Urbanization is one of the main processes driving environmental transformation, altering the structure and functioning of biological communities across multiple spatial scales. In this study, we evaluated the effects of local and landscape variables on the taxonomic and functional composition of ants in different types of urban green spaces in the city of Salvador, Brazil. A total of 62 sampling points were surveyed across forest fragments, squares, streets medians, and vacant lots, using specific methods for both ground-dwelling and arboreal strata. We recorded 93 ant species distributed among 20 functional groups. Our results indicated that, at the local scale, leaf litter depth was the primary explanatory factor for both taxonomic and functional richness, as well as for functional composition. At the landscape scale, human population density and vegetation cover surrounding the sampling points influenced the distribution of species and functional groups, revealing contrasting patterns between specialist and generalist species. While arboreal, hypogeic, and fungivorous ants were more dependent on structurally complex and conserved habitats, epigeic, omnivorous, and some predatory species were favored in more simplified and heterogeneous environments. These findings highlight that biodiversity conservation in urban areas depends on integrated strategies across multiple scales, encompassing management practices that ensure local structural complexity alongside planning that promotes habitat heterogeneity at the landscape level. Overall, the study demonstrates that the arrangement and quality of urban green spaces play a central role in maintaining both taxonomic and functional diversity of ant communities in tropical cities.
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RBINS Staff Publications 2026
Local extinction of specialist species due to fragmentation is one of the major causes of biodiversity loss. Increased extinction rates in smaller fragments are expected to result from both smaller local population sizes, which increase the effect of environmental or demographic stochasticity, and increased edge effects. However, the relative effect sizes of these two factors are still poorly investigated. We attempt to disentangle these effects on ground beetle communities of temperate broadleaved woodland fragments situated in one of the most urbanized regions in Belgium. Assemblages were sampled along transects that extended from 30 m outside to 100 m inside both small and large historic forest fragments. Although species assemblages within the forest were highly distinct compared to those sampled outside the forest, species turnover along these transects was less pronounced within forest fragments indicating only weak edge effects. The magnitude of edge effects did not differ significantly between large and small fragments. However, larger differences in species composition were observed with respect to fragment size, wherein highly specialized species persisted only in the largest fragment. In sum, increased local extinction processes in smaller fragments, which led to a strong reduction of specialized and wingless forest species, appeared to be the most important factor that drives changes in species composition in this historic and fragmented woodland complex.
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Dams affect aquatic biota in running water by altering the environmental dynamics. One of the communities affected are benthic invertebrates, that perform important functions such as nutrient cycling and energy transfer in reservoirs. We investigated the influence of the following factors: spatial, abiotic variables, reservoir characteristics and land use on the richness, biomass and composition of benthic invertebrates in 29 reservoirs in southern Brazil. Sediment samples and abiotic variables were collected in the littoral and profundal zones of reservoirs during the dry (July) and rainy (November) seasons in 2001. We used principal coordinates of neighbour matrices to obtain the spatial factors. We analysed the unique and overall effects of the four factors. We found that the factors analysed significantly influenced the composition and biomass of the invertebrates (22%). The percentage of variation explained by the unique effects of the different factors showed similar values, but the spatial factors showed the highest value (4%). This indicates that closer reservoirs have higher similarities in terms of composition and biomass of benthic invertebrates. On the other hand, the abiotic variables had the highest explained value when evaluating the overall effects (10%). Therefore, for invertebrate richness, only the reservoir characteristics were significant for the overall and unique effects (49%). More specifically, we observed lower taxon richness in older reservoirs, probably because the age of such artificial aquatic ecosystems influences other variables, which structure the benthic communities. In conclusion, the structure of benthic invertebrate communities in reservoirs of southern Brazil are mainly driven by spatial and reservoir characteristics.
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RBINS Staff Publications 2024
