Abstract
Background: Ground-dwelling spider assemblages in shrublands and cultivated pastures in the South African Grassland Biome have never been comprehensively studied.Objectives: Epigeic spiders were collected in eight different habitats in the Amanzi Private Game Reserve in the Free State to determine assemblages of different vegetation types.Methods: Three of the sampled habitats were contrasting low-lying shrublands; three were contrasting hill aspects (northern slope, southern slope and plateau) in the Buddleja saligna–Searsia burchellii–Olea europaea africana subcommunity; one habitat was cultivated Digitaria eriantha pastures, and the last habitat was an area in and around a freshwater dam. Spiders were sampled by pitfall trapping in early spring (Sept. 2012), mid-summer (Jan. 2013), mid-autumn (Apr. 2013) and mid-winter (July 2013).Results: A total of 2982 adult spiders were collected, representing 129 species and 33 families. Ammoxenidae was the most abundant family (40.85%), followed by Gnaphosidae (21.26%), Zodariidae (10.80%) and Salticidae (10.26%). Gnaphosidae was the most species-rich family (24.81%), followed by Salticidae (13.18%), Lycosidae (11.63%) and Zodariidae (6.20%). Spider activity densities and species richness did not differ significantly between habitats, although significant seasonal fluctuations were detected. The three hill aspects and cultivated D. eriantha pastures had the most distinct assemblages, while those of the three low-lying shrublands and freshwater dam showed considerable overlap.Conclusions: Our results indicate that the aspect of hills has a significant effect in shaping spider assemblages, while the vegetation composition of shrublands is not strongly influential. The unique spider assemblages of cultivated D. eriantha pastures can be attributed to the absence of woody plants.Conservation implications: This was the first study to investigate ground-dwelling spider assemblages in shrublands and cultivated pastures in the South African Grassland Biome. Our study confirms that hill aspects, shrublands and pastures harbour very different spider faunas. When identifying land for potential expansion or establishment of protected areas, conservation planners should ensure that the greatest diversity of vegetation units are included to optimise the conservation of biodiversity.
Highlights
In Africa, the Grassland Biome is largely limited to the central plateau of South Africa, Lesotho and parts of Swaziland (Mucina & Rutherford 2006)
Nearly 910 point localities have been sampled for spiders in South African grasslands, only 27 of these have more than 100 specimen records (Foord, Dippenaar-Schoeman & Haddad 2011)
Previous studies on ground-dwelling spiders in the Grassland Biome have focused on open grasslands, while the shrubland faunas have received little attention (Butler & Haddad 2011)
Summary
In Africa, the Grassland Biome is largely limited to the central plateau of South Africa, Lesotho and parts of Swaziland (Mucina & Rutherford 2006). It is characterised by extremely high plant biodiversity, second only to that of the Fynbos Biome (Low & Rebelo 1996). Nearly 910 point localities have been sampled for spiders in South African grasslands, only 27 of these have more than 100 specimen records (Foord, Dippenaar-Schoeman & Haddad 2011). Ground-dwelling spider assemblages in shrublands and cultivated pastures in the South African Grassland Biome have never been comprehensively studied
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