Four working packages (WP) were designed to address the primary research objective:
WP1. FTIR Fire Intensity Protocol. FTIR analysis was used to quantify combustion temperatures of charred plant material as an indication of past fire intensity, a key component missing in reconstructing past fire regimes. Deliverable 1.1: a protocol was developed to quantify combustion temperatures of macrocharcoal in sediment cores to determine past fire intensity. I then traveled to UBFC for my secondment to collect samples for FTIR analysis and was trained in paleofire database management for WP4 (discussed below). Deliverable 1.2: a paper describing the results of WP1 was published (Maezumi et al. 2021). A second publication applying this new technique to the fossil charcoal record is currently in review (Maezumi et al., PNAS, In Review).
WP2. Leaf-wax extraction and analysis of δDwax isotope samples. A one-month field season to collect modern leaf samples along a precipitation gradient in the Bolivian ARE was cancelled as a result of COVID. Additionally, facilities at UVA were intermittently restricted during the pandemic and I was delayed out of the Netherlands for 5 months due to boarder closures at the onset of the pandemic. To ensure the completion of WP2, I developed a new collaboration with Dr. Bronwen Konecky and PhD student Alessandro Mauceri at the University of Washington in St. Louis, USA. As research labs in the US were not closed during the pandemic, Mauceri incorporated the leaf-wax analysis component of this project into his PhD. He is currently co-supervised by Dr. Konecky and myself. Mauceri has completed the preliminary analysis of the leaf-wax samples and is in the process of writing up his first dissertation chapter pertaining to the methods and results from this analysis. These data will be used to test the quantitative relationship between δDwax and water-stress and develop a quantitative paleohydrological dataset. Deliverable 2.2: a paper describing the results of WP2 will be submitted as one of Mauceri ‘s dissertation chapters and as a manuscript for publication.
WP3. Structural-equation modeling. Once completed, the data generated in WP1 and WP2 will be integrated with existing pollen, macrocharcoal, geochemistry and archaeology data for SEM model development. As a result of COVID delays, we are still awaiting the palaeoclimatology data from WP2 to develop the SEM model. As an alternative to the SEM model, I developed a new model-based collaboration with Dr. Tyler Kukla at Stanford University to model the past direct (human) and indirect (climate) drivers of fire across the Amazon. Deliverable 3.1: was be a new model parameterizing climate-fire-vegetation-human linkages. Deliverable 3.2: was a paper describing the results of this new model (Kukla, Ahlström, Maezumi et al. 2021).
WP4. Data Synthesis: Paleofire Database Management. During my secondment at UBFC I was trained in Global Charcoal Database (GCD) management and have updated with database with recently published charcoal records from the Amazon. Deliverable 4.1: is a paper describing the results of WP4 (Gosling, Maezumi et al. In Revision). Additionally, I have recently been appointed to the Scientific Steering Committee for the International Paleofire Network who administer the GCD. Updating the database with new records from the Amazon will increase public data accessibility and enable comparisons between new data contributions and existing datasets for future analyses.
