Archaeological charcoal as a window on palaeovegetation and wood-use during the Middle Stone Age at Sibudu Cave.

Analysis of charcoal from Middle Stone Age layers in Sibudu Cave shows evidence for environmental change and wood selection during the Last Glacial. Layers analysed encompass the end of the cold stadial, Oxygen Isotope Stage (OIS) 4, and the warmer interstadial, OIS 3. Layers are grouped into > 60 ka, ∼60 ka, ∼50 ka and ∼37 ka assemblages. Pre-60 ka layers within the Howiesons Poort (HP) occupations are dominated by evergreen forest taxa, including Podocarpus spp., Buxus sp., Brachylaena sp., Sapium/Spirostachys and Ptaeroxylon obliquum. Kirkia sp. suggests that a warm, woodland savanna habitat grew beyond the forest vegetation. At ∼60 ka there are taxa from evergreen, riverine forest communities, including Erica spp., Leucosidea sericea and Rapanea melanophloeos. Some of the taxa in these layers suggest a shift in vegetation, possibly related to the marine regression of the Last Glacial. A lowered sea-level and slightly cooler climates in South Africa may have enabled taxa currently found farther inland in the mountain foothills to grow closer to the rock shelter than at present. By ∼50 ka, fewer evergreen forest components and more bushveld taxa, which are common in northern, drier regions of South Africa, are present. These ∼50 ka layers also contain more Acacia spp. and other Fabaceae taxa, and fewer Erica spp., than the samples from the ∼60 ka layers. This may be a result of environmental change, a change in wood selection, charcoal fragmentation, or sampling bias. At ∼37 ka, there are evergreen and deciduous taxa, many of which grow in KwaZulu-Natal today, while Kirkia sp. again provides evidence for a dry habitat. Taxa that are currently unidentified may indicate that a vegetation community existed for which there is currently no reference material. Fuel-woods commonly used by modern societies in Africa were routinely collected by ∼60 ka. In contrast, the pre-60 ka HP layers are dominated by Podocarpus spp. and the 'good' fuel-woods, Acacia spp. and Erica spp., are absent. This pattern may be a result of changes in the local vegetation, sample bias or simply a different approach to wood collection and use between the HP and ∼60 ka occupations. [ABSTRACT FROM AUTHOR]