SYSTEMATIC MONITORING OF THE CONVERSION OF PEDUNCULATE OAK (Quercus robur L.) AND SESSILE OAK (Quercus petraea L.) SEEDLINGS WITH REGARD TO DIFFERENT PLANTING METHODS

The research was carried out in the lowland region at a distance of about 3 km from the Drava River at an altitude of 190 m, in an area where mostly spruce, white pine and black locust are planted, although the habitat is suitable for planting and growing oak. Considering the changed ecological and climatological conditions, an experimental plot of 2.00 ha was established. Three-year-old (2 + 1) seedlings of pedunculate oak (Quercus robur) and sessile oak (Quercus petraea) were planted on the plot according to two different methods. The first group was planted at a distance of 3 x 3 m in polypropylene shelters. The second group was planted at a distance of 2 x 2 m in the regular way (without the shelters). The entire area was divided into 24 plots of approximately the same size. Each plot contained only one tree species. The arrangement of species alternated between the plots. A randomized block design was used, with 4 blocks and 3 replicates. Tree heights were measured for 5 consecutive years not during the growing season. Breast height diameters were measured at the end of the observed period. The impact and intensity of powdery mildew has been observed for three years during the summer months. The aim of the research is to study the growth and development of pedunculate oak and sessile oak seedlings in an area where these species were not commonly grown, although there are adequate ecological and economic conditions. After 5 years of measurement, the number of plants was reduced by 14%. In pedunculate oak the number of trees was reduced by 4 to 8%, and in sessile oak by 17 to 22%. The height and breast height diameters of the trees grown within the shelters were significantly higher regardless of the tree species. The height and breast height diameter of pedunculate oak trees was significantly larger than of sessile oak trees. No correlation was found between tree height and the presence of powdery mildew.