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A HIGH RESOLUTION RECORD OF MACROSCOPIC CHARCOAL AS AN INDICATOR
OF HOLOCENE CLIMATE CHANGE FROM SWAMP LAKE, YOSEMITE NATIONAL
PARK, CALIFORNIA
MEEKER, C. B.1, ANDERSON, R.S.1,2,
SMITH, S.J.1 AND CAPRIO, A.J.3
1 Quaternary Sciences Program, Box 5644, Northern
Arizona University, Flagstaff, AZ 8601, 2 Center
for Environmental Sciences & Education,
Box 5694, Northern Arizona University, Flagstaff, AZ 8601, 3 Sequoia
and Kings Canyon National Park, 47050 Generals Hwy, Three Rivers,
CA 93271.
Fire histories reconstructed from lake sediment records
provide
long-term paleoecological information at a variety of timescales. Resolution
of these records generally ranges from multidecadal to centennial,
limiting reconstructions to broader trends in fire frequency
variations. These low resolution studies are sufficient when
comparing the relationship between fire and major climate trends;
however, recent findings demonstrate the importance of smaller,
short-term climate fluctuations throughout the Quaternary. In
order to better define the geographical scope and ecological
effects of small-scale climate fluctuations, high resolution
studies are required
In this study, lake sediments from Swamp
Lake, Yosemite National Park, were examined at subdecadal
resolution for macroscopic
charcoal and plant macrofossils. Fire scar records from around
the lake show pre-historically high fire frequencies of 5-7 years. The
Swamp Lake site therefore provides an opportunity to observe
the sensitivity of high frequency fire regimes to both large
and small scale climate change. Preliminary results from Swamp
Lake sediments reveal a ~15,000 yr fire record that varies significantly
and fluctuates in accordance with the timing of documented climate
changes in the region. Vegetation changes identified in the
pollen record coincide with some shifts in fire frequency. However,
fluctuations in charcoal accumulation occur more frequently than
vegetation change, suggesting that fire regimes are a more sensitive
indicator to variations in climate.
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