Periodic Reporting for period 1 - FIRE (Fire Impacts in Rainforest Ecotones)
Berichtszeitraum: 2019-08-01 bis 2021-07-31
Amazonian rainforest ecotones (AREs) are hotspots for biodiversity and harbors some of the earliest records of human occupation and plant domestication in Amazonia. In recent decades, increased human activity has caused AREs to be one of the most heavily exploited and most threatened ecosystems in the Amazon. Modern synergies between direct human activity and indirect climate change impacts threaten to accelerate forest to savanna transformation through positive feedback loops by increasing future fire susceptibility, fuel loads and fire intensity. While modern human-influence in the ARE is large, the long-term (>centennial time-scale) ecological effects of natural- and human-caused fire in AREs remain poorly understood. In the upcoming century, regional precipitation is expected to decrease due to deforestation and reduced evapotranspiration, while natural- and human-caused ignitions are projected to increase fire in AREs. These combined results will likely drive the expansion of savanna forests at the expense of rainforest vegetation. The loss of rainforest vegetation will decrease CO2 uptake and contribute to future warming temperatures. Thus, there is an urgent societal need to understand the long-term effects of climate variability and human disturbance of fire in these vital ecosystems to inform future land-management and conservation efforts. Through a state-of-the art interdisciplinary framework combining paleoecology, paleoclimatology, archaeology data, and statistical modeling the FIRE project has enabled me to address my primary research objective: to determine the long-term natural- and human-caused drivers of fire in the ARE. Publications detailing the conclusions of the action are detailed below.
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.
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.
The wider societal implications of this project have the potential to engage local stakeholder communities in the ARE through the adoption of new environmental policies that may deter agricultural expansion into the rainforest and encourage the adoption of fire-free farming practices. Research communities impacted by the results of this research include: (a) the paleodata community; (b) the ecosystem and fire modelers; and (c) land managers and local stakeholders. Since the onset of the project, I have published 12 co-author, peer-reviewed articles related human-fire interactions and currently have 4 in review. To increase public accessibility, source code and datasets from this research have been published online in relevant data repositories. I have further promoted knowledge transfer by presenting 18 international online presentations during the course of the project, curated a popular science blog featuring some of the highlights of my research (e.g. fieldwork, laboratory research, and manuscript publications), and participated in numerous public outreach events (e.g. National Geographic Scientist in the Spotlight and Earth Science Women’s Network: Science-A-Thon). I have also co-organized an international Paleoecology webinar series and am co-hosting a new podcast called Talkin’ Tropics for Early Career Researchers working in Tropical Environments. To mobilize global scientific interest and increase the impact of my research activities, all online videos, talks, blogs, podcasts and recorded outreach events are hosted on my website and other social media platforms (e.g. Twitter and Facebook).