The “eco-story” of a mountain range: the development of Socio-Ecological Disturbance Regimes in the northern Drakensberg and consequences for grassland-plant diversity

Abstract

The phenomenal level of biodiversity in the Drakensberg mountains was shaped by and depends on the disturbance regimes which prevailed before the intensification of human settlement in the region. Global change has, however, changed these disturbance regimes leaving an uncertain future for biodiversity. In order to reduce uncertainty around the influence of human society on biodiversity, we propose the Socio-Ecological Disturbance Regime (S-EDR) construct, which implicitly considers the effects of interactions between society, ecosystems, and associated disturbance regimes. We aimed to provide insight into how disturbance regimes have deviated from their “natural” range of variation, and developed into novel S-EDRs that are increasing uncertainty around the fate of plant diversity in the region. Drakensberg grasslands house high levels of indigenous grassland-plant species, many of which only occur in this mountain range. To achieve this we present findings from palaeoecological, through to more recent history, to establish the context of disturbance regimes in this landscape. Over the last 150–200 years there have been rapid and large changes in disturbance regimes, and these novel S-EDRs are demonstrated to have been shaped by interactions between the dominant “social systems” in the study area, that is, communal, private, and protected areas, and the nature of the ecosystems they inhabit. Owing to their prevalence in the landscape the disturbance regime components, fire and herbivory, and land transformation, are focused on. Understanding the nature of developed S-EDRs will be important for understanding contemporary research, guiding future investigations, and the maintenance of plant diversity in Drakensberg grasslands.

Keywords:

• Drakensberg grassland
• disturbance regime
• socio-ecological system
• global change
• fire and grazing

Acknowledgements

The South African Environmental Observation Network funded this project. The USGS, Earth Observation and Science Centre are thanked for the provision of Landsat imagery, respectively. We are grateful to Dr Ed Granger for his plant ecology work in this landscape.

Disclosure statement

No potential conflict of interest was reported by the author(s).