24-17 Application of Charcoal and Polycyclic Aromatic Hydrocarbons to Reconstruct the Holocene Fire History of North-Central Maine

Session: Lake Sedimentary Records of Past Climate and Environment (Posters)

Poster Booth No.: 45

Presenting Author:

Isabelle Sander

Authors:

Sander, Isabelle¹, Balascio, Nicholas², Cook, Timothy³, Feng, Yufan⁴, Vullo, Chris⁵, Tsalickis, Alexandra⁶, Vachula, Richard⁷, Karmalkar, Ambarish⁸, Snyder, Noah⁹

(1) Department of Earth and Climate Sciences, Bates College, Lewiston, , (2) Department of Earth and Climate Sciences, Bates College, Lewiston, , (3) Department of Earth, Geographic, and Climate Sciences, University of Massachusetts, Amherst, , (4) Department of Geosciences, Auburn University, Auburn, , (5) Department of Earth and Climate Sciences, Bates College, Lewiston, , (6) Department of Geosciences, Auburn University, Auburn, , (7) Department of Geosciences, Auburn University, Auburn, , (8) Department of Geosciences, University of Rhode Island, Kingston, , (9) Department of Earth and Environmental Sciences, Boston College, Chestnut Hill, ,

Abstract:

Forest fires are a key driver of ecosystem disturbance and impact environments though biomass removal, negative water and air quality, release of sequestered carbon, and loss of biodiversity. The analysis of past fire dynamics provides long-term perspectives on their role in ecosystems and the association between fire activity and climate. The paleofire history of the eastern United States (US) is relatively under-studied in comparison to the western US. However, climate models predict eastern North America will undergo drying which will likely lead to longer fire seasons and increasing fire intensity. Therefore, understanding eastern US fire regimes is crucial for preparing future responses to wildfires. This study investigates the long-term fire history of central Maine using a sediment core from Lower South Branch Pond in Baxter State Park that spans the last c. 7,200 yr BP. We analyzed charcoal  accumulation rates  (>125 µm and 63-125 µm) and trends in 15 polycyclic aromatic hydrocarbons (PAHs) as fire proxies. The 63-125 µm charcoal accumulation rate ranged from 0.02-2.76 #/cm³/yr while the >125 um rates were between 0.01-0.88 #/cm³/yr. There were two distinct peaks in both sizes at c. 5900 cal yr BP and 50 cal yr BP, as well as a period of elevated charcoal from c. 3500-6000 cal yr BP. Eight PAHs were present with concentrations from 68.2 to 20722.6 ng/g of dry sediment, with three peaks at 5650 cal yr BP, 4800 cal yr BP, and 50 cal yr BP. These data show evidence for higher fire activity in the mid- to early Holocene, as well as evidence of historic fire. Differences in trends between charcoal and PAHs suggests the PAHs reflect a regional signal outside of the watershed, while charcoal is more sensitive to local fires. PAH distributions may also be attributed to regional differences in biomass burnings. The paleofire study of Lower South Branch Pond will be used in combination with other fire records to reconstruct wildfire history on a regional scale.

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