Forest Structure and Composition Are Critical to Hurricane Mortality

Hurricanes can cause severe damage to tropical forests. To understand the nature of hurricane impacts, we analyze and compare immediate effects from category-4 hurricane Maria in 2017 and category-3 hurricane Hugo in 1989 at Bisley Experimental Watersheds (BEW) in the Luquillo Experimental Forest, Puerto Rico. We show that hurricane Maria caused lower mortality than hurricane Hugo, even though hurricane Maria was a stronger event with higher sustained wind. The lower mortality was due to the combination of lower accumulated cyclone energy at the site and more wind-resistant forest structure and composition at the time of disturbance. We compare our study site with a nearby location that has the same forest type, Luquillo Forest Dynamics Plot (LFDP), and describe the similarities and differences of mortality and impact factors between the two sites during the two events. During hurricane Hugo, LFDP experienced much lower mortality than BEW, even though the accumulated cyclone energy at LFDP was higher. The difference in mortality was due to contrasting forest structure and composition of the two sites. Our results demonstrate that forest structure and composition at the time of the disturbance were more critical to hurricane-induced mortality at the two sites than accumulated cyclone energy.

Automated summary

Hurricanes can cause severe damage to tropical forests, but the impact varies depending on the intensity of the hurricane and the structure and composition of the forest. By analyzing and comparing two hurricane events in the Luquillo Experimental Forest, Puerto Rico, it was found that even though hurricane Maria in 2017 had higher sustained wind, it caused lower mortality compared to hurricane Hugo in 1989. This was attributed to lower accumulated cyclone energy at the site and a more wind-resistant forest structure and composition during the disturbance.