Solar Cycles in Salvage Logging: National Data from the Czech Republic Confirm Significant Correlation

Abstract

Forest ecosystems in Europe undergo cyclic fluctuations with alternating periods of forest prosperity and disturbances. Forest disturbances are caused by large-scale calamities (climate-induced and unforeseen events) resulting in an increased volume of salvage logging. In recent decades, climate change (warming, long-term droughts, more frequent storms, bark beetle outbreaks) has contributed to an increased frequency of salvage logging. However, until now, it has not been revealed what triggers national-scale forest calamities. All of the above-mentioned natural disturbances are connected to solar activity, which is the driver of climate change. This research relates the total volume of harvested timber and salvage logging to the climate and cosmic factors in the Czech Republic, Central Europe. Data of total and salvage logging are compared with air temperatures, precipitation, extreme climatic events, sunspot areas, and cosmic ray intensities. The results document a significant effect of average annual temperatures on the total and salvage logging for the entire period of observations since 1961. A significant correlation of salvage logging to the sunspot area and cosmic ray intensity was observed. The link between salvage logging and sunspots and cosmic ray intensity is supported by spectral analysis in which a significant 11-year cycle was observed since 1973. The results also show an increasing significant effect of sunspots and cosmic ray intensity on logging in recent years in connection with synergism of extreme climate events and the subsequent bark beetle outbreaks. Space and cosmic effects are factors that substantially influence forest ecosystems. Therefore, this paper provides new knowledge about, and possible predictions of, the forest response under climate change.