Holocene climatic reconstructions from the fossil pollen record at Qigai Nuur in the southern Mongolian Plateau

This study focuses on the reconstructions of vegetation and climate changes during the past ~11,000 years on the basis of 222 fossil pollen samples from Qigai Nuur (core QGN-2004) in the southern part of the Mongolian Plateau. Plant Functional Type – Modern Analogue Technique was used for quantitative climatic reconstructions from fossil pollen data. Our results showed that regional vegetation experienced dramatic shifts between steppe forest and dry steppe before 9200 cal. yr BP in the Qigai Nuur region. The reconstructed mean annual temperature and especially mean annual precipitation also showed fluctuations at that time. From ~9200 to ~2800 cal. yr BP, the vegetation was dominated by steppe forests, and the reconstructed climate was generally warm and wet, but with two cold and dry intervals at ~7400 to ~6000 cal. yr BP and at ~4000 to ~2800 cal. yr BP. From ~2800 to ~850 cal. yr BP, dry steppe vegetation dominated the landscape under slightly cooler and much drier climate conditions. During the past ~850 years, the vegetation was characterized by abundant herbs and the climate showed rising temperature and fluctuating precipitation. The comparison of the reconstructed precipitation from the Qigai Nuur core with monsoon-strength records from southern China shows that the first-order variation in the precipitation was most likely controlled by the summer insolation-dictated Inter-Tropical Convergence Zone movements (i.e. N–S shifts). The comparison of the reconstructed precipitation from Qigai Nuur core with surface sea temperature in the Western Tropical Pacific Ocean suggests that the second-order variation in the precipitation was most likely modulated by the El Niño-Southern Oscillation dynamics (i.e. E–W shifts).