EJPAU, 2007, Volume 10, Issue 2
Forestry

The effect of age of trees on their slenderness (s) and the relationship between slenderness and tree d.b.h. (d) and height (h) were determined on the basis of measurements of d.b.h. and height of 6070 the upper story trees growing in over 400 circular plots established in stands of age class II and older in the Niepołomice Forest District. The following eight tree species were investigated: Pinus sylvestris, Quercus robur, Carpinus betulus, Betula verrucosa, Alnus glutinosa, Fraxinus excelsior, Tilia cordata, and Larix decidua. From among these species F. excelsior was characterized by the highest mean slenderness (1.047), while P. sylvestris by the lowest one (0.773). High, usually over 0.800 in value, coefficients of correlation between slenderness and d.b.h. indicated a great usefulness of d.b.h. for elaboration of formulae determining slenderness of analyzed tree species. A logarithmic function (s = α · ln d + β) turned out to be the best in estimation of slenderness of P. sylvestris, L. decidua, A. glutinosa, and B. verrucosa, while in the case of Q. robur, C. betulus, and F. excelsior an involution function (s = α · d ^β ) was the best, and for T. cordata – an exponential function (s = α · e ^β·d ).

The study was carried out in the 78-year-old black locust (Robinia pseudoacacia L.) stand growing in the Krosno Odrzańskie Forest District in western Poland. Its aims were to evaluate biometric characteristics of trees and to analyze climatic factors which condition radial increment of wood. On the basis of dendroclimatic analyses it was found that frosty winters and low temperatures in early spring months (January – April) as well as low precipitation during summer, especially in June and July, were among important factors limiting diameter increment of black locust trees. Also low precipitation in autumn of the previous year and low precipitation of February before the current growing season had a negative effect on diameter increment of this species. In spite of these limitations a dendrometric estimation of the stand showed that its characteristics exceeded values given in available volume tables [24] which are a deterministic model of growth of a pure even-aged black locust stand.