Interspecific differences in lightning mortality and damage among tropical trees

Jeannine H. Richards, Biology, University of Louisville, Louisville, KY, Stephen P. Yanoviak, Biology Department, University of Louisville, Louisville, KY, Evan Gora, Cary Institute of Ecosystem Studies, Millbrook, NY, Phillip M. Bitzer and Jeffrey C Burchfield, Atmospheric Science, University of Alabama in Huntsville, Huntsville, AL

Background/Question/Methods
Lightning is a major driver of large tree mortality in tropical forests with consequences for forest structure and biomass dynamics. However, it is unknown whether tree species differ in their vulnerability to death and damage from lightning. Anecdotal accounts suggest that some tree species are more vulnerable to lightning strikes while others are resistant or resilient, but empirical support for such patterns is lacking, especially in the tropics. We used a unique dataset of lightning-caused mortality and damage from five years of lightning strikes recorded on Barro Colorado Island, Panama, to test for interspecific differences in susceptibility to lightning damage. Using multi-level models, we tested for interspecific differences in tree mortality among trees that were exposed to electrical current from lightning, examined whether some species deviated from lightning damage expectations that were based solely on structural characteristics, and considered whether there were interspecific differences in a tree’s ability to recover following lightning damage.
Results/Conclusions
The results of this work indicate that some tropical forest species are less likely to be damaged or die from lightning strikes, while others appear to be especially susceptible. In particular, one common forest emergent species in Panama, Dipteryx oleifera, appears to be nearly immune to lightning, with multiple individuals experiencing direct lightning strikes with little to no evidence of damage. There is some evidence that species also differ in their ability to recover from damage following lightning strikes, with some recovering fully even after considerable canopy loss and others slowly declining over time following damage. These results have important implications for our understanding of forest dynamics and species turnover in tropical forests, especially where lightning strikes are frequent. Moreover, as lightning is projected to increase with stronger storms under climate change scenarios, these results will strengthen predictions regarding compositional shifts in future forests.