Evaluating sampling methods in charcoal-rich layers and high diversity environment: A case study from the Later Stone Age of Bushman Rock Shelter, South Africa

Abstract

In southern Africa, archaeobotanical studies are intrinsically linked to prehistoric investigation and the discipline of anthracology has already proved its potential for palaeoenvironmental and palaeoecological reconstructions. While the region benefits from particularly good preservation of macro charcoal remains in its sites, anthracological studies remain underexplored and the methodological framework still needs to be developed and adapted to the diverse southern African ecological contexts. Here we provide a review of sampling methods and sample representativeness and we compare it with wood charcoal analyses performed in southern Africa. We used the charcoal-rich layers from the Later Stone Age sequence of Bushman Rock Shelter (BRS) to elaborate a sampling strategy producing samples that can both be analysed in a timely manner and that are statistically representative of the whole assemblage. In light of our results, we discuss the relevance of applying anthracological methods developed in European contexts. The evaluation of the taxa richness, diversity and size distribution at BRS leads to the recommendation of the identification of at least 500 charcoal fragments per stratigraphic unit. Thick layers should be split into two distinct samples, one comprising the top half and the other one the bottom half of the layer. The analysis of thin layers with limited charcoal abundance necessitates increasing the surface of sampling. All size-classes should be analysed to avoid any sampling bias.