Global Change Research and Monitoring in the Maloti-Drakensberg Mountain System (South Africa-Lesotho)
Jemma Finch – University of KwaZulu-Natal
Trevor Hill – University of KwaZulu-Natal
Global change has highlighted the need for long-term environmental monitoring to address the limited temporal range of instrumental and historical records. Palaeoecological approaches track ecological change over several thousands of years, providing a baseline understanding of ecosystems prior to human intervention. Here we use a series of sediment cores from four wetland sites in the montane and subalpine belts at Cathedral Peak (KwaZulu-Natal Drakensberg) to reconstruct vegetation and fire history. A combination of proxies is applied, including fossil pollen, stable isotopes, macroscopic charcoal, and radiocarbon dating. We use these data to analyse (i) shifts in the dominance of grassland and forest communities over time; (ii) recent changes in fire frequency and/or intensity that may be linked to human activity; and (iii) the appearance of exotic plant types. Radiocarbon results revealed that the oldest sediment cores date back to the mid-Holocene, covering the past 5,000-years. Exotic Pinus pollen was observed in the recent portions of the Catchment VI and Baboon Swamp records and can be used as a supporting time marker for the sediment profiles. Pollen and charcoal records indicate considerable variability between sites, which may be attributed to site-specific characteristics and altitudinal differences. The longest record from Catchment VI suggests relatively stable vegetation through the past 5,000-years, with no obvious shifts in dominance between grassland and forest communities. Two of the four wetland sites showed a clear recent increase in macroscopic charcoal in the past century, suggesting that recent fire frequencies and/or intensities are generally higher than those observed for the precolonial period. Increases in trilete fern spores towards the present day likely include the invasive bracken fern and coincide with increased charcoal in the record. Such long-term insights gained from palaeoecological evidence can be used to inform grassland management in the Drakensberg.