KMS XINJIANG INSTITUTE OF ECOLOGY AND GEOGRAPHY，CAS
| 中国天山全新世植被与气候变化及其驱动机理研究 | |
| Alternative Title | Holocene vegetation and climate variations in the Chinese Tianshan Mountains and the associated controlling mechanisms |
| 杨运鹏 | |
| Subtype | 博士 |
| Thesis Advisor | 冯兆东 ; 穆桂金 |
| 2019-06-30 | |
| Degree Grantor | 中国科学院大学 |
| Place of Conferral | 北京 |
| Degree Discipline | 理学博士 |
| Keyword | 天山 全新世 孢粉 植被变化 气候变化 Tianshan Mountains Holocene Pollen Vegetation change Climate change |
| Abstract | 天山位于中亚干旱区（50-100°E； 35-55°N） 的核心地带， 从气候学角度来看，天山处于东部季风区和西风带控制的交接地带。从生物地理学角度来看，沿天山北部准噶尔盆地继续向北不远就是西伯利亚泰加林的边缘地带，而天山南部的塔克拉玛干沙漠是荒漠植被的典型分布区。天山全新世植被和气候变化已经得到了比较充分的研究，也取得到了不少成果。但是， 关于天山全新世以来植被-气候演替格局以及控制植被-气候演替的具体机制仍然没有一个被广泛接受的说法。为了进一步提升对上述问题的认识，我们分别在中国天山西部的伊犁谷地、中部的尤尔都斯盆地和中东部的柴窝堡盆地选定研究点，以 AMS 14C 年代为支撑，以孢粉为主要手段，以定量重建为主要方法，分析研究了中国天山全新世期间的植被和气候演替历史，并进一步深化了对控制天山植被-气候演替机理的认识。 我们主要得出以下结论：（1）伊犁谷地 Y-1 剖面孢粉和地化指标资料揭示了：在~11,000-~6500 cal. yrBP 期间，伊犁谷地温度逐渐下降而降水量相对较高，气候总体冷湿，区域植被主要以蒿属草原和禾本草甸为主； ~6500-~5000 cal. yr BP 期间出现了一段明显的高温低降水期； ~5000-~3000 cal. yr BP 期间，温度降低，降水量有一定程度的增加，木本分布范围达到最大；在过去~3000 年以来，区域温度上升，降水量下降，湿度水平持续降低，盆地内部藜科植被分布达到最大。（2）尤尔都斯盆地孢粉和地化指标揭示：早全新世期间（~11,000-~9000 cal.yr BP），尤尔都斯盆地降水和温度都比较高，盆地内部发育了大面积蒿属草原，得益于大量冰川融水，该阶段湖泊水位处于最高；中全新世期间（~9000-~3750 cal.yr BP），温度有所下降，降水波动较为明显但总体水平较高，由于冰川融水补给量下降，湖泊逐渐萎缩； ~3750-~2400 cal. yr BP 期间，温度和降水有较为明显的上升，随着冰川融水补给量进一步下降，湖泊逐渐演变为湿地沼泽，盆地内部大量沼泽植物发育。（3）柴窝堡孢粉资料显示：在~11,300-~8000 cal. yr BP 期间，区域温度较高，降水量较低，气候总体暖干，植被主要以旱生草本为主，木本含量极低；在~8000-~3000 cal. yr BP 期间，温度下降明显，降水量较高，气候总体冷湿，区域植被中木本比例逐渐增加并在~3000 cal. yr BP 左右达到最高；在过去~3000 年以来，温度有所升高，降水量仍然较高，该阶段木本有所下降，低海拔地区藜科植被有较为明显的增加。（4） 区域对比结果显示，伊犁谷地全新世以来平均年降水量是下降的，而尤尔都斯盆地以及柴窝堡平均年降水量是增加的。与上游西风区降水重建对比结果显示，地中海地区全新世以来的冬季和夏季降水量都是下降的，而西北欧地区全新世以来的冬季和夏季降水量都是上升的。湿度对比结果显示，伊犁谷地全新世以来的湿度变化与西天山及西风带上游欧亚大陆中纬度南部一线基本是一致的（变干）；而尤尔都斯盆地以及柴窝堡全新世以来的湿度变化与新疆北部及西风带上游欧亚大陆中纬度北部一线是一致的（变湿）。（5） 西天山平均年降水量下降的主要原因是冬季降水量的下降，而冬季降水量的下降主要是由于 NAO 不断偏于负相导致西风扰动（Western Disturbances）强度下降引起的。造成北疆地区全新世平均年降水量增加的主要原因是夏季降水量的上升，而夏季降水量的上升主要是因为全新世以来控制北疆夏季降水的AMO 逐渐偏向于正相，这有利于低纬地区的水汽不断进入新疆北部地区形成降水。 |
| Other Abstract | Our study area, the Tianshan Mountains, is situated in the core area of the AridCentral Asia (50-100°E; 35-55°N). Climatologically, the Tianshan Mountains is theconjunctional area between the East Asia monsoon system and the westerlies system.Biogeographically, the Tianshan Mountains is near the southern part of Siberian taigaforests to the north and touches the northern edge of the Taklimakan Deserts in thesouth. The vegetation and climate changes over the past ~11,500 years (i.e., theHolocene) in the Tianshan Mountains have been intensively investigated. However,the discrepancies among different datasets on the issues of vegetation and climatechanges and the associated controlling mechanisms still exist. This study focused onpollen analyses of three sections selected from the Tianshan Mountains in attempt tofurther elevate our understanding of the above-mentioned issues. This study draws thefollowing six conclusions:(1) Pollen data of the Y-1 profile from Yili Valley reveal that the period from~11,000 to ~6500 cal. yr BP was typified by relatively low temperature and highprecipitation, supporting the Artemisia-steppe to be maintained in the lower altitudearea and the Poaceae-meadow to be maintained from the middle to higher altitudearea. A higher-temperature and lower-precipitation phase appeared from ~6500 to~5000 cal. yr BP. The period lasting from ~5000 to ~3000 cal. yr BP was marked bylower-than-average temperature and higher-than-average precipitation, favoring theexpansion of forest. During the past ~3000 years, the dropped precipitation andelevated temperature accompanied by the lower-than-average RDI favored theexpansion of Chenopodiaceae-dominated desert-steppe.(2) Multi-proxy analysis of BY profile from Youerdusi Basin indicate that theperiod lasting from ~11,000 to ~9000 cal. yr BP was marked by the highest lake levelfeeding by the plenty of ice-melt water. This period was also typified by relativelyhigh temperature and precipitation, leading to the expansion of Artemisia-steppe in the basin. During the middle Holocene (~9000-~3750 cal. yr BP), the basin-wideclimate was typified by a decreased temperature and fluctuant precipitation conditioncorresponding to the shrinkage of lake area. The period spanning from ~3750 to~2400 cal. yr BP was warmer and wetter than the early period and the lake graduallyevolved into wetlands which benefits the expansion of wetland herbs (e.g.,Cyperaceae).(3) Pollen data of CWP profile from Chaiwopu Basin reveal that the climateduring ~11,300 and ~8000 cal. yr BP was marked by a higher-than-averagetemperature and lower-than-average precipitation, supporting the xerophytic herbs tobe maintained in the basin. During the middle Holocene (~8000-~3000 cal. yr BP),the climate was colder and warmer than the preceding period, which favored theexpansion of forest in the higher altitude regions. In the past ~3000 years, theexpansion of Chenopodiaceae-steppe is in alignment with the quantitativereconstructions.(4) The regional comparisons show that the dropped precipitation in Yili valleymay attribute to the debasement of winter precipitation, and the elevatedprecipitations in Youerdusi Basin and Chaiwopu Basin are primarily the result ofelevated summer precipitation. Comparisons between our research area and the upperstream of westerlies show that both Holocene summer and winter precipitation ofMediterranean region persistently decreased, and the Holocene summer and winterprecipitation of northwestern Europe persistently increased. The moisturecomparisons reveal consistent drying trends in the large area from Yili Valley to theeastern Mediterranean region, and also exhibit wetting trends in the area fromnorthern Xinjiang to the northwestern Europe.(5) The declining trend of Holocene winter precipitation in western TianshanMountains is related to the more negative NAO phases-weakened WesternDisturbances and the increasing trend of Holocene summer precipitation in northernXinjiang is associated with the positive AMO phase-enhanced water vapor amountfrom lower latitude regions. |
| Subject Area | 自然地理学 |
| Language | 中文 |
| Document Type | 学位论文 |
| Identifier | http://ir.xjlas.org/handle/365004/15368 |
| Collection | 中国科学院新疆生态与地理研究所 研究系统 |
| Affiliation | 中国科学院新疆生态与地理研究所 |
| First Author Affilication | 中国科学院新疆生态与地理研究所 |
| Recommended Citation GB/T 7714 | 杨运鹏. 中国天山全新世植被与气候变化及其驱动机理研究[D]. 北京. 中国科学院大学,2019. |
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