Environmental Evolution Revealed By Pollen Records In The Central Asia Arid Zone Since The Last Glacial Period

People pay more and more attention to sand and dust storm source area in Asia. The last glacial period is an important timeframe for understanding climate change and climate variability because the climatic boundary conditions are similar to those experienced now and possibly in the near-future. The Central Asia arid zone (including eastern Kazakhstan and northwestern Xinjiang), which is a climatic transitional zone between the westerly-dominated "European" system to the west and the monsoon-dominated "East Asian" system to the east, projected to be highly sensitive to future changes. To better understand the bioclimatic changes in the core area of the Asian arid zone, with support from AMS14C age data, Pollen data from4Loess sections (VA/TR/RM/ZKT) were analyzed.At first, Characteristics of the modern pollen distribution and their relationship to vegetation in Central Asia is summarized. Different vegetation zones are represented by different modern pollen assemblages. Vegetation formations such as coniferous forests, alpine meadows, halophytic meadows, temperate steppes, temperate deserts, and sandy deserts in the study area have well-defined pollen assemblages.According to AMS14C age data and pollen assemblages, vegetation and climate history in Central Asia Arid Zone during last50kyr is reconstructed as below:50-42kyr BP, Artermisia steppe dominated and Climate inclined to be dry at TR and RM section; Grass steppe dominated and Climate was mild at ZKT section. In summary, Artermisia steppe and grass steppe dominated in this area and climate was dry slightly.42-28kyr BP, Artermisia steppe dominated and climate inclined to be humid at ZKT section. Artermisia steppe dominated and climate inclined to be humid at RM section. Artermisia steppe dominated and climate was humid at TR section. In detail:42-40kyr, climate was mild and humid;40-36kyr, climate was mild and become dry slightly;36-33kyr, climate was warm and humid;33-30kyr, climate became dry slightly;30-28kyr, climate became wet and cold slightly. In summary, Artermisia steppe dominated in central Asia and climate was humid during42～28kyr BP. 28-15kyr BP (MIS2), Artermisia-grass arid steppe dominated in this area. Climate was cold and dry.15-5kyr BP (Last deglacial stage and early Holocene), Artermisia steppe dominated in this area. Climate was probably warm and wet.After5kyr BP (Late Holocene), Chenopodiaceae-Artermisia steppe dominated in this area. Climate was humid.No pollen zone with both high steppe herbs pollen and high total pollen concentration. It means climate was not humid very much at any time. No pollen zone with both high desert herbs pollen and low total pollen concentration. It means climate was not dry very much at any time.Main entisol developed between48and30kyr BP in Central Asian. Gleyed Loess developed during last glaciation Maximum in Central Asian Loess area. It indicates that climate in Central Asian Loess area was wetter than climate in East Asian Loess area during last glaciation Maximum. Westerly dominated climate change in Central Asia arid zone. Insolation variation is important factor to climate change. Climate change in Central Asia arid zone is consistent with insolation variation in northern semi-sphere. Climate was warm and humid during Deglacial period. Climate was cold and dry during glacial period, but it was not very dry.