Insignificant effect of management using irregular shelterwood system on the genetic diversity of European beech (Fagus sylvatica L.): A case study of managed stand and old growth forest in Slovenia

In the presented case study, we aim to understand the impact of an irregular shelterwood system (ISS) on the genetic diversity of European beech (Fagus sylvatica L) firstly by comparing managed stand to old growth beech forest and secondly by comparing two successive generations in both managed and old growth stands. Studies on European beech to date have not yet investigated the effect of ISS on its genetic diversity and have rarely addressed the effect of management on the genetic diversity of successive generations. The study was conducted in two mixed beech stands in Slovenia; the unmanaged Rajhenavski Rog old-growth European beech forest reserve and beech forest in Osankarica, managed according to ISS. All 140 sampled adult trees and saplings were genotyped at 16 nuclear microsatellite loci. ISS mimics genetic processes of the old growth rather well in the studied managed stand. The comparisons of diversity measures between managed and old growth stands did not reveal any significant differences between the two for any of the cohorts; the differences between the cohorts from the same stand were not significant. The observed significant shift in allele frequencies at four loci between successive generations could not be unambiguously attributed to management. Cohorts from the same stand had similar genetic structure, but six individuals from the managed stand formed a unique cluster. No convincing evidence of the effect of ISS on genetic diversity of the studied managed beech stand was found. (C) 2014 The Authors. Published by Elsevier B.V.