Estrutura e distribuição de comunidades de formigas (Hymenoptera: Formicidae) em ambientes de várzea

Abstract

Ants play essential roles in tropical ecosystems and exhibit high diversity, particularly in the Neotropical region. In floodplain environments, flood pulses act as important environmental filters, shaping the composition and distribution of communities. This study evaluated the influence of hydrological variation on ant communities (Hymenoptera: Formicidae) across different forest strata in the Parque Estadual das Várzeas do Rio Ivinhema (MS, Brazil). Eight forest fragments were sampled — four floodable and four non-floodable — using active sampling with entomological beating sheets and pitfall traps. A total of 148 morphospecies were recorded, distributed across 36 genera and seven subfamilies, with a predominance of Myrmicinae. Epigeic assemblages exhibited higher richness and diversity compared to arboreal ones, reflecting patterns widely reported for tropical forests. However, marked differences between environments were observed only for the arboreal stratum: floodable fragments showed higher diversity, particularly for common and dominant species (q = 1 and q = 2), suggesting that temporary inundation may increase heterogeneity and microhabitat availability in the canopy. For epigeic assemblages, no significant distinction between environments was detected, indicating that local factors and landscape features may exert influences distinct from hydrology. The results suggest that the effects of flood pulses differ in intensity, acting more strongly upon arboreal strata, whereas epigeic communities exhibit greater structural stability. We conclude that flood pulses operate with variable intensity across the vertical gradient, affecting the arboreal stratum more markedly, while other environmental filters appear to dominate the structuring of ground-dwelling assemblages.