Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

Abstract The purpose of this study was to recognize the thermic and pluvial factors affecting the radial increment of partial populations of Douglas-fir growing in the Polish Carpathians. The investigated trees were growing in 12 localities situated in the area from the Silesian Beskid to Bieszczady and the eastern part of the Carpathian foot-hills (Fig. 1). In each locality increment cores were taken from 25 healthy trees. The relationship between the tree-ring width and temperature, as well as precipitation, were analyzed by a linear correlation and multiple regression – response function [Fritts 1976]. It was found that in spite of similarities in the course of chronologies (Fig. 2, 3, Tab. 1), as well as in the models of associations climate-increment (Fig. 6), of different populations of trees there are differences in their susceptibility to thermic and pluvial conditions prevailing in respective regions of the Carpathians. These differences are connected not only with the specific climate associated with the geographic location, but also with microclimatic conditions of the place of their growth. The air temperature of winter (January-March) is the factor having the strongest influence (Fig. 4, 5). While the air temperature and precipitation of summer (July-August) is the main factor differentiating the increment rhythm of Douglas-fir (Fig. 4, 5). However, Douglas-fir seems to be the species which has been well adapted to climatic conditions of the Carpathians, in spite of the fact that even when mature it is susceptible to winter frosts, dry growing season, and deficiency of warmth in summer (Fig. 6).