PhD Project on Palaeoecology of South America
NERC-funded PhD Project on Tropical Palaeoecology of South America
Proxy-Based Late Quaternary Environmental Reconstruction in Lowland Tropical South America
Co-supervisors: Prof. F. Alayne Street-Perrott (Univ. of Wales Swansea),
Prof. Sarah Metcalfe & Prof. Melanie Leng (Univ. of Nottingham)
PROJECT BACKGROUND AND PROBLEM
The overall aim is to improve understanding of Late Quaternary ecosystem and climatic changes in the Southern Hemisphere tropics of South America (SHTSA). Although high-quality Quaternary palaeoenvironmental data exist for the Bolivian/Peruvian Andes (e.g. Lake Titicaca) and eastern Brazil, very little research has been undertaken in the continental interior of SHTSA. This project will test the following hypotheses:
1) SHTSA was more arid than present during the Last Glacial Maximum (LGM), in contrast to prediction from the Astronomical Theory and Bolivian Andean lake-level records.
2) The Bolivian lowland dry forests were reduced during the last glacial period compared with present, in contrast to prediction from the Pleistocene Dry Forest Arc hypothesis.
3) Late Quaternary changes in the extent of Pantanal wetlands (and hence methane emissions) are synchronous with polar ice-core methane records (if true, this would suggest a causal link).
Please note: These hypotheses are only suggestions. The applicant is free to steer the focus of the project to their own particular interests within the broad theme of the topic.
APPROACH AND METHODOLOGY
The study site is Laguna La Gaiba (LLG), a very large 55 km2 seasonally-flooded lake, located in the heart of SHTSA on the Bolivian/Brazilian border between the Pantanal wetland to the east (the largest tropical wetland on Earth) and the Chiquitano Dry Forest to the west. The Quaternary history of both of these ecosystems is unknown. This site is ideal for study because its extensive hydrological catchment from rivers that span the Pantanal and beyond means that its palaeo records likely reflect large-scale climate change in the heart of SHTSA. Furthermore, a suite of 12 AMS 14C dates (on twigs) demonstrate a continuous sedimentary sequence spanning at least the past 40,000 years. Ongoing pollen analyses (another PhD project) from the 6 metre LLG core suggest that the LGM climate may have been more arid than today and that the surrounding dry forest may be only Holocene in age. However, environmental reconstruction is hampered by difficulty in distinguishing between upland savanna versus wetland habitats by pollen alone. The student will complement this pollen study by using recently-developed grass cuticle analysis, molecular delta-13C analysis, and diatom analysis to distinguish between upland savanna versus wetland/aquatic grasses, differentiate between terrestrial and aquatic carbon inputs, and reconstruct water-level changes, respectively. This multi-proxy approach will provide a much more complete and detailed palaeoenvironmental reconstruction than is possible from any single line of evidence. Training in grass cuticle analysis, integration with the pollen data, and tropical palaeoecology will be provided at Edinburgh. The student will visit Nottingham and Swansea to be trained in diatom and carbon isotope analyses, respectively. There will be opportunities to visit the study site for further sample collection. (Note: The student should not feel constrained by this choice of proxies and may choose to focus on one in particular, or indeed may wish to employ additional or alternative ones).
Note:
Deadline for receipt of application forms: 31st May 2007.
Only UK citizens are eligible to apply for the full NERC funding available.
Details of how to apply can be found at:
Queries about the application process should be made to the postgraduate secretary, Helena Simm: helena.sim@ed.ac.uk
Queries about the project should be made to the supervisor, Francis Mayle: Francis.Mayle@ed.ac.uk
Tuesday, May 22, 2007
