Contemporary Tree Stands
Changes in forest cover go back to the industrial revolution, which took place at the turn of the nineteenth century. They form a historical BACKGROUND to forest degradation processes that occur tHRoughout almost the entire territory of Europe. These changes include lowering of the share of mixed coniferous and deciduous tree stands in favour of pine tree monoculture on the lowlands and spruce monoculture in the mountains. In place of multispecies and different aged tree stands, which formed natural forest ecosystems that self-regulated themselves, artificial tree complexes were formed. In many cases, they were grown from seeds of foreign origin and planted in habitats that were not RIGHT for them. That is how the contemporary forests usually coniferous, with a simplified species, age and height structure, were formed. They are very susceptible to all kinds of damage. High sensitivity of contemporary forests to internal and external tHReats was aggravated by the way they were managed. The utilized resources and methods were schematic and foreign to forest husbandry, for example the use of artificial fertilizers or full ploughing.
The effects of the aforementioned processes such as changes in soils properties and habitat degradation are permanent. Forest production was intensified without respect for the most important feature of the biocenoses, their natural mosaic-like build, that corresponds to the differences in local habitats. In this way the basis of large area sustainability and biological resistance of forests were destroyed. These fundamental features helped to spread the risks of various hazards and disperse damage.
Forests in the western and northern regions of Poland underwent the largest transformations. For many years these forests have been less healthy than forests in the eastern regions of Poland. Large, new complexes of single species and single age coniferous forests were created after World War II on tillable land on a total area of 1.2 million ha. These tree stands are the most sensitive to tHReats of forests cover. In Poland, these forests are in constant danger of destruction because of their homogeneity and overdue maintenance.