Sallie L. Burrough

Late Quaternary Environmental Change and Human Occupation of the Southern African Interior

The interior southern African basin (Kalahari) is a remarkable region, with a complex and dynamic environmental history and a long record of utilization by human populations during the late Quaternary. Paleoenvironmental reconstructions are beginning to provide a spatially detailed record of landscape and hydrological dynamics in the Kalahari, with a strong chronometric underpinning for records of environmental extremes. Theories concerning the distribution of early people in the landscape place great importance on the temporal dynamics of water availability, and may be particularly relevant in the Kalahari where there is significant evidence of hydrologic/climatic-driven landscape change. High amplitude environmental variability during MIS 6-2 is evidenced by periods of dune building within currently stabilized dunefields and the intermittent existence of large lacustrine systems such as Megalake Makgadikgadi that remain all but ephemerally dry under present-day conditions. That the wider Kalahari was, at times, a key resource for Stone Age populations is evident from the extensive occurrence of stone tools, most notably in association with the fluvial networks and lake basins of the Okavango-Chobe-Zambezi system. Today, these riparian corridors link the semiarid desert region to the southern subtropics and, in the past, drove environmental change in the Kalahari, potentially impacting the occupation and dispersal of hominins within the interior southern African basin.

Ecosystem resilience to late-Holocene climate change in the Upper Zambezi Valley

Peat deposits from wetlands in the Upper Zambezi Valley provide an important long-term window on ecosystem dynamics in the Kalahari basin during the late Holocene. We use fossil pollen and macro-charcoal extracted from peat cores contained in three wetland sites to examine the response of vegetation to regional climate change. We find that during the last 6 ka, internal ecosystem dynamics are more important than climate, as observed by independent records, in determining vegetation assemblage change. Fire was found to be a persistent and important component of this savanna landscape for the duration of the ecological record, but biomass burning has increased markedly over the last 1000 years. The vegetation of the Upper Zambezi Valley appears to have a larger grassland component in the last few hundred years suggesting a more open landscape today than at any other time in the last 6000 years.