Disentangling environmental change in the Amazon: vegetation responses to Holocene drivers in the Yasuni National Park, Ecuador.

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Amazonia is widely recognized for its high levels of biodiversity and the importance of the ecological services it provides from local to global scales. The tropical forests we see today, however, have been shaped by long term processes such as changing climate conditions and geomorphology. Understanding how these forests have responded to past perturbations can reveal important information regarding ecosystem resilience and vulnerability which can be applied as we look towards future environmental change. Palaeoecological studies, therefore, are crucial to forecasting tropical forest response to disturbance and to inform planning of conservation efforts. This project aims to characterize the nature and composition of vegetation in lowland forests of western Amazonia throughout the Holocene and to investigate the extent to which changes can be attributed to shifts in climatic conditions, local hydrology, and anthropogenic influence. The impact of local hydrology on long-term lowland forest dynamics, especially that of river migration, has barely been explored in the palaeoecological studies performed to date in this neotectonically active region. Similarly, the scope of human occupation and its consequential impact on forest community structure and composition remains the subject of contentious debate throughout greater Amazonia. Pollen analysis will be conducted on modern samples and sedimentary records from the Yasuni National Park in Ecuador to reconstruct the local vegetational history. This approach will be complemented by further analyses, including: (1) biomarkers, that will assist in unravelling climate history; (2) charcoal analysis, that will be employed to establish fire history; (3) X-Ray fluorescence (XRF) and luminescence dating (OSL) that will be utilized to investigate the impact of changes in local hydrology; and (4) remote sensing via optical satellites and drones which will provide a link to current landscape dynamics. Once the palaeo record has been established, the information gathered will be used to chart future trajectories for the Yasuni National Park to assist in future conservation efforts. BACKGROUND: Environmental change is a global phenomenon for which understanding thebiota responses is essential. Tropical South America holds some of the most biodiverseecosystems, so long-term vegetation dynamics' studies are needed to understand the functioning and conservation of these globally important and under-studied areas. Moreover, lately observed human occupation may have played in some areas a key role in shaping the current landscapes and diversity, which might be important when analysing the resilience of a given ecosystem in facing perturbations. OBJECTIVES: The project aims to study the long-term dynamics of Amazonian forests in the Yasuni National Park (Ecuador). Main objectives are to:1. Characterize the nature and composition of vegetation on the lowland forests in north-western Amazonia during the Holocene unravelling the onset dates and environmentalconditions of the current landscape establishment. 2. Establish fire history, climate conditionsand depositional environment including fluvial influence. 3. Assess the amount of vegetation change within Amazonian forests as a result of Holocene (i) climate change, (ii) river migration, or (iii) human influence. 4. Using the palaeo signatures to try and chart future trajectories for the National Park. NOVELTY: The novel combination of proxies including pollen (vegetation), non-pollen palynomorphs (land-use), charcoal (fires), XRF (erosion), OSL (transportation) and biomarkers (precipitation) is unprecedented in the tropics and will generate a dataset capable of providing pioneer insights on long-term vegetation dynamics facing environmental changes. Besides a wide range of lab and computer techniques,environmental skills will be enlarged by fieldwork.