Predation on artificial caterpillars following understorey fires in human-modified Amazonian forests

Abstract

Tropical forests are facing several impacts from anthropogenic disturbances, climate change, and extreme climate events, with potentially severe consequences for ecological functions, such as predation on folivorous invertebrates. Folivory has a major influence on tropical forests by affecting plant fitness and overall seedling performance. However, we do not know whether the predation of folivorous arthropods by birds, mammals, reptiles, and other arthropods is affected by anthropogenic disturbances such as selective logging and forest fires. We investigated the impacts of both pre-El Niño human disturbances and the 2015–2016 El Niño understorey fires on the predation of 4500 artificial caterpillars across 30 Amazonian forest plots. Plots were distributed in four pre-El Niño forest classes: undisturbed, logged, logged-and-burned, and secondary forests, of which 14 burned in 2015–16. We found a higher predation incidence in forests that burned during the El Niño in comparison with unburned ones. Moreover, logged-and-burned forests that burned again in 2015–16 were found to have significantly higher predation incidence by vertebrates than other forest classes. However, overall predation incidence in pre-El Niño forest disturbance classes was similar to undisturbed forests. Arthropods were the dominant predators of artificial caterpillars, accounting for 91.5% of total predation attempts. Our results highlight the resilience of predation incidence in human-modified forests, although the mechanisms underpinning this resilience remain unclear. Abstract in Portuguese is available with online material.