Studies On Holocene Wildfire And Environmental Changes And Their Comparison In The Eastern And Western Loess Plateau

Nowadays, climatic changes, vegetational succession and human effects on the environment etc are hotspots of international research on Holocene environmental changes. The Holocene loess-soil sequence in the loess Plateau constitutes an excellent record of the environmental changes. Charcoal, the product of the incomplete combustion of plant organisms, is embedded in the soil and can be used to reconstruct 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.In this research, three typical high-resolution Holocene soil profiles in the Eastern and western Loess Plateau were studied by proxy environmental data of magnetic susceptibility and charcoal concentration. The result provides insights into the law of Holocene wildfires activities and the relationship with wildfire activities and environmental changes.The results are as follows:1. In the last ice age (~ 11500 aB.P.), the climate was arid and the most deposit of Aeolian dust accumulated in the semi-desert grassland; In the early Holocene(11500~ 8500 aB.P.), the vegetation began to develop with the amelioration of climate. The Holocene Megathermal(8500~3100 aB.P.) was the wettest and warmest during the whole Holocene. In this period, the vegetation was flourishing, but there was still no forest in the tableland region and forest only developed in the gully region; Both the analytical data and literal indicate that increased climatic aridity from 3100 aB.P. caused a considerable environmental deterioration and degradation of natural resource. And degradation of natural resource was accelerated because of the increasing human activities during this period.2. In the last ice age (~ 11500 aB.P.), the climate was arid. At that time, on semi-desert grassland, the local and regional natural wildfire often occurred. In early Holocene(11500~8500 aB.P.), the climate was still drier though it began to become...