中国黄土高原洛川剖面 S5以来的孢粉学记录

摘要

The loess-paleosol sequence in northwest of China is considered as one of the most continuous continental records since the last 2 .6 Ma .Pollen ,a direct recorder for vegetation change , has been widely used to reconstruct paleovegetation . However , the pollen record of long time scale especially in the central Chinese Loess Plateau has not been well studied .In this study ,we preliminarily focus on the palynological records of the loess-paleosol sequence at Luochuan and aim to understand the vegetation evolution spanning the last 0 .6 Ma in this region .The palynological results show that the grassland has been dominant vegetation in the Luochuan area since 0 .6 Ma . The present steppe environment on the loess plateau is mainly caused by natural conditions .T herefore ,the restoration and reconstruction of ecosystem on the loess plateau area should be focused on planting grassland rather than forests .These discoveries provide a solid theoretical foundation for revegetation of “Yuan” region ,and have significant practical significance .%中国黄土古土壤序列记录了距今约2．6 Ma以来的环境变迁。孢粉作为恢复植被演替的敏感指标，被广泛用于古植被重建，但是针对高原中部地区长时间尺度植被演替历史的孢粉学研究还较缺乏。通过对黄土高原洛川剖面S5以来的黄土古土壤序列开展较高分辨率的孢粉学工作，揭示出该区约0．6 Ma以来的植被演化历史。孢粉谱分析表明，洛川地区0．6 Ma以来以温带草原植被为主，不支持塬区历史时期存在大范围落叶阔叶林的观点。现代黄土高原缺少森林植被主要是由自然原因引起，因此塬区的现代生态恢复应以退耕还草为主。