Response of ground-dwelling spider assemblages (Arachnida, Araneae) to Montane Grassland management practices in South Africa

Abstract

1.Frequent and extensive burning practices coupled with intensive grazing management are known to impact negatively on the vegetation diversity of grassland ecosystems. Few studies have investigated the impacts on spider diversity and community structure as a result of these management practices, and no studies have been conducted in high mountain grasslands on how these spider assemblages are influenced by this form of management. 2.Here, we present the results of a study conducted in the Mpumalanga grasslands on the eastern escarpment of South Africa. Ground-dwelling spiders were sampled in the summer season from 180 pit-fall traps in five study sites that varied from either being burnt annually and grazed heavily, burnt biennially and conservatively grazed, to communal land with no set management practice. Variations between sites were assessed and based on spider species composition and assemblage structure. 3.A total of 1145 individuals were collected representing 86 species from 60 genera and 43 families. Our results show that a majority of genera in these grasslands were represented by very few individuals, where a total of 37 species were represented by singletons and 17 species that were doubletons. The most abundant families were the Lycosidae (64.3%), Gnaphosidae (9.0%), Zodariidae (5.3%), Linyphiidae (4.7%) and Salticidae (3.1%). 4.Grazing intensity and fire frequency had no measurable effect on ground-dwelling spider abundance diversity or assemblage structure. Only when rare or single species occurrence was included, was there some form of association with sites. This study has provided for the first preliminary inventory of ground-dwelling spiders for this habitat.