藏嵩草高寒湿地中孢粉记录的古植被与古环境状况

Pollen record and paleovegetation and paleoenvironment in Kobresia tibetica alpine wetland

高寒沼泽湿地是青藏高原重要的水源涵养地,其沉积物是研究过去环境变化的重要载体.在三江源区果洛州（GLS）和青海湖北岸（QHHS）选取典型高寒沼泽湿地作为研究样地,调查其植被群落特征,并根据湿地沉积剖面的光释光年代和孢粉数据,分析湿地的古植被和古环境状况.结果表明：优势种（藏嵩草）在三江源区湿地群落和青海湖流域湿地群落中所占的优势度分别是24.43和14.74;从土壤孢粉信息表现出两个沼泽湿地自发育以来植被优势种以莎草科为主.GLS剖面显示,0~50 cm深和80~140 cm深的孢粉浓度显著高于50~80 cm深处的浓度;20 cm以下的沉积物中,花粉浓度与有机质含量呈正相关趋势,与δ13C呈负相关趋势.高寒沼泽湿地中,孢粉数据能较好地反映植物群落中莎草科的优势地位,与现生植物群落具有较好的一致性.

Alpine wetland is an important water conservation region in the Qinghai-Tibetan Plateau, and its sedi-ment is a geological carrier to study palaeoenvironment global changes. This study chosed two typical alpine wet-lands on the Quoluo Tibet Autonomous Prefecture in the three rivers source region（GLS）and north shore of Qin-ghai Lake（QHHS）as study sites. Pollen analysis and OSL（optically stimulated luminescence）dating have been applied to discuss paleovegetation evolution process since the late Pleistocene on the northeast Qinghai-Ti-betan Plateau. The main results are summarized as follows：dominance index of dominant species（Kobresia ti-betica）are 24. 43 and 14. 74 in GLS and QHHS sections, respectively. Pollen results show that the dominant veg-etation family is Cyperaceae since alpine wetland development;the pollen concentration at the depth of 50-80 cm is obviously lower than at the depth of 0-50 cm and 80-140 cm in the GLS section. Below 20 cm of sedi-ment core, pollen concentration and TOC show positive relationship;but pollen concentration andδ13C show neg-ative correlation. Cyperaceae pollen data are well-represented for its dominance degree, according with modern vegetation community.