Effect of planting time and seedling production technology on growth of Scots pine in the Olesnica Forest District experiment

The aim of the study was to compare growth and survival of plug and bare-root seedlings planted at different dates. The experiment was established in 2003 in the Olegnica Forest District (south-western Poland). Seedlings were planted at four dates: the end of August, September and October 2003 and the beginning of April 2004. The two-factorial experiment comprised eight treatments. It was established in the randomized complete block design in five replications. In each plot a total of 390 seedlings were planted. The objects were measured in the years 2004-2008 and 2013. At first height of all trees was measured using a scaled rod. In 2013 diameter at breast height was measured on all trees and height was measured for some randomly selected individuals. The ANOVA was supplemented with with Tukey's multiple comparison test. The height and diameter distributions in analysed variants were compared with Kolmogorov-Smirnov test. Treatments were found rather not to vary in terms of their survival rates (fig. 1). No variation was found for mean diameters at breast height (tab. 1). The difference between the treatment with the maximum (August planting, bare-root seedlings) and minimum (April planting, bare-root seedlings) tree height equaled 69 cm. No significant differences were recorded between mean heights of trees planted in August, September and October regarding the planting material type. Variation in basal area results both from survival rates and diameter at breast height. Only spring planting of bare-root seedlings was found significantly different from all other variants (tab. 1). Differences in height between the control and the mean for the experiment increased continuously (fig. 4). Scots pine seedlings may be successfully planted in late summer and autumn. Under relatively advantageous conditions, particularly moisture levels, 1 year old bare-root pine seedlings are not inferior to plug seedlings. Plug seedlings tolerate soil drought conditions better than bare-root seedlings. The effect of stress connected with drought after planting, measured by mean height, rather than disappearing, is continuously increasing with age.