Structure of the biocenosis

Each organism lives in the environment of others, have diverse relations with both negative and positive consequences for themselves and ultimately can not exist without this living environment.

Interaction with other organisms is the necessary condition for nutrition and reproduction, the possibility of protection, mitigation of adverse environmental conditions, and on the other hand, it is danger of harm and often even immediate threat to the existence of the individual.

The immediate living environment of the organism is its biocenotic environment. Representatives of each species are able to exist only in such living environment where connections with other species provide them with normal living conditions. In other words, diverse living organisms are found on the Earth not in any combination, but form certain cohabitations, or communities, which include species adapted to co-habitation.

Groups of coexisting and mutually related species are called biocenoses (from Latin "bios" - life, "cenosis" - common).

The concept "biocenosis" is one of the most important in ecology. This term was proposed in 1877 by the German hydrobiologist K. Mobius. The study of the regularities of the addition and development of biocenoses led to the uprise of the special division of the general ecology - biocenology.

The scale of biocenotic groupings of organisms is very different, from communities of lichen cushions on tree trunks or decaying stumps to the population of whole landscapes: forests, steppes, deserts, etc.

The structure of any system means regularities in the relationship and connections of its parts. The structure of the biocenosis is multifaceted, and the different aspects are distinguished in its study.

There is distinction between such concepts as "species wealth" and "species diversity" of biocenosis.

Biocenoses could be poor and rich in species. What is more the species composition of biocenoses depends on duration of their existence, and history of each biocenosis. Young, emerging communities usually include a smaller set of species than long established, mature ones. Biocenoses created by man (fields, gardens, vegetable gardens) are also poorer in species than similar natural systems (forest, steppe, meadow). The uniformity and species poverty of agrocenoses are supported by special complex system of agrotechnical measures - control of weeds and pests of plants.

Almost all terrestrial and most aquatic biocenoses include microorganisms, plants, and animals. However, under certain conditions, biocenoses are formed in which there are no plants (for example, in caves or water bodies below the photic zone), and in exceptional cases - consisting only of microorganisms (for example, in an anaerobic environment at the bottom of reservoirs, rotting ooze, hydrogen sulphide sources, etc.).

The species of the same dimensional class which are part of a single biocenosis vary greatly in number. Some of them are rare, others are so frequent that determine the external appearance of the biocenosis. Species prevailing in numbers are the dominants of the community. Among them there are those which by their vital activity create the environment for the entire community, and without which the existence of most other species is impossible. Such species are called edificators (literal translation from Latin - builders). The main edificators of terrestrial biocenoses are some plant species: in spruce forests - spruce, in pine forest - pine, in the steppes - sod grasses (stipas, fescue grass, etc.).

That part of the abiotic environment that the biocenosis occupies is called the biotope, i.e., the biotope is the habitat of the biocenosis (from Latin bios - life, topos - place).

The spatial structure of terrestrial biocenosis is determined primarily by the addition of its plant part - phytocenosis, distribution of upper and underground masses of plants.

During the cohabitation of plants, different in height, the phytocenosis often acquires a clear tiered layering. For example, the vertical layering of a forest: layers from top to bottom consist of the upper canopy, the low-tree layer, the shrub understory, the ground layer of herbaceous plants, the forest floor, and the root layer.