华南全新世水松发育与消亡的沉积记录及其驱动因素分析

Glyptostrobus pensilis(Taxodiaceae) is a national protected plant in China. It is considered as a typical wooded swamp taxon, and its wild populations are extremely rare. Nevertheless, this species was widespread in south China during the Holocene. For example, the Holocene deposits in the edge of Pearl River Delta include large accumulation of buried Glyptostrobus residues, and the height of which ranges from 4 up to 8 m. However, until now, the evolution process of Glyptostrobus communities during Holocene is still not clear, with debates concerning influences from both climate change and anthropogenic activities. In this project, sediment from two different geomorphic units in south China will be collected, including a core from Tianhuding swamp and a profile at Pearl River Delta (Gaoming). High resolution pollen analysis will be carried out for Holocene vegetation reconstruction; meanwhile optical microscope and scanning electron microscope will be used for identifying Glyptostrobus pollen. This project aims to demonstrate the evolution history of Glyptostrobus during Holocene and its relationship between climatic elements such as precipitation, coldest mean temperature etc. Analysis of the Gaoming profile (near archaeological sediments) will also focuses on phytoliths, palynomorphs and charcoal to understand regional agriculture development, revealing possible impacts of human activities on the extinction of Glyptostrobus. The expected outcomes of this project will demonstrate Holocene Glyptostrobus evolution and affecting factors from both climate change and anthropogenic activities. In addition, regional hydrological process (precipitation) revealed by evolution of Glyptostrobus ecosystem will provide new scientific reference for the study of Asian monsoon change.

水松被列为我国一级保护植物，是少有的湿地乔木，现野生群落极为稀少。然而，该种在全新世曾广泛发育于华南地区，珠三角边缘区全新世沉积曾发现4-8 m的埋藏水松残体堆积。目前对各地全新世水松群落的演变过程及其影响因素仍不十分清楚，并存在气候变化与人类干扰两方面的争论。本项目拟通过两个地点（福建天湖顶沼泽钻孔和珠三角高明剖面）的全新世高分辨孢粉研究，在利用光学和扫描电镜精确识别水松花粉的基础上，探讨全新世水松的变化历史，揭示其发育与衰退过程与最冷月温度、降水等气候要素之间的关系。同时，结合高明剖面（遗址附近）的孢粉、植硅体、碳屑等多指标综合分析，重建区域农业文明发展历史，揭示历史上人类活动对天然水松林消亡的可能影响。该项目不仅可探明水松在全新世的演变过程及其自然和人为影响因素，同时天然沉积序列孢粉分析获得的水松生态系统变化特征可为揭示区域水文过程（降雨）所反映的季风气候演变等科学问题提供新证据。

现存水松的发现曾被誉为“中国十大地理发现”之一，作为濒临灭绝的第三纪刁遗植物，其生存和消亡历史对在未来快速变化的气候下何如制定生态保护措施有重要的意义。在青年基金的支持下，我们首先对华南地区的气候变化以及人类活动历史做了深入的研究，之后再分别探讨了气候变化以及人类活动对水松消亡的影响。研究揭示出全新世气候变化对水松消亡的影响甚微，而多个钻孔水松花粉记录显示，水稻农业向南发展的人类历史进程对水松逐渐消亡的起到关键影响。