Vegetation And Climate Changed During The Holocene In Huhenaoer Area Of Siziwang Banner,Inner Mongolia

In this paper,spatial-temporal pattern of Holocene climate and its driving mechanism of marginal monsoon China were studied,in hope that references for predicting the change of climate and ecological response in the future could be provided.We studied the core of HH in Huhenaoer area of Siziwang Banner,Inner Mongolia,China.Based on 14 valid AMS 14C dates,using pollen and grain-size proxies records,detailed Holocene vegetation and climate changes were reconstructed.Furthermore,with comparing the paleo-climate of our study area with regional and extra-regional to discuss the spatial-temporal pattern and driving mechanism of the Holocene climate in the monsoon marginal zone.The primary recognition and conclusions are as follows:(1)Using the 14 AMS14C dates in HH core,with reasonable evaluating the Lake Reservoir Effect(LRE),we established a reliable age-depth model through the piecewise linear regression method,the correlation coefficient of two linears were high,and the bottom age is 9820 cal.yr BP of core.(2)Basing on the age-depth model and using the palynological assemblage,and combining,the biomes index,the climate sequence,lithology and grain-size,we reconstructed the changes of vegetation and climate since 9820 cal.yr BP in Huhenaoer area.Between 9820?9590 cal.yr BP,vegetation of study area was steppe and the climate was somewhat wet.During 9590?8260 cal.yr BP,the steppe increase in cover and the climate change wetter.Between 8260 cal.yr BP and 7380 cal.yr BP,vegetation deteriorated and the climate began to change dry.During 7380?6900 cal.yr BP,the vegetation deteriorated into desert or steppe-desert and the climate was the driest of the Holocene.Between 6900?3580 cal.yr BP,the vegetation turned into desert steppe and the climate was ameliorated a little.Between 3580?2520 cal.yr BP,desert steppe sustained with desert component increasing at the cost of steppe components,and the climate changed dry.Since 2520 cal.yr BP,the vegetation change into sparse desert steppe and the climate was drier.(3)Comparing the Huhenaoer with other lakes in regional,the results show that the climate changes during the Holocene in Huhenaoer area are similar to some lakes like Baiyan Nur and Bayanchagan,which indicate that climate was wettest in the early-Holocene while turned drier in the middle-Holocene.Comparing the Huhenaoer with other lakes extra regional,the results show that the climate changes during the Holocene in Huhenaoer area are similar to some lakes like Qinghai Lake,Huguangyan Maar Lake,Xingyun Lake,Dongge Cave,Kesang Cave and Hoton Nur,which reflact that precipitation was abundant and climate was moist during the early-Holocene.(4)The solar radiation of summer in the Northern Hemisphere caused by the precession intensified,which lead to the thermal difference from sea-land and the summer monsoon stretch into inland,the result was precipitation was abundant and climate was moist during the early-Holocene in Huhanaoer area.In addition,the weaker ENSO dedicated to the summer monsoon intensified during the early-Holocene.