High-resolution climate and vegetation reconstruction for the last 2000 years based on palaeorecord from lake Ureg-Nur (Mongolia): historical and palaeoecological context

This paper provides the results of a detailed pollen study of bottom sediments from the drainless salt lake Ureg-Nur located in northwestern Mongolia. Based on pollen data, vegetation and average annual precipitation were reconstructed. The age model for bottom sediments was created on the basis offour radiocarbon dates. The obtained palaeo-archive describes the period of the last 2000 years. Precipitation level reconstruction was made by using the method of a transfer function with calibration dataset of surface pollen spectra. Vegetation reconstruction was made using the method of biomization. In general, reconstructions are consistent with previously obtained data from northwestern Mongolia and refined it in details. A maximum spread of taiga is reconstructed about 1800 cal BP and the last 200 years; maximum spread of steppes is about 1500 cal BP, 1200 cal BP, and 700-200 cal BP. The wettest period was ca. 950-700 cal BP (up to 370 mm/year); the driest period was ca. 1650-1400 cal BP (up to 290 mm/year). Periods of increasing soil erosion are associated with a sharp increase in precipitation levels. The presence of coprophilous fungi spores around 2000 cal BP and their permanent presence after 1300 cal BP coincide with other data from the study area and historical periods when grazing activity increased. Over the last 200years, there has been an increase in soil erosion and a change in the nutrient status of the lake, which may be related to agricultural development in the study area.