Effects of a fast-burning spring fire on the ground-dwelling spider assemblages (Arachnida: Araneae) in a central South African grassland habitat

Abstract

Fire is widely used as a management strategy in grasslands to maintain vegetation structure and improve grazing quality for large herbivores. The impacts of burning on invertebrates in South Africa remain poorly understood. A study was initiated in spring 2005 to determine the impact of a fast hot burn on ground-dwelling spider assemblages in a grassland habitat in the central Free State. Pitfall traps were set out at six sites in the reserve, with three sites each in the burnt and unburnt areas, to sample spiders over a 12-month period. A total of 5 253 spiders were collected, representing 33 families and 120 species. Spider abundance was significantly lower in the burnt (n = 1 956) than unburnt sites (n = 3 297), and burnt sites had, on average, considerably fewer species than unburnt sites. The dominant families in the burnt sites were Lycosidae (29.5%), Gnaphosidae (16.9%), Ammoxenidae (9.6%) and Zodariidae (5.7%), whereas Ammoxenidae (22.7%), Lycosidae (20.6%), Gnaphosidae (15.3%) and Amaurobiidae (10.2%) dominated the unburnt sites. Of the nine most abundant families collected, only Caponiidae were more abundant in the burnt than unburnt sites. Our data suggest that fast-burning hot spring fires cause a considerable initial post-fire decline in spider abundance, and have a negative influence on the abundance as well as the resistance of assemblages to disturbances other than fire (e.g. rain). However, most of the dominant families had abundances comparable to unburnt areas within a year post-burn.

The effect of elevation and time on mountain spider diversity: a view of two aspects in the Cederberg mountains of South Africa

“…Richness was higher during the wet season, following the peak rainfall period in the region and corresponds with other work in southern Africa (Dippenaar‐Schoeman et al ., ; Haddad et al ., ). Contrary to our expectation, richness values at the higher elevations peaked in the dry season, giving rise to a third‐order polynomial response of richness to elevation on the western aspect and a U‐shaped response on the east (Fig.…”

“…S1). Other studies have also shown that the impacts of fire in particular can be small and short term (Underwood & Quinn, ; Haddad et al ., ), while the impacts of agriculture are often more longer term and negative (Prieto‐Benítez & Méndez, ). The impacts of these disturbances were, however, transient and did not affect the broader scale patterns over the period of the study.…”

Short-term spider community monitoring after cattle removal in grazed grassland

“…In terms of grasslands, richness and abundance of spider vary. For African grassland, Ammoxenidae, Lycosidae and Salticidae seems to be the most abundant (Jansen et al, 2013;Haddad et al, 2015; as Gnaphosidae, Salticidae and Thomisidae were the richest (Foord et al, 2011;Haddad et al, 2015; in most recent studies. For South American grasslands Linyphiidae, Lycosidae and Salticidae seems to be the most abundant and richest families Pompozzi et al, 2011;Podgaiski et al, 2013;Cunha et al, 2015;Zanetti, 2016).…”

Ground-dwelling spider assemblages in contrasting habitats in the central South African Grassland Biome

“…This is higher than the eight species collected during nearly 22 000 pitfall trap-days' sampling in open grasslands in the Erfenis Dam Nature Reserve was not collected in this study but has been recorded from the other two sites (Fourie et al 2011;Haddad et al 2015). In addition, an unidentified Harpactira sp.…”