COS 230-4 - How some trees benefit from being struck by lightning

Background/Question/Methods

Lightning strikes are among the most powerful phenomena in existence. A typical lightning strike carries 30,000 amperes of electric current and heats is path to temperatures hotter than the surface of the sun. Accordingly, lightning strikes are universally viewed as destructive, particularly in forests where they often kill groups of trees or ignite fires. However, scattered anecdotes suggest that some trees are not damaged by lightning and potentially even benefit from being struck. If some trees do benefit from being struck by lightning, that will likely shape their ecology, evolutionary history, and ability to coexist in a forest community. Here we evaluate whether certain trees benefit from being directly struck by lightning and explore the potential for lightning to shape a species’ niche. Specifically, we combine field surveys and drone imagery of systematically located lightning strikes to test whether a common canopy species, Dipteryx oleifera, benefits from direct lightning strikes.

Results/Conclusions

Direct lightning strikes caused no mortality and minimal damage to D. oleifera trees while simultaneously killing neighboring trees and parasitic lianas. By contrast, among all other tree species, 64% of directly struck tress died within 2 years of the strike and 77% died within 6 years. During their long residence time as large trees (i.e., > 60 cm in diameter), we estimate that an average D. oleifera tree is directly struck by lightning 5.6 times, killing 17.8 total lianas and 11.7 Mg of total competitor biomass. The ability to survive lightning is key to the life history strategy of D. oleifera; using detailed data on survivorship, growth, and seed production, we estimate that lightning facilitates ca. 50% of total seed production. The association between D. oleifera trees and lightning likely facilitates the persistence of this species and expands its realized niche space.