What explains the longline structure of phytocenoses?

An important ecological property and sign of a community is its spatial composition – morphological structure. This applies primarily to plant communities (phytocenoses), but also indirectly – and to the animals inhabiting them (zoocenoses).
The joint existence of different species and life forms in the community leads to their spatial isolation. This is expressed in the horizontal and vertical division of the phytocenosis into separate elements, each of which plays a role in the accumulation and conversion of matter and energy.
Vertically, the plant community is divided into tiers in which the aboveground or underground parts of plants of certain life forms are located. This layering is especially pronounced in forest phytocenoses. There are usually five to six tiers: tree tiers (tall and low trees), shrub (undergrowth), grass-shrub, mossy (or lichen), litter (leaf litter). Small-tier communities – meadow, steppe, swamp – have two or three tiers.
The longline structure of the phytocenosis gives plants the opportunity to more fully use the resources of the environment, especially light, heat and moisture. Plants of different tiers live in different environmental conditions, which reduces competition between them and contributes to an increase in species diversity. The more favorable the habitat conditions, the more difficult the layering.
The animal population of the biocenosis, “attached” to plants, is also distributed in tiers. For example, the microfauna of soil animals is most abundant in the litter. Certain groups of insects are fairly clearly confined to the tiers. Different types of birds build nests and feed in different tiers on the ground, in shrubs, in the crowns of trees.
Horizontal community is also divided into individual elements – microgroups, the location of which reflects the heterogeneity of living conditions.