Long-term responses of gastropods to simulated hurricanes in a tropical montane rainforest

Climate-induced disturbances such as hurricanes affect the structure and functioning of ecosystems, especially those in the Caribbean Basin, where high-energy storms have long affected ecosystem dynamics. Because climate change will likely continue to alter the frequency and intensity of hurricanes in the Caribbean, it is increasingly important to understand the mechanistic bases for ecosystem responses. Although long-term surveys and nonmanipulative "natural experiments" provide considerable insight, manipulative experiments are required to decouple confounded factors associated with high-intensity storms. To address this, we exploited a replicated factorial design to experimentally isolate the long-term effects of canopy opening and debris deposition on population- and community-level characteristics of gastropods in the Luquillo Experimental Forest of Puerto Rico. The canopy trimming experiment included four treatments: (1) the reference treatment received no manipulations; (2) canopy trimmed, but debris from trimming not deposited on the forest floor (trim only); (3) canopy not trimmed, but debris deposited on the forest floor (debris only); and (4) canopy trimmed and debris deposited on the forest floor (trim and debris). After 10 years, the trim and debris treatment was repeated to simulate reoccurring hurricane events, whereas the trim-only and debris-only treatments were not subject to additional manipulation at this time. We evaluated responses to treatment and time for gastropod populations (abundance) and communities (biodiversity and composition). Population-level responses were species specific. Three species and total gastropod abundance exhibited consistent responses to treatments regardless of time, four species exhibited consistent temporal trends regardless of treatment, and five species exhibited an interaction in which the effects of time depended on treatment. In general, point-, alpha-, and gamma-biodiversity decreased through time, whereas beta-biodiversity increased through time. Gastropod populations and communities were resistant and resilient to the simulated disturbances, exhibiting quick recovery from any short-term changes in abundance or biodiversity. From an evolutionary perspective, long-term exposure to hurricane-induced disturbances likely leads to species-specific adaptations that enhance resistance and resilience.