Ants in an Induced Drought Experiment at the Caxiuana National Forest in Brazil 2011-2012

Environmental change scenarios caused by low precipitation forecast species loss in tropical regions. We used one year of data from a rainwater exclusion experiment in primary Amazonian rainforest to test whether induced water stress, and covarying changes in humidity, soil respiration, and tree species richness, size, and total biomass and its diversity affected species richness and composition (relative abundance) of ground-dwelling ants. Induced drought reduced ant richness, whereas increased humidity and variability in biomass increased it. Species composition differed between control and rainfall-excluded plots. Occurrence of many ant species was strongly reduced, but some generalist groups of ants were favored by induced drought. The expected loss of ant species and changes in ant species composition in tropical forests likely will lead to cascading effects on ecosystem processes and services they mediate.