【摘要】：理解過去生態(tài)系統(tǒng)對氣候變化的響應(yīng)是評估未來氣候變化影響的關(guān)鍵.在全新世氣候逐漸變化背景下,薩赫勒-撒哈拉生態(tài)系統(tǒng)經(jīng)歷了由薩瓦拉到荒漠的突變.這樣的非線性響應(yīng)現(xiàn)象是否具有普遍意義仍需深入研究.本研究基于38個高質(zhì)量的化石孢粉記錄,系統(tǒng)分析了全新世中亞地區(qū)植被與氣候的關(guān)系.結(jié)果顯示全新世中亞地區(qū)的植被發(fā)生了兩次大的突變,一次在早全新世(突變Ⅰ,"建立式"突變),另一次在晚全新世(突變Ⅱ,"崩潰式"突變),全新世中期則較穩(wěn)定.然而這些植被突變無法與任何已知的氣候突變事件相關(guān)聯(lián),并且不同區(qū)域發(fā)生植被轉(zhuǎn)型的時間表現(xiàn)出異步性,顯示出與當(dāng)?shù)亟邓孔兓芮邢嚓P(guān).這些植被突變可歸因于植被響應(yīng)軌道驅(qū)動的氣候漸變的閾值效應(yīng).早全新世在軌道驅(qū)動下降水量增加,較濕潤的區(qū)域首先達到植被"建立"的閾值,而在較干旱的區(qū)域明顯較晚才達到該閾值.與之相反,晚全新世時在軌道驅(qū)動下降水量降低,首先在較干旱的區(qū)域達到閾值,導(dǎo)致植被"崩潰",而在較濕潤地區(qū)延后達到閾值.另外,4.2kyr BP左右的干旱事件以及人類活動干擾對植被的崩潰退化也起到了一定的作用.上述認識得到了現(xiàn)代孢粉-氣候關(guān)系分析以及生態(tài)系統(tǒng)模擬結(jié)果的支持.這些結(jié)果暗示未來氣候變化一旦達到閾值將導(dǎo)致干旱生態(tài)系統(tǒng)產(chǎn)生突變.
[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，

本文編號：2404851