DIVERSITY AND COMPOSITION OF ANT SPECIES IN FRAGMENTED LANDSCAPES OF CHACO FOREST (CÓRDOBA, ARGENTINA).

PEREYRA, M; POL, RODRIGO; GALETTO, L

Curitiba

Simposio; XXII Simpósio de Mirmecologia; 2017

Ants are sensitive to land use changes and they have been largely utilized as bioindicators in different contexts. In relation to habitat fragmentation process, ant diversity has shown complex responses to patch size reduction. But when considering a set of different indicators of the same framework, as edge effect and matrix types, these two processes have shown more consistent patterns negatively affecting ant communities. More studies are needed to disentangle these complex effects, moreover considering the rate of forest loss of some dry biomes as Chaco forest. In this study, we assessed the effects of forest fragmentation process (i.e., patch size, edge effect and matrix use) on ant communities in fragmented Chaco forests. Field work was performed in forest patches located in the middle of Argentina near Córdoba city, and the surrounding matrix was composed by soybean and maize monocultures. We collected ants using pit-fall traps (5 traps along 50 m transects) and hand collecting in quadrats (2 x 2 m) at 17 forest patches from different size (1-830 ha). In total, 60 samples (30 pit-fall traps and 30 hand collecting quadrats) were obtained from each fragment, 20 in each microsite: matrix, forest edge and interior. We collected 9164 individuals corresponding to 26 genera and 66 ant species. The richest subfamilies were Myrmicinae with 37 species and Formicinae with 11. Also, we collected individuals from subfamily Dolichoderinae with seven ant species, Dorylinae with four, Ectatomminae and Pseudomyrmecinae with three, and Ponerinae with one species. The abundance and richness of ants were lower in the matrix than in the forest edge and interior of fragments, where they were similar. By contrast, we did not detect significant differences in the abundance and richness with patch size reduction. Analysis performed to assess the effect of microsite on ant species composition showed consistent patterns: ant species composition varied among the matrix compared to the edge and interior of fragments (differences between edge and interior were not detected). But, we did not find an effect of forest fragment size on ant species composition. In sum, our results are consistent with previous studies that shown a negative effect of monocultures matrix on ant community. However, we did not detect a consistent response of the abundance, richness and composition of ants with patch size and edge effect. Forest replacement by monocultures represents a contemporary threaten to ant population persistence and conservation for the Chaco region.