Ecologists are worried not only because of the massive felling of trees. As it turned out, too dense green zones are also unsafe, as they can lead to drought.
"The forest is the lungs of the planet" - they taught us in school, so they must be protected and protected. But what will happen if there are too many forests? Large amounts of green plantations on a limited plot of land can trigger the drying of the soil. Why? Whether it is necessary to explain, what for to plants to the moisture which they receive from depth. With water, trees receive nutrient components. Moreover, without it, the flow of most biochemical processes is impossible.
But such processes consume about 1% of moisture coming through the root system. The rest of the water evaporates through the leaves - without this phenomenon, called transpiration, the tree also can not exist. A constant circulation of moisture ensures its presence in plant tissues, allowing it to circulate from the lower to the upper sections.
Now, environmentalists propose to imagine that in some arid area where there is a lack of moisture, green areas grow. The mass of plantations sends huge volumes of water into the atmosphere. It is not known when this water can return to the soil with precipitation. If the region is characterized by long dry seasons with complete cessation of precipitation, large forests can turn into big problems.
An example can be the forests growing on the California range of Sierra Nevada. Scientists representing the University in Merced analyzed the change in total transpiration in green areas in the Kings River and American River basins over an 18-year period. Further, ecologists compared the volumes of evaporation of moisture and the dynamics of forest fires.
It turned out that in those times when strong fires occurred in the forests, the saving of fresh water by the ecosystem was more pronounced. If the forests burned less often, then the economy became smaller (correspondingly, 17 billion tons of water and 3.7 billion tons annually). In general, for eighteen years the water supply of the Sierra Nevada rivers in arid years increased by 10% - due to the thinning of forest areas by fires.
Mankind has become accustomed to assess forest fires only from a negative point of view. But in fact, according to scientists, this is a kind of natural selection, necessary for the stabilization of the ecosystem. Of course, too frequent ignition is in any case not good. But the lack of such makes the forests too tight, and the dry period can become even drier, because a huge mass of plantations sends tons of moisture into the atmosphere.
Thus, the timely thinning of forests will lead to the filling of local rivers and other water bodies, and the drought period will be more comfortable, first of all, for the forest dwellers themselves.
The problem is described on the pages of Ecohydrology (https://onlinelibrary.wiley.com/doi/10.1002/eco.1978).