A 'large infrequent disturbance' in an East African savanna

Abstract

There is growing interest in large infrequent disturbances (LIDs), but by definition they occur rarely and long-term data are needed in order to study their effects and frequency. Palaeoecological records have the potential to provide information on the effects and frequency of LIDs. By comparing recent sedimentary records with known historical data, the effects of LIDs on pollen, charcoal and sedimentary sequences can be assessed. In this study, a LID in East Africa is described, and its representation in the palaeoecological record is explored. Historical records show that there was severe drought and famine in East Africa at the end of the 19th century. Fossil pollen and charcoal records from this period show evidence of a disturbance event that occurred at approximately this time. Statistical comparison of pollen and charcoal data from before, during and after the disturbance event identified it as a LID. The data also suggest that an erosion event occurred part way through the drought, indicating that an environmental threshold was exceeded. © 2006 The Author.