Mid-Holocene Charcoal Records and Fire History in the East Edge of the Mu Us Sandy Land, China
Received date: 2014-11-07
Revised date: 2014-12-29
Online published: 2015-09-20
Charcoal is an important proxy to explore wildfire and human use of fire and its driving forces. The author tried to collect the mid-Holocene(7.5-4.6 ka) charcoal records by pollen extract method at Jinjie profile to reveal the charcoal concentrations and fire history in the east edge of the Mu Us Sandy Land, then explore its relationships with paleoclimate and paleoenvironment changes. The results showed that during 7.5-4.6 ka, the charcoal concentrations range between 340 and 17 42 grains·g-1, with an average of 3 350 grains·g-1. The curve of charcoal concentrations expressed a shape of 'bow', characterized by relatively low values before 7.2 ka, with an average of 1 840 grains·g-1; high values during 7.2-6.6 ka, with an average 5 280 grains·g-1; the peak occurred at 6.8 ka, attained 17 400 grains·g-1; After 6.6 ka, the concentration decreased, with an average of 1 720 grains·g-1. Meanwhile, the charcoal grain-size showed that the part of <50 μm dominated the whole profile. The charcoal concentrations mainly reflect the fire frequencies and intensities, while the charcoal grain-size reflects the fire distances and ranges. So, at the JJ profile, the fire activity was relatively frequent and reached the maximum in 7.2-6.6 ka in the east edge of the Mu Us Sandy Land, and the fire source was from a relatively farther distance. At the same time, the variations of the chemical weathering index, geochemical elements, and grain-size of the sedimentary materials at the JJ profile indicated an optimal climate between 7.2 and 6.6 ka, characterized by the relatively most humid condition. The strongest wildfire in the Mu Us Sandy Land occurred in the relatively better environment. Combining with the pollen data in the Mu Us Sandy Land and the surrounding areas to the southeast(e.g., Loess Plateau) showed that the relatively exuberant vegetation during the Holocene climatic optimum may have provided enough biomass for the fire.
Key words： Mu Us Sandy Land; charcoal; fire; Holocene; driving mechanism
Cai Xiaomin , Miao Yunfa , Jin Heling , Liu Bing , Yan Yongyao . Mid-Holocene Charcoal Records and Fire History in the East Edge of the Mu Us Sandy Land, China[J]. Journal of Desert Research, 2015 , 35(5) : 1156 -1162 . DOI: 10.7522/j.issn.1000-694X.2014.00218
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