Effect of Pitfall Trap Spacing on Sample Independence in Ant Community Studies in Homogeneous Grasslands (Hymenoptera: Formicidae)

The spacing between traps is one of the variables that can influence pitfall-trapping results. Very short distances between traps could cause pseudoreplication, which means that samples are not statistically independent. In this study, we evaluated how trap spacing affects the similarity in the composition and abundance of ant communities in two homogeneous grasslands sampled with pitfall traps separated by 0.5, 1, 2, 5, 10, 20, or 40 m. The results show that dissimilarity between the samples increases progressively with the distance between traps and that, in general, from 5 m onwards, the samples tend to be more independent of each other. These findings suggest that, in homogeneous grasslands, a distance of 5 m between pitfall traps may serve as a practical reference to reduce pseudoreplication. However, the independence threshold between samples should not be generalized directly to more heterogeneous ecosystems.