Riqueza de árvores e cobertura herbácea estruturam a assembleia de aranhas arborícolas em cidades do semiárido brasileiro

Abstract

Although urbanization is widely recognized as a major driver of biodiversity loss, cities can also buffer negative effects and promote species survival. This study examined the effects of urbanization on arboreal spider diversity, focusing on the influence of tree diversity, climatic conditions, and landscape composition. We tested the hypothesis that urban arboreal spider assemblages are shaped by local, landscape, and climatic factors. The study was conducted in the semiarid region of Paraíba, northeastern Brazil, encompassing 10 of the 15 most populous cities in the region. Spiders were collected from identified and georeferenced street trees using entomological umbrellas. Land cover data were obtained through remote sensing, while climatic variables were extracted from the WorldClim database. Relationships between spider diversity and environmental, climatic, and landscape variables were analyzed using Generalized Linear Models (GLMs), and assemblage composition was assessed with PERMANOVA. In total, 3,401 spider individuals were sampled, representing 88 morphospecies across 23 families. Spider abundance was higher in areas with greater herbaceous cover within a 100-meter radius and, together with species richness, increased in locations with higher tree diversity. Climatic variables such as temperature and precipitation did not significantly influence spider diversity. However, the composition of spider assemblages varied according to tree species richness. These findings partially support the proposed hypothesis, revealing that both the richness and abundance of arboreal spiders increase with tree diversity, while highly urbanized areas with low vegetation cover harbor fewer individuals. The study underscores the importance of maintaining and enhancing tree diversity in urban areas as a key strategy for supporting richer arboreal spider assemblages, offering a valuable foundation for biodiversity conservation in semiarid urban ecosystems.