极端气候背景下生态工程建设对区域植被变化影响的评估研究

Increased trends in vegetation activity have been reported in China over the last three decades and large-scale afforestation and reforestation is one of the main factors for this increasing trend. However, the increasing trend in vegetation activity over the 2000-2012 decreased in comparison to that of the 1982-1999 period. Extreme climatic events like droughts, heat wave are contributed to this trend in last decades. Therefore, the vegetation dynamics and the driving mechanism of vegetation change are more complicated in the ecological restoration program area. Moreover, the role of extreme climatic events on vegetation change in these programs is uncertain. When we assess the effects of ecological restoration program, whether we should consider the impact of extreme climatic events or not? And the key issue is separating the two different causation effects on vegetation change. Consequently, taking the Beijing-Tianjin Sandstorm Source Region (BTSSR) as study area, we will investigate the impact assessment of ecological restoration program on vegetation dynamics under climatic events, based on the large-scale field investigation data, long term remote sensing data and modeling data. The main findings of this research will allow us to easily understand and model terrestrial ecosystem dynamics. Moreover, these findings will enrich our knowledge of the impact of climate change and human activities on vegetation dynamics in the ecological vulnerable area. Furthermore, these findings will provide a scientific basis for the management of first phase in the BTSSR and will give the guidance for the second phase ecological restoration program in future.

重大生态工程建设对我国近30年植被活动增强发挥了重要的作用。2000年以后植被活动增强的速度较2000年之前有所减缓，其中近年来极端气候事件如干旱、热浪等是导致这种现象的原因之一。因此，在典型生态工程区，植被变化过程及变化的根本原因日趋复杂。极端气候事件对生态工程建设引起的植被变化会产生怎样的影响，如何剥离自然因素和人类活动对植被变化的影响，定量评价生态工程建设对的区域生态环境的影响是急需解决的问题。本研究拟以京津风沙源区为研究区，基于大量野外观测、遥感监测和模型模拟的手段，开展极端气候背景下生态工程建设对区域植被变化影响的定量评估，以期更好地理解和模拟陆地生态系统的动态变化特征、摸清极端气候事件和人类活动对生态脆弱区植被变化影响的认识，揭示区域环境状况的演化与变迁，为京津风沙源一期工程建设的生态效果评估和更加有效地进行二期工程建设提供重要的科学依据，具有重要的科学意义和现实指导意义。

研究植被变化及其驱动机制具有重要的科学意义。在极端气候和重大生态工程建设的影响下，区域植被变化及其驱动机制更加复杂。本项目系统分析了京津风沙源区2000-2014年的植被时空特征，定量剥离了重大干旱和大规模生态工程建设对区域植被变化的影响。研究发现：（1）2000-2014年京津风沙源区的植被活动在增强，其中夏季植被活动增加最为显著，其相对增加率为12.50%。（2）重大干旱是区域植被活动减弱的重要原因。从干旱的趋势、干旱面积和干旱频率均表明工程实施的近15年，研究区的干旱程度在加重。夏季的严重干旱和极端干旱分别导致夏季植被活动的下降率大于9%和20%。（3）京津风沙源区治理工程促进了植被的恢复。通过模型模拟，1991-2001年研究区91.23%的区域由于不合理的人类活动导致了植被的退化，而从2001年开始实施生态工程后，49.43%的区域人类活动促进了植被恢复，仅1.64%的区域不合理人类活动导致植被的显著退化。截止项目结题，本项目共发表和接收学术论文13篇，SCI 5篇，其中SCI 1区TOP 1篇, SCI 2区两篇；正在出版专著1部，约30万字；申请获得软件著作权1项；培养研究生4名；参加8次学术会议交流，并做3次分会场报告。未来预计将有5篇与本项目相关的论文发表，超额完成了项目预期的成果。