Model składu gatunkowego drzewostanu dla lasów w Sudetach z uwzględnieniem zmian klimatycznych

Climate change creates a big challenge for forest science. One of several problems calling for urgent solution concerns the elaboration of the scientific foundations for determination of the species composition of forest stands under changing environmental conditions. This problem is particularly acute in case of declining Norway spruce stands in the Sudety Mountains (SW Poland). The paper presents the main principles used to develop a model allowing determination of the most desirable species composition for any given forest stand occurring in the Sudety region. These principles include: 1) an assumption that a basis for species composition planning should be a forest site type, corrected by means of site index of the currently existing forest stand, 2) a supposition that one should broadly consider present processes taking place in Sudety stands, particularly, an intense forest dieback caused by recurring drought periods and strong winds, 3) a postulate that one should consider the differences between tree species in respect to their reaction to particular abiotic factors, 4) an assumption that majority of stands should consist of several different tree species, 5) an assumption that introducing on a wide scale Douglas fir, well−adapted to the conditions of the Sudety Mountains, is allowed, 6) an idea that one should take into account differentiated production potential and varied timber quality of particular tree species, 7) an assumption that one should consider the main features of topography (altitude, exposition, slope) as well as 8) fine elements of micro−topographical situation, as a basis for introduction of different tree species. The results obtained by means of the model based on the above mentioned principles are presented on the example of two forest districts: Lądek−Zdrój (fig. 4a, b) and Szklarska Poręba (fig. 5a, b). In both cases, a necessity to diminish the share of Norway spruce and to increase the share of such species like common beech, silver fir, Douglas fir and European larch is demonstrated. One may expect that projected compositions, taking into account the most appropriate tree species and their most suitable localizations, will allow establishment of forest stands which will be more resistant to drought and wind and, thus, will be more able to fulfill several important forest functions (related to water and soil protection, protection of forest biodiversity and timber production).