Relationship between soil charcoal in Holocene and wildfire in the Zhouyuan Region

The relationships among soil charcoal in Holocene,wildfire and its change of ecological environment were studied.The results show that in the phase of piling of Malan loess,the climate was arid and wildfire often occurred on semi-desert grassland.During the period of soil formation,bio-pedogenic processes were so active that forests or forest-grassland formed. However,by the time of 3100aB.P,with the settlement of Zhouyuan people and human manipulation of the environment through the use of the fire,great changes had taken place,varying from natural ecology to semi-natural and semi-artificial ecology.Since 1500aB.P,the arable farmland almost disappeared,resulting in artificial ecology in place of natural ecology.For hundreds of years,with the growth of the world population,tremendous requirements of fires had increased with a large amount production of rubbish and human activities had also caused great damage to the soil environment.