A late quaternary palaeoenvironmental record from Ntsikeni Wetland, KwaZulu-Natal Maloti-Drakensberg, South Africa

摘要

Ntsikeni wetland is one of the largest high-altitude wetlands in southern Africa (-1795 m asl) located in the Swartberg area of the foothills of the Maloti-Drakensberg, southern Africa. The site has been designated a Ramsar Wetland of International Importance which, with limited anthropogenic influence, renders it ideal for palaeoenvironmental investigation. This study presents a pollen-derived palaeoenvironmental reconstruction for Ntsikeni, spanning the period-25,100-650 cal BP, one of the longest, continuous records for southern Africa. The record commences with evidence of coldest conditions consistent with the peak of the Last Glacial Maximum. This is followed by progressive climatic amelioration, culminating in a warm, moist period from-7500 to 5500 cal BP. Pronounced cold periods at-13,500 cal BP,-8500 cal BP and-4000 cal BP are broadly consistent with coeval global scale temperature fluctuations. Two distinct dry events are inferred from the pollen record, spanning-19,600-18,000 and-6500-4900 cal BP. Wet events occur more frequently throughout the record, resulting in fluctuations in moisture availability, and are inferred to result in the expansion and contraction of the wetland extent similar to those recorded in the palaeorecords of the Lesotho Highlands. The Ntsikeni record provides a longer-term temporal framework with which the shorter sequences for adjacent sites in the Maloti-Drakensberg can be compared, and supports evidence for the significance of the rugged topography in inducing lags in moisture transitions.