Führen Durchforstungen zu Veränderungen der genetischen Struktur von Buchenbeständen?

Alfeld

Verlag M. & H. Schaper

2005

S. 184-188

3 Abb., 17 Lit. Ang.

Artikel aus einer ZeitschriftUnselbständiges Werk

200123292

Forst und Holz 2005, 60(5) : Forstegenetik : Speierling : Wurzelschwamm, S. 184-188

The effect of different thinning procedure on the genetic structure of European beech (Fagus sylvatica L.) stands was studied on five growth and yield experimental plots located in the German Federal States of Lower Saxony and Rhineland-Palatinate as well as in two beech sections on beech-spruce mixed stands in Saxony. Simulating the beginning procedures on the reference plots of the gorwth and yield plots and the beech sections of the mixed stands, the genetic structures of the stand were compared with each other prior to and following the relevant thinning operations. For this study each an elite tree-oriented thinning in the upper storey was simulated comprising the three intensity levels 'moderate', 'strong' and 'very strong'. Applying isozyme gene markers, the trees were genotyped by analyzing seven gene loci in common. Additionally, an extreme variant was analyzed being characterized by the presence of exclusively elite trees. Moreover, as exemplified by the growth and yield plots, the elite tree collective was compared with those trees that would have been removed in case of thinning (trees oppressing the elite trees) with respect to their genetic structures. It could be derived from the results obtained for the genetical comparisons of the different collectives, that one-time silvicultural operations bring about a rather low effect on the genetic structures of the beech stands. Besides, no tendency becomes apparent that the genetic variation is reduced significantly if the thinning intensity increases. However, when assuming regular repeated thinning operations and considering a period of several decades. It cannot be excluded completely due to three results, that the genetic variation may become restricted. Any silvicultural operation carried out evenly over the plot reduces th danger for rare alleles being frequently not present randomly but in clusters, to be removed as a group.