Growth and quality of 16-year-old sessile oak (Quercus petraea (Matt.) Liebl.) planted in traditional and alternative row planting patterns

Traditional oak silviculture is costly due to high initial planting density required to obtain management goals of producing high quality timber. New methods therefore reduce the initial planting density and use a planting pattern that allows the inclusion of naturally regenerated trees of other species. The study presents the results of a 13-year experiment on the growth and quality of sessile oak planted in traditional and three alternative planting patterns. We hypothesized that increasing of initial spacing and use of natural regeneration to compensate for lower intra-specific competition does not deteriorate growth and quality parameters of oak. Breast height diameter, height, slenderness, height of the first live branch, diameter of the thickest branch, stem shape and potential future crop oak trees (PFCT) were measured and analysed. The local competition of admixture species was estimated on the basis of the relationship between the height of the oak and the height of admixture trees in its close proximity. The type of planting pattern had no significant effect on oak diameter, but oak height was greater in the traditional pattern than in alternative patterns. Height of the first live branch was the only qualitative trait that differed significantly between the compared planting patterns. The probability of an oak being selected as a PFCT was similar in traditional and alternative patterns, but PFCT absolute number was increasing with an increase of oak planting density. Analysis of competition of admixture species in alternative methods shows that it can reduce height, diameter and stability of oaks. On the other hand, the probability of trees being selected as a PFCT increases significantly with increasing interspecific competition. We conclude that, with controlled competition and at least moderate natural regeneration, the alternative planting patterns can produce oaks with similar growth and quality to those in the traditional pattern.