Analysis of charcoal particles preserved in lake sediments has been frequently used to reconstruct fire, vegetation and climate history. Larger macroscopic particles (>125 μm) are attributed to local fires, whereas microscopic charcoal particles (<125 μm), observed on pollen slides, are a signal of regional fire. Taxonomic identification of the charcoal particles adds to the fire-history reconstruction by providing information about fuel composition and past fire conditions. Identification of charcoal can unravel one of the longstanding questions regarding past fire regimes, namely what was burning. This paper describes an analysis of charcoal particles preserved in the sediments of a small closed-basin lake in Yellowstone National Park. Blacktail Pond (44.954°N, 110.604°W; 2012 m elev) is located in steppe vegetation surrounded by conifer forest. Previous studies of the site have presented a multi-proxy environmental history of the last 14,650 years. The focus of this investigation was on the fire history of the early-Holocene (11,500–9900 cal yr BP). Thirty-nine sediment samples were taken at 0.5 cm intervals to examine macroscopic charcoal particles, with attention on two large charcoal peaks at 10,970 and 10,200 cal yr BP that registered large or near-site fires. Twenty-eight samples contained 243 large-enough particles (180–250 μm) to be examined with scanning electron microscopy. We were able to identify charcoal of conifers (Pinus, Picea, and Abies or Juniperus), Artemisia and unidentified deciduous shrubs, and unidentified monocotyledons. The first fire burned a mixture of fuels, whereas the second episode burned Artemisia, shrubs and herbs but no conifers. The results are consistent with previous pollen interpretations at Blacktail Pond that indicate an open mixed-conifer forest in the early Holocene prior to 10,750 cal yr BP, replaced by Pinus contorta forest on the slopes and steppe in the valley. The relative dominance of Pinus contorta-type charcoal points to the importance of fire as a catalyst for the spread of this species.
Bibliographical noteFunding Information:
SEM sessions took place in the Imaging and Chemical Analysis Laboratory (ICAL) at Montana State University, Bozeman, thanks to Nancy Equall and the Centre de Microscopie Electronique à Balayage et de microAnalyse (CMEBA) of the University of Rennes 1, thanks of Francis Gouttefangeas and Loïc Joanny. Yann Rantier carried out systematic quality adjustments of SEM images at the ECOBIO research unit of the CNRS and University of Rennes 1. We also acknowledge Peter Kováčik from the PaleoResearch Institute at Golden, Colorado (USA) and Alan Crivellaro from the Department Land, Environment, Agriculture and Forestry (TESAF), University of Padova (Italy) for their advice and help on problematic specimens. The MSU research was supported by NSF grant ( 0966472 ) to CW. We thank two anonymous reviewers for their helpful comments on the manuscript.
Copyright 2020 Elsevier B.V., All rights reserved.
- Vegetation history
- Wood anatomy
- Yellowstone National park
Continental Scientific Drilling Facility tags