The Structure of Beech Stands in Their Optimum Developmentalphase

1991

S. 15-40

4 Lit. Ang.

Unselbständiges Werk

200047486

In many beech-dominated forest sites, stand are more or less uniform in their optimum phase of development. Their uniformity is due to predominant trees forming the stand canopy. The two lower coenotical classes (4th and 5th class, according to Kraft) consist of a relatively small number of trees. Uniform height structure, however, is in sharp contrast to a wide variety in breast-height diameter (dbh). The value of variance coefficient of the dbh of trees forming the stand canopy (1st, 2nd and 3rd coenotical class) is between 10 and 35%. In most of the analyzed plots, this value is between 21 and 25%. The values depend primarily on site and origin of a stand. There is a relatively high degree of homogeneity of dbh among trees forming the top height (100 of the widest trees per hectare). The analysis of the age structure of stands indicates the mode of their origin. Only a few stands are even-aged. The age difference of trees belonging to the upper three coenotical classes is between 10 and 150 years. In most plots the age difference is over 20 years. Despite their uniformity, the stand are distinctly uneven-aged. Some stand consist of individuals from two different generations. It is most interesting to note that even trees forming the top heigh vary substantially in age in plots of 9 ares (30x30m). In individual plots the age difference was found to exceed 120 years. This indicates a considerable capacity of individual beech trees to reach the upper coenotical class despite unfavourable light conditions. The dbh of stem and h/d ratio depend on site, stand density and age structure of stand. The widest trees forming the top height are of vital importance for the stability of a stand as their h/d ratio is extremely low despite their considerable height. The study involved the most important sites in Slovenia from 17 sample plots.