Lightning is a major disturbance in forest ecosystems, yet the ecological effects of direct lightning strikes are largely undescribed. In temperate forests, the direct effects of lightning are assumed to be minor, but lightning frequently causes tree death indirectly via the initiation of fire and attraction of insect pests. By contrast, recent work reveal that the direct effects of lightning are responsible for ca. 50% of large tree deaths in central Panama, and the potential for lightning to interact with other agents of mortality in tropical forests is unknown. Here we use a unique lightning monitoring system in Panama to quantify the spatial and temporal patterns of lightning caused disturbance and explore interactions between lightning and beetles.
Results/Conclusions
A typical lightning strike in this lowland tropical forest disturbs an average area of 683 m2 (range: 6 – 2251 m2) and damages an average of 23.6 trees (CI: 20.8 – 27.60 trees). Correcting for background mortality, 23% of these trees (5.5 trees per strike) die from their injuries within a year of the strike. The severity of lightning damage increased over time since the strike occurred and decreased with distance from the directly struck tree. Beetle damage, estimated as counts of beetle holes in tree trunks, increased with tree damage severity and tree size. These damage patterns are consistent with xylem and phloem damage caused by tree heating, and the associated beetle damage highlights a potential role for insect pests in the subsequent mortality of lightning-struck trees.