新疆中部天山大龙池2000年以来高分辨率硅藻记录及其对气候变化的响应

Lake ecological environment evolution in northwestern China is sensitive to global climate changes. Understanding of the lake ecological effects to climate changes is of great significance for lake ecological environment assessment and restoration in this region. The past 2000 years experienced obvious cooling and warming alternant processes, and thus become the important interval for discussing the impact of climate change on lake ecosystems. We choose Lake Dalongchi in Tianshan mountains (central Xinjiang) as our study area. By analyzing the diatom community assemblage in surface sediment and combining with the measured water environment parameters, the main impact factors of the diatom community distribution will be discussed. Sedimentary diatom records from Lake Dalongchi will be used to reconstruct changes in diatom assemblage and productivity during the past 2000 years. Based on the climate changes inferred from other proxies in Lake Dalongchi, the response mechanisms of lake ecological environment to climate changes will be discussed. By comparing with other diatom records from mountain lakes and basin lakes in arid central Asia, and analyzing the differences in local climate, geomorphology, vegetation and the characteristic of lake, the similarities and differences of the lake ecological environment changes in this region will be elucidated. It is expected that the information obtain from this study will provide scientific data for further understanding the ecological effects of climate changes in northwestern China, and historical similarity for predicting and evaluating the potential influence of future climate change on ecosystem.

我国西北干旱区湖泊生态环境演化对于全球气候变化响应敏感。了解气候变化的湖泊生态效应，对于西北干旱区湖泊生态环境的评估和修复具有重要意义。过去2000年气候经历了多次冷暖交替过程，是探讨湖泊生态环境对气候变化响应的重要时段。本项目以新疆中部天山大龙池为研究对象，通过分析表层沉积物硅藻群落组成和分布特征，结合实测的水环境参数，探讨影响硅藻群落分布的主要因素；利用高分率硅藻记录重建过去2000年硅藻群落组合和生物量变化过程；基于该湖沉积物其他指标反映的气候变化过程，探讨以硅藻为代表的湖泊生态环境对过去2000年特征时期气候变化的响应过程和机理；对比中亚干旱区其他山地湖泊和盆地湖泊硅藻记录，揭示该区湖泊生态环境变化的特性和共性，并从气候、流域地貌、流域植被和湖泊特征方面探讨其产生原因。本研究将为我国西北干旱区气候变化的湖泊生态效应提供进一步认识，并为未来气候变化对生态系统影响的评估提供科学依据。

我国西北干旱区具有复杂的地貌格局和局部地理条件，不同区域湖泊生态环境对气候变化的响应存在着不同程度的差异。目前关于我国西北干旱区湖泊生态对气候变化响应的研究较为缺乏，且已有记录分辨率较低或存在较大的碳库效应。因此，亟需在我国西北干旱区寻找年代可靠、分辨率高、生物化石保存较好的记录来恢复过去气候和湖泊生态环境变化历史，理解湖泊生态对气候变化的响应过程和响应模式。本研究以新疆中部天山大龙池为研究对象，通过现生介形类和硅藻的调查，查明了影响介形类和硅藻群落空间分布的主要因素；基于DLC1819沉积岩芯高分辨率介形类记录，重建了大龙池地区过去1000年湿度演化历史及其可能的驱动机制；在此基础上，通过分析沉积岩芯高分辨率硅藻记录，探讨硅藻群落对气候变化的响应特征和模式。本研究结果表明，过去千年气候湿度变化和全球变暖对大龙池硅藻种群结构产生了显著的影响，其中底栖/附生硅藻种群结构的突变线性响应于湿度变化，浮游硅藻的突变非线性响应于温度变化。