ABSTRACT

     We reconstruct Holocene vegetation dynamics and associated hydroclimate change in the Chaiwopu Basin of the
eastern Tianshan Mountains, China. Our study is based on 160 palynological samples from a well-dated peat
core. Palynological, assemblages and the associated biome scores show that from ~11.5 to ~9.5 cal. Kyr BP
desert vegetation dominated and from ~9.5 to ~7.9 cal. Kyr BP steppe and wetland vegetation expanded. From
~7.9 to ~6.5 cal. Kyr BP wetland continued to be important but coniferous forest also expanded. The period
from ~6.5 to ~3.0 cal. Kyr BP was characterized by coniferous forest while wetlands contracted. Further
expansion of coniferous forest coverage and contracted desert cover were features of the last 3000 years. The
percentage of Picea and changes in the taiga biome indicate a persistent wetting trend during the Holocene. We
infer that this was controlled by the increasing frequency of AMO (Atlantic Multi-decadal Oscillations)-like
events-linked in Siberian warm-season precipitation. The tundra biome score and the associated percentage of
Poaceae+Cyperaceae in the Chaiwopu Basin indicate two major stages of wetland expansion. Wetland expansion
can be possibly attributed to i) an increased glacier melt water supply when the ice extent was large, ii) an
increase in precipitation when temperature remained more or less constant, or iii) a combined effect of increased
precipitation and decreased temperature.