How does the abundance of horned powder-post beetles (Stephanopachys spp.) correlate with fire intensity in the Boreal Forest?

Sammanfattning

Fire has always been a natural disturbance that shaped boreal forest structure and species composition by creating habitats for pyrophilic species such as Stephanopachys spp. Today, natural fires have decreased in the forest landscape, and therefore, it is important to understand how fire affects these rare species. This study aimed to investigate how the abundance of Stephanopachys spp. correlates with fire intensity in the Boreal forest. Data such as flame height, diameter at breast height, bark thickness, tree vitality, and the occurrence of Stephanopachys spp. from individual fire-damaged pines in five different burnt areas s in northern Sweden were collected, and tree density and basal area were measured. In this study, Stephanopachys spp. was not affected by tree diameter or bark thickness. However, a strong positive correlation was found between flame height and the occurrence of the species. Poorer tree vitality and lower stand density also had a significant impact on the species’ presence. This suggests that both fire intensity and forest structural characteristics are crucial factors shaping the habitat and survival opportunities for Stephanopachys spp. in boreal forest ecosystems. Moderate fire intensity and open post-fire environments appear particularly important for the species’ occurrence. These findings can contribute to a better understanding of how prescribed burning should be carried out with the right fire intensity to benefit Stephanopachys spp. in boreal forests. Keywords: Stephanopachys spp., pyrophilous insects, fire intensity, flame height, boreal forest, conservation burning, forest structure, tree vitality, post-fire ecology, conservation management