Production potential of Douglas fir at mesotrophic sites of Křtiny Training Forest Enterprise

: The study evaluates production parameters (height, diameter at breast height, volume) of Douglas fir (Pseudotsuga menziesii [Mirb.] Franco) at mesotrophic sites of the Křtiny Training Forest Enterprise in mature stands. In total, 29 mixed stands were assessed with the registered proportion of Douglas fir at an age of 85 to 136 years. Comparing the 10 largest Douglas firs with the 10 largest spruces or larches higher, and as a rule markedly higher, production potential of introduced Douglas fir was found in all assessed stands. There were also groups of trees where the volume of Douglas fir was twice to 3 times higher than the volume of spruce or larch (see Tabs. 5 to 10). For example, in stand 177B11, the mean volume of 9.12 m3 was recorded in the 10 largest Douglas fir trees but the volume of spruce reached only 3.17 m3 and the volume of larch was 3.70 m3. Differences in mensurational parameters of Douglas fir found on the one hand and of Norway spruce (Picea abies [L.] Karst.) or European larch (Larix decidua Mill.) on the other hand compared by ANOVA tests were statistically highly significant. Annual ring analyses have shown that at present the volume increment of particular Douglas fir trees ranges from 0.12 to 0.16 m3 per year in mature stands (i.e. about 1.5 m3 every 10 years).