东北地区沼泽湿地花粉现代过程研究与全新世古环境定量重建

Pollen records in peat deposits have been widely used as a critical proxy to reconstruct climate and vegetation variations in geological past. While such a work should be surely based on the thorough understanding of the relationships between modern pollen, plant and climates. During recent years, although a large number of pollen studies have been performed, few of them refer to the modern pollen process in wetlands, which should be the most important factor hindering the paleo-environment reconstruction in quantitative level with the pollen fossils in peat deposits. In present study, we will perform a thorough investigation of the pollen assembles of different plant communities in modern wetlands in northeastern China, and built the modern pollen-plant-climate relations accordingly. Meanwhile, a series of peat cores will be collected and treated with high-resolution pollen analysis, and reconstruct the plant and climate variations in different wetlands during the Holocene using the modern pollen-plant-climate relations. Additionally, with assistance of the integrated Holocene climate records from published papers and the records in present study, we will discuss and reveal the evolution histories of different wetlands types, and their relations to the Holocene climate variations, providing a robust basis for modern wetlands’ conservation and restoration.

泥炭孢粉是记录沼泽湿地生态系统长期演化的良好信息载体，而利用泥炭孢粉资料准确重建古环境的基本前提是要充分了解沼泽湿地现代花粉-植被-气候的关系。针对目前沼泽湿地花粉现代过程研究薄弱导致泥炭孢粉学研究难以定量化的现状，本项目利用人工花粉捕捉器对东北地区典型沼泽湿地开展花粉现代过程研究，揭示不同沼泽湿地植物群落花粉组合特征并建立现代花粉-植被-气候函数关系。在此基础上，对东北地区典型沼泽湿地采集泥炭沉积柱芯并进行详细年代学研究和高分辨率孢粉分析。在现代花粉-植被-气候关系支持下利用泥炭孢粉资料定量重建全新世典型沼泽湿地植被和气候演化序列，揭示不同湿地生态系统长期演化规律。结合东北地区已有的古气候研究结果，探讨沼泽湿地生态系统演化对气候变化的响应机理，为丰富湿地生态系统长期演化理论以及在未来全球变化条件下制定沼泽湿地保护和恢复策略提供科学依据。

沼泽湿地的泥炭沉积物由于含量古环境代用指标种类丰富、沉积速率快、分辨率高等优势在第四纪环境重建研究领域具有独特优势。然而，当前泥炭沉积学研究仍局限于定性描述，显著落后于湖泊、黄土等沉积物的定量化研究现状，其根本原因之一在于与泥炭相关的代用指标现代过程研究薄弱，导致其环境指示意义仍存诸多争议。针对此科学问题，本研究首先以东北地区天然沼泽湿地为对象，针对典型植物群落进行环境因子调查，包括植被组成、水文、土壤、气候定参数。于此同时，采集表层沉积物并进行孢粉、粒度、磁化率、有机质含量等环境代用指标分析，初步建立了东北地区沼泽湿地现代古环境代用指标与植被和气候定量函数关系。然后，针对东北地区不同沼泽湿地类型选取发育典型、受人类活动干扰相对较小的泥炭地采集泥炭柱芯，在AMS C-14、Pb-210和Cs-137测年技术支持下建立各柱芯年代标尺。在此基础上，对各泥炭柱芯进行孢粉、粒度、磁化率等指标分析，在现代古环境代用指标与植被、气候定量函数关系参照下，定量重建了不同沼泽湿地古植被与古气候演化历史，并进一步探讨了上述湿地生态过程对全新世环境变化的响应机理。项目执行期间发表SCI论文5篇，获得授权专利2项，培养博士研究生2名，获得吉林省科技进步一等奖1项，较好的完成了项目成果目标。