Agrocenosis (agroecosystem), its difference from biogeocenosis. Cycle of substances in agrocenosis and ways to increase its productivity.

1. Agrocenosis (agroecosystem) - an artificial system created as a result of human activity. Examples of agrocenoses: park, field, garden, pasture, personal plot.

2. The similarity of agrocenosis and biogeocenosis, the presence of three links: organisms - producers, consumers and destroyers of organic matter, the circulation of substances, territorial and food relations between organisms, plants - the initial link in the food chain.

4. Agrocenosis is an ecologically unstable system, its causes are a weak circulation of substances, insufficiently expressed self-regulation, a small number of species, etc.

5. The role of man in increasing the productivity of agrocenoses: breeding highly productive varieties of plants and animal breeds, growing them using the latest technologies, taking into account the biology of organisms (need for nutrients, plant needs for heat, humidity, etc.), combating diseases and pests, timely implementation of agricultural work, etc.

6. Agrocenoses as a source of environmental pollution: biological (mass reproduction, outbreak of insect pests), chemical (washout of excess pesticides, fertilizers into water bodies, death of pollinating insects from pesticides, changes in soil fauna under the influence of chemicals and etc.).

7. Protection of nature from pollution by agricultural production - compliance with the norms and deadlines for the application of mineral fertilizers, the use of pesticides, and new technologies for tillage.

57 Basic methods of plant and animal breeding: hybridization and artificial selection.

1. Selection is evolution controlled by man (N. I. Vavilov). The results of the evolution of the organic world are the diversity of plant and animal species. The results of selection are the diversity of plant varieties and animal breeds. Driving forces of evolution: hereditary variability and natural selection; the basis for the creation of new varieties of plants and animal breeds: hereditary variability and artificial selection.

2. Plant and animal breeding methods: crossbreeding and artificial selection. Crossing different varieties of plants and animal breeds is the basis for increasing the genetic diversity of offspring. Types of plant crossing: cross-pollination and self-pollination. Self-pollination of cross-pollinated plants is a way to obtain offspring that are homozygous for a number of traits. Cross-pollination is a way to increase the diversity of offspring.

3. Types of animal crossing: related and unrelated. Unrelated - crossing individuals of the same or different breeds, aimed at maintaining or improving the characteristics of the breed. Closely related - crossing between brothers and sisters, parents and offspring, aimed at obtaining offspring that are homozygous for a number of traits, to preserve valuable traits in it. Closely related crossing is one of the stages of selection work.

4. Artificial selection - preservation for further reproduction of individuals with traits of interest to the breeder. Forms of selection: mass and individual. Mass selection - the preservation of a group of individuals from offspring that have valuable traits. Individual selection - selection of individual individuals with traits of interest to a person and obtaining offspring from them.

5. The use of mass selection in plant breeding to obtain genetically heterogeneous material, heterozygous individuals. The results of multiple individual selection - breeding pure (homozygous) lines.

6. The reasons for the use of only individual selection in animal breeding is a small offspring. When selecting individuals, it is necessary to take into account the development of their exterior traits (body build, ratio of body parts, external traits), which are associated with the formation of economic traits (for example, milk production in cows).

7. Crossing and selection - universal breeding methods, the possibility of their application in the creation of new varieties of plants and animal breeds.

The cycle of substances in biogeocenosis, the role of organisms - producers, consumers and destroyers in it. The main source of energy that ensures the circulation of substances in the biogeocenosis.

1. The connection of organisms of different species in biogeocenosis with each other and with the environment is a necessary condition for the metabolism and energy conversion in organisms. Metabolism is the main sign of life.

2. Depletion of stocks of inorganic substances in the biogeocenosis as a result of their constant use by organisms in the process of metabolism. Replenishment of stocks of inorganic substances due to the breakdown of organic substances in the process of vital activity of organisms.

3. Consistent transformation of substances and energy in biogeocenoses is the basis of the circulation of substances. The constant transition of some elements from inanimate nature to organisms, from organisms of one species to others, their return from organisms to inanimate nature is the biological cycle of substances. Circulation is the basis for the repeated use of substances, the same elements by organisms.

4. Metabolism, growth, reproduction of organisms are the main life processes that ensure the circulation of substances and the transformation of energy. Plants are producer organisms that create the primary biological products used by all organisms. Animals are consumer organisms that convert primary biological products into secondary (animal) products. Bacteria, fungi and other organisms - destroyers of primary and secondary production to inorganic substances. They ensure the entry of inorganic substances into the soil, water bodies, atmosphere and the possibility of reuse by plants.

5. Circulation of substances - the process of complex successive transformations of substances, which consume a lot of energy. The sun is the main source of energy that ensures the circulation of matter. The role of plants in the use of solar energy and its inclusion in the cycle of matter.

6. Food connections between organisms are the basis for the transfer of matter and energy along food chains.

Large energy costs for life processes, its loss in the form of heat - the reason for the single use of energy received by organisms with food.

An ecosystem is a special unity of plants, microorganisms and animals, within which various substances and energy are exchanged between them. Each ecosystem has its own characteristic soil composition, temperature, and other indicators. They are divided into two categories - natural (natural) and artificial (agroecosystems). What are their similarities and differences? Let's figure it out.

Main differences

What is the greatest difference between a natural ecosystem and an agroecosystem? First of all - a variety of species on its territory. The first type (agrocenosis) exists for a much longer time, has the ability to independently regulate the processes occurring in it. The natural ecosystem, in contrast to the agroecosystem, is more sustainable and stable. The biomass created within its limits is used to enrich its own resources and does not leave the limits of this system. The category of natural ecosystems includes seas, forests, steppes, swamps. The second group includes those systems that are created by human hands.

Agricultural development and natural balance

Since ancient times, when agriculture was just beginning to emerge, man has completely destroyed the vegetation cover in order to grow those species that would be most suitable for food. At the dawn of history, human activity did not disturb the balance in the biochemical cycle. However, modern agriculture uses mostly synthesized energy, cultivates the land mechanically. In the vast majority of cases, fertilizers and pesticides are used to obtain a high yield. All these actions can lead to unpredictable consequences.

Danger to nature

Another difference between an ecosystem and an agroecosystem is the area they occupy. The latter occupy no more than 10% of the total land area. But at the same time they are sources of 90% of food for mankind. Their biological productivity is an order of magnitude higher than that of natural ecosystems. However, agroecosystems are less resilient. What is the difference between a natural ecosystem and an agroecosystem in addition to these factors? One of the most important differences between these two types of systems is that the agroecosystem is soil depleting and can also be hazardous to soil fertility. The first type, on the contrary, forms high-quality soil.

Those man-made systems also produce various wastes and pollutants. They must undergo disinfection, and this happens at the expense of a person. Natural ecosystems are disinfected on their own - no payment or effort from people is needed for this. They also have the ability to keep themselves for a long time. As for agroecosystems, a large amount of costs are required to maintain them.

Rationality in nature management

Often, the answer to the question of what is the difference between an ecosystem and an agroecosystem needs to be prepared by schoolchildren or students of environmental faculties. The main aspect that needs to be voiced when preparing such material is the creation of an agroecosystem by human hands. Those species that are cultivated by human hands are supported by artificial selection. They receive energy flow only due to external actions. Without human support, this type of system disintegrates very quickly and returns to its normal, natural state.

We examined the differences between an ecosystem and an agroecosystem. From this analysis it can be concluded that with a long-term use of natural resources - in particular, with a constant withdrawal of crops - soil fertility is steadily declining. This position in ecological science is called waning fertility. In order to conduct agriculture prudently and rationally, it is necessary to take into account the depletion of soil resources. A person can preserve soil fertility if he uses improved techniques for their cultivation, makes crop rotation rational, and also uses other methods.

How is a natural ecosystem different from an agroecosystem? List of differences

All the differences between these types of systems can be represented as a list:

• Agrocenosis created by human hands. A natural ecosystem is formed and functions in nature without intentional human intervention.
• Diversity of species is characteristic only of natural ecosystems. On a wheat or rye field created by human hands, you can only find a few types of weeds.
• The natural ecosystem constantly receives, accumulates, and also transforms energy. Agrocenosis constantly needs an influx of energy in the form of fertilizers or fuel.
• The change of vegetation cover in the agroecosystem occurs at the will of man. In nature, this process proceeds naturally.
• Agrocenosis consumes a large amount of water. The natural ecosystem accumulates water, spending it gradually.
• The agroecosystem requires significant costs to maintain its existence, and the natural ecosystem has the ability to self-repair.

Ecology deals with the question of how a natural ecosystem differs from an agroecosystem. Those students or schoolchildren who would like to study this issue in more detail can read the special literature. For example, the textbook "General Ecology" by N. M. Chernova and A. M. Bylova, or the publication "Stability and Sustainability of Agroecosystems" by I. Yu. Vinokurov.

Agrocenoses. Unlike cities, agrocenoses, or agricultural ecosystems, are characterized by the main component - autotrophic organisms.

Unlike cities agrocenoses, or agricultural ecosystems, are characterized by the main component - autotrophic organisms, which provide them with organic matter and release oxygen. They differ from natural biogeocenoses in the following features.

1. In addition to solar energy, additional energy is required to maintain agrocenoses: chemical in the form of fertilizers, mechanical in the form of the work of human and animal muscles, as well as the energy of combustible materials and electricity.

2. The species diversity of organisms is sharply reduced and is represented by individual agricultural crops, sometimes even only one, with weeds and pests of agricultural plants, as well as a limited number of domestic animal species.

3. The dominant species of plants and animals are under the control of artificial selection. Agrocenoses are organized in such a way as to receive the maximum amount of food. Currently, about 10% of ice-free land is occupied by arable land, another 20% is used as pasture.

There are two main types of agricultural ecosystems: extensive and intense agrocenoses. The former exist with the use of the main muscular energy of humans and animals. The products of these systems are used to feed the families of small farmers and to be sold or exchanged in the local market. The latter are associated with large expenditures of chemical energy and machines. Food is produced here in excess of local needs and exported for sale, playing an important role in the economy.

About 60% of agricultural land is used extensively. Most of them are concentrated in Asia, Africa and South America. In some cases, they can be very complex and harmonize with natural ecosystems. The efficiency of extensive agrocenoses can be very high, especially in cases where a significant number of plant and animal species are cultivated in limited areas. Thus, on the islands of New Guinea and the Philippines, the population receives food products containing approximately 96 million kJ/ha at the cost of labor equivalent to 6 million kJ. The ratio of received and expended energy corresponds to 16:1.

However, even the most productive extensive agrocenoses cannot produce enough surplus products to supply large cities. Thus, non-industrial agriculture is efficient in saving energy, but it is not very productive when taking into account the amount of food produced by one farmer.

Intensive agro-ecosystems occupy 40% of cultivated land. They are concentrated mainly in Europe, Central and North America and Australia. Their efficiency is so high that 4% of the US population living in rural areas provide not only the entire country with basic foodstuffs, but also exports.

The yield of many agricultural crops used in industrial agrocenoses is currently reaching a biologically possible maximum. Characteristically, there is an increase in the loss of agricultural land due to soil erosion, as well as the deterioration of water quality as a result of the runoff of surface water saturated with pesticides and mineral fertilizers into lakes and rivers.

In recent years, there have been trends in industrial agriculture aimed at the joint cultivation of several crops, reducing the size of sown areas with their alternation with orchards, reservoirs, vineyards, pastures and forest plantations. Against the background of the use of tillage technologies without deep plowing, the use of mainly organic fertilizers and predominantly biological measures to control pests and weeds, these activities contribute to the creation of artificial ecosystems that, in a number of indicators, approach natural biogeocenoses. Soil depletion and erosion, as well as environmental pollution, are minimized with such a management system.

Unlike a natural ecosystem, an artificial ecosystem is characterized. Write your answer in numbers without spaces.

1) a wide variety of species

2) diverse supply chains

3) open circulation of substances

4) the predominance of one or two species

5) the influence of the anthropogenic factor

6) closed circulation of substances

Explanation.

Differences of agrocenoses from natural biogeocenoses. Between natural and artificial biogeocenoses, along with similarities, there are also big differences that are important to take into account in agricultural practice.

The first difference is in the different direction of selection. In natural ecosystems, there is natural selection that rejects non-competitive species and forms of organisms and their communities in the ecosystem and thereby ensures its main property - sustainability. In agrocenoses, mainly artificial selection operates, directed by man primarily to maximize the yield of agricultural crops. For this reason, the ecological stability of agrocenoses is low. They are not capable of self-regulation and self-renewal, they are subject to the threat of death during the mass reproduction of pests or pathogens. Therefore, without human participation, his tireless attention and active intervention in their lives, agrocenoses of grain and vegetable crops exist for no more than a year, perennial grasses - 3-4 years, fruit crops - 20-30 years. Then they disintegrate or die.

The second difference is in the source of energy used. For natural biogeocenosis, the only source of energy is the Sun. At the same time, agrocenoses, in addition to solar energy, receive additional energy that a person spent on the production of fertilizers, chemicals against weeds, pests and diseases, on irrigation or drainage of land, etc. Without such additional energy consumption, the long-term existence of agrocenoses is almost impossible .

The third difference is that the species diversity of living organisms is sharply reduced in agroecosystems. One or several species (varieties) of plants are usually cultivated in the fields, which leads to a significant depletion of the species composition of animals, fungi, and bacteria. In addition, the biological uniformity of cultivated plant varieties occupying large areas (sometimes tens of thousands of hectares) is often the main reason for their mass destruction by specialized insects (for example, the Colorado potato beetle) or damage by pathogens (powdery hummock, rust, smut fungi, late blight and etc.).

The fourth difference is the different balance of nutrients. In natural biogeocenosis, the primary production of plants (crop) is consumed in numerous food chains (networks) and is again returned to the biological cycle system in the form of carbon dioxide, water and mineral nutrition elements.

In the agrocenosis, such a cycle of elements is sharply disturbed, since a person removes a significant part of them with the harvest. Therefore, in order to compensate for their losses and, consequently, to increase the yield of cultivated plants, it is necessary to constantly apply fertilizers to the soil.

Thus, in comparison with natural biogeocenoses, agrocenoses have a limited species composition of plants and animals, are not capable of self-renewal and self-regulation, are subject to the threat of death as a result of mass reproduction of pests or pathogens, and require tireless human activity to maintain them.

Under the numbers 3, 4, 5 - characterizes agrocenosis; 1, 2, 6 - natural biogeocenosis.

Answer: 345.

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