El Nio is global in its impact. In deserts and tropical seasonally-dry forests world-wide, a warm tropical Pacific Ocean surface is associated with increased rainfall resulting in seed germination and plant growth. The effects of increased primary productivity cascade upward into higher trophic levels resulting in periodic outbreaks of herbivorous species and migratory activity.
Neotropical wet forests are different because El Nio years are drier, but moderate drought results in increased primary productivity similar to that in desert and tropical dry forests. Thus the lowland forests of Panama fall into a set of habitats encircling the globe in which insect migrations are larger during El Nio years. However the Panamanian wet forest is in a class of forests that have the greatest abundance and diversity of herbivorous insects in the world, "It is like we had seen the tip of the iceberg and suddenly we realize its true size", Srygley suggested. The authors predict widespread insect migrations during El Nino years.
According to Srygley, "Understanding how global climate cycles and local weather influence tropical insect migrations should ultimately improve our ability to predict insect movements and effects such as crop damage."
|Contact: Beth King|
Smithsonian Tropical Research Institute