A study on 34 years development results for douglas fir (Pseudotsuga menziesii (Mirb.) Franco) in İzmit-Kerpe research forest

This study was carried out determine the 34 years development results of Douglas fir plantations which were planted as demonstrative purposes in 31 hectares areas at 4 different division and as 3 provences in 1974 and 1975 by Poplar and Fast Growing Tree Species Resaerch Instute in İzmit Kerpe Research Forest.Firstly, pure douglas fir stands were determined. Later, determining the number of sample plots and their location, diameter and height of the trees were measured. A total of 22 sample plots were taken and 22 trees from each sample plot (400 m2 ) were cut and analysed for annual ring width in order to examine increment and growth differences for the provenances. Analyses of variance were used to determine whether the significant differences between increment and growth. In order to learn which mean values are significantly differences, Duncan?s Multiple Range test used.According to the results, Douglas fir from Washington provenance showed the best development with 19 cm diameter, 20 m height and 357 m3 volume and 10.5 m3 mean annual increment. California provenance showed development 16.4 cm diameter, 17 m height and 244 m3 volume and 7.1 m3 mean annual increment and the lowest values were obtained from Oregon provenance as 16.1 cm diameter, 14.4 m height and 196 m3 volume and 5.7 m3 mean annual increment.It might be concluded that, the main reason for these different values were provenance differences among the origins according to the previous studies and the this study. From this point of view, it can be suggested that the best provenance for our country is Washington origin.