The thesis presents the results of analysis of growth characteristics of the silver birch tree (Betula pendula Roth.) and aspen tree (Populus tremula L.) in abandoned agriculture areas in Suha krajina. 10 plots measuring 30 × 30 m have been put up, five plots in the stands dominated by birch tree and five dominated by aspen tree and the measurement of trees has been carried out. On each plot, 5 dominant trees of the target species have been cut down, namely 25 birch trees and 25 aspen trees, the stem analysis has been made and inner defects of the stems have been established. Lawfulness of height, diameter and volume growth and production capacity have been found on growth sites Hedero-Fagetum and Querco-Carpinetum. The results showed that the aspen tree on the white hornbeam site reaches greater heights than the birch tree, whereas on the beech site they both show identical growth. The aspen tree has, in comparison with the birch tree, faster volume growth on both sites. There are small growth differences in the diameter growth in both pioneer species. Very large crowns show influence on faster thickness and volume growth of the birch tree. The analysis of site productivity showed differences between the plots. For birch tree plots with a higher site quality we expect from 8 to 9 m3ha-1year-1 of the mean volume increment at the time of culmination whereas for the aspen tree it is expected to be around 11 m3ha-1year-1. The quality of the stems of the felled trees indicates an unfavorable assortment structure.