No abstract

The impact of solar cycles on forest stands, while important in the development of the forest environment during climate change, has not yet been sufficiently researched. This work evaluates the radial growth of European beech (Fagus sylvatica L.) in the mountain areas of southern Italy and central Europe (Czech Republic, Poland) in correlation to solar cycles (sunspot number), extreme climatic events, air temperatures and precipitation totals. This research is focused on the evaluation of the radial growth of beech (140 dendrochronological samples with 90–247 years of age) from 1900 to 2019. The time span was divided into the following three periods: 1) a period of regular harvesting (1900–1969), 2) a period of air pollution crisis (1970–1985) and 3) a period of forest protection (1986–2019). The results indicate that the solar cycle was significantly involved in radial growth on all research plots. With regard to the evaluated precipitation totals, seasonal temperatures and the sunspot number, the latter was the most significant. Temperatures had a positive effect and precipitation had a negative effect on the radial increment of beech in central Europe, while in southern Italy, the effect of temperature and precipitation on the increment is reversed. In general, the limiting factor for beech growth is the lack of precipitation during the vegetation season. The number of negative pointer years (NPY) with an extremely low increment rose in relation to the decreasing southward latitude and the increasing influence of climate change over time, while a higher number of NPY was found in nutrient-richer habitats compared to nutrient-poorer ones. Precipitation and temperature were also reflected in the cyclical radial growth of European beech. The relationship between solar cycles and the tree ring increment was reversed in southern Italy and central Europe in the second and third (1970–2019) time periods. In the first time period (1900–1969), there was a positive relationship of the increment to solar cycles on all research plots. In the tree rings of European beech from southern Italy and central Europe, a relationship to the 11-year solar cycle has been documented. This study will attempt to describe the differences in beech growth within Europe, and also to educate forest managers about the relevant influence of solar cycles. Solar activity can play an important role in the growth of European beech in central and southern Europe, especially during the recent years of global climate change.

No abstract

The growth, structure and production of mixed beech (Fagus sylvatica L.) forests were analysed  in the Broumovsko Protected Landscape Area, Czech Republic. The objective of the paper was to evaluate stand structure, timber production and dynamics of forests with historically different silvicultural practices in relation to climate conditions, management and game damage. The results indicate that scree forests (coppices and coppices with standards) were stands with high-rich species diversity and structure compared to herb-rich beech forests (high forests) with higher timber production. The Norway spruce (Picea abies [L.] Karst.) was the most sensitive tree species compared to low growth variability in European beech. The climate factors had the highest effect on radial growth from June to August. Natural regeneration showed great density potential (13,880–186,462 recruits·ha^–1), especially in expansion of maples and European ash (Fraxinus excelsior L.). However, recruits were seriously limiting by damage caused by hoofed game, especially in silver fir (Abies alba Mill.; 53% browsing damage), wych elm (Ulmus glabra Hudson; 51%) and rowan (Sorbus aucuparia L.; 50%).

The Jizerské hory Mts. (the Czech Republic) are part of the Black Triangle region strongly affected by a decline and dieback of Norway spruce (Picea abies [L.] Karst.) stands since the 1970s. In the studied peaty spruce stands in the summit parts of the Jizerské hory Mts., the health status, radial growth and foliar nutrient content in relation to air pollution (SO 2 , NO X and O 3) and climate factors (temperature, precipitation) were investigated in 1960-2015. A considerable disturbance of the stand structure induced by an increased mortality was observed in 1981-1983 when more than a half of the tree individuals died. Severe defoliation occurred in 1981 as a consequence of the synergic effects of air pollution, winter desiccation and spruce bark beetle outbreak, as well as in 2015 due to the drought and high temperatures. Tree ring analyses indicated significant growth depression in 1979-1987, a period of the highest SO 2 load, and in 2010-2015. Foliation and diameter increment were significantly influenced by SO 2 and NO X concentrations, the maximum daily concentration being the most negative factor; no significant correlation of the ozone exposure was detected, though. Foliar analyses also document significant negative impacts of air pollutants on the nutrient status of forest stands, mainly in the increase of the sulphur level. Since 1990, a significant increase in calcium and magnesium has been observed, as a result of forest liming. Interaction between radial growth and temperature was stronger compared to precipitation. Low temperatures and high precipitation in growing season were the limiting factors for radial growth in waterlogged mountain areas.