Forest dieback process in the Polish mountains in the past and nowadays – literature review on selected topics

Mountain forests constitute one of the most diverse ecosystems, not only in Europe but also all over the world. Mountain ranges, which frequently encompass multiple countries, constitute a unique link between various natural areas, which are very often completely different from the historical point, or which are characterized by different use and management types. Although the role of mountain forests is relatively well recognized nowadays, in the distant past, these areas were poorly penetrated, mainly due to the unfavourable climate and natural topography, which discouraged not only from settling down but also from moving around. Despite the fact that mountains had been the object of interest of mining, weaving, and glassmaking industries for hundreds of years, dramatic changes in the stands in these areas were sealed by the industrial revolution in the 18th and 19th centuries. The purpose of this paper is the analysis of forest dieback process in the mountain ranges of Sudetes and Western Carpathians placed in Poland. Stress factors have been divided into three main groups, however, it should be remembered that it is a very simplified division and some factors could be partially found in the anthropogenic, as well as biotic, and even abiotic factor groups. Neither the beginning nor the end of deforestation process was defined precisely in the study, which was deliberate in taking into account constant changes in the ecosystems. Generally, three periods may be distinguished here, regarding the spruce forests dieback process. Typically anthropogenic deforestation, caused by the industrialization of the areas during the industrial revolution and earlier, deforestation in the years 1970–1980 and partially before the year 2000 (Western Carpathians) caused by a set of various stress factors and the latest period, that is, generally understood climate change. The last several years have particularly contributed to the expansion of detailed knowledge about the dependencies and the influence of abiotic, biotic, and anthropogenic factors on the health condition of spruce trees. Although models have already been developed, which describe the course of insect outbreaks, the growth and health condition of spruces, or climate factors, no model has been developed so far that would allow to depict the process of hitherto deforestation, and to enable modelling the forthcoming changes. It seems that the development of such tool, not only from the forest management point of view, would constitute a milestone on the way to precision forestry.