Differences between agroecosystems and natural communities. Natural and artificial ecosystems

Agroecosystem- a biotic community deliberately planned by man, created and regularly maintained by man for the purpose of obtaining agricultural products. Usually includes a set of organisms living on agricultural lands. Feature agroecosystems – low ecological reliability, but high productivity of one or several plant species (or varieties of cultivated plants).

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

Agroecosystems, like natural ecosystems, are characterized by a set of their constituent species (ᴛ.ᴇ. have a certain composition of organisms) and certain relationships between organisms and the environment. In an agrocenosis, the same food chains develop as in natural ecosystems.

Agrocenosis- an artificially created and constantly maintained by man biotic community with high productivity of one or several selected species (varieties, breeds) of plants and animals. Eg, the trophic structure of a rye field is determined by a set producers(rye, weeds), consumers(insects, birds, voles, foxes) and decomposers(fungi, microorganisms).

At the same time, in difference from natural ecosystem An obligatory link in the food chain here is a person who forms agrocenoses based on their practical significance - and ensures their high productivity.

the main objective creating an agroecosystem – rational use those biological resources agroecosystems that are directly involved in human activity - sources 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 humans to obtain high yields - pure production of autotrophs. Summarizing everything that has already been said above about agroecosystems, we emphasize the following main ones: differences from natural ones:

1. The diversity of species in them is sharply reduced: 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 humans is negligible compared to nature; cultivated pastures (with underseeding of grasses) are similar in species diversity to agricultural fields.

2. Species of plants and animals cultivated by humans “evolve” due to artificial selection and are uncompetitive in the fight against wild species without human support.

3. Agroecosystems receive additional energy subsidized by humans, in addition to solar energy.

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

5. Ecosystems of fields, gardens, pastures, vegetable gardens and other agrocenoses are simplified systems supported by humans 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 .

Today, over 30% of the land is occupied by arable land and pastures, and human activities to maintain these systems are becoming a global environmental factor.

Despite the significant simplification of agroecosystems, they still retain many biocenotic connections, which ultimately affect the fate of the crop. A comparison of information about the fauna and flora of wheat fields shows the enormous complexity of even an extremely simple agrocenosis; more than a thousand species are preserved here.

The conditions that ideally should correspond to fields of agricultural crops are to be highly productive and at the same time stable - with ecological point visions are incompatible. IN natural ecosystems Oh primary production plants are consumed in numerous food chains and are returned again in the form of mineral salts and carbon dioxide into the system biological cycle. By protecting the crop from its natural consumers, alienating it and replacing it with organic and mineral fertilizers, we break many food chains and imbalance the community. Essentially, all efforts to create high dense production of individual crops are a struggle “against nature”, which require large amounts of labor and material resources.

Ecosystems are one of the key concepts 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 occurs.

In science, there are several classifications of ecosystems. One of them divides all known ecosystems into two large class: 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 ecosystems were formed as a result of the action of natural forces. They are characterized by:

• The close relationship between organic and inorganic substances
• Full, vicious circle cycle of substances: starting from the appearance organic matter and ending with its disintegration and decomposition into inorganic components.
• Resilience and self-healing ability.

All natural ecosystems are defined by the following characteristics:

• 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 the 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 carry out the reverse process: organic matter is converted into inorganic substances.

The spatial boundaries of each natural ecosystem are very arbitrary. In science, it is customary to define these boundaries by the natural contours of the relief: for example, a swamp, a lake, mountains, rivers. But in the aggregate, all ecosystems that make up the bioshell of our planet are considered open, since they interact with the environment and with space. In the very general idea the picture looks like this: living organisms are obtained from environment energy, cosmic and terrestrial substances, and the output is sedimentary rocks and gases, which ultimately escape into space.

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

By the way, introducing additional elements into ecosystems can also disrupt it. For example, if a person begins to breed animals in the chosen ecosystem that were not there initially. A clear confirmation of this is the breeding of rabbits in Australia. At first it was profitable, since in such a fertile environment and excellent for breeding climatic conditions, the rabbits began to multiply at incredible speed. But in the end everything came to a crash. Countless hordes of rabbits devastated the pastures where sheep had previously grazed. The number of sheep began to decline. And a person gets much more food from one sheep than from 10 rabbits. This incident even became a saying: “The rabbits ate Australia.” It took incredible effort from scientists and a lot of expense before they managed to get rid of the rabbit population. It was not possible to completely exterminate their population in Australia, but their numbers decreased and no longer threatened the ecosystem.

Artificial ecosystems

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

The most simple example artificial ecosystem is an aquarium. Here the habitat is limited by the walls of the aquarium, the flow of energy, light and nutrients 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 ready-made food. Let's take a city as an example, one of the largest artificial ecosystems. The influx of artificially created energy (gas pipeline, electricity, food) plays a huge role here. At the same time, such ecosystems are characterized big yield toxic substances. That is, those substances that later serve for the production of organic matter in a natural ecosystem often become unsuitable in artificial ones.

Another distinctive feature of artificial ecosystems is an open metabolic cycle. Let’s take agroecosystems as an example—the most important for humans. These include fields, gardens, vegetable gardens, pastures, farms and other agricultural lands on which people create conditions for the production of consumer products. People take out part of the food chain in such ecosystems (in the form of crops), and therefore the food chain becomes destroyed.

The third difference between artificial ecosystems and natural ones is their small number of species. Indeed, a person creates an ecosystem for the sake of breeding one (less often several) species of plants or animals. For example, in a wheat field, all pests and weeds are destroyed, and only wheat is cultivated. This makes it possible to get a better harvest. But at the same time, the destruction of organisms that are “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 socioecosystems in the form of a table:

A man gets a lot different types products from natural ecosystems. However, its main source of food resources is agriculture. Human agricultural activities can change natural ecosystems. In addition, humans are able to form artificial ecosystems and maintain their existence in order to obtain agricultural products. These artificial ecosystems are called agroecosystems.

Agroecosystems(from Greek agros- field) - artificial ecosystems created and used by humans to obtain agricultural products or recreation.

Agroecosystems occupy approximately 30% of the planet's ice-free land mass. Of these, about 10% are arable lands, almost 20% are pastures.

In the Republic of Belarus, agricultural products play a role as a commodity important role in economics. Our agricultural land area is about 75%. Of this, arable land accounts for approximately 60%. The main types of agroecosystems in our country are: arable fields, hayfields and pastures, orchards, vegetable gardens, greenhouses, farms, ponds.

Industrialization Agriculture has not only advantages, but also disadvantages. Modern agroecosystems pose an environmental threat to natural ecosystems. The chemical pest control agents they use are: pesticides With the help of water and air, they are transferred through food chains into natural ecosystems, polluting them. Therefore, there is a need to expand the use biological methods struggle. Excessive application of mineral and organic fertilizers can cause contamination of groundwater and surface water bodies. Weeds and insect pests from agroecosystems are capable of migrating into natural ecosystems and negatively affecting them.

In order to reduce negative impact agroecosystems on the natural environment, in the Republic of Belarus is carried out big job to create productive, highly economical and environmentally friendly agricultural complexes.

The Institute of Vegetable Growing of the National Academy of Sciences of the Republic of Belarus has developed a set of machines for cultivating vegetable crops using modern technologies. For example, a cultivator sprayer not only processes the rows of vegetable crops, but also applies soluble pesticides and mineral fertilizers. It can be used to process potatoes and other row crops. The combined seeding unit simultaneously cultivates the soil, prepares it for sowing and sows vegetable seeds in a dotted manner. At the same time, he carries out dosed application of granular mineral fertilizers. OAO Bobruiskagromash was the first to produce machines for intrasoil application of liquid organic fertilizers. This enterprise has developed machines for dosed application of solid organic and mineral fertilizers.

Agroecosystem structure

Agroecosystems are biosystems at the same level of organization as natural ecosystems. They include a community and a biotope that are connected by the exchange of matter and energy.

Agroecosystems differ significantly from natural ecosystems:

Agroecosystems - artificial systems created and maintained by man for the purpose of obtaining agricultural products or recreation. Distinctive Features agroecosystems are: low species diversity, low stability, inability to self-regulation, incomplete and open circulation of substances, the presence additional source energy, high biological productivity.

An ecosystem is a collection of living organisms and their habitat. An indispensable condition for the unification of organisms into an ecosystem is the presence of a system of connections through which energy and substances are exchanged. The concept of ecosystem is one of fundamental categories ontologies. At the same time, this is a kind of scientific abstraction.

The fact is that all living organisms on earth, one way or another, are interconnected. When we're talking about, about any specific ecosystem, then, as a rule, a certain isolation of a section of space and the living organisms that inhabit it and are in pain with each other is implied close ties than with others.

Thus, ecosystems can have different sizes and are divided into 4 types: micro-, meso-, macro- and biogeocenosis. Microecosystems include small systems like a drop of water or an aquarium. Mesoecosystems include such large formations as a pond, forest, field. A continent or sea is classified as a Macroecosystem, but the global ecosystem of the Earth is called a biogeocenosis. Ecosystems are also usually divided into natural and human-created.

Natural ecosystems

A natural ecosystem occurs in natural conditions without human intervention. Her distinctive feature have the ability to self-regulate. Mechanisms of interaction of living organisms on pain high level allow the ecosystem to change its structure, adapting it to new conditions. Any ecosystem should be considered as a certain object that has developed under certain conditions. If living conditions exceed the limits of vital indicators of organisms, then the ecosystem is deprived of its components.

Another characteristic feature of the functioning of ecosystems is ability to self-organize. The absence of any coordination center is compensated by the activity and interaction of its elements. The desire of living organisms to survive, grow and develop allows the ecosystem to regulate its life activities. Wherever the minimum prerequisites for the existence of several species of creatures appear, ecosystems arise.

Each ecosystem also has its own structure. It consists of trophic levels- upper and lower. Top level located at the level earth's surface and higher. Organisms of plant origin belonging to photosynthetic biomass are located there. At the lower level underground there are a variety of organisms involved in the processes of decomposition of organic matter.

The structure of the ecosystem elements is as follows:

• Inorganic substances.
• Organic substances.
• Substrate environment.
• Producers.
• Consumers.
• Decomposers.

Inorganic substances take part in the cycle of substances. Organic ones serve as a depot for bound chemical energy. The substrate environment is represented by earth, water and air.

Producers capture light energy from the sun and convert it into energy through the process of photosynthesis. chemical bonds. Consumers eat producers and assimilate together with chemicals energy, but no more than 10% of the previous level goes to the next level. In the face of such an imbalance between at different levels energy transitions are possible due to the existence ecological pyramids. The mass of each link is ten times less than the previous one. A typical power circuit consists of 3 elements:

• Producers.
• Consumers.
• Decomposers.

State internal balance ecosystem is called homeostasis. The ecosystem achieves this state through internal mechanisms of self-regulation. For example, excessive reproduction of herbivores would lead to a decrease in photosynthetic mass, but at the same time the number of predators increases, which reduces the population of first-order consumers.

Agroecosystems

A distinctive feature of these ecosystems is their artificial origin. Just like natural ecosystems, they are characterized by a certain structure and interconnectedness of elements. In addition to their origin, these ecosystems also owe their continued existence to humans. The lack of natural self-regulation mechanisms forces a person to constantly exercise control. The structure of the agricultural ecosystem also differs from the natural one in its simplified structure. This is due to the fact that when creating agroecosystems, people use only part of the elements and their relationships for their own purposes.

The lifespan of agroecosystems is very short. Most of these ecosystems exist during one growing season and cease to exist at harvest time. In agroecosystems, the number of links in trophic chains not much. Ideally, consumers are represented predominantly by humans.

Difference between natural and agroecosystems

One of the main differences is the regulatory mechanisms. If natural system is capable of self-regulation, the agroecosystem is completely dependent on human intervention. Also, both ecosystems differ in their substrate environment. If natural ones arise spontaneously on any substrate, then the substrates of agroecosystems are formed by people based on their needs.

Also, a natural ecosystem differs from an agroecosystem in its greater species diversity and the number of trophic levels. The only basis of a natural ecosystem is the desire of living beings for growth and development, but the structure of agroecosystems is determined by the expediency laid down by man. Both ecosystems also differ in life expectancy - the natural one exists until it is exhausted resource base. While the lifespan of an agroecosystem depends on human needs.

In the biosphere, in addition to natural biogeocenoses (forest, meadow, swamp, river, etc.) and ecosystems, there are also communities created economic activity person. Such a human-made community is called an agroecosystem (agrocenosis, agrobiocenosis, agricultural ecosystem).

Agroecosystem (from the Greek agros - field - agricultural ecosystem, agrocenosis, agrobiocenosis) - a biotic community created and regularly maintained by humans for the purpose of producing agricultural products. Usually includes a set of organisms living on agricultural lands.

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 or several species (or varieties of cultivated plants) or animals.

Agroecosystems differ from natural ecosystems in a number of features.

Agroecosystems have several differences from natural ecosystems.

1. Species diversity in them is sharply reduced to obtain the highest possible output. In a rye or wheat field, in addition to the cereal monoculture, you can find only a few types of weeds. On a natural meadow biological diversity significantly higher, but biological productivity is many times lower than that of the sown field.

2. Species of agricultural plants and animals in agroecosystems are obtained as a result of the action of artificial, and not natural selection, which significantly affects the narrowing of their genetic base. In agroecosystems, there is a sharp narrowing of the genetic base of agricultural crops, which are extremely sensitive to mass reproduction of pests and diseases.

3. Agroecosystems, compared to natural biocenoses, are characterized by greater openness. This means that in natural biocenoses, the primary production of plants is consumed in numerous food chains and again returns to the biological cycle system in the form of carbon dioxide, water and mineral nutrition elements. Agroecosystems are more open, and matter and energy are removed from them with crops, livestock products, and also as a result of soil destruction.

4. Change of vegetation cover in agroecosystems does not occur naturally, but by the will of man, which does not always reflect well on the quality of those included in it abiotic factors. This is especially true for soil fertility.

Soil is the most important life support system and the existence of agricultural production. However, the productivity of agroecosystems depends not only on soil fertility and maintaining its quality. It is no less influenced by the preservation of the habitat of beneficial insects (pollinators) and other representatives of the animal world. In addition, many natural enemies of agricultural pests live in this environment. Thus, the example of the mass death of pollinators in buckwheat fields in the United States, which occurred when they collided with cars in places where agricultural land was close to highways, has already become a textbook example.

5. One of the main features of ecosystems is to obtain additional energy for normal functioning. Without the supply of additional energy from outside, agroecosystems, unlike natural ecosystems, cannot exist. Additional energy refers to any type of energy introduced into agroecosystems. This may be the muscular strength of humans or animals, different kinds fuel for operating agricultural machinery, fertilizers, pesticides, pesticides, additional lighting, etc. Additional energy can also be understood as new breeds of domestic animals and varieties cultivated plants, introduced into the structure of agroecosystems.

6. All agroecosystems of fields, gardens, pasture meadows, vegetable gardens, and greenhouses artificially created in agricultural practice are systems specifically maintained by humans.

It should be noted that agroecosystems are extremely unstable communities. They are not Capable of self-healing and self-regulation, they are subject to the threat of death from mass reproduction of pests or diseases. To maintain them it is necessary permanent activity of people.

What signs of a community or ecosystem are considered sustainable? First of all, it is a complex, polydominant structure, including the largest possible number of species and populations under given conditions. Then, maximum biomass. And the last thing is the relative balance between energy intake and expenditure. What is certain is that such ecosystems exhibit the lowest level of productivity. Biomass is large and productivity is low. This is due to the fact that the main part entering the ecosystem energy goes to maintain life processes.

The most important negative consequence existence of agroecosystems is their destabilizing impact on biogeochemical cycles biosphere, where reproduction of the main species takes place environmental resources and regulation takes place chemical composition living environments. On agricultural lands, the nutrient cycle is open by tens of percent. Therefore, there is every reason to say that agrocenoses from the very beginning of their existence are in an antagonistic relationship with the environment. natural environment. It has now become obvious that they threaten to destroy fundamental biosphere processes and are responsible for global ecological crisis. This applies to all forms created by man, including the most productive varieties and breeds.

What has been said is apparently enough to demonstrate the fundamental inability of agrocenoses to take on the functions of natural ecosystems. It should only be added that at present humanity has not yet come up with any other way to supply itself with food than by creating artificial agroecosystems.

QUESTIONS

1. What is the meaning of the ecosystem concept?

2. What size can ecosystems be?

4. What signs are inherent natural ecosystems?

5. Define a food chain.

6. What types of ecological pyramids do you know?

7. What is biogeocenosis:

8. Give examples of biogeocenoses.

9. What is common and what is the difference between biogeocenosis and ecosystem?

10. What functionally related parts can be distinguished in a biogeocenosis?

11. How are the boundaries of biogeocenosis determined?

12. What determines the dynamics of ecosystems?

13. Describe the daily and seasonal dynamics of ecosystems.

14. What is succession? Give examples of successions.

15. How does primary succession differ from secondary succession?

16. What is anthropogenic succession?

17. Define an agroecosystem, give examples of agroecosystems.

18. What are the significant differences between natural ecosystems and agroecosystems?