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

Definition

Biogeocenosis is a self-developed ecosystem in which representatives of the living world are closely related to the inorganic components that make up their habitat. Examples: coniferous forest, flower meadow.

Agrocenosis is a system that appears when human intervention in the space of the natural environment. Like biogeocenosis, it includes organic and inorganic parts. Examples: personal plot, corn field.

Comparison

When comparing the systems under consideration, one should first of all pay attention to their species composition. Biogeocenosis in this regard is characterized by greater diversity. In an agrocenosis, one or several crops chosen by humans for cultivation predominate (for example, potatoes planted on a plot), and, accordingly, the number of species of animals and lower organisms (bacteria, fungi) is also limited.

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

The difference between biogeocenosis and agrocenosis also lies in how the circulation of substances occurs in each case. In natural natural community he is closed. Everything produced by plants (as well as their remains) is consumed by representatives of numerous food chains and returns to the soil, enriching it. At the same time, the agrocenosis is created precisely for the purpose of obtaining a harvest. Accordingly, at the time of harvesting operations, accompanied by a significant removal of biomass, the circulation of substances in such a system is disrupted, therefore in this case it is called unclosed. To maintain balance, fertilizers are added to the soil.

It is also important that the structure of the biogeocenosis is formed during the implementation of natural selection, eliminating weak species organisms. Agrocenosis involves crops carefully selected by man, taking into account the degree of their productivity. In other words, in formations of this type, to a greater extent, artificial selection. 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 and 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 is that the latter brings real benefits to a person, since it serves as a source of necessary products. Biogeocenosis, in turn, is not always useful from a practical point of view. However, it is a stable self-regulating formation. Agrocenosis exists happily for a more or less long period of time only under the condition of human control. To maintain such a system, the use of all kinds of agricultural techniques is required.

Table

Biogeocenosis	Agrocenosis
Created by nature	Artificially organized system
It is characterized by stability and self-regulation	Unstable, human adjustable
Species diversity	Small number of crops
Branched power circuits	Food chains are shorter and simpler
Less susceptible to pests, therefore more viable	Pests feel more comfortable in it, which can shorten the life of such a system
The cycle of substances is closed	The cycle of substances is not closed
Formed by natural selection	Artificial selection is leading
Receiving light and heat from the Sun	Sometimes additional energy is used, the supply of which is provided by a person
Doesn't always bring practical benefit to a person	Source of required products

Objective of the lesson:

• To form in students a system of knowledge about the structure and functioning of biocenoses created by man, about the main features characterizing an agrocenosis.
• Teach schoolchildren to compare natural biogeocenosis and agrocenosis; explain the reasons for the identified similarities and differences and be able to predict changes in them.
• Convince high school students that a harmonious combination can be achieved between agrocenosis and natural biogeocenosis, that natural communities should not be completely replaced by agricultural land.
• Learn to apply the acquired knowledge in life.
• Ensure mastery of the material using educational resources "Electronic tool educational publication"Ecology" LLC "Drofa" CJSC "1C".

1. Organizational moment

Music is turned on with recordings of forest noise and birdsong.

Address to schoolchildren: “We have guests in our lesson today, look at them and smile, because you are glad to see them here today.”

2. Test of knowledge.

(The guys complete the task given on the sheets to the music)

1. In the list given, find and underline the names of producers, consumers and decomposers in different colors.

Fern, ant, porcini mushroom, chemosynthesizing bacterium, dragonfly, earthworm, putrefactive bacterium, cyanobacterium, lion, fly agaric, cactus, human.

2. Indicate (indicate by numbers) in what order the following organisms can enter the food chain: humans, unicellular algae, daphnia, pike perch, gudgeon.

3. Among the given statements, highlight the correct ones:

A. The source of energy for decomposers is the oxidation of inorganic substances.

B. The number of consumers is usually less than the number of producers.

B. The most highly productive ecosystem is the World Ocean.

D. The most unproductive ecosystems are deserts.

D. Highly productive ecosystems are self-reproducing, while low-productive ecosystems are not.

E. Ecosystems with low species diversity are unstable.

G. The existence of food webs is a condition for the sustainability of the ecosystem.

H. The mechanism of self-regulation of ecosystems is genetic drift.

I. Agrocenosis is one of the most stable ecosystems, because the effect of natural selection is reduced in it.

4. Complete the table using the list below

Artificial ecosystems	Natural ecosystems

Taiga, pond, lake, alpine meadow, wheat field, park, coral island.

What is the name of the natural biocenosis? (biogeocenosis).

What is the artificial biocenosis called? (agrocenosis).

Together with the students we check task 4.

The following diagram is written on the board:

Working with the definition of "agrocenosis"

From the Greek "agros" - field, "bios" - life, "cenosis" - general.

Definition: agrocenosis is a human-created biocenosis.

Using the electronic means of the educational publication "Ecology" LLC

"Bustard" JSC "1C" - video fragment "Agrocenosis and agroecosystem"

Let's turn to the table and compare biogeocenosis with agrocenosis. The material is printed on a separate sheet.

Look at the table and compare what is the peculiarity of artificial biogeocenosis?

Comparative characteristics of biogeocenoses and agrocenoses.

Comparison category	biogeocenosis	agrocenosis
Direction of selection action	Natural selection operates, culling non-viable individuals and preserving adaptations to environmental conditions, i.e. selection forms a stable ecosystem	The action of natural selection is weakened by man; predominantly artificial selection is carried out in the direction of preserving organisms with maximum productivity
Cycling of essential nutrients	All elements consumed by plants, animals and other organisms are returned to the soil, i.e. the cycle is completed completely.	Some of the nutrients are removed from the cycle with the mass of organisms grown and harvested, i.e. the cycle does not occur
Species diversity and sustainability	As a rule, they are distinguished by a large species diversity of organisms that are in complex relationships with each other, ensuring stability	The number of species is often limited to one or two; the interconnections of organisms cannot ensure stability.
Ability for self-regulation, self-maintenance and turnover	Self-regulating, constantly renewing, capable of directed replacement of one community by another (succession).	They are regulated and controlled by humans through changing natural factors (irrigation), weed and pest control, changing varieties, and increasing productivity.
Productivity (amount of biomass created per unit area)	Biomass of terrestrial ecosystems exceeds the productivity of the World Ocean ecosystems by 3 times; The main biomass production is consumed by consumers.	Occupying 10% of the land area, they produce 2.5 billion tons of agricultural products annually; are significantly more productive than biogeocenoses

Compare the ecosystem of a meadow and a field. Fill out the table:

Similarities between agrocenosis and natural biogeocenosis.

1. Are open systems(for example, absorb solar energy from outside).
2. Within each of them there are factors of evolution (artificial or natural selection, struggle for existence, hereditary variability)
3. They have a similar structure (consist of producers, consumers, decomposers).
4. In both biogeocenoses the rule of the ecological pyramid applies.
5. The community is based on producers (autotrophic organisms) that directly use the energy of the Sun for the synthesis of organic substances.
6. In biogeocenoses of any type, there are food chains.

This is interesting:

At the first stages of the development of agriculture agrocenoses were more stable than modern ones. Arable lands occupied relatively small areas surrounded by natural vegetation. The world of animals - regulators and pollinators - was rich. Cultivated plants were not pure varieties and represented a mixture of forms with different hereditary qualities. In dry years, some forms survived, in wet years, others. Weeds in the fields attracted a variety of insects. There was a system of connections close to natural. Such agrocenoses produced relatively low but reliable yields, and outbreaks of pests in them were rare.

With the development of intensive commercial farming, field productivity increased, but the stability and safety margins of ecosystems sharply decreased. More than 100 years ago, the law of diminishing returns was formulated, according to which agricultural production certainly leads to soil depletion and degradation.

With development ecology It became clear that only planning of agricultural production based on ecosystem principles could suspend the operation of this law.

The advantage of biological methods of pest control is their selective action only on certain, undesirable ones in the agrocenosis species.

Rice. 1.
Equestrians and egg eaters are human assistants in the fight against agricultural pests:
at the top and bottom left - female egg eaters on the eggs of the host insect
top right - aphid rider
bottom right - dead aphids after the development of parasites in them

Leaf-eating insects useful in small quantities cultivated plants. Their activity brightens the leaf canopy and improves the light regime for photosynthesis. With a low percentage of damage, plants quickly regrow eaten foliage without loss of overall yield. Insect species that consume crop plants are considered pests when they exceed a certain level of abundance and their activity begins to reduce the yield. This level is called " threshold of harmfulness "If a species does not reach the threshold of harmfulness, it is not considered a pest and is not combated.

Cultivated plants vary greatly in their resistance to weeds. The amount of weeds that is detrimental to one species is almost not harmful to another. If we take the yield in pure sowing as one, then in heavily weeded areas it will leave 0.75 for wheat, 0.65 for potatoes, 0.56 for corn, 0.42 for flax, 0.23 for sugar beets, and 0.23 for cotton. 0.12. Thus, wheat is the most resistant crop to clogging. When 10-15% of the soil is covered with weeds, the costs of chemical weeding in wheat fields are usually not recouped by the increase in yield and the use of pesticides can be avoided.

Solve the problem.

Researchers have found that on every square meter In small cabbage fields there are on average up to 69 cabbage white caterpillars, and in one square meter of large fields no more than one caterpillar was found. At the same time, pests and large fields, and in small fields they are more concentrated in the marginal strip of agrocenoses 30-40 meters wide. Similar results were obtained when taking into account the population density of other crop pests: the cruciferous flea beetle complex, the flax flea beetle, the clover seed-eater and other phytophagous insects. Why is the number of insect pests of agricultural crops significantly higher at the edges of agrocenoses and small fields? What measures can be recommended to reduce the degree of damage to crops by phytophagous insects, taking into account the characteristics of their distribution.

Fixing the material:

1. Write down the food chains in agrocenoses. Why are food chains in agrocenosis small? What conditions should be observed when creating agrocenoses?

Why can’t agrocenoses prevail on the planet? What could this lead to?

Select from the following provisions what applies to agrocenosis and what to biogeocenosis:

• consist of large number species;
• capable of self-regulation;
• incapable of self-regulation;
• consist of a small number of species;
• all nutrients absorbed by plants are returned to the soil over time;
• a significant part of the nutrients is removed from the soil; to compensate for losses, it is necessary to constantly apply fertilizers;
• the only source of energy is sunlight;
• the main driving force of evolution is artificial selection;
• the main driving force of evolution is natural selection;
• prosperity, conservation and high productivity are linked to human activity.

2. Think about why crop rotation is used in agrocenosis?

Homework:

General biology textbook for grades 10-11, edited by D.K. Belyaeva p.261-262.

1. Build a model of an artificial aquarium ecosystem, taking into account all the necessary conditions.

2. Draw up your own 5-field crop rotation scheme, taking into account the necessary requirements.

is an interaction between living and inanimate nature, which consists of living organisms and their habitat. An ecological system is a large-scale balance and connection that allows the maintenance of a population of species of living things. Nowadays, there are natural and anthropogenic ecosystems. The differences between them are that the first is created by the forces of nature, and the second with the help of humans.

The meaning of agrocenosis

Agrocenosis is an ecosystem created by human hands for the purpose of producing crops, animals and mushrooms. An agrocenosis is also called an agroecosystem. Examples of agrocenosis are:

• apple and other orchards;
• corn and sunflower fields;
• cow and sheep pastures;
• vineyards;
• vegetable gardens

Man, due to the satisfaction of his needs and the increase in population in lately forced to change and destroy natural ecosystems. In order to rationalize and increase the volume of agricultural crops, people create agroecosystems. Nowadays, 10% of all available land is occupied by land for growing crops, and 20% is pasture.

The difference between natural ecosystems and agrocenosis

The main differences between agrocenosis and natural ecosystems are:

• artificially created crops cannot compete in the fight against wild species and;
• agroecosystems are not adapted to self-healing, and are completely dependent on humans and without him they quickly weaken and die;
• a large number of one species in the agroecosystem contributes to the large-scale development of viruses, bacteria and harmful insects;
• There is a much greater diversity of species in nature than in human-grown crops.

Artificially created agricultural plots must be under full human control. A disadvantage of agrocenosis is the frequent increase in populations of pests and fungi, which not only harm the crop, but can also worsen the condition environment. The population size of a crop in an agrocenosis increases only through the use of:

• weed and pest control;
• dryland irrigation;
• drying waterlogged soil;
• replacement of crop varieties;
• fertilizers with organic and mineral substances.

In the process of creating an agroecosystem, man built a completely artificial stages development Soil reclamation is very popular - an extensive set of measures aimed at improving natural conditions in order to obtain the maximum high level harvest. Only the correct scientific approach, monitoring soil conditions, moisture levels and mineral fertilizers are able to increase the productivity of agrocenosis in comparison with the natural ecosystem.

Negative consequences of agrocenosis

It is important for humanity to maintain a balance of agro- and natural ecosystems. People create agroecosystems to increase food supply and use them for food industry. However, the creation of artificial agroecosystems requires additional territories, so people often plow the land and thereby destroy existing natural ecosystems. This upsets the balance of wild and cultivated species of animals and plants.

The second negative role is played by pesticides, which are often used to control pests in agroecosystems. These chemicals enter natural ecosystems through water, air and insect pests and pollute them. In addition, excessive use of fertilizers for agroecosystems also causes groundwater problems.

Having worked through these topics, you should be able to:

1. Give definitions: “ecology”, “ecological factor”, “photoperiodism”, “ecological niche”, “habitat”, “population”, “biocenosis”, “ecosystem”, “producer”, “consumer”, “decomposer”, "succession", "agrocenosis".
2. Give examples of photoperiodic reactions of plants and, if possible, animals.
3. Explain the difference between a population's habitat and its niche. Give examples for each of these concepts.
4. Comment on Shelford's law and be able to construct a graph of the dependence of organisms on abiotic environmental factors.
5. Describe an example of a successful biological pest control method.
6. Explain the causes of the population explosion and possible consequences, as well as the significance of the decline in fertility, which typically follows a decline in mortality.
7. Build a circuit food chain; correctly indicate the traffic level of each component of a given ecosystem.
8. Construct a diagram of the simple cycle of the following elements: oxygen, nitrogen, carbon.
9. Describe the events that occur when the lake becomes overgrown; after deforestation.
10. Indicate the differences between agrocenosis and biocenosis.
11. Talk about the meaning and structure of the biosphere.
12. Explain how agriculture, the use of fossil fuels and the production of plastics contribute to environmental pollution and suggest measures to prevent this.

Ivanova T.V., Kalinova G.S., Myagkova A.N. "General Biology". Moscow, "Enlightenment", 2000

• Topic 18. “Habitat. Environmental factors"Chapter 1; pp. 10-58
• Topic 19. "Populations. Types of relationships between organisms." chapter 2 §8-14; pp. 60-99; Chapter 5 § 30-33
• Topic 20. "Ecosystems." chapter 2 §15-22; pp. 106-137
• Topic 21. "Biosphere. Cycles of matter." Chapter 6 §34-42; pp. 217-290

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 occurs.

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 ecosystems were formed as a result of the action of natural forces. They are characterized by:

• Close relationship between organic and inorganic substances
• A complete, closed circle of the cycle of substances: starting from the appearance of organic matter and ending with its decay 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 located 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 receive energy, cosmic and terrestrial substances from the environment, 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, the food chain is immediately disrupted, 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 this was beneficial, since in such a fertile environment and excellent climatic conditions for breeding, the rabbits began to reproduce with 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, society, 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. Here huge role plays an influx of artificially created energy (gas pipeline, electricity, food). At the same time, such ecosystems are characterized by a large release of 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.

One more distinctive feature artificial ecosystems - 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. Part of the food chain in such ecosystems is removed by humans (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 best 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:

Natural ecosystems	Artificial ecosystems
Main component- solar energy.	Mainly receives energy from fuels and prepared foods (heterotrophic)
Forms fertile soil	Depletes the soil
All natural ecosystems absorb carbon dioxide and produce oxygen	Most artificial ecosystems consume oxygen and produce carbon dioxide
Great species diversity	Limited number of species of organisms
High stability, ability for self-regulation and self-healing	Weak sustainability, since such an ecosystem depends on human activities
Closed metabolism	Open metabolic chain
Creates habitats for wild animals and plants	Destroys habitats wildlife
Accumulates water, using it wisely and purifying it	High water consumption and pollution