Ecology of the past

Teunissen van Manen, M.L. (2020) Plant wax n-alkane biomarkers in the tropical Andes (Ecuador). PhD Thesis, University of Amsterdam, Amsterdam. ISBN: 9789491407857

Abstract

Developing new applications for plant wax n-alkane biomarkers can deepen our understanding of ecosystem history. In this thesis I study modern and sedimentary n-alkane signals, sourced along the tropical Andes, to better understand how they can be used as a proxy for past environmental change. The overarching question addressed in this thesis is: what do n-alkane patterns extracted from sedimentary records reflect? Specifically, I address:• Do environmental or taxonomic factors dominate the n-alkane signal?• Does the n-alkane signal alter as the plant material degrades?• How much of the n-alkane variability can be explained by our analytical protocols?I find that the taxonomic and environmental signals of n-alkane patterns are entangled, especially in leaf n-alkanes. Soil n-alkane patterns reflect environmental conditions at the site, but the results cannot rule out a taxonomic signal in soil n-alkane patterns. I also find that, as the source material degrades (leaves), the n-alkane patterns are altered. Although the n-alkane signal is recognizable as having plant origin, there is a reduction in n-alkane pattern variability and the metric for degradation becomes an increasingly important descriptor of the n-alkane pattern shifts observed in soils and sediments. I find evidence that the metric for degradation can be used as proxy for past environmental change, but the application of this n-alkane signal proxy is not straightforward. Finally, I find there is little understanding of how much extraction and measurement protocols contribute to the n-alkane pattern variability and what implications this has on interpretations of the n-alkane signal.

Handel: http://hdl.handle.net/11245.1/716e0c42-7bc7-4270-9d76-e4c556c51e1a