Untangling anthropogenic and climatic influence on riverine forest in the Kruger National Park, South Africa

Understanding the interplay between climatic and anthropogenic factors is a major challenge in palaeoecology. In particular, it is often difficult to distinguish anthropogenic and "natural" fire in the charcoal record. In this paper, analysis of fossil pollen, charcoal, diatoms and isotopic evidence from Mapimbi, a small lake in the Kruger National Park, South Africa, suggests that for most of the past ca. 700 years, the riverine gallery forests surrounding Mapimbi were primarily influenced by climate, and benefited during warmer, wetter periods. The transitions between four, statistically different phases in the time-series data coincide with regional climate records previously constructed from speleothem data, and are consistent with the transition from the medieval warm period ending in the 14th century A.D. to the cooler, drier conditions prevailing during the little ice age of ca. A.D. 1400-1800. The data also suggest a period of significant, anthropogenic influence after A.D. 1800, when maize was grown and the incidence of localised fires increased. An increase in woody cover in recent decades may be associated with the management of the area by Kruger National Park. A decline in cultivation occurred in the end of the 20th century linked with changes in socio-political organisation.