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ŠUMARSKI LIST 7-8/2013 str. 25     <-- 25 -->        PDF

underestimated, presumably due to more suitable growth conditions in NP Šumava (lower altitude, more oceanic climate, deeper soil). That’s why the number of gap recruited trees has to be considered as a minimal recorded value. Further analysis is necessary for more accurate estimation, because it is not clear if the tree growing in harsh environment reacts on the increased light income by higher radial increment than the sapling growing under more suitable conditions. We expect the share of gap recruited trees of approximately 70 % as reported by Svoboda et al. (2012) from Šumava. As the spruce growing in higher altitudes needs more light income for sufficient regeneration (Holeksa 2001), the recruitment waves should be, as a rule, connected with the removal of overstory individuals.
Analysis of height shifts revealed that almost 34 % of individuals established under canopy reached canopy position during the first 50 years of their life, while more than 17 % of trees reached the canopy after the 100 years of suppression. Despite the increased light requirements of trees growing in harsh environment, spruce is able to regenerate under the closed canopy (e.g. on the logs) and wait for several decades till the overstory is opened (Leibundgut 1993; Kucbel 2011). Such structure creates a structural basis for the silvicultural concept of so-called mountain selection forest (Korpeľ, Saniga 1995; Schütz 2011).This fact suggests that beside the large-scale wind disturbance, the development of spruce forest is affected by small-scale local disturbances or individual dieback of canopy trees due to bark