Sunspot area as unexplored trend inside radial growth of European beech in Krkonoše Mountains: a forest science from different perspective.

Many studies have examined the relationships between the effects of the sunspot area and growth of trees; however, none of them considered European beech (Fagus sylvatica L.). We investigated the relationships between the sunspot area, climate factors (temperature and precipitation) and radial growth of beech in the Krkonoše Mts. in the Czech Republic. We used the core samples of 199 beech trees representing the century-long growth, two sets of climate data (local short-term data and general long-term climate data), and more than a century-long sunspot area dataset acquired from the National Oceanic Atmospheric Administration. Our results showed the significant effects of the sunspot area, temperature and precipitation on the radial growth of beech. The correlations between sunspot area and tree-ring width index varied from 0.9 to 0.5 in the period between 1986 and 2017, a period during which none of the significant anthropogenic disturbances occurred in the study area. The strong correlations were found between the sunspot area and climate factors for a longer period. The largest effect of the sunspot area on the radial growth was observed in the previous year, especially in growing season. Structurally diversified (heterogeneous) beech stands were less affected by the sunspot area compared to the homogeneous stands. In conclusion, the sunspot area is one of the important factors that significantly influence the radial growth of beech in the Krkonoše Mts. Our results will be useful for understanding beech forests in the context of global change, and will have an important contribution to the knowledge for predicting potential impact of the sunspot area on the Earth's surface. [ABSTRACT FROM AUTHOR]