Abundances of three spider (Araneae) species in native and managed ecosystems in Rio Grande do Sul State, Brazil

Ronei Baldissera, Gislene Ganade, Antonio D. Brescovit, Sandra M. Hartz

Abstract


We assessed the abundance patterns of three theridiid species: Hetschkia gracilis (Keyserling 1886); Phycosoma altum (Keyserling 1886); and Thwaitesia affinis O.P.-Cambridge, 1882 in four habitats: Araucaria Forest (native forest) and plantations of A. angustifolia, Pinus spp., and Eucalyptus spp. in Floresta Nacional de São Francisco de Paula Reserve, southern Brazil. The plantation stands in the study system are managed by the selective cutting of adult trees, allowing longer rotation intervals. We collected spiders in 2003 and 2004 by beating the vegetation inside three replicates of each forest type. We performed a permanova to test whether there were differences on species abundances between habitats. We tested the influence of the stand sizes, distance between stands, and vegetation cover composition on each spider species abundance. Stands with higher vegetation cover of bushes and vines presented higher abundances of Hetschkia gracilis and Thwaitesia affinis. Phycosoma altum abundance did not respond to any explanatory variables. Results highlighted the importance of alternative management of plantation stands to enhance and maintain the understory vegetation diversity, which in turn support the spider populations.

Key words: Araucaria Forest, Habitat structure, Pinus plantation, Eucalyptus plantation, Forest management.


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