Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

Abstract In years 2002 and 2003, pairs of experimental plots were established in some selected forest divisions in pine stands of the IIIrd and IVth age class and, on each of these surfaces, crown defoliation of 25 trees from the main stand was assessed according to the, so called, European criteria. Mean defoliations were calculated for each experimental plot and this information was used to allocate individual stands to the appropriate defoliation class. Moreover, the author investigated, whether there were statistically significant differences among mean defoliations and referred the findings to the membership of specific pairs of stands to a defoliation class.