Induced drought strongly affects richness and composition of ground-dwelling ants in the eastern Amazon

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