Spiders were collected by sifting leaf litter of three common tree species, Cussonia paniculata sinuata, Olea europaea africana and Searsia lancea, in an undisturbed grassland habitat in central South Africa. The study aimed to collect baseline data on spider assemblage structure, seasonality and the effects of litter structure on spider assemblages. In total, 1385 spiders were collected, representing 26 families and 56 species. Four species, Obatala sp. (Amaurobiidae, 22.7%), Camillina maun Platnick & Murphy (Gnaphosidae, 17.0%), Proevippa sp. (Lycosidae, 11.4%) and Zelotes frenchi Tucker (Gnaphosidae, 9.2%) dominated the fauna. Spider abundance was the highest in Olea litter (n = 607), followed by Searsia (n = 453) and Cussonia (n = 325). Searsia had the greatest number of species (41 spp.), followed by Olea (35 spp.) and Cussonia (30 spp.). Both spider abundance and species richness per sample varied significantly between the tree species. Of the ten most abundant species, all but two showed a significant preference for particular litter types. Mean spider abundance and species richness per sample were the lowest in Cussonia litter, which was the deepest litter type, but with the most interstitial space, whereas mean abundance and species richness per sample were the highest in Olea litter, which was the shallowest and moderately compact in structure. RésuméDes araignées furent collectées en tamisant de la litière de feuilles de trois espèces d'arbres communes, Cussonia paniculata sinuata, Olea europaea africana et Searsia lancea, dans un habitat de prairies intact du centre de l'Afrique du Sud.L'étude visait à récolter des données de référence sur la structure des assemblages d'araignées, sur leur saisonnalité, et sur les effets de la structure de la litière sur les assemblages d'araignées. Au total, 1 385 araignées ont été collectées, représentant 26 familles et 56 espèces. Quatre espèces Obatala sp. (Amaurobiidae, 22,7%), Camillina maun Platnick & Murphy (Gnaphosidae, 17,0%), Proevippa sp. (Lycosidae, 11,4%) et Zelotes frenchi Tucker (Gnaphosidae, 9,2%) dominaient la faune. L'abondance des araignées était au maximum dans la litière d'Olea (n = 607), suivi de Searsia (n = 453) et de Cussonia (n = 325). Searsia comptait le plus grand nombre d'espèces (41 spp.), suivi par Olea (35 spp.) et par Cussonia (30 spp.). L'abondance des araignées et la richesse en espèces par échantillon variaient significativement entre les espèces d'arbres. Parmi les dix espèces les plus abondantes, toutes sauf deux montraient une préférence significative pour des types de litière particuliers. L'abondance moyenne des araignées et la richesse moyenne en espèces par échantillon étaient plus faibles dans la litière de Cussonia, qui était le type de litière le plus profond mais avec le plus d'espaces interstitiels, alors que l'abondance moyenne et la richesse moyenne en espèces par échantillon étaient les plus hautes dans la litière d'Olea, qui est aussi la plus mince et dont la structure est modérément compacte.
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 salignaSearsia 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.
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