The impact of shelterwood cutting on twig growth in understoried beech trees (Fagus sylvatica L.)

The work deals with impact of cutting on annual length increment in understoried trees. Partial plots (PPs) in a beech ecosystem with varying stand density (0.3, 0.5, 0.7, 0.9) were generated by shelterwood cutting. Crowns of trees responded to cutting through variation in the length increment of twigs. Dynamics of variance in growth increment response to cutting was observed and analyzed on 1282 annual length increments from 4 understoried trees. After the evaluation of annual length increments from 1980 to 1997 using multiple comparison of mean values (LSD test), this interval was divided into two growth periods (primary period and period of accelerated growth). Twigs in each third of the crown responded to cutting by means of enhanced length increment always in the 2(nd) vegetation period after cutting. After the cutting intervention, the greatest twig increments in the upper third of the crown and middle third of the crown were observed on the sample tree from the PP with stand density 0.3, and ill the lower third of the crown, were the increments from the PP with stand density: 0.5. The most sensitive response to the various intensity of cutting was observed in the upper third of the crown and the least sensitive response in the lower third of the crown. This means that on all PPs the impact of cutting on twig growth decreased with the position of the twig within the crown (i. e. the upper third of the crown - greatest impact, the lower third of the crown - smallest impact). Impact of precipitation on the twig growth was highly significant in all thirds of the crown. On the contrary, the impact of temperature was not significant.