Habitats and cardinal directions are key variables structuring spider leaf litter assemblages under Searsia lancea
de Jager, L.J.C.
MetadataShow full item record
Spiders are a prominent component of leaf litter assemblages, where they function as critical predators of other invertebrates. We investigated the influence of habitat, cardinal directions and position on Searsia lancea litter-dwelling spider assemblages in central South Africa. A total of 1521 spiders were collected, representing 27 families and 77 species. Species richness, abundance and coverage per tree were highest in the grassland, followed by the hillside and riparian habitats. Neither of the finer scale filters, direction nor position, had significant effects on species richness or abundance, although there was weak evidence for an increase in spider abundance toward the periphery of a tree (p=0.09) and a decrease in abundance towards the western cardinal direction (p=0.08). Species composition, though, was significantly affected by habitat (p=0.001) and direction (p=0.014), as well as a three way-interaction between habitat, direction and position (p=0.01). Hillside assemblage structure is intermediate between the other two habitats. Species abundance distributions of all three habitats were multimodal, indicating disturbance. Particularly, the log-series distribution of both the grassland and riparian woodland point to more disturbed assemblages than the hillside (Poisson log-normal distribution). Habitat therefore played a significant role in affecting richness, abundance and assemblage structure (composition and abundance). Although finer scale variables only had a weak effect on abundance, spider assemblages were influenced by direction, particularly for the climatically more variable habitats of the grassland and hillside. The significantly higher evenness and less disturbed nature of the hillside emphasize the conservation significance of this habitat.
- RESEARCH: Foord, S