Influence of Elevation and Stand Age on the Abundance of the Beech Bark Beetle (Taphrorychus bicolor Her.) and Its Potential Threat to Beech Stands

Abstract

In 2023, branches of European beech (Fagus sylvatica L.) were placed on 24 different study sites within beech stands in the Czech Republic to study the distribution of the beech bark beetle (Taphrorychus bicolor Her.). After infestation, the branches were placed in emergence traps to capture adults of the offspring generation. In total, 2167 adults of T. bicolor were captured across the 24 study sites. The average capture (mean ± SE) was 90.3 ± 24.4 adults per site. Statistical analyses, including GLMM and GLM, were employed to assess the influence of elevation and stand age on the abundance of T. bicolor. The results indicate that the distribution of T. bicolor is mainly influenced by the elevation and age of the beech stand. The number of captured adults decreased with elevation and increased with stand age. Climatic region, volumes of beech, and volumes of felled beech wood from principal felling and thinning felling had no significant effect on the number of T. bicolor adults captured. We found that, overall, 73.37% of Czech beech stands (at elevations 300–650 m a.s.l.) are possibly threatened (either highly or slightly) by the large occurrence of T. bicolor, because they are present at elevations where T. bicolor is widespread. No outbreaks of T. bicolor have yet been reported in the Czech Republic, but with the increasing amount of beech planted, combined with global climate change, the possibility of outbreaks in the future cannot be excluded.