obtaining a crop. Accordingly, at the time of harvesting, accompanied by a significant removal of biomass, the circulation of substances in such a system is disturbed, therefore, in this case, it is called open. To maintain balance, fertilizers are applied to the ground.

It is also important that the structure of biogeocenosis is formed during the implementation of natural selection, which eliminates weak species of organisms. The agrocenosis also involves crops carefully selected by man, taking into account the degree of their productivity. In other words, in formations of this type, to a large extent, artificial selection operates. At the same time, a person not only determines what will grow on the land area, but also ensures that additional energy enters the agrocenosis. For example, greenhouses are heated, artificial lighting is created. Meanwhile, ecosystems that exist without human intervention receive energy mainly from the Sun.

What is the difference between biogeocenosis and agrocenosis? The fact that the latter brings a real benefit to a person, since it serves as a source of the necessary products. Biogeocenosis, in turn, is not always useful from a practical point of view. However, it is a stable self-regulating entity. Agrocenosis, on the other hand, exists safely for a more or less long time only under the condition of control by people. To maintain such a system requires the use of all kinds of agricultural practices.

table