Historical & Paleo Fires
Wildfire is an essential disturbance of Earth's climate and ecosystems. Its activity can significantly alter vegetation community, terrestrial biogeochemistry, and ecosystem carbon cycling. The recent increase in wildfire occurrence worldwide has raised concerns about future changes in fire activity due to human-induced climate change. Understanding past fire dynamics and their interrelationships to climate and environment is thus a key to improving our knowledge of the long-term relationships between wildfire activities and climate variability, enhancing our ability to project future ecosystem changes due to wildfire property shifts. I use lake sediment-based proxies, instrumental data, and GIS to learn about past fire activities, specifically in the Arctic region.
Highlights
Wildfire reconstruction
Charcoals are produced when fire incompletely burned biomasses. I use macroscopic charcoal particulates preserved in the lake sediments to analyze past wildfire properties (e.g., intensity and frequency). Together with other paleoclimate proxies (e.g., Glycerol Dialkyl Glycerol Tetraethers, and bulk analysis of carbon and nitrogen, etc.), I assess linkages among wildfire activities, climate, and environments. Using these paleoclimate tools, I find that fire frequency in the Yukon-Kuskokwim Delta of the Alaskan tundra increases when the climate is relatively warmer, but the fire severity may decrease due to limited biomass accumulating between fires. [Holocene; Read here]
Proxy evaluation
Assessing the performance of the charcoal-based fire proxy is crucial steps to improve our understanding of proxy limitations and controls on sedimentary charcoal abundance, particularly in the tundra ecosystems. My collaborators and I compile published charcoal-based tundra fire reconstructions and compare with the instrumental fire observations using Geographic Information System (GIS) and statistical approaches. We find that analyses of charcoal peaks accurately identified local fire events in the historical periods despite methodological differences in published studies. [PPP; Read here]
We also compare published charcoal morphology with plant phylogeny. We find that the length:width (L:W) of charcoals can be used as a proxy of fuel type burned. Specifically, experimental charcoal L:W values greater than ca. 3.5 signify grass, non-woody fuels. The L:W values less than 2.5 signify charcoal derived from woody sources. [QSR, Read here]