Fire effects on the ant community in areas of native and exotic vegetation

Acacia melanoxylon is an invasive species of the mountain grassland of the southeastern part of the Buenos Aires province, Argentina. Fires are a natural disturbance, characteristic of the area, and favor the germination of this invasive plant. However, they are used as the first step in management systems for the Acacia species. Moreover, the use of ants in monitoring programs is very scarce for Argentina. The objectives of this work are: 1) to analyze the response and resilience capacity of native and invaded sites by A. melanoxylon after a fire for controlling this invasive species; 2) to detect groups of ants considered to be indicators of the recovery phase subsequent to the burning; and 3) to apply the concept of groups of disturbances, proposed by Roig and Espadaler, as an effective tool for monitoring. The sampling design consisted of three replicates of 10 pitfall traps for each environment, native and invaded. Ant species were grouped into functional groups, trophic guilds, and disturbance groups. The fire did not generate significant changes in the richness and abundance of ants in the mountain grassland. However, it generated a positive effect on the sites invaded by Acacia during the first year after the fire. The groups of minimum specialists of vegetation and the dominant Dolichoderinae are considered good bioindicators. Finally, the disturbance indicators can be considered reliable management tools if the biology of the species that compose it is known beforehand.