南岭地区末次盛冰期沉积物水青冈花粉和DNA识别及古环境意义

The Nanling Mountains are the main barriers for the southward migration of boreal plants and provide important refugia for them during the last glacial period. Fagus, being the dominant deciduous pollen type in the study region during the last glacial maximum (LGM), could provide important clues on species migration and palaeoclimate. However, five species of Fagus are living in China with varied distribution range and ecological envelopes. Relying on traditional pollen technology, It is not possible to identify Fagus to the species level, limiting the accuracy of climatic inference and species migration. The newly developed ancient DNA (aDNA) technology could enable a species level identification of plants. Thus, the present project plans to focus on one peat core drilled in the Nanling Mountains and conduct high resolution pollen analysis for the period of LGM. By integrating the scanning electron microscope and DNA technology, we identify fossil Fagus to a species level and explore change in species abundance and migration dynamic history. We also predict the potential distribution of different fagus species and quantified the correlations between their distribution and different climate parameters. By such, we explore the climate inference by the presence of specific Fagus species during the glacial period. Our study could provide new pollen and molecular reference for ecological response to palaeoclimatic change, promoting the synthesis and comparasion of pollen and aDNA in vegetaion study and enhancing the understanding of species migration under the future climate warming scenario.

南岭山脉在冰期阶段是北方植被带南移的主要屏障和重要避难所。而水青冈属是该区末次盛冰期阶段的主要落叶类花粉类型，具有重要的物种迁移和气候指示意义。但水青冈属在我国分布有5种，其潜在分布和生态阈值各不相同，依赖传统孢粉分析技术迄今为止无法鉴定到种一级单位，导致定量气候解释和物种迁移研究缺乏精度。新发展的沉积物DNA测序技术已经可以实现物种的识别。为此，本项目拟对南岭山脉末次盛冰期的泥炭进行高分辨率孢粉分析以外，结合扫描电镜和DNA技术对沉积物水青冈属进行种一级的识别研究，从而以更高的精度揭示不同种在冰期过程中的分布扩张和迁移。此外，利用生态位模型模拟水青冈各种的潜在分布及其与不同气候参数的相关性，进而阐明水青冈属植物种指示的冰期气候区间。本研究可为古气候变化的生态响应提供孢粉和分子水平上的新依据，提升孢粉学与沉积物DNA对比的研究水平，并为未来气候变暖条件物种的迁移演变等预测提供依据。

包括南岭山脉在内的很多华南山地是亚热带植物在冰期的避难所，但关于末次盛冰期以来亚热带地区的植物迁移、森林群落演替、气候机制都不十分清楚。本项目一方面对南岭的泥炭钻孔进行了基于孢粉的古植被和古气候定量重建，揭示了亚热带森林群落演替的规律和气候响应机制，表明了末次盛冰期与现代相比南岭地区出现的最大温差在大约8℃；另一方面对水青冈属不同种开展了一系列基于化石、分子和模型的学科交叉研究，阐明了水青冈属植物在冰期过程中的迁移扩张和物种进化历史，为未来气候变暖条件物种的迁移演变等预测提供了重要依据。