Tiers biography

The tiers of forest tiers are forests of forests of forest plants have its own characteristics. The trees forming the forest grow more or less closely, affecting each other and the rest of the forest vegetation. Plants in the forest are arranged by tiers that can be compared with floors. The upper, first tier is represented by the main trees of the first degree of significance of spruce, pine, oak.

The second tier is formed by trees of the second magnitude of the bird cherry, mountain ash, apple tree.

The third tier consists of shrubs, for example, rose hips, hazel, viburnum, birch bark. The fourth tier is a grassy cover, and the fifth is mosses and lichens. Light access to plants of various tiers is not the same. The crowns of the trees of the first tier are better illuminated. From the upper to the lower tiers, the illumination decreases, since the plants of the upper tiers are delayed the fraction of sunlight.

Mosses and lichens occupying the fifth tier receive a very small amount of light. These are the most shade -tolerant forest plants. Different forests have a different number of tiers. For example, only two or three tiers are distinguishable in the dark spruce forest. On the first tier there are the main trees of spruce, on the second - a small number of herbaceous plants, and the third is formed by mosses.

Other woody and shrub plants do not grow in the second tier of the spruce forest, as they cannot stand strong shading. Also not observed in a spruce forest and grassy cover. The tier arrangement is characteristic not only for the aboveground parts of plants, but also for their underground organs - roots. Tall trees have roots deeply penetrating the ground, while the root system of trees of the second tier is smaller and forms conditionally the second tier of the roots.

The roots of other forest plants are even shorter and are located in the upper soil layers. Thus, plants in the forest are absorbed by nutrients from different soil layers. Trees of the first size of oaks, pine, spruce are closed with their crowns and form the canopy of the forest, under which a small share of sunlight penetrates. Therefore, herbaceous forest plants are usually shade -tolerant and have wide sheet plates.

Many of them do not withstand the effects of direct sunlight and can die in open space. A feature of herbs of a broad -leaved forest is flowering in early spring, when there are no foliage on the trees. With the help of wide leaves, the forest plants accumulate organic substances in low light and put them in the underground organs, for example, Medunitsa in rhizomes.

In gloomy spruce thickets, the flowers of herbaceous plants have white corolla so that they are visible from afar. For example, such flowers have lily of the valley, pears, weekly, dreams, mining. But, despite these devices, the flowers of forest herbs are often not pollinated and do not form seeds. Therefore, the propagation of many herbaceous plants is carried out by dividing rhizomes, for example, in a sour, lily of the valley, purchased, weekly, a mining.

This explains the placement of these herbs in the forest in groups. The forest litter covering the soil consists of fallen leaves or needles, respectively, in deciduous or coniferous forests, as well as from the cortex and branches of trees, dead sections of herbs, mosses. Loof forest litter is wet, which is favorable for the development of mold and hat mushrooms. Mushrooms of various mushrooms thoroughly pierce the litter thoroughly, gradually converting organic substances into humus and mineral salts for the nutrition of green plants of the forest.