During June to July this summer, CPCC members Heather Plumpton, Richard Smith, John Carson and Prof. Frank Mayle went on an expedition to collect sediment samples from lowland tropical Bolivia.
The team’s fieldwork spread across two regions: the town of Riberalta in the north of Beni Department and the Chiquitania region of Santa Cruz department. This meant studying a range of modern ecosystems; from the old-growth humid evergreen rainforest to seasonally dry tropical forest and chaco. Around Riberalta the group also visited the impressive pre-Columbian earthworks at the ancient village sites of Tumichucua and Las Piedras. Their time was split between taking core samples from oxbow lakes from their floating platform (pic1), wading into bogs to take samples with a Russian corer (pic2) and digging 1m x 1.5 m pits to sample terrestrial soils for phytoliths (pic3). The Reading scientists also accompanied their colleague Daniel Soto of the Natural History Museum in Santa Craz, Bolivia, to make botanical surveys of the forest around their sample sites (pic4). Once back in the UK, these sediment samples will be analysed for microfossil remains (pollen, phytoliths and charcoal) and undergo geochemical analyses, in order to reconstruct how vegetation has changed around these sites over the past several thousand years.
What’s it for?
The samples from this field season have been collected for two projects that the group is working on. The first, “Amazonia and the 6K drought”, aims to reconstruct how Amazonian/central South American vegetation reacted to a major drought period during the mid Holocene (6000 years before present). The 6K drought can be said to be an “imperfect analogue” for the drier climatic conditions that are projected to take hold in Amazonia over the coming 100 years. A better understanding of how past ecosystems reacted to lower precipitation will help us to improve our predictions of future climate-driven vegetation change. Heather will focus on how drought at 6K might have triggered floristic changes in two distinct types of central South American forest. Richard will be using his reconstruction data from the lake and bog records to improve the performance of coupled climate-dynamic-vegetation models.
The second project, led by John Carson is “Amazonia and the Anthropocene: pre-modern human impacts and their legacy in the landscape”. John aims to investigate how and to what extent pre-Columbian natives and early European colonists changed Amazonian environments, and what legacy they may have left behind in doing so. The project uses the same palaeo-proxy techniques mentioned above, but the sampling is aimed at lakes and terrestrial soils around archaeological sites.