Due to a lack of oak seeds and planting material at the north-eastern limit of the distribution range of European oak forests (study area: Republic of Tatarstan, Russia), the high initial plant densities typical of oak stands established in central Europe for the production of valuable timber is not feasible in this region. In Russia, the low numbers of oak trees in planted stands (about 4500 oaks/ha) are complemented by abundant natural regeneration of admixed tree species. In this study, the chronosequence method was used to determine the probability of survival and the quality development of young oaks (10-27 years) in Tatarstan as a factor of initial plant numbers, interspecific competition (lime, maple, hazel), oak age and tending measures. The results provided by LMM and GLMM models revealed that the probability of oak survival rises with increasing initial oak plant density and tending, and declines with increasing competitive pressure of maple. While the competition exerted by all admixed tree species had a negative effect on oak growth parameters, it had a positive effect on important oak quality parameters (e.g., diameter and height of the thickest branches, branch-free bole length). However, a positive impact of high initial plant density on oak quality was reduced by strong interspecific competition. Age had a positive effect on oak quality development, and tending a negative effect. The findings of this study demonstrate that the competitive pressure of admixed tree species can successfully compensate for the positive effects of oak intraspecific competition on oak quality, and may therefore be exploited by forest managers as a means to reduce the cost of oak establishment by using lower plant numbers without risking any loss of oak quality.
