Hydromelioration in Forestry: History of Research

Abstract

Wetlands cover more than 220 mln ha of Russia’s forests. Swamps alone represent more than 100 mln of them. There are low-quality and low-yield stands on waterlogged areas. Much of such land is treeless. Many years of hydromelioration have shown the possibility of growing here high-quality stands of natural or artificial origin. The Lisino training and experimental forest serves as an example. Earlier in Lisino out of 28 ths ha normal stands covered 25–30% of the area; swamps – more than 30 %, a significant part of them was treeless. Currently, after hydromeliation, swamps represent slightly more than 4 % of the territory. There are significant, but largely ad hoc, studies of drainage efficiency in forestry practice. This article considers multi-year studies carried out simultaneously in stands of different composition and age, which allowed defining the features that determine the silvicultural effect of drainage. The forestry efficiency of drainage largely depends on the drainage rate – the degree of lowering of the groundwater level by drainage channels. After hydromelioration, there is always an increase in stand growth, however, the efficiency of drainage and the volume of stand growth is determined by the abundance of peat, the type of swamp, which is predictable by the ash content of peat. Multi-year studies on stationary lands have shown that it is possible to grow stands of the I quality class with a stock of up to 500–600 m3/ha on abundant eutrophic swamps. It was found that the drainage efficiency also depends on the stand initial composition. In relatively single-age stands, which are rich in composition, growth is also higher; in mixed-age stands, old trees may fall off and, therefore, growth is likely to decrease temporarily. Studies have shown that in mixed stands the efficiency of drainage is increased by regulating the stand composition by improvement thinning.