The coexistence of different species and life forms in a community leads to their spatial isolation, which manifests itself in the division of the phytocenosis into separate parts that perform a specific function in the general circulation of substances and the conversion of energy. The spatial structure of the community is being formed.
Vertical structure – tiered
In terrestrial biocenoses, plants of different heights play the main role in the formation of the vertical structure. They make up tiers, which are formed by aboveground or underground parts of different plants.
Layering is especially clearly expressed in forest phytocenoses, where there are usually 5–6 layers: arboreal layers of tall and low trees, undergrowth consisting of shrubs, a layer of grasses and shrubs, a layer above the soil of mosses and lichens, and forest litter.
Other communities (meadow, steppe, swamp) consist of two or three tiers.
The layering of the phytocenosis ensures a more complete use of natural resources. Plants of different tiers find themselves in different conditions of existence. This leads to a decrease in the severity of competition and an increase in the number of species inhabiting the biocenosis.
The animal population of the community, “attached” to plants, is also distributed over the tiers.
Example: the microfauna of soil animals is richest in the litter. Different birds build nests and feed in different tiers – on the ground (wagtail), in bushes (robin, nightingale), in tree crowns (rooks, magpies).
Horizontal stratification of the community – mosaic
Horizontally, the community is also divided into separate elements – microgroups, the location of which reflects the heterogeneity of living conditions. This is especially clearly seen in the structure of the ground (ground) cover – in the presence of a “mosaic” of various microgroups.
Example: bumps or clumps of grasses, shade-tolerant grasses under trees, patches of moss or bare ground, light-loving grasses in the “windows” of forest glades.
The distribution of organisms in space reflects the variety of ways living organisms use the resources of the environment and, to a certain extent, shows the resistance of the community to changes in the conditions of existence.