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Human and climate impacts on tropical Andean ecosystems

Williams, Joseph James (2011). Human and climate impacts on tropical Andean ecosystems. PhD thesis The Open University.

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Abstract

Population growth and predicted global climate change are applying new, and increasing, pressure to mountain environments, but the consequences of these changes upon the biodiverse and vulnerable Tropical Andean ecosystems are poorly understood. This thesis explores past human-climate-ecosystem interactions using multi-proxy palaeolimnological investigations (fossil pollen, spore, charcoal and Chironomidae (midges); elemental abundance, colour spectra and magnetic susceptibility) of two sites in the eastern Bolivian Andes (Lake Challacaba and Laguna Khomer Kocha Upper) over the last c. 18,000 years. During the deglaciation and Holocene, ecosystems were exposed to varying climatic stress levels, and pressures imposed by the development of human cultures. Examination of preserved ecological assemblages, including the first assessment of subfossil central Andean Chironomidae, reveals ecosystem sensitivity to changes in temperature, moisture, fire regime, lake level, nutrients and salinity. Charcoal analysis from Laguna Khomer Kotcha Upper reveals changes in burning at c. 14,500, 10,100 and 6,400 cal yr BP. Concomitant palynological shifts shows climatically controlled fire regime was a transformative agent of Andean vegetation, particularly for the threatened, high elevation, Polylepis woodlands. Pollen and geochemical data from Lake Challacaba indicate two periods of aridity (c. 4,000-3,370 and 2,190-1,020 cal yr BP), these broadly correlated to El Nino/Southern Oscillation variations. Increased Sporormiella abundance after c. 1,340 cal yr BP indicate changes in trade-route use and agricultural practices; demonstrating human adaptation to environmental change and interconnectivity to Tiwanaku and Inca civilizations. The long-term response of the terrestrial and aquatic ecosystems, reconstructed from these lakes, has provided insights into how Tropical Andean ecosystems may respond to future changes in temperature, precipitation and human interference. The palaeoenvironmental data has implications for conservation management; it indicates that spatial and temporal variations in site sensitivity, exposure and resilience should be assessed, and that planting strategies should mimic the present day natural patchy distribution of Polylepis woodlands.

Item Type: Thesis (PhD)
Copyright Holders: 2011 The Author
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
Research Group: OpenSpace Research Centre (OSRC)
Item ID: 61088
Depositing User: ORO Import
Date Deposited: 10 May 2019 12:24
Last Modified: 12 Jul 2019 00:03
URI: http://oro.open.ac.uk/id/eprint/61088
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