Synthesising the pollen records for the Drakensberg-Maloti through quantitative modelling

Abstract

The Drakensberg-Maloti has been a region of great hydrological importance for thousands of years, captured in the archaeological record as a region of refuge under dry conditions, and in recent decades supplying adjacent South Africa with water through the Lesotho Highlands Water Scheme. This is due in large part to its high amounts of orographically induced rainfall. The high amounts of rainfall mean the area lends itself well to the preservation of multiple proxies in the region's many wetlands, a very valuable resource for palaeoecological studies in the generally dry southern Africa. However, there have been few quantitative palaeoclimatic studies taking advantage of this, and none using multiple sites within the Drakensberg-Maloti region. This study represents the first attempt at such a regional synthesis. We utilised all published pollen records from the area to produce a dataset from which the standard Modern Analogue Technique was performed to reconstruct mean temperature of the warmest month, mean annual precipitation, mean winter precipitation and an annual climatic moisture index for the past 8000 years. The moisture index showed a very low amount of variation, most likely due to the low amount of variation in the modern climate data associated with the sites in the modern calibration dataset, being so near the saturation point of this index. We found evidence for a cool, wet period at around 2 cal ka BP, a period that has been identified in records from across South Africa as a Neoglacial, and which is consistent with diatom and sedimentary records from the Drakensberg-Maloti.