© Science China Press and Springer-Verlag Berlin Heidelberg 2010 csb.scichina.com www.springerlink.com Article SPECIAL TOPICS: Geology August 2010 Vol.55 No.22: 2449–2457 doi: 10.1007/s11434-010-3174-8 Pollen-inferred vegetation and environmental changes since 16.7 ka BP at Balikun Lake, Xinjiang TAO ShiChen 1 , AN ChenBang 1* , CHEN FaHu 1 , TANG LingYu 2 , Wang ZongLi 1 , LüYanBin 1 , LI ZhiFei 1 , ZHENG TongMing 1 & ZHAO JiaJu 1 1 MOR Key Laboratory of West China’s Environmental System, Lanzhou University, Lanzhou 730000, China; 2 Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing 210008, China Received June 18, 2009; accepted October 9, 2009 A high-resolution fossil pollen record from the sedimentary cores of Balikun Lake, northwestern China, combined with modern surface pollen data, is used to reconstruct the history of vegetation and climatic change since 16.7 cal. ka BP. Fossil pollen assem- blages and lithology indicate that the study area was dominated by desert. The desert had extremely arid climate and lower effec- tive moisture during 16.7–7.9 cal. ka BP, especially from 16.7 to 8.9 cal. ka BP when the lake maybe dried up. During 8.9–7.9 cal. ka BP, the environment gradually recovered in this area. It was then followed by the optimum period from 7.9 to 4.3 cal. Ka BP, when the effective moisture obviously increased. It was characterized by the typical desert-steppe/steppe vegetation and was ac- companied with several patch-birch woodlands around the lake. After that, a short but extremely arid climatic event occurred during 4.3–3.8 cal. ka BP, and the vegetation quickly changed from desert-steppe/steppe to desert. It was a relatively optimum period from 3.8 to 0.53 cal. ka BP showing typical desert-steppe/meadow-steppe landscape. Since 0.53 cal. ka BP, the climate has shown signs of deteriorating again. Furthermore, regional comparison shows that the characteristics of climatic and environmental evolution in this area were clearly different from East Asia monsoonal area during the last 16.7 cal. ka BP. It was characterized by the arid climate during the late-glacial and early Holocene, and relatively wet during the mid-late Holocene. Xinjiang, Balikun Lake, Holocene, pollen, vegetation, climate Citation: Tao S C, An C B, Chen F H, et al. Pollen-inferred vegetation and environmental changes since 16.7 ka BP at Balikun Lake, Xinjiang. Chinese Sci Bull, 2010, 55: 2449−2457, doi: 10.1007/s11434-010-3174-8 A critical problem people face today is climatic change. Studies of Holocene climate change in several sensitive regions have provided insights into future global warming. Right now in East and South Asia, Asian summer monsoon variations have been well-documented by precisely dated speleothems [1–5]. The Asian monsoon was enhanced at the onset of the Holocene. It was strongest in the early and mid-Holocene, but weakened after the mid-Holocene. Similar changes in the strength of the Asian monsoons have been documented by other proxies records from peats [6,7], lake sediments [8–11], and marine sediments [12,13]. In contrast, in arid and semiarid region of Xinjiang, the records *Corresponding author (email: cban@lzu.edu.cn) of the climate change were relatively complicated during the Holocene. The oxygen isotope of carbonate and pollen data from Manas Lake indicated that Holocene climatic changes were similar to those in east China [14–17]. Pollen records from Lake Kendegelukol and Lake Tashkol in the Altay Mountains [18] also suggest that the climate was quite humid from the early Holocene to middle Holocene. However, re- cent studies [19–22] indicated that the climate was ex- tremely dry during the late-glacial and early Holocene pe- riod. The mid-Holocene was humid and relatively dry dur- ing the late Holocene, suggesting the climate was mainly con- trolled by westerly. All of these suggest that the patterns of the climate change are still inconsistent in this region during the Holocene. Thus, in order to fully understand the regional