The link between climate change and biodiversity of lacustrine inhabitants and terrestrial plant communities of the Uvs Nuur Basin (Mongolia) during the last three millennia

In August 2016 the lacustrine sediment core was obtained from lake Bayan Nuur one of the northern lakes in the Great Lake Depression of Mongolia. Exact location of coring site (50.01072 N, 93.9745 E; 932 m a.s.l.) was in a water depth of 29 m at the deepest part of the lake. Corning was performed by small platform using a 60-mm gravity corer UWITEC. A 112-cm-long sediment core (BN2016-1) was studied by number of proxies including: radiocarbon dating, geochemical, pollen, diatoms and cladocera analyses. Acquired data were used for numerical analyses such as biomization, reconstruction of annual precipitation rate based on pollen data and reconstruction mean July temperature based on chironomid data, additionally was evaluated past biodiversity of the lake's microflora and microfauna using Hill numbers (Hill, 1973) based on all bioproxies data (pollen, diatoms, cladoceran, and chironomids). Six AMS radiocarbon measurements for bulk sediment samples were used for calibration and the age modeling. The average sediment accumulation rate is estimated at 0.37 mm/year. The reservoir effect calculated as 736 years was subtracted from the age-depth model. Core BN2016-1 covers the last 2885 cal. years BP.2016年8月，研究团队从蒙古国大湖洼地北部的湖泊之一——巴彦淖尔湖（Lake Bayan Nuur）采集了湖相沉积岩芯。采样点精确坐标为北纬50.01072°、东经93.9745°，海拔932米，位于该湖最深水区，水深29米。岩芯采集工作由小型平台搭载60毫米重力采样器（UWITEC重力采样器）完成。本研究针对编号为BN2016-1的112厘米长沉积岩芯，采用多种代用指标开展分析，包括：放射性碳测年、地球化学分析、孢粉分析、硅藻分析以及枝角类（Cladocera）分析。所获实验数据被用于多项数值分析工作，例如生物群落化分析（biomization）、基于孢粉数据重建年降水量，以及基于摇蚊（chironomid）数据重建7月平均气温；此外，研究还基于所有生物代用指标（孢粉、硅藻、枝角类及摇蚊）的数据，通过希尔数（Hill numbers, Hill, 1973）评估了该湖泊过去的微植物群落与微动物群落的古生物多样性水平。本研究共对全岩沉积物样品开展了6次加速器质谱（AMS）放射性碳测年，用于年龄校准与年龄模型构建。沉积岩芯的平均沉积速率估算为0.37毫米/年。研究中计算得到的储库效应为736年，已从年龄-深度模型中予以扣除。BN2016-1号岩芯覆盖了过去2885个校准年前（cal. years BP）的沉积记录。