科研之友
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摘要
Charcoal records of past fires are important for reconstruction of palaeoenvironments and palaeoclimate, particularly when compared with pollen records of past vegetation, but such records are scarce in the southeastern US. To address the question of how fire activity changed from the Last Glacial Maximum (LGM) into the Holocene as vegetation changed, we chose a site in central Tennessee for which a pollen record exists back to 23,000cal yr BP. We developed a new microscopic charcoal record based on point counting of microscopic charcoal fragments on pollen slides from Anderson Pond studied by Hazel Delcourt (1979). The record we produced spans the interval from the LGM to recent and is directly tied to the original pollen record. Charcoal:pollen ratios and charcoal area concentrations are high during the late glacial and track the coniferous pollen record from the LGM to the late glacial, at which point spruce and jack pine pollen markedly diminished along with fire activity. From around 15,000cal yr BP to the beginning of the middle Holocene, charcoal indices are low. High fire activity began around 8200cal yr BP, and remained high from ca. 8200-5000cal yr BP, an interval broadly corresponding to the Mid-Holocene Warm Period (MHWP). The evidence of higher fire activity during the MHWP is coincident with increased percentages of indeterminate pollen grains that are interpreted to signal drier conditions. Charcoal area concentrations declined following the MHWP. Viewed against the original pollen record, the patterns in microscopic charcoal abundance from the LGM to recent at Anderson Pond argue for the strong influence of vegetation as well as climate in driving fire occurrence in eastern temperate North America.
- 出版日期2017
- 单位Los Alamos
