ZLV Online

Of the 4th group of experimental series (established in the period 1964 – 1969), only nine series persisted to present time – Polička I and II, Nasavrky, Bruntál, Blaník I and II, Planá, Železná Ruda I and II. The thinning experiments were projected in order to compare two basic ways of thinning: positive selection from above (2ú or 4ú) and negative selection from below (3p or 5p). The test element of each experimental series is control plot (1k) without intentional thinning. The method used in the thinning experiment did not suppose the replication inside the individual series, but using particular variants inside the group of the series as replication was not possible because of high initial differences between series. Therefore the final evaluation of the 4th group of series was aimed at common phenomena observed on particular series after 35 – 40 years of investigation. Effects of thinning were observed: (a) on thinned variants, amount of basal area removed by salvage cut was evidently lower than on control unthinned plots, (b) on thinned variants, abundance of small-sized individuals decreased (ioncluding variants with positive selection from above) and abundance of thickest tree increased compared to control unthinned plots 1k, (c) static stability, characterized by h/d ratio of mean stem and of dominant trees, was influenced by thinning positively in the majority of experiments on this series.