Biocoenosis - examples. Natural and artificial biocenoses

In the process of everyday life, not all people notice their interaction with various natural complexes. Hurrying to work, hardly anyone, except perhaps a professional ecologist or biologist, will pay special attention to the fact that he crossed the park or park. Well passed and passed, what from that? But this is already a biocenosis. Examples of this involuntary, but constant interaction with ecosystems, each of us can remember, if only think. We will try to consider in more detail the question of what are biocenoses, what they are and what they depend on.

What is biocenosis?

Most likely, very few people remember that he studied biocenosis at school. Grade 7, when the biology of this topic is, was far in the past, and quite different events are recalled. Recall what is a biocenosis. The word is formed by the fusion of two Latin words: "bios" - life and "cenosis" - common. This term denotes the totality of microorganisms, fungi, plants and animals that live in one territory, interconnected and interacting among themselves.

Any biological community includes such components of the biocenosis:

• Microorganisms (microbiocenosis);
• Vegetation (phytocenosis);
• Animals (zoocenosis).

Each of these components plays an important role and can be represented by individuals of different species. However, it should be noted that phytocenosis is the leading component determining microbiocenosis and zoocenosis.

When did this concept appear?

The concept of "biocenosis" was proposed by the German hydrobiologist Möbius at the end of the XIX century, when he studied the habitats of oysters in the North Sea. During the study, he established that these animals can live only in strictly defined conditions, characterized by depth, flow velocity, salinity and water temperature. In addition, Moebius noted that together with oysters in one territory, strictly defined species of marine plants and animals live. Based on the data obtained, in 1937 the scientist introduced the concept we are considering to denote the unification of groups of living organisms that live and coexist in one territory, owing to the historical development of species and prolonged natural selection. The modern concept of "biocenosis" biology and ecology is interpreted somewhat differently.

Classification

Today, there are several signs that it is possible to classify a biocenosis. Examples of classification based on size:

• Macrobiocenosis (sea, mountain ranges, oceans);
• Mesobiocenosis (swamp, forest, field);
• Microbiocenosis (flower, old stump, leaf).

Also, biocenoses can be classified according to their habitat. The following three types are recognized as main ones:

• nautical;
• freshwater;
• Ground.

Each of them can be divided into subordinate, smaller and local groups. Thus, marine biocenoses can be subdivided into benthic, pelagic, shelf and other. Freshwater biological communities are river, marsh and lake. Ground biocoenoses include coastal and inland, mountain and plain subtypes.

The simplest classification of biological communities is their division into natural and artificial biocenoses. Among the first allocate primary, formed without human influence, as well as secondary, which have undergone a change due to the impact of natural elements or the activities of human civilization. Let us consider in more detail their features.

Natural biological communities

Natural biocenoses are associations of living beings created by nature itself. Such communities are natural systems that develop, develop and function according to their own specific laws. German ecologist V. Tischler highlighted the following features that characterize such entities:

1. There are communities of ready-made elements, which can act as representatives of individual species, and whole complexes.

2. Certain parts of the community can be replaceable. Thus, one species can be superseded and completely replaced by another, having similar requirements to the conditions of existence, without negative consequences for the entire system.

3. Due to the fact that in the biocenosis the interests of different species are opposite, the entire superorganism system is based and exists due to the balancing of oppositely directed forces.

4. Each natural community is built on the quantitative regulation of one species by others.

5. The dimensions of any superorganismic systems depend on external factors.

Artificial biological systems

Biocenosis artificial are created, maintained and controlled by man. Professor BG Johansen introduced the concept of anthropocenosis into the ecology, that is, artificially created by people of the natural system, for example, a square, a terrarium or an aquarium. Among the artificial biocenoses are allocated agrobiocenoses (agrocenoses) - communities created by man for obtaining any products. These include:

• Reservoirs;
• Channels;
• Ponds;
• Drained swamps;
• Pastures;
• Fields for cultivation of various agricultural crops;
• Forest shelter belts;
• Artificially renewed plantations.

Typical features of agrocenoses are:

Such artificial systems are environmentally rather unstable, and without human participation, the agrocenosis of vegetable and grain crops will last about a year, agrobiocenoses of perennial grasses will last about three years. The most resistant to biocoenosis are artificial fruit crops, since without human exposure they can exist for several decades.

• Agrophytocenosis as the basis of vital activity;
• Lack of system self-regulation;
• Low species diversity;
• Domination of domestic animals or cultivated plants;
• Obtaining additional support from a person (control of weeds and pests, fertilization, etc.);
• The impossibility of a long existence without human participation.

However, it should be noted that even the poorest in the species diversity of agrocenoses have dozens of species of organisms belonging to different ecological and systematic groups. Any field, sown by man fodder or crops, is a biocenosis inhabited by different living organisms. Examples - this is the field of rye or wheat, where, in addition to the main crop, "weeds" also live; And various insects (both pests and their antagonists); And many microorganisms and invertebrates.

Structural units of biosystems

As already mentioned, natural and artificial biocenoses consist of several stable structural components, such as phytocenosis, zoocenosis and microbiocenosis. Leading among them is phytocenosis, which is a stable community of plants. Due to its fixedness and immobility, it serves as a relatively permanent basis for the structure of the biological system. Microorganisms, unlike plants, are not attached to any part of the surface and can be transported by wind or water over fairly long distances. The interconnection of the components of the biocenosis is manifested in the dependence of animals on plants, since only representatives of the flora can convert inorganic substances into organic substances.

A large role in the life of any biocenosis is played by a variety of microorganisms that contribute to the transformation of dead organic matter into minerals.

Structure of biological systems

Each biocenosis is characterized by a certain structure:

• Spatial, vertical or horizontal, resulting from the development of the species of space of the biological community and is the result of competing relationships for energy sources.
• Species, determined by the composition, richness and diversity of elements of the biosystem, and by the ratio of the number of all the populations entering it. The types of biocenosis, having the greatest quantitative representation, are called dominants.
• Trophic or food, which is determined by food chains between organisms.

All the various structural aspects of biocenosis are closely interrelated. As a rule, the more complex the spatial structure is organized, the richer and more diverse is its species representation. Over time, the structure of the biocenosis changes in insignificant limits. Such a state of relative stability, arising during the interaction of constituent elements, is called homeostasis.

Let us examine in more detail the main structures characterizing biocenosis.

Spatial structure

Biocoenosis has its own structure in space, which can be either vertical or horizontal.

Vertical structure is formed as a result of the distribution of different species of plants and animals at different altitude levels of the biosystem, which leads to the formation of longline. Such a system is largely determined by the stratification of the plant community, namely the horizons of the location of the most productive parts of plants, such as the root system and photosynthetic foliage. For phytocenosis is characteristic of both above-ground and underground stratum. The first is manifested in the possibility of joint growth of a variety of plant species that have a different need for sunlight. This is most pronounced in the forests of the temperate climatic belt, where there are tree and shrubby upper layers, slightly below the semi-shrubs and grasses, and directly above the surface of the earth is the above-ground stage, usually consisting of mosses or lichens.

Underground stratification in biological systems allows phytocenosis to make full use of soil moisture, thanks to the varying depth of the root system of plants. Steppe regions are characterized by a three-level arrangement: the most deeply embedded root systems, then the roots of various cereal crops, and quite close to the surface - tubers, bulbs and root systems of annual plants.

The reflection of the horizontal structure of the biocenosis is a sinusia - part of the phytocenosis, consisting of plants of one or several closely related species, ecologically or spatially separated from each other. They can be temporary or permanent, epiphytic, longline or intrasoil.

Species structure of biological communities

A distinctive feature of any biocenosis is its specific structure. The complexity and diversity of species composition is largely determined by the habitat and the degree of complexity of the conditions in which biocenosis exists. Examples of poor species diversity - highlands, tundra, deserts. Biosystems with a rich set of species - coral reefs and tropical forests.

Biological species, predominant in number, are a species core and are called dominant. So, in a birch forest it will be a birch, on a wheat field - wheat. In any biocenosis there are species that exist only due to dominants, these are the so-called "pre-dominants", for example, roe deer in a forest undergrowth or a squirrel in a pine-spruce forest.

In addition, in biological communities there are edificators, that is, animals or plant species that create the necessary conditions for life to other beings. So, for example, in steppe biocenoses the most powerful edificator is the feather grass.

In order to assess the role of a species in the structure of the biological community, quantitative accounting indicators such as abundance, frequency, Shannon diversity index, and species saturation are used.