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Mixed stands are currently supported as effective management options to reduce forest vulnerability to climate change. However, our issues about benefits of mixtures, mechanisms of their incidence and conditions for their effectiveness have yet been only partly clarified. We assessed the crown condition of Norway spruce (Picea abies /L./ Karst) and occurrence of symptoms caused by Armillaria spp. on spruce in a small area in the Drahanská vrchovina Highlands (Czech Republic) in differently mixed stands in 2002 and 2019. We found that although the broadleaf abundance affected the total defoliation of Norway spruce, the effect was unstable in time. The observed effect of altitudinal zones and Norway spruce abundance on the occurrence of symptoms of Armillaria root rot in spruce was also unstable. The drought during recent four years and the implemented forestry measures (salvage and intermediate felling) can be reasons for the relationship instability. We did not identify any statistically significant relationship between tree species diversity (Simpson's Index) and defoliation. [ABSTRACT FROM AUTHOR]

The aims of the study were to determine the effect of temperatures and precipitation on the ring width and to compare the results with the results of previous studies conducted in other mountain ranges of the Czech Republic. The research was performedin the central part of the Ceskomoravská Uplandin the vicinity of Herálec municipality in selected 70- up to 110-year-old spruce stands at altitudes from 680ma.s.l. to 779 m a.s.l. Measuring of tree-ring widths and synchronization of individual ring series were conducted in PAST4. The age trend was removed by ARSTAN and climatic effects were modelled in Dendro Clim 2002. The correlation of tree-ring width with monthly precipitation is positive and statistically significant for July of the previous year andfor the entire summer periodfrom June to September of the current year. The correlation of tree-ring width with mean monthly temperatures is negative andstatistically significant for July and Septem - ber andpositive andstatistically significant for October of the previous year. Negative correlation was also foundfor temperatures of the entire summer periodfrom June to September of the previous year. The regional tree-ring chronology mainly shows two periods of highly reduced increment: from 1992 to 1996 and from 2003 to the end of the analysed period. The results thus confirm the hypothesis that the tree-ring width is in positive correlation with summer precipitation andnegative correlation with summer temperatures. Also the results of the habitual diagnostics have shown a relatively low degree of crown transformation which indicates a weak or short-term stress load. [ABSTRACT FROM AUTHOR]

Norway spruce has experienced unprecedented forest declines in recent decades, leading to extensive salvage logging. Currently, because of the conversion of conifer forests into more natural mixed forests in Central Europe, spruce has begun to be replaced, mainly by European beech. The frequently discussed changing climate has a crucial effect on the vitality of both species. To improve our understanding of spruce and beech responses to climate change, including more frequent temperature and drought extremes, we investigated the impact of temporal climate variability on the growth of these species along an elevation gradient. In total, 79 spruce and 90 beech trees were used to build species-specific tree-ring width chronologies representing the altitudinal range in which both species grow (450, 650, 800, and 950 m asl) under the conditions of the Czech Republic. The climate–growth relationship indicates strong dependence of spruce and beech tree-ring growth on spring temperature (Mar–May) at all sites and summer (Jun–Aug) water availability at lower altitudes. Significant temporal shifts in the climate–growth relationships of both species indicate an increasing negative effect of summer temperature and positive effect of water availability in summer. The increasing drought and temperature sensitivity of both species suggest a significant impact of the predicted climate change on such forest ecosystems. Discussion emphasizes the current importance of adaptive forest management strategies. [ABSTRACT FROM AUTHOR]