Chin J Plant Ecol ›› 2005, Vol. 29 ›› Issue (4): 692-696.DOI: 10.17521/cjpe.2005.0092

• Research Articles • Previous Articles    

PRELIMINARY STUDIES OF WILD FIRE FREQUENCY AND ENVIRONMENTAL CHANGES DURING THE HOLOCENE ON THE ALLUVIAL PLAIN OF THE YUNCHENG BASIN

CAO Yan-Feng(), HUANG Chun-Chang, PANG Jiang-Li   

  1. College of Tourism & Environment, Shaanxi Normal University, Xi'an 710062, China
  • Received:2004-10-18 Accepted:2005-01-02 Online:2005-07-31 Published:2005-07-31

Abstract:

Charcoal, the product of the incomplete combustion of plant organisms, remains embedded in the soil and other kinds of sediments and can be used to construct a chronosequence of fire frequency over thousands to tens of thousands of years. The higher the charcoal concentration was, the more intense and frequent the wildfires were. Wildfire activity is related to both climatic changes and human activities, and this study was undertaken to document changes in the frequency of fire during the Holocene and related these to climatic changes and human activities. This research was carried out on the alluvial plain of the Yuncheng Basin in Xiaxian County, northwest of Zhongtiao Mountain. We analyzed charcoal content in soil samples in three different particle fractions obtained from a DXF-S profile.
During the early Holocene (11500-8500 a B.P.), the climate was dry although it was becoming warmer and wetter. Large amounts of charcoal found in the soil during this period indicated that wildfires were frequent. The dry climate apparently creating favorable conditions for natural fires to occur, suggested the fire frequency was climatically controlled.
The Holocene Megathermal (8500-3100 a B.P.) was the warmest and wettest period during the Holocene, and we found very little charcoal in the soil with the exception of the Xia and Shang dynasties (3800-3500 a B.P.), when a peak in the charcoal content was showed. The high precipitation during this period apparently suppressed natural fires, but human activities increased the fire frequency during the Xia and Shang dynasties.
During the late Holocene (3100-0 a B.P.), the climate became drier and conditions were once again favorable for fires to occur naturally. The amount of charcoal in the soil greatly increased during this period that showed the greatest levels of fire activity of the entire Holocene. The high fire frequency was related to both the arid climate and increased human activities.
In conclusion, climatic conditions and human activities are two important factors that influence fire frequency. Under drier climatic conditions, natural fires are more prevalent and human activities increase both the frequency and intensity of fires.

Key words: Yuncheng Basin, Alluvial fan, Holocene, Fire, Environment