DIAMETER STRUCTURE AND HEIGHT OF TREES DYNAMICS OF FIR (Abies alba Mill.) AND SPRUCE (Picea abies Karst.) STANDS IN MANAGEMENT UNIT „IGMAN“(permanent sample plots 43 and 58)
UDK: 630*52:630*24(234.422 Igman) This paper analyses the dynamics of diameter structure and height curves as the main indicators of a simple stand structure, uneven-aged multi-storied fir and spruce stands in the management unit „Igman“ where selective felling is applied based on the principle of positive selection. The data for analysis was collected by periodical measurement during fifty years on two permanent sample plots, forest sections 43 and 58. It has been determined that during the observation period there had been a change in diameter structure in the sense of increase in the proportion of trees in the lower, and decrease in higher diameter classes as well as the increase of tree height in the complete interval of empirical data. It has been concluded that due to selective felling, with higher diameter classes trees included, conditions have been created for the occurrence of new and the development of the existing young crop; diameter structures of a shape characteristic for even-aged stands have gradually assumed the shape characteristic for selective stands. Thus, due to the increase of competition among the trees of lower diameter classes and the felling of lower height and lower quality trees of higher diameter classes, there has been an increase in the height of trees of the same diameter.