A patch of potatoes and a garden of fruit trees? All these are agrocenoses. In our article, we will get acquainted with the main characteristics of this concept.
Communities of organisms
Under natural conditions, different types of living beings do not live separately. As a result, various communities are formed. One of them is biocenosis. Its structure includes populations of various species living in a site with homogeneous conditions. The basis of such a community is phytocenosis.
But living organisms are connected not only with each other. also have some effect on them. Therefore, ecologists call another structure - biogeocenosis. This is a territory with approximately the same conditions, in which populations of various species are united with each other and the physical environment through the circulation of matter and energy.
Agrocenosis is also a community of organisms, but it differs significantly from all the others. What is the difference? Let's figure it out.
Biogeocenosis and agrocenosis
Agrocenosis is a community of organisms created by man. It may include plants, animals, fungi and microorganisms. The purpose of its creation is to obtain agricultural products. But most often an agrocenosis is called an artificial field, a vegetable garden, a garden or a garden bed.
Biogeocenosis is a natural, self-developing structure.
The characteristics of agrocenosis also include the almost complete absence of self-regulation. All processes in this community are controlled by a person. When its activity ceases, the agrocenosis ceases to exist.
Biogeocenosis uses only solar energy for its development. There are additional reserves in the agrocenosis. This is the energy that a person contributes when irrigating, plowing land, using fertilizers, special feed, chemicals to control weeds and rodents.
Signs of agrocenosis
Agrocenoses are characterized by low species diversity. Since these communities are created with the aim of obtaining certain agricultural products, they include one or two representatives of the organic world. As a result, the number of other species inhabiting the area is decreasing.
Agrocenosis is a weakly stable structure. Its development occurs only under the influence of a person in artificially recreated conditions. Therefore, the ability to withstand fluctuations in the intensity of environmental factors without abrupt changes in the structure and functions of agrocenosis is practically impossible.
Trophic connections
Any natural community is characterized by the presence of food chains. Agrocenosis is no exception. Its food webs are very poorly branched. This is due to the depleted species diversity.
In biogeocenosis there is a continuous circulation of substances and energy. For example, plant products are consumed by other organisms and then returned to the natural system in an altered form. It can be water, carbon dioxide or mineral elements.
This does not happen in agrocenosis chains. Receiving a crop, a person simply withdraws it from circulation. Trophic bonds are broken. To compensate for such losses, it is necessary to systematically apply fertilizers.
Development conditions
To increase the yield and productivity of agrocenoses, a person uses artificial selection. During this process, a person selects individuals with the most useful qualities, capable of producing viable and prolific offspring. This type of selection is faster and more efficient than natural selection.
On the other hand, it leads to an inability to self-regulate and self-renewal. If a person stops his activity, the agrocenosis is destroyed. It won't happen right away. So, perennial herbaceous cultivated plants will last about 4 years, and trees - several dozen.
To maintain the development of agrocenoses, a person must constantly prevent the processes of succession. This term means the destruction or replacement of some natural communities by others. For example, if weeds are not removed, they will first become the dominant species. Over time, they will completely replace the culture. The fact is that weeds have a number of adaptations that help to successfully survive adverse conditions. This is the presence of underground - rhizomes, bulbs, a large number of seeds, a variety of methods of distribution and vegetative propagation.
The value of agrocenoses
Thanks to agrocenoses, a person receives agricultural products, which he uses as food and the basis for the food industry. The advantage of artificial communities is their manageability and unlimited ability to increase productivity. But human activity also leads to negative consequences. Plowing of land, deforestation and other manifestations of irrational nature management lead to an imbalance. Therefore, when creating agrocenoses, it is necessary to take into account the relationship between wild and cultivated species.
So, agrocenosis is an artificial biogeocenosis. Man creates it to obtain various types of products. To do this, he selects productive plant varieties, animal breeds, fungal species or microorganism strains. The main characteristics of agrocenosis include: poorly branched lack of circulation of matter and energy, low species diversity and constant human control.
Comparison of natural and simplified anthropogenic ecosystems (according to Miller, 1993)
|
natural ecosystem (swamp, meadow, forest) |
Anthropogenic ecosystem (field, plant, house) |
|
|
Receives, transforms, accumulates solar energy. |
Consumes energy from fossil and nuclear fuels. |
|
|
Produces oxygen and consumes carbon dioxide. |
Consumes oxygen and produces carbon dioxide when fossil fuels are burned. |
|
|
Forms fertile soil. |
Depletes or poses a threat to fertile soils. |
|
|
Accumulates, purifies and gradually consumes water. |
Uses a lot of water, pollutes it. |
|
|
Creates habitats for various types of wildlife. |
Destroys the habitats of many species of wildlife. |
|
|
Filters and disinfects pollutants and waste free of charge. |
Produces pollutants and waste that must be decontaminated at the expense of the public. |
|
|
It has the ability of self-preservation and self-healing. |
Requires large expenditures for constant maintenance and restoration. |
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.
Agroecosystems are created by man to obtain a high yield - pure production of autotrophs.
Summarizing everything that has already been said about agroecosystems, we emphasize the following main differences from natural ones (Table 2).
1. In agroecosystems, the diversity of species is sharply reduced:
§ the decrease in the species of cultivated plants also reduces the visible 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 sowing 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. Net production (crop) is removed from the ecosystem and does not enter the food chains of the biocenosis, but its partial use by pests, losses during harvesting, which can also fall into natural trophic chains. In every possible way suppressed by man.
5. Ecosystems of fields, orchards, pastures, kitchen 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 2
Comparative characteristics of natural ecosystems and agroecosystems.
|
natural ecosystems |
Agroecosystems |
|
|
Primary natural elementary units of the biosphere, formed in the course of evolution. |
Secondary human-transformed artificial elementary units of the biosphere. |
|
|
Complex systems with a significant number of animal and plant species dominated by populations of several species. They are characterized by a stable dynamic balance achieved by self-regulation. |
Simplified systems with the dominance of populations of one species of plant and animal. They are stable and characterized by the variability of the structure of their biomass. |
|
|
Productivity is determined by the adapted characteristics of the organisms involved in the cycle of substances. |
Productivity is determined by the level of economic activity and depends on economic and technical capabilities. |
|
|
Primary production is used by animals and participates in the cycle of substances. "Consumption" occurs almost simultaneously with "production". |
The crop is harvested to meet human needs and to feed livestock. Living matter accumulates for some time without being consumed. The highest productivity develops only for a short time. |
- The similarity of natural ecosystems and agrocenoses;
- Differences between natural ecosystems and agrocenoses.
1. The presence of three functional groups
(producers, consumers, decomposers)
Wheat field
producers
consumers
decomposers
Similarities of agrocenosis with a natural ecosystem:
2. Presence of food webs
rider
plants
owl
caterpillars
quail
lark
a fox
mouse
Food web of agrocenosis
plants
caterpillars
mouse
rider
quail
lark
a fox
owl
Similarities of agrocenosis with a natural ecosystem:
3. Tiered structure
Similarities of agrocenosis with a natural ecosystem:
abiotic factors
Similarities of agrocenosis with a natural ecosystem:
4. Influence of environmental factors
biotic factors
Similarities of agrocenosis with a natural ecosystem:
4. Influence of environmental factors
anthropogenic factors
Similarities of agrocenosis with a natural ecosystem:
5. Eat often view - dominant
View - dominant- a species that prevails in the ecosystem in terms of abundance and influence
Differences
characteristics
natural ecosystem
1. Species diversity
Agrocenosis
Many species forming highly branched food webs
There are fewer species, the dominant species is determined by a person
Differences agrocenosis and natural ecosystem:
characteristics
natural ecosystem
2. Sustainability
Agrocenosis
Unstable, without a person perishes
sustainable
Differences agrocenosis and natural ecosystem:
characteristics
natural ecosystem
3. Selection action
Agrocenosis
Active natural selection , more adapted individuals remain
Natural selection is weakened artificial selection , valuable individuals remain
Differences agrocenosis and natural ecosystem:
characteristics
natural ecosystem
4. Energy source
Agrocenosis
Solar energy and human input (watering, weeding, fertilizing, etc.)
Energy of sun
Differences agrocenosis and natural ecosystem:
characteristics
natural ecosystem
5. Cycle of elements
Agrocenosis
Part of the elements is taken by a person with a harvest, the cycle is incomplete
Full circle
Differences agrocenosis and natural ecosystem:
characteristics
natural ecosystem
6. Self-regulation
Agrocenosis
Man regulates
Capable of self-regulation
Differences agrocenosis and natural ecosystem:
characteristics
natural ecosystem
7. Productivity (creation of organic matter during photosynthesis per unit of time)
Agrocenosis
High thanks to the man
Depends on natural conditions
Fill the table.
natural community
Natural selection
Agrocenosis
artificial selection
Assess the driving forces that shape natural and artificial ecosystems:
- Does not affect the ecosystem;
- Acts on the ecosystem;
- The impact on the ecosystem is minimal;
- The action is aimed at achieving maximum productivity.
Species composition of the community
natural community
species composition
Agrocenosis
Less/more for each position.
Distribute features:
General characteristic characteristic
characteristics only for only for
natural agrocenosis
ecosystems
Characteristics:
1. Inorganic substances absorbed by producers from the soil are removed from the ecosystem.
2. Presence of decomposers in the ecosystem.
3. The ecosystem is rapidly deteriorating without human intervention.
4. Presence of producers in food chains.
5. The main source of energy is the sun.
6. Inorganic substances absorbed by producers from the soil are returned to the ecosystem.
Characteristics:
7. The ecosystem is stable over time without human intervention.
8. Some of the energy or chemicals may be artificially introduced by humans.
9. Man has little effect on the circulation of substances.
10. Characterized by a variety of ecological niches.
11. Presence of consumers in food chains.
12. Man is an obligatory element of food chains.
Natural ecosystems and man-made agrocenoses have common characteristics: _____________________.
The differences are related to _________________
____________________________________.
Having worked through these topics, you should be able to:
- Give definitions: "ecology", "environmental factor", "photoperiodism", "ecological niche", "habitat", "population", "biocenosis", "ecosystem", "producer", "consumer", "reducer", "succession", "agrocenosis".
- Give examples of photoperiodic reactions in plants and, if possible, animals.
- Explain the difference between a population's habitat and its niche. Give examples for each of these concepts.
- Comment on Shelford's law and be able to plot the dependence of organisms on abiotic environmental factors.
- Describe an example of a successful biological pest control method.
- Explain the causes of the population explosion and the possible consequences, as well as the significance of the decline in the birth rate, which, as a rule, follows the decline in mortality.
- Build a food chain diagram; correctly indicate the traffic level of each component of this ecosystem.
- Construct a diagram of a simple cycle of the following elements: oxygen, nitrogen, carbon.
- Describe the events that occur during the overgrowth of the lake; after deforestation.
- Indicate the differences between agrocenosis and biocenosis.
- Tell about the meaning and structure of the biosphere.
- Explain how agriculture, the use of fossil fuels and the production of plastics contribute to pollution and suggest measures to prevent it.
Ivanova T.V., Kalinova G.S., Myagkova A.N. "General Biology". Moscow, "Enlightenment", 2000
- Topic 18. "Habitat. Ecological 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
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 destruction. 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
| Biogeocenosis | Agrocenosis |
| Created by nature | Artificially organized system |
| It is characterized by stability and self-regulation. | Unstable, human controlled |
| Species diversity | A small number of crops |
| Branched food chains | 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 matter is closed | The cycle of matter is open |
| Formed by natural selection | Artificial selection is leading |
| Getting light and heat from the sun | Sometimes additional energy is used, the supply of which is provided by a person. |
| Does not always bring practical benefits to a person | Source of necessary products |
