Effects of climatic seasonality on the vertical stratification of ant biodiversity in the Dry Chaco ecoregion (Argentina)

Abstract

Dry forests are characterized by a marked climatic seasonality, which causes an annual fluctuation of resources and could have a strong impact on ant biodiversity. In these forests, three main vertical strata (ground, understory and canopy) can be differenciated, all of whichare inhabited by formicids. This work aims to study how seasonality in dry forests affects the vertical stratification of ant biodiversity in two contrasting environments (native forest and open area) of the Argentine dry Chaco. In each of these physiognomies, the sampling was carried out during winter and summer, applying specific capture techniques for each taxon and according to the characteristics of each strata. Stratification and the influence of climatic seasonality on Formicidae were determined by differences in the values of richness, activity density, dominance, diversity and similarity indexes. In total, 43 species belonging to 21 genera and 7 subfamilies were identified. The native forest supports the greatest ant biodiversity. A clear stratification of the myrmecofauna is observed, with the highest values at ground level. The climatic seasonality of the region influenced the stratification of ants of both physiognomies in different ways, being more evident in the open area where the disappearance of a stratum of vegetation in the winter season was observed. This work constitutes the first contribution about the effects of climatic seasonality on the biodiversity and stratification of ants in dry forests of Argentine Chaco, and the largest record of ant species number reported for this environment in Argentina.