Jemma M. Finch

Ecosystem change in the South Pare Mountain bloc, Eastern Arc Mountains of Tanzania

Palaeoecological evidence is used to investigate climatic and anthropogenic drivers of vegetation and fire dynamics through the past ~1200 years in the Eastern Arc Mountains, Tanzania. Pollen and charcoal analyses are supported by a chronology derived from five accelerator mass spectrometry ages, a 137Cs activity profile and marker horizons from two exotic pollen taxa. Pollen indicator taxa are used to develop a series of environmental indices, and compared with fluctuations in key timber species, and a fire history reconstruction. Prior to AD 1274, the ecosystem is characterised by moist montane forest that is somewhat anomalous with other East African records, providing evidence for the persistence of a mesic environment and ecosystem resilience of the Eastern Arc Mountains. An open drier forest type is recorded from AD 1275 to 1512, resulting from regional aridity; when the aforementioned buffering ability was exceeded and ecosystem resilience curtailed. Maize appears from ~AD 1737, possibly associated with the regional expansion of agriculture to supply the ivory trade. The peak of the caravan trade in the mid-19th century, and later colonial administration, coincides with intensified human impacts, specifically forest clearance suggested by substantial declines in the timber tree Ocotea. Following independence, there are tentative signals of montane forest recovery, which coincide with the establishment of forest reserves, and associated timber bans. Palaeoecological understanding of historical ecosystem change in the Eastern Arc Mountains biodiversity hotspot is vital to build informed conservation and forest management policies for a future characterised by growing human populations coupled with changing climate–ecosystem relationships.

Distribution of Salt-Marsh Foraminifera in Two South African Estuaries and the Application as Sea-Level Indicators

ABSTRACT Strachan, K.L.; Hill, T.R.; Finch, J.M.; Barnett, R.L., and Frenzel, P., 2017. Distribution of salt-marsh foraminifera in two South African estuaries and the application as sea-level indicators. The global mean sea level is rising as a result of climate change and is likely to affect millions of people. It is essential to understand and quantify regional relative sea-level variability to be able to predict future changes. Proxy evidence is necessary for extending our understanding of past sea-level changes beyond the industrial era, and salt-marsh foraminifera have become an important tool for reconstructing late Holocene sea-level changes. In South Africa, little is known regarding the distribution of salt-marsh foraminifera and their use as sea-level indicators, thereby limiting their application in sea-level research. This study therefore describes the distribution of living and dead surface foraminifera from two study sites along the SE South African coastline. The full surface dataset has been compiled from 139 samples that are used to describe the contemporary distribution of salt-marsh foraminifera. Cluster analysis is used to define four biozones; high marsh, middle marsh, low marsh, and mudflats. In the high marsh, where environmental conditions reach the survival threshold, a greater abundance of agglutinated foraminifera occurs. In the low-marsh zone, where subaerial exposure is restricted and environmental conditions are usually stable, a greater diversity of calcareous species occurs. The tidal mudflats have the highest diversity of calcareous assemblages with some agglutinated taxa present. Distributions of living foraminiferal populations are similar to the population distributions of dead foraminifera at both sites in the low-marsh and mudflat zones. In the high-marsh zones, however, the living-to-dead ratio and distributions are different, which could be a result of different influences of environmental variables along with seasonal variations. This study provides insights into foraminiferal distributions along the SE coastline of South Africa, which will be useful for interpreting late Holocene sea-level changes.

The history and development of Quaternary Science in South Africa

Abstract Research in Quaternary Science in South Africa has developed rapidly over recent decades, growing into a strongly interdisciplinary and increasingly applied science. A historical overview of the discipline is provided, outlining its roots and placing the first studies in southern Africa in context, highlighting the contributions of pioneering researchers within the field here. The inherent methodological difficulties of working in a semi-arid environment have promoted the application and development of diverse, and sometimes novel archives and proxies. Indeed, there has been a noticeable shift away from traditional pollen-based climate reconstructions to a more diverse range of approaches, including multi-proxy evidence. The growth of the palaeosciences in South Africa has been supported by national research strategies and targeted funding instruments, and the promotion of environmental change research in general by national research networks.

South African Biomes and Their Changes Over Time

A biome is the largest geographical unit used for biotic classification, based on plant and animal life in conjunction with climate. Here we introduce the biomes of South Africa, and illustrate their changes over time through the use of case studies. An historical context for this analysis is provided by summarising key national vegetation classification schemes, including the most recent classification of nine biomes. Each of these biomes is briefly introduced, describing their location, characteristics, climate, ecology and conservation importance. Longer-term vegetation changes linked to climate and human activity in the Succulent Karoo/Fynbos ecotone are explored using palaeoecological evidence. Recent bush encroachment in the grassy biomes is reviewed, drawing on results from a range of methodologies. Finally, we review future projections for the ecologically important Fynbos biome under anthropogenic climate change, based on bioclimatic modelling. These studies demonstrate the dynamic nature of South African biomes, and the range of natural and anthropogenic drivers which influence their composition and distributions.