The concept of "ecosystem" was introduced in 1935 by A. Tensley, an English botanist. By this term he designated any combination of organisms that live together, as well as their environment. Its definition emphasizes the presence of interdependence, relationships, cause-effect relationships existing between the abiotic environment and the biological community, their combination into a certain functional whole. The ecosystem, according to biologists, is a collection of all kinds of populations of various species that live in a common territory, as well as their inanimate environment.
Biogeocenosis is a natural entity that has clear boundaries. It consists of a set of biocenoses (living creatures) that occupy a specific place. For example, for aquatic organisms this place is water, for those who live on land, the atmosphere and soil. Below we will consider examples of biogeocenosis that will help you understand what it is. We will describe these systems in detail. You will learn about their structure, their types and how their change occurs.
Biogeocenosis and the ecosystem: differences
To some extent, the concepts of "ecosystem" and "biogeocenosis" are unambiguous. Nevertheless, they do not always coincide in volume. Biogeocenosis and ecosystem are related as a less wide and broader concept. The ecosystem is not associated with a certain limited area of the earth's surface. This concept can be applied to all stable systems of inanimate and living components in which the internal and external circulation of energy and substances takes place. Ecosystems, for example, include a drop of water with microorganisms in it, a flower pot, an aquarium, a biofilter, aeration tank, and a spaceship. But they cannot be called biogeocenoses. An ecosystem can include several biogeocenoses. Let's look at some examples. It is possible to distinguish the biogeocenoses of the ocean and the biosphere as a whole, the continent, the belt, the soil-climatic region, zone, province, and okrug. Thus, not every ecosystem can be considered a biogeocenosis. We found this out by looking at examples. But any biogeocenosis can be called an ecological system. We hope that now you have understood the specifics of these concepts. "Biogeocenosis" and "ecosystem" are often used as synonyms, but there is still a difference between them.
Features of biogeocenosis
Many species usually live in any of the limited spaces. Complex and ongoing relationships are established between them. In other words, different types of organisms that exist in a certain space characterized by a complex of special physicochemical conditions represent a complex system that persists for a more or less long time in nature. Refining the definition, we note that biogeocenosis is a community of organisms of various species (historically established) that are closely related to each other and to the inanimate nature surrounding them, the exchange of energy and substances. A specific characteristic of biogeocenosis is that it is spatially limited and quite uniform in the species composition of the living creatures included in it, as well as in the complex of various abiotic factors. Existence as a holistic system ensures the constant flow of solar energy into this complex. As a rule, the boundary of biogeocenosis is established along the boundary of the phytocenosis (plant community), which is its most important component. These are its main features. The role of biogeocenosis is great. At its level, all processes of energy flow and the circulation of substances in the biosphere occur.
Three groups of biocenosis
The main role in the interaction between its various components belongs to the biocenosis, that is, living creatures. According to their functions, they are divided into 3 groups - reducers, consumers and producers - and closely interact with the biotope (inanimate nature) and with each other. These living beings are united by the nutritional relationships that exist between them.
Producers are a group of autotrophic living organisms. Consuming the energy of sunlight and minerals from the biotope, they thereby create primary organic matter. This group includes some bacteria, as well as plants.
Consumers are heterotrophic organisms that use ready-made organic substances in the form of food, which serve as their source of energy, as well as the substances that consumers need for their life. We can attribute to them almost all animals, parasitic plants, predator plants, as well as some (parasitic) bacteria and fungi.
Reducers decompose the remnants of dead organisms, and also decompose organic substances into inorganic substances, thereby returning mineral substances “recovered” by producers to the biotope. These are, for example, some types of unicellular fungi and bacteria.
Nutritional relationships between biocenosis groups
The nutritional relationship existing between the three components of biogeocenosis determines the circulation of substances and energy flows in it. By capturing the energy of the sun and absorbing minerals, producers create organic matter. Their body is built from them. Thus, solar energy is converted into the energy of chemical bonds. Eating each other and producers, consumers (herbivorous, parasitic and predatory organisms) thereby break down organic matter. They use them, as well as the energy released as a result of this, to ensure their vital functions and build their own bodies. Reducers, eating dead organisms, decompose their organic substances. They thus extract the energy and materials they need, and also ensure the return of inorganic substances to the biotope. So in the biogeocenosis is a cycle of substances. Its constancy is the key to the long existence of the ecological system, despite the fact that the supply of mineral substances is limited in it.
Dynamic equilibrium system
Dynamic equilibrium is characterized by the relationship of organisms between themselves and with their inanimate nature. For example, in a year when weather conditions are favorable (a lot of sunny days, humidity and temperature are optimal), plants produce an increased amount of primary organic substances. Such an abundance of food leads to the fact that rodents begin to multiply in mass. This, in turn, causes an increase in parasites and predators, which reduce the number of rodents. As a result, this leads to a decrease in the number of predators, since some of them die from a lack of food. Thus, the initial state of the ecosystem is restored.
Types of biogeocenosis
Biogeocenosis can be natural and artificial. Types of the latter include agrobiocenoses and urban biogeocenoses. Let us dwell on each of them.
Natural biogeocenosis
Note that each natural natural biogeocenosis is a system that has developed over a long time - thousands and millions of years. Therefore, all its elements are "ground" to each other. This leads to the fact that the resistance of biogeocenosis to various changes occurring in the environment is very high. The “strength” of ecosystems is not unlimited. Deep and sharp changes in the conditions of existence, a reduction in the number of species of organisms (for example, as a result of large-scale fishing of commercial species) lead to the fact that the balance can be disturbed and it can be destroyed. In this case, there is a change in biogeocenoses.
Agrobiocenoses
Agrobiocenoses are special communities of organisms that take shape in territories used by people for agricultural purposes (planting, sowing of cultivated plants). Producers (plants), unlike natural biogeocenoses, are represented here by one type of culture grown by humans, as well as a certain number of weed species. A variety of herbivorous animals (rodents, birds, insects, etc.) determines the vegetation cover. These are species that can feed on plants growing on the territory of agrobiocenoses, as well as be in the conditions of their cultivation. These conditions determine the presence of other species of animals, plants, microorganisms and fungi.
Agrobiocenosis depends, first of all, on human activities (fertilization, mechanical tillage, irrigation, pesticides, etc.). The stability of the biogeocenosis of this species is weak - it will collapse very quickly without human intervention. This is partly due to the fact that cultivated plants are much more whimsical than wild ones. Therefore, they cannot withstand competition with them.
Urban biogeocenoses
Urban biogeocenoses are of particular interest. This is another variety of anthropogenic ecosystems. An example is parks. The main environmental factors, as in the case of agrobiocenoses, are anthropogenic in them. The species composition of plants is determined by man. He plants them, and also takes care of them and processes them. The changes in the external environment are most pronounced precisely in cities - temperature increase (from 2 to 7 ° ), specific features of soil and atmospheric composition, special regime of humidity, light exposure, and winds. All these factors form urban biogeocenoses. These are very interesting and specific systems.
Examples of biogeocenosis are numerous. Different systems differ from each other in the species composition of organisms, as well as in the properties of the environment in which they live. Examples of biogeocenosis, which we dwell on in detail, are deciduous forest and a pond.
Deciduous forest as an example of biogeocenosis
Deciduous forest is a complex ecological system. The composition of the biogeocenosis in our example includes plant species such as oaks, beeches, lindens, hornbeams, birches, maples, mountain ash, aspen and other trees whose foliage falls in autumn. Several of their tiers stand out in the forest: low and high woody, mossy ground cover, grasses, shrubs. The plants inhabiting the upper tiers are more photophilous. They better withstand fluctuations in humidity and temperature than representatives of the lower tiers. Mosses, grasses and shrubs are shade tolerant. They exist in the summer in the twilight formed after the deployment of tree foliage. The litter lies on the surface of the soil. It is formed from decaying residues, branches of bushes and trees, fallen leaves, dead herbs.
Forest biogeocenoses, including deciduous forests, are characterized by rich fauna. They are inhabited by many burrowing rodents, predators (bear, badger, fox), earth-moving insectivores. There are mammals living on trees (chipmunk, squirrel, lynx). Roe deer, elk, and deer are part of a group of large herbivores. Wild boars are widespread. Birds nest in different tiers of the forest: on trunks, in bushes, on the ground or on tops of trees and in hollows. There are many insects that feed on leaves (for example, caterpillars), as well as wood (bark beetles). In the upper layers of the soil, as well as in the litter, besides insects, there are a huge number of other vertebrates (ticks, earthworms, insect larvae), many bacteria and fungi.
Pond as a biogeocenosis
Consider now the pond. This is an example of biogeocenosis, in which water is the living environment of organisms. Large floating or rooting plants (pond, water lilies, bulrushes) settle in the shallow waters of ponds. Small floating plants are distributed throughout the thickness of the water, to the depth where light penetrates. These are mainly algae called phytoplankton. Sometimes there are many of them, as a result of which the water turns green, "blooms". Many blue-green, green, and diatoms are found in phytoplankton. Tadpoles, insect larvae, herbivorous fish, crustaceans feed on plant debris or living plants. Fish and predatory insects eat small animals. And large predatory fish prey on herbivorous and smaller predatory fish. Organisms decomposing organic substances (fungi, flagella, bacteria) are widespread throughout the pond. In particular, there are a lot of them at the bottom, since the remains of dead animals and plants accumulate here.
Comparison of two examples
Comparing the examples of biogeocenosis, we see how dissimilar both in species composition and in appearance the ecosystems of the pond and forest are. This is due to the fact that the organisms that inhabit them have a different habitat. In the pond it is water and air, in the forest - soil and air. Nevertheless, the functional groups of organisms are of the same type. In the forest, producers are mosses, grasses, shrubs, trees; in the pond - algae and floating plants. In the forest, consumers include insects, birds, animals and other invertebrates inhabiting the litter and soil. Consumers in the pond include various amphibians, insects, crustaceans, carnivorous and herbivorous fish. In the forest, reducers (bacteria and fungi) are represented by terrestrial forms, and in the pond by aquatic forms. We also note that both the pond and the deciduous forest are a natural biogeocenosis. Examples of artificial we gave above.
Why do biogeocenoses replace each other?
Biogeocenosis cannot exist forever. It is inevitably sooner or later replaced by another. This occurs as a result of a change in the environment by living organisms, under the influence of man, in the process of evolution, with changing climatic conditions.
Example change biogeocenosis
Let us consider as an example the case when living organisms themselves are the cause of a change in ecosystems. This is the settlement of rocks by vegetation. Of great importance in the first stages of this process is the weathering of rocks: partial dissolution of minerals and a change in their chemical properties, destruction. In the initial stages, the first settlers play a very large role: algae, bacteria, scale lichens, blue-green. The producers are blue-green, algae in the composition of lichens and free-living algae. They create organic matter. Blue-green from the air take nitrogen and enrich it is still unsuitable for living environment. Lichens dissolve rock by secretions of organic acids. They contribute to the fact that the elements of mineral nutrition gradually accumulate. Mushrooms and bacteria destroy the organic matter created by producers. The latter are not fully mineralized. Gradually, a mixture of mineral and organic compounds and nitrogen-rich plant residues accumulates. Conditions are created for the existence of bushy lichens and mosses. The process of accumulation of nitrogen and organic matter is accelerated, a thin layer of soil is formed.
A primitive community is being formed that can exist in this unfavorable environment. The first settlers are well adapted to the harsh conditions of the rocks - they withstand frost, heat, and land. Gradually, they change their habitat, creating conditions for the formation of new populations. After herbaceous plants appear (clover, cereals, sedge, bell, etc.), competition for nutrients, light, water is tightened. In this struggle, pioneer settlers are being superseded by new species. Shrubs settle for herbs. They fasten the emerging soil with their roots. Forest communities are replaced by grass and shrub.
During the long process of development and change of biogeocenosis, the number of species of living organisms included in it gradually grows. The community becomes more complex, its food web becomes more and more ramified . The diversity of bonds existing between organisms is increasing. An increasingly full community is using the resources of the environment. So it turns into a mature one, which is well adapted to environmental conditions and has self-regulation. In it, the populations of species are well reproduced and are not replaced by other species. The described change of biogeocenoses lasts for thousands of years. However, there are shifts that occur before the eyes of just one generation of people. For example, this is the overgrowing of small reservoirs.
So, we talked about what is biogeocenosis. The examples described above provide a visual representation of it. Everything we talked about is important for understanding this topic. Types of biogeocenoses, their structure, features, examples - all this should be studied in order to have a complete picture of them.