Late Holocene climate and land-use history in the Mongolian Altai Mountains: Combined evidence from palynological, macro-charcoal and tree-ring analyses

Abstract

The Mongolian Altai is an ecologically sensitive region in Central Asia where changes in climate and anthropogenic activities have a strong impact on the forest-steppe vegetation. We combine high-resolution data (pollen, non-pollen palynomorphs (NPP), charcoal) of two new sedimentological archives from the Altai Tavan Bogd National Park with dendrochronological analyses on Larix sibirica trees to study climatic changes and human landscape interactions over the last 1,350 cal yr BP. Multi-proxy palaeoenvironmental reconstructions show that the present landscape is a result of both short- and long-term climatic variations and of locally different land use. Combined evidence suggests that in the period from 1,350 to 670 cal yr BP western Mongolia was impacted by a rather cold and dry climate, followed by an episode of improved warmer and wetter climatic conditions from 670 to 400 cal yr BP. From around 400 to 200 cal yr BP, the Little Ice Age influenced the forest-steppe vegetation in the area, favoring an expansion of steppe vegetation. Over the last 70 years, climatic conditions were characterized by markedly high summer temperatures. NPP data reveal periods of increased grazing activities in the forests especially during unfavorable climatic periods. During the late 20th century, a decreasing deposition of coprophilous fungal spores with a simultaneous slight decrease of Larix sibirica forest suggest that economic timber harvesting seemed to be of more significance for forest degradation than pastural activities.