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Pařezová výmladnost jako základ obnovy a produkce nízkého lesa =: Stump sprouting as a basis for the regeneration and production of coppice /
Uherková, Barbora
In 2008, a young coppice was established and studied in the south-eastern part of the Czech Republic. The main studied species Quercus petraea (Matt.) Liebl agg. and Carpinus betulus L. are typical species of Central European coppices. The aim of the dissertation thesis was to study the topic of re-sprouting, the process when the new regeneration of sprouts is created. Re-sprouting occurred after thinning carried out at the turn of the years 2014/2015. The number of live and dead new sprouts was recorded, and their heights were measured. Subsequently, the effects of the stump basal area before and after thinning, the thinning intensity, leaf area index and light conditions (gap fraction, openness, direct, indirect and total site factor) were studied on the newly established generation of sprouts. Another aim of the dissertation thesis was to find out the effect of thinning on the growth of the coppice in the current changing climate conditions. For three growing seasons (2015 –2017) after the thinning, the growth (diameter and height increments) and soil water content were observed. To study the effect of climatic conditions, a throughfall reduction was simulated by using drainage channels. Similar system of drainage channels was used in Spain, France and other countries. To address the topic of soil degradation, the impact of throughfall reduction and thinning on soil CO2 efflux was investigated. Comparison between subplots with and without thinning, subplots with and without throughfall reduction and coppice with false high forest (control area to the research area of coppice forest) were carried out. As far as the re-sprouting is concerned, the stump basal area before thinning and the thinning intensity statistically significantly influenced the number and height of the new sprouts. Among all factors of light condition, only the indirect site factor was statistically significant. Therefore, the thinning affected soil moisture and the amount of light in the coppice. In the first year after the thinning, the diameter increments of sessile oak and European hornbeam were positively influenced by thinning. In the following two growing seasons, thinning did not significantly influence the diameter increment. However, the height increment of both trees during the whole study period has not been positively affected by thinning. On the other hand, thinning significantly affected the soil moisture. During the three-year study period, soil moisture was higher on thinned plots. This finding is in coincidence with research experiments carried out in southern Europe. The second studied factor, which was the throughfall reduction, did not influence neither the diameter increment, nor the height increment and nor the soil moisture in both species for the entire period. Thinning did not affect soil CO2 efflux rates, whereas the throughfall reduction did. Coppice reached almost the same soil CO2 efflux rates as the false high forest. In conclusion, thinning in coppice leads to an increase of available soil water. The water availability will be very actual issue at lower altitudes – here the tree species are sensitive to high air temperatures and drought stress. It should be noted that the younger developmental stages of the forest stands show increased sensitivity to water deficit due to drought. Thanks to sprouting ability, coppicing can therefore be appropriate management in some deciduous stands at lower altitudes under changing climate conditions.
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