Part 11
We've already talked about the fact that all trees without exception can multiply seeds. But for some it is the only way to leave offspring (almost all conifers), other trees can breed not only with seeds, but also in a vegetative way (almost all deciduous). Their biological possibilities are much wider and they have a better chance of leaving their offspring. What are the ways of vegetative propagation of trees? They are quite diverse. One of them is with the help of the branches. The point is that the lowest branches of adult trees, lying on the ground, take root and give rise to vertical shoots. And these shoots can then grow into new trees. Another way is root offspring. In this case, the new daughter species grow from the horizontal roots of the mother tree. A classic example is aspen. Finally, vegetative reproduction can also occur due to growth from the root neck of an adult tree.
So far, we have only talked about the reproduction of trees in nature, i.e. in their natural development. We have considered the potential biological possibilities of reproduction, which are realized if necessary. Now let's see how the trees are restored vegetatively after felling. Our coniferous trees have no recovery in this case. Neither pine, spruce, fir, nor larch trees give rise to stumps; they do not have this ability. This is not the case with deciduous trees. After felling on fresh stumps, young shoots usually appear, which then grow into adult trees. Stump pigs form, for example, oaks and lindens, maples and ash, elms and birch trees. But there are exceptions. Some deciduous trees do not have the ability to recover in the way described above. The most typical example is the common aspen. It almost never gives rise to stump growth. However, this resilient tree is perfectly restored after felling. And this happens due to the root offspring. They grow from the roots of the felled mother tree. On clearcuts one can often see a real thicket of young aspen shoots rising from the ground. They grow rapidly and eventually turn into trees. The stumps, on the other hand, remain naked and devoid of any growth. Something similar can be observed in grey alder. However, alder is not as energetic as aspen, forming new shoots from the roots, they appear in a much smaller number.
It is necessary to say a little about the attitude of our trees to light. The light factor plays a very important role in the life of the forest and forest plants. It is for the light that the most intense competition between trees is most often for the light.
Different species of wood have completely different requirements for light, and each of them in this sense is individual, unique. But there are still two groups of trees that are light-loving and shady. The first group includes all types of larch, various types of birch, as well as ordinary pine, aspen, etc. All these trees need full access to light. When shaded, they grow badly and die more or less quickly. Shade-treated trees are the exact opposite of light-loving trees. They are satisfied with little light and tolerate shading. These are, for example, different types of spruce and fir, and linden is finely leafed. Some of them simply surprise with their extreme resistance to shading: lime-tree, for example, is so shady that it grows even under the canopy of a thick spruce forest, where it is very dark. However, in these conditions, it does not look like a tree, but rather like a shrub.
The attitude of a tree to light can be judged first of all by the density of its crown. Light-loving tree species have very loose, openworked crowns (at least remember the birch), while shady species have very thick, dense (spruce, fir) crowns. To a certain extent, the bark thickness (or crust) of adult specimens is also related to the ratio of the tree to light. Light-loving tree species usually have thicker bark (pine, larch, birch), while shady species have thinner bark (spruce, fir).
Coniferous tree species have some connection between the degree of light-loving of the tree and the longevity of individual needles. For example, a particularly light-loving larch has only a few months of life (from spring to autumn), while a pine tree is usually 2-3 years old. Shady spruce has a much longer period of time - 5-7 years. The fir, which is even more shady, has a lifespan of 10-12 years.
There are, of course, some other signs, which are related to a certain degree of exactingness of the tree to the light. Thus, light-loving wood species grow much faster in their youth than shady ones. Young pines, birches, larches rise up quickly, and firs and spruce at a young age "sit" for a long time, growing little in height.
The continuation should be...