Landscape characteristics effects on Diptera assemblages and their relation with seasonal variations in urban green patches

Abstract

The growth of cities results in the fragmentation of natural habitats, and the alteration of the remaining ones. The effects of landscape-level drivers on arthropod assemblages in urban green spaces remain poorly understood. The aim of this study was to evaluate the effects of landscape characteristics in Diptera assemblages of urban green patches and their relation with seasonality in a southern hemisphere temperate city. Flies were sampled in urban green patches in Córdoba city, Argentina, in summer and winter of the same year. Landscape metrics derived from Sentinel 2 images were calculated at two levels of spatial heterogeneity hierarchy, at increasing buffer areas. We used generalized linear models to analyse the effects of landscape characteristics on family abundance and richness. Landscape and seasonal effects on Diptera family composition were also assessed. Abundance, richness and composition of dipteran assemblages were associated with the contrasting conditions of summer and winter, urban landscape fragmentation and the aggregation of vegetation patches. In general, fly assemblages were favoured by the aggregation of vegetation patches. The response of dipterans to landscape characteristics differed between seasons. The effects of landscape characteristics on Diptera assemblages' composition were stronger in winter. We concluded that landscape characteristics appear to have a bigger effect when environmental conditions are less favourable for these organisms. Our study provides further understanding of the effects landscape level drivers have on arthropods in green urban patches. This is particularly relevant if we wish to maintain and manage biodiversity through landscape planning.