全新世气候渐变导致中亚地区植被突变
发布时间：2019-01-08 16:30
【摘要】：理解过去生态系统对气候变化的响应是评估未来气候变化影响的关键.在全新世气候逐渐变化背景下,萨赫勒-撒哈拉生态系统经历了由萨瓦拉到荒漠的突变.这样的非线性响应现象是否具有普遍意义仍需深入研究.本研究基于38个高质量的化石孢粉记录,系统分析了全新世中亚地区植被与气候的关系.结果显示全新世中亚地区的植被发生了两次大的突变,一次在早全新世(突变Ⅰ,"建立式"突变),另一次在晚全新世(突变Ⅱ,"崩溃式"突变),全新世中期则较稳定.然而这些植被突变无法与任何已知的气候突变事件相关联,并且不同区域发生植被转型的时间表现出异步性,显示出与当地降水量变化密切相关.这些植被突变可归因于植被响应轨道驱动的气候渐变的阈值效应.早全新世在轨道驱动下降水量增加,较湿润的区域首先达到植被"建立"的阈值,而在较干旱的区域明显较晚才达到该阈值.与之相反,晚全新世时在轨道驱动下降水量降低,首先在较干旱的区域达到阈值,导致植被"崩溃",而在较湿润地区延后达到阈值.另外,4.2kyr BP左右的干旱事件以及人类活动干扰对植被的崩溃退化也起到了一定的作用.上述认识得到了现代孢粉-气候关系分析以及生态系统模拟结果的支持.这些结果暗示未来气候变化一旦达到阈值将导致干旱生态系统产生突变.
[Abstract]:Understanding past ecosystem responses to climate change is key to assessing future impacts of climate change. Under the background of the gradual change of Holocene climate, the Sahelo-Saharan ecosystem experienced a sudden change from Zavala to desert. Whether such nonlinear response is of universal significance still needs to be deeply studied. Based on 38 high quality fossil pollen records, the relationship between vegetation and climate in Central Asia of Holocene was systematically analyzed. The results show that there were two major mutations in the vegetation of Central Asia in Holocene, one in the early Holocene (mutation I, "establishing" mutation) and the other in the late Holocene (mutation 鈪，
本文编号：2404851
[Abstract]:Understanding past ecosystem responses to climate change is key to assessing future impacts of climate change. Under the background of the gradual change of Holocene climate, the Sahelo-Saharan ecosystem experienced a sudden change from Zavala to desert. Whether such nonlinear response is of universal significance still needs to be deeply studied. Based on 38 high quality fossil pollen records, the relationship between vegetation and climate in Central Asia of Holocene was systematically analyzed. The results show that there were two major mutations in the vegetation of Central Asia in Holocene, one in the early Holocene (mutation I, "establishing" mutation) and the other in the late Holocene (mutation 鈪，
本文编号：2404851
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