The montane cloud forests of South America are some of the most biodiverse habitats in the world, whilst also being especially vulnerable to climate change and human disturbance.
Today much of this landscape has been transformed into a mosaic of secondary forest and agricultural fields. This thesis uses palaeoecological proxies (pollen, non-pollen palynomorphs, charcoal, organic content) to interpret ecosystem dynamics during the late Quaternary, unravelling the vegetation history of the landscape and the relationship between people and the montane cloud forest of the eastern Andean flank of Ecuador. Two new sedimentary records are examined from the montane forest adjacent to the Río Cosanga (Vinillos) and in the Quijos Valley (Huila). These sites characterise the natural dynamics of a pre-human arrival montane forest and reveal how vegetation responded during historical changes in local human populations.
Non-pollen palynomorphs (NPPs) are employed in a novel approach to analyse a forest cover gradient across these sites. The analysis identifies a distinctive NPP assemblage connected to low forest cover and increased regional burning. Investigation into the late Pleistocene Vinillos sediments show volcanic activity to be the primary landscape-scale driver of ecosystem dynamics prior to human arrival, influencing montane forest populations but having little effect on vegetation composition.
Lake sediments at Huila from the last 700 years indicate the presence of pre-Hispanic peoples, managing and cultivating an open landscape. The subsequent colonization of the region by Europeans in the late 1500’s decimated the indigenous population, leading to the abandonment of the region in conjunction with an expansion in forest cover ca. 1588 CE. After approximately 130 years of vegetation recovery, montane cloud forest reached a stage of structural maturity comparable to that seen in the pre-human arrival forest. The following 100 years (1718-1822 CE) of low human population and minimal human impact in the region is proposed as a shifted ecological baseline for future restoration and conservation goals. This ‘cultural ecological baseline’ features a landscape that retains many of the ecosystem service provided by a pristine montane forest, while retaining the cultural history of its indigenous people within the vegetation. Continue Reading
Supervsiory team:Dr. Sandra Nogué, Prof Mary Edwards, Prof. David Sear, Dr. William Gosling (University of Amsterdam), Prof. Inger (Tromso University), Prof. Janet Wilmshurst (Landcare research and University of Auckland)
Rationale: The Pacific islands of Polynesia were among the last places on earth to be colonised by humans. The precise dates of colonisation are debated – a situation which arises from the different sources of evidence (1, 2). New lake sediment records from the Cook Islands (Atiu, Mangaia) and Samoa (Upolu) and Tonga show very clear evidence of disturbance, but what is unclear is to what extent the signal represents the arrival of humans or a change in climate (2). A key question for the analysis of sedimentary records is the ability to distinguish natural variability in the environment of Pacific Islands from that arising from the arrival of humans in a temporal and spatial context. We aim to use a multi-proxy approach based on SedDNA, lipid biomarkers, fossil charcoal, and pollen preserved in lake sediments to identify: a) the presence of humans and/or livestock that were brought with them, and b) the related environmental change. Multiproxy approaches supported by statistical analysis, will be deployed to four sites where we already have good chronological controls and high resolution records of palaeoclimate. We are well placed to apply new methods and higher resolution analyses to address fundamental questions about the response of remote pacific islands to climate and human forcings.
Kissling, W.D., Blach-Overgaard, A., Zwaan, R.E. & Wagner, P. (2016) Historical colonization and dispersal limitation supplement climate and topography in shaping species richness of African lizards (Reptilia: Agaminae). Scientific Reports 6, 34014. DOI: 10.1038/srep34014
Lutz, H.L., Weckstein, J.D., Patane, J.S.L., Bates, J.M. & Aleixo, A. (2013) Biogeography and spatio-temporal diversification of Selenidera and Andigena Toucans (Aves: Ramphastidae). Molecular Phylogenetics and Evolution 69, 873-883. DOI: 10.1016/j.ympev.2013.06.017
Malhi Y. , Gardner T.A., Goldsmith G.R., Silman M.R., Zelazowski P. (2014) Tropical forests in the Anthropocene. Annual Review of Environment and Resources39, 125-159. DOI: 10.1146/annurev-environ-030713-155141
Morueta-Holme, N., Engemann, K., Sandoval-Acuña, P., Jonas, J.D., Segnitz, R.M. & Svenning, J. (2015) Strong upslope shifts in Chimborazo’s vegetation over two centuries since Humboldt. Proceedings of the National Academy of Sciences 112, 12741-12745. DOI: 10.1073/pnas.1509938112