Taxonomic and Functional Trait Diversity of Summer Spiders (Araneae) in Riparian Zones of Native and Exotic Forests of a Subtropical System

Here, we analyze the effect of exotic tree plantation in riparian zones on the diversity of spiders. We accessed the taxonomic and, for the first time in the Subtropical region of Brazil, the functional diversity of ground-dwelling spiders. We sampled spiders in six riparian zones: three in a native forest and three in an exotic forest. Pitfall traps were distributed in transects distant 5, 25 and 45m from the streams. Richness was higher in the native forest associated with lower luminosity and lower acidity of soil, and abundance was also higher in the native forest associated with a litter with lower biomass of leaves. Small-bodied web builders with nocturnal circadian preference were associated with the native forest, while hunter spiders were associated with the exotic forest. Exotic forest showed higher luminosity, soil acidity and leaves in the ground layer leading to lower richness and abundance, and to an increase in the occurrence of hunter spiders. This plantation may be acting as secondary habitat and/or corridor for some spider species with specific functional traits. We suggest that managers should avoid the substitution of native vegetation by exotic forests at the region.