As part of the South African National Survey of Arachnida in the Grassland Biome, foliagedwelling
and grass-dwelling spiders (Arachnida: Araneae) were collected in the Erfenis
Dam Nature Reserve in the central Free State Province from November 2005 to August 2007.
Foliage-dwelling spiders were collected from three common tree or shrub species (Acacia
karroo, Searsia ciliata and Searsia lancea) and grass-dwellers from four contrasting grasslands
(uniform Themeda triandra, mixed, weedy and woodland grasslands). From the grass layer,
1649 spiders were collected, representing 15 families and 82 species, whilst 496 tree-dwelling
spiders were collected that represented 17 families and 52 species. There was some overlap
in the fauna of the two strata, resulting in a total of 108 species from 18 families being
collected. The Araneidae, Philodromidae, Salticidae and Thomisidae were consistently the
most abundant in all grassland types and tree species, although Salticidae were scarce on
A. karroo. Assemblage analysis indicates high similarity and overlap in the fauna of the four
grassland types, suggesting that the structural complexity of grasslands has a limited effect
on species composition. In contrast, the foliage-dwelling assemblages were more distinct,
with only some overlap between the faunas of S. ciliata and A. karroo, suggesting a stronger
vegetation structural effect in shaping arboreal spider assemblages. The isolation of trees
and shrubs within the extensive grassy habitat may contribute to the more unique fauna and
lower species richness of the woody vegetation.
CONSERVATION IMPLICATIONS: This study uncovered a rich diversity of plant-dwelling spiders
from central South Africa. Grassland faunas show considerable temporal variation and some
variability in microhabitat preferences, and sampling protocols should take this into account
when spiders are considered in management plans and biodiversity surveys in reserves and
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This study formed part of R.F.’s (University of the Free State)
MSc on spider ecology in the Erfenis Dam Nature Reserve.
R.F. conducted field work, sorted and tallied specimens,
performed some statistical analyses and wrote part of the
manuscript. C.R.H. (University of the Free State) supervised
R.F., performed initial identifications, performed some statistical analyses and wrote part of the manuscript. A.S.D-S.
(Agricultural Research Council – Plant Protection Research
Institute) conducted final identifications and contributed to
writing the manuscript. A.G. (University of the Free State)
assisted with field work and sorting specimens.