Late Holocene vegetation, climate, human and fire history of the forest-steppe-ecosystem inferred from core G2-A in the ‘Altai Tavan Bogd’ conservation area in Mongolia

Abstract

The ‘Altai Tavan Bogd’ conservation area, located between 2,000 and 4,000 m a.s.l. in the north-western part of the Mongolian Altai, is a montane forest-steppe-ecosystem which has developed under extreme continental and alpine climatic conditions and is very sensitive to natural variations. Nomadic peoples have influenced the area due to grazing, logging of trees and fire for a long time. To reconstruct the dynamics of this unique forest-steppe ecosystem for the last 4,000 years under the influence of climatic changes and/or nomads, palynological and macro-charcoal analyses of the radiocarbon dated core G2-A have been performed. Between 3,880 and 2,610 cal bp the vegetation was represented by a mixture of rather open forests and non-forested high mountain steppe areas suggesting a moist and warm climate similar to the present conditions. Macro-charcoal analysis reveals three main fire events, which are probably of anthropogenic origin. In the period from 2,610 to 550 cal bp a decrease in precipitation and temperature is suggested by a higher representation of herbaceous species, retreating open forests and an increase in macro-charcoal concentration. Since 550 cal bp the forest spread out again, whereas the composition of trees differs from the period between 3,880 and 2,610 cal bp. It is characterized by the shrubs Betula rotundifolia and Juniperus indicating a more open forest, which is probably related to human activities. The advancing upper forest line and a higher plant diversity reveals that the conditions changed to a more humid climate again, lasting until present.