Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

The present research was conducted in managed stands of Scots pine (Pinus sylvestris L.) at different age in Poland. All the investigated stands were planted and thinned according to selection thinning. Analysis of spatial structure concerned trees of different categories (DBH classess) depending on the age of stand. Spatial distribution of trees was investigated using two commonly used methods: Clark-Evans R index and Ripley’s L(t) function. In stands of age 43 and 65 the effect of the initial spacing was observed and all living trees were distributed regularly at the smallest distances and at larger spatial scale they were spaced randomly. Random type of spatial structure of trees was observed when smaller and larger trees were taken into consideration, separately. In case of stands at the age 90 the effect of the initial planting on the spatial structure of trees was not observed even at the smallest distances independently of the category of trees taken into account. All living trees in these stands were distributed randomly. Only in two stands clumps of trees were observed and one concerned smaller trees and the other – larger trees. Size differentiation index was small for all stands. The lowest values was ascertained in the oldest stands.