An analysis of the fire regime and its effects on post-fire recovery in Namaqualand Granite Renosterveld vegetation

Abstract

Namaqualand Granite Renosterveld (NGR) is a fire-prone shrubland largely confined to the Kamiesberg Uplands. More than 20% has been transformed by agricultural activities such as grazing and dryland cropping. The history of fires of Namaqualand Granite Renosterveld was assessed over a period from 2000 - 2015. Furthermore, this study aimed to assess the effects of fire and grazing on the dynamics of Elytropappus rhinocerotis and the post-fire vegetation recovery. Satellite imagery, field observations and combination of field sampling techniques were used to compile a comprehensive fire database and to collect data on vegetation parameters. The Kamiesberg Uplands has a human-induced fire regime with a fire frequency of 4.2 years, which appears to be shorter for NGR compared to other Renosterveld - types. The majority of the fires were in summer and early autumn which is the ecologically accepted season with high fire intensities. Fire Danger Index ratings for summer burns were in the dangerous and very dangerous categories. In terms of cover, the distances between E. rhinocerotis individuals were significantly more on the burnt than on the unburnt sites. The density of unpalatable species on the burnt sites is also strongly associated with E. rhinocerotis. Elytropappus rhinocerotis appears to facilitate a role as a nurse-plant for various species in renosterveld. The local biotic and abiotic conditions, allows E. rhinocerotis to maintain its abundance, thus displaying niche construction by a single species.