Landscape mosaic attributes for maintaining ground-living spider diversity in a biodiversity hotspot

摘要

Spiders often dominate predator assemblages in vineyard agroecosystems. Land-use practices that enhance their diversity may be important for regional biodiversity conservation as well as biological control of vineyard pests. We surveyed ground-dwelling spiders in habitats at different management intensities (natural habitat remnants, organic vineyards, and conventional vineyards) in the vineyard landscape of the Cape Floristic Region (CFR) biodiversity hotspot, South Africa, to examine the effects of local land use on spider diversity. Natural habitat remnants contributed significantly to the overall diversity, and supported rare families and unique species that were not found in the agricultural matrix. Nevertheless, vineyards still supported fairly high spider diversity, with a tendency for higher species richness in organic vineyards. Environmental variables relating to plant diversity, management intensity and distance to nearest natural habitat influenced spider abundance and species richness, and changes to these factors may improve the habitability of the vineyard landscape for spiders. All habitats supported various spider families that are known to prey on South African crop pests. In addition, spiders were abundant in both sampling seasons (autumn and spring), but showed a significant increase in vineyards early in the growing season, suggesting that they may provide early-season background regulation of pests. There is considerable opportunity for spider conservation in the CFR vineyard landscape, as well as the possibility of associated benefits to biological control within vineyards