The trees in the snow-covered forest seem dead and completely lifeless. However, this is not the case. Even in severe, crackling frosts, life does not leave these majestic plants. In winter, trees rest and accumulate energy in order to throw off the winter shackles with the onset of warm days.
How trees endure winter
With the onset of winter, the trees become dormant. The metabolism inside the trunk is inhibited, the visible growth of trees is suspended. But life processes do not completely stop. During the period of long winter dormancy, mutual transformations of substances occur, albeit with a much lower intensity than in summer (Journal of Chemistry and Life, Plants in Winter, VI Artamonov, February 1979).
Trees grow in winter, although outwardly it practically does not appear. In the cold, the so-called educational tissue actively develops, from which new cells and tissues of the tree subsequently arise. In deciduous trees, leaf buds are laid in winter. Without such processes, the transition of plants to active life with the arrival of spring would be impossible. The phase of winter dormancy is an indispensable condition for the normal growth of trees during the growing season.
The ability of trees to plunge into a state of dormancy developed during a long evolution and became the most important mechanism of adaptation to unfavorable and harsh external conditions. Similar mechanisms are included in other difficult periods of the life of trees, including in summer. For example, in severe drought, plants can shed their foliage and almost completely stop growing.
Features of winter dormancy in trees
The signal for the transition to a special winter state for most trees is a reduction in the length of daylight hours. Leaves and buds are responsible for the perception of such changes. When the day is noticeably shortened, in plants there is a change in the ratio between substances that stimulate the processes of metabolism and growth. The tree is gradually preparing to slow down all life processes.
The trees remain in a state of forced dormancy until the end of the winter period, gradually preparing for full awakening. If you cut a birch branch in the forest at the end of February and place it in water in a warm room, after a while the buds will swell, preparing to sprout. But if a similar procedure is done at the beginning of winter, the birch will not bloom for a very long time, because it is already completely ready for rest.
The duration of the winter dormancy period is different for different types of trees and shrubs. In lilacs, this period is very short and often ends by November. In poplar or birch, the deep dormancy phase lasts much longer, until January. Maple, linden, pine and spruce are capable of being in a state of deep forced dormancy for four to six months. After wintering, trees slowly but steadily begin to restore life processes, resuming their growth.