我国中部地区树木生长对20世纪增温的响应及过去250年气候重建

As a consequence of recent global warming and its social impact, extreme climatic events happened frequently around the world. Regional climate change is attracting an increasing amount of attention from both governments and scientists. For better understanding the process of climate change, investigating the causes of extreme climatic events and whether the recent changes are unusual or within the bounds of normal climatic variability, studies based on high-resolution proxies were imperatively needed. An improved knowledge of the characteristics of climate change will enable us to prevent and manage future natural disasters and promote the sustainable development of our society..The central region of China (CRC) is an important grain production base in China. To date, high resolution long-term climatic reconstructions are very rare in this region. Annually dated tree rings are preferable climatic proxies for extending the limited modern meteorological record by analyzing the relationship between tree-ring indexes and climatic factors, thereby reconstructing the climate history for centuries. In this application, we aim to focus on the middle-south part of CRC to carry out dendroclimatological study. We’ll collect tree-ring cores from different coniferous species (Pinus massoniana Lamb., Pinus taiwanensis Hayata, et al.) from different habitats. Tree-ring width will be measured and cross dated and the standard tree-ring chronologies will be developed. To strengthen the hydroclimatic history research, tree-ring δ18O will also be measured. The goals of this project are to (1) investigate the climatic response of different tree-ring indexes from different species; (2) investigate how do trees respond to recent warming? (3) reconstruct the climate (temperature, precipitation/drought) history for the last 250 years, reveal the spatial and temporal characteristics of climate change in CRC and (4) disclose the possible driving mechanism of climate variation, especially the extreme climatic events. Our climatic reconstructions will be checked by statistical methods, historical documents and other climatic indexes. The results will enrich the dendroclimatological network in China and promote the development of the discipline itself. The results can also provide scientific data for future agricultural production management, forest tending, climatic modeling, as well as climate forecast.

作为我国重要粮食生产基地的中部地区近年来干旱和冷冬灾害频发，给国家造成严重经济损失，气候变化问题必须引起重视。过去数百年气候变化历史重建对未来防灾减灾至关重要。本申请拟重点在秦淮以南地区开展具有年分辨率的树轮气候学研究。以黄山松、马尾松、冷杉等特有针叶树种为研究对象，建立可靠的树轮宽度年表；通过高分辨率的树轮宽度和树轮δ18O指标综合研究，查明不同树种树木生长对20世纪增温及其它气候要素的空间响应特征；重建研究区过去250年来的气候（温度、降水）变化历史；与其它代用资料对比分析，揭示区域气候变化规律，在较长时间框架内检测极端气候事件发生的特征及可能形成机制。该成果将进一步丰富我国的树轮气候网络，同时促进学科自身发展。研究成果可为我国农业生产管理、森林抚育等合理政策制定提供自然背景的理解，为气候模拟和未来气候趋势预测提供重要科学数据。

气候变化作为一个全球性问题，需要世界各国共同应对。项目立足我国中部地区、重点秦淮以南区域，在准确定年的基础上，以高分辨率树轮宽度（TRW）研究为主，结合树轮δ18O和δ13C开展了不同树种、不同生境的树轮气候响应研究，重建了过去近300年研究区多地气候要素（温度、降水、相对湿度等）变化历史。研究团队紧扣项目研究内容和目标开展工作，取得了一系列重要成果：分析了大别山不同海拔高度TRW对气候的响应差异，发现随海拔升高，温度对TRW的影响由生长季的限制作用变为上年生长季的促进作用，海拔越高，温度对TRW的滞后影响越明显。温度对树木径向生长的影响与树种无关，随时间变化不稳定；重建了北亚热带165年来的温度变化历史，发现1970年代以来的显著增温趋势，进而提出“我国东部季风区最近几十年增温的起始时间存在由北至南变晚的趋势”的推论，可为未来区域气候变化预警提供参考；利用树轮δ18O和δ13C重建了多地相对湿度变化历史，分析了研究区300多年干湿变化与亚洲季风强度、太阳活动及大尺度海气耦合作用的联系；明确树轮δ18O是亚热带水文气候重建的一个重要指标，指出树轮多指标联合在亚热带水文气候重建中的光明前景，为未来亚热带水文气候重建提供了一个新思路；重建了区内亚热带首条基于树轮宽度的过去141年生长季4-11月降水量变化序列和首条224年的地表最低温度变化序列，分析了气候变化的特征和可能影响机制（PDO，NAO，WPSH），并在此基础上首次以树轮方法揭示了研究区过去一百多年来的水热配置模式；通过重建174年水文气候历史，揭示我国北方中部过去近两百年水文气候变化、尤其是极端干旱事件特征的时空异同，揭示印度夏季风和东亚夏季风对研究区干湿变化的贡献。项目圆满完成预期目标，既丰富了我国的树轮气候网络，又有助于促进学科自身发展。成果可为理解区域气候变化及机制、为未来气候趋势预测提供重要科学数据。已发表相关论文14篇（其中SCI论文9篇，中文核心期刊论文5篇），还有2篇文章在SCI期刊审稿中。