How are arthropod communities structured in a modified wetland under different productive activities?

Abstract

Wetlands are among the most threatened ecosystems around the world due to changes in land use. Particularly, in the Lower Parana River Delta the main productive activities with economic impact in the region are planted forest and silvopastoral systems. To carry out these productive activities, natural hydrology of this wetland has been deeply modified and different management practices are implemented. Ground-dwelling arthropods are among the most sensitive taxa to environmental changes, so they are good bioindicators of the effect of these changes on biodiversity. In this context, we compare the structure and composition of ground-dwelling arthropod communities and their seasonal variations in the planted forest and silvopastoral systems of the Lower Parana River Delta, to characterize these land use associated with different management practices. We recorded a total of 73 families using pitfall traps (N = 1728). We observed that communities in intensive-managed planted forests were less rich and more evenness, while communities in less-managed planted forests were richer and less evenness. Also, we observed that warm seasons presented more arthropod family richness than cold seasons. The intensity of management practices, the presence of cattle and seasonality are factors that significantly decrease ground-dwelling arthropod richness. So, Silvopastoral systems negatively affect ground-dwelling arthropod communities compared to planted forest. A decrease in the intensity of management practices favors the understory growth, offering more resources for the arthropod families already established and facilitating the establishment of new ones. This increase in arthropod diversity promotes the presence of benefic species and the conservation of biodiversity in this modified wetland ecosystem.