Disentangling Environmental Change in the Amazon: vegetation response to Holocene drivers in the Yasuní Biosphere Reserve, Ecuador

Spater, Molly (2025) Disentangling Environmental Change in the Amazon: vegetation response to Holocene drivers in the Yasuní Biosphere Reserve, Ecuador PhD thesis, University of Liverpool.

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Abstract

The north-western Amazon is one of the world’s last remaining high-biodiversity wilderness areas and is hypothesised to become a key refuge and corridor for climate change-driven species migrations in the future. It is unclear how ecosystems in this region will respond to future climate change and growing anthropogenic pressures. This study aims to 1) characterise forest composition within the north-western Amazon over the course of the mid-to-late Holocene and to 2) evaluate long-term drivers of vegetation change using a multi-proxy palaeoecological approach. The overarching goal is to improve understanding of long-term forest dynamics and responses to disturbance in the north-western Amazon in order to support data-driven conservation planning in the future. The Yasuní Biosphere Reserve (YBR) of Ecuador was selected for case study. Analysis of modern pollen rain from major forest types (upland, seasonally inundated, swamp) demonstrated the ability of pollen to capture landscape level patterns of forest composition and dominance. Novel application of a text-mining method to modern pollen samples enabled the formation of guidelines for interpreting fossil pollen assemblages in the Yasuní region. This approach highlighted the importance of locally based calibration data in hyper-diverse environments where high proportions of taxa overlap along environmental gradients. Results from two sedimentary archives (spanning 7000 and 900 years respectively) indicated that intact wetland forests with minimal fire activity were resilient to hydroclimatic variability over the course of the Holocene, though shifts in forest composition, carbon storage, and aquatic communities were observed in response to periods of greater or lessened moisture availability. No signal of human occupation was found in the sequences despite regional archaeological and palaeoecological evidence for anthropogenic activity. Geochemical analyses revealed the potential influence of volcanic activity in the Andes on aquatic communities in the lowlands. Overall, this study highlights the potential sensitivity of wetland forests in the north-western Amazon to future periods of hydroclimatic change and the need for further studies on the long-term ecology of these complex systems.

Item Type:	Thesis (PhD)
Uncontrolled Keywords:	Amazon, Climate, Fire, Holocene, Palaeoecology, Yasuní
Divisions:	Faculty of Science & Engineering Faculty of Science & Engineering > School of Environmental Sciences
Depositing User:	Symplectic Admin
Date Deposited:	10 Feb 2026 09:49
Last Modified:	10 Feb 2026 09:52
DOI:	10.17638/03193675
Supervisors:	Montoya Romo, Encarnacion Smedley, Rachel Jeffreys, Rachel Wolff, George ORCID: 0000-0002-9380-1039 Marchant, Robert
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3193675
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