台湾头社盆地湖沼相沉积孢粉记录的6.2~1.3 cal ka BP以来气候研究

头社盆地位于中国台湾省中部,东亚季风区的最前沿,对东亚季风的响应十分敏感,研究其中晚全新世以来古植被、重建古气候序列,探讨其气候与东亚夏季风的关系具有重要的科学意义。文章对头社盆地泥炭—湖泊沉积的AMS14C测年、体积磁化率测试的基础上,基于孢粉记录,重建晚全新世来植被变化,恢复古气候。结果表明全新世中晚期以来分六个阶段：6.2~6.0 cal ka BP,气候凉干,植被类型是亚热带常绿阔叶林;6.0~4.0 cal ka BP,气候转暖湿,植被类型为含较多热带成分的亚热带常绿阔叶林;4.0~2.2 cal ka BP,气候相对凉干,植被类型转为亚热带常绿阔叶林;2.2~1.9 cal ka BP,气候又变暖湿;1.9~1.7 cal ka BP,气候快速冷干事件,森林退化;1.7~1.3 cal ka BP,气候重转温暖湿润,植被类型为接近现代的沼泽草原。整体上6.2~2.2 cal ka BP的气候变化是由温暖湿润向温凉干燥转变的趋势,这是全新世中晚期以来的太阳辐射量减少所导致的,太阳辐射量的减少导致热带辐合南移,进而导致东亚夏季风减弱,而2.2 cal ka BP之后气候波动较大,可能是在东亚夏季风减弱的背景下,ENSO活动加强与人类活动的干扰下耦合的结果。     

全新世以来岱海盆地植被演替和气候变化的孢粉学证据

岱海盆地99A孔11.01 m以上地层较高分辨率的孢粉分析揭示了该区12 000 cal a BP以来的植被演替和气候变化. 早全新世时期, 岱海盆地受冬季风影响强烈, 气候波动以冷湿、暖干为主, 12 000～11 000 cal a BP为以白桦林为主的森林草原植被, 气候寒凉湿润; 11 000～7 900 cal a BP白桦林退缩, 气候温干; 中全新世时, 主要受控于夏季风影响下, 气候波动以冷干、暖湿为主, 7 900～4 450 cal a BP是岱海盆地森林植被发育最好的时期, 气候温暖湿润, 4 450～2 900 cal a BP森林开始退缩, 气候温干; 2 900～0 cal a BP在气候变凉干和人类活动的影响下, 森林植被几近消失.     

北疆地区早全新世环境演化的湖泊沉积记录

通过对北疆地区艾比湖沉积物的孢粉组合及其碳酸盐δ^18O,δ^13C,δ^13Corg，TOC，TON和Rb/Sr比等地球化学指标分析，重点对全新世早期气候环境演化特征进行了研究。结果表明，研究时段（8.0-11.cal ka B.P.)温度总体偏低，初期（11.5-10.6cal ka B.P.)较为温湿；早全新世向中全新世转换时期（8.9-8.0cal ka B.P.)气候波动显著。特别是3层泥炭沉积显示了艾比湖地区早全新世气候的强烈不稳定性。泥炭的发育程度及其同位素、孢粉分析数据等都显示，8.2cal ka B.P.,8.6cal ka B.P.,10.5cal ka B.P.的气候状况具有显著的冷湿特征，反映了早全新世的3次冷湿事件。     

基于孢粉数据的珠江三角洲QZK6孔全新世气候定量重建

依据珠江三角洲QZK6钻孔孢粉组合特征及AMS14C测年结果,基于CONISS软件对剖面孢粉组合进行分带分析,其结果分为A、B、C和D四个孢粉带。根据10981a cal BP以来的孢粉组合特点,结合东亚孢粉数据库中位于广东的122个天然植被下的表层土壤样点的孢粉组成特征,利用软件Polygon 1.5定量重建了QZK6孔的全新世古气候参数。结果显示,全新世气候基本以暖湿为主,总体趋势为凉干—热湿—温凉;D带(10981~8500a cal BP)年均温度为21.7~22.1°C,年降水量1778~1888mm,年均温度和年降水量均比较高;C带(8500~8105a cal BP)年均温度为21.9~22.3°C,年降水量为1845~1929mm,达到各带中最高值;B带(8105~4343a cal BP)年均温度和年降水量开始降低,年均温度为20.8~21.7°C,年降水量为1595~1806mm。人类活动从B带开始增强(在A带达到最强);A带(4343a cal BP至今)年均温度为20.3~21.5°C,年降水量为1587~1765 mm,为各带中年均温度最低、年降水量最少的阶段。     

长江下游巢湖9870cal.aB.P.以来孢粉记录的环境演变

根据对巢湖490cm湖泊沉积物柱样7个AMS¹⁴C年龄的测定以及98个孢粉样品的分析,植物种类分属于86个（科）属,可以划分为6个孢粉组合带:孢粉带Ⅰ（9870～6040cal.aB.P.）代表了末次冰期之后全新世温暖气候到来之前气候转暖的早全新世过渡时期,气候呈现温和略干的特点,其中亚带Ⅰ-1（9870～7700cal.aB.P.）,Ⅰ-2（7700～6250cal.aB.P.）和Ⅰ-3（6250～6040cal.aB.P.）分别对应温暖湿润→温暖较湿→温和干燥的气候波动;孢粉带Ⅱ（6040～4860cal.aB.P.）代表中全新世温暖湿润期,水热配置条件最佳;孢粉带Ⅲ（4860～2170cal.aB.P.）体现中全新世后期温和干燥的气候,约2170cal.aB.P.干旱程度达到最高;孢粉带Ⅳ（2170～1040cal.aB.P.）反映巢湖流域由干燥向湿润气候的转型,气候总体上温和湿润;孢粉带Ⅴ（1040～200cal.aB.P.）反映了晚全新世巢湖流域温凉稍湿的气候;孢粉带Ⅵ（200cal.aB.P.至今）则体现巢湖流域处在相对温暖湿润的时期。植被类型演替大体为:以壳斗科的落叶、常绿属种为主的落叶阔叶、常绿阔叶混交林→以落叶栎类、栗属、青冈属和栲/石栎属为主的落叶阔叶、常绿阔叶混交林→以落叶栎类占绝对优势的落叶阔叶、常绿阔叶混交林→以禾本科为主的草地→以禾本科、蒿属和蓼属等为主的草丛。     

青藏高原东北部泥炭沉积粒度与元素记录的全新世千年尺度的气候变化

通过对青藏高原东北部共和盆地泥炭沉积的粒度与地球化学元素分析, 重建了区域全新世千年尺度的气候变化过程. 结果显示: 10.0~8.6 cal ka BP区域暖湿程度逐渐增加, 但在8.6~7.1 cal ka BP气候相对寒冷干燥, 7.1~3.8 cal ka BP 暖湿程度总体上为全新世最佳, 但也出现明显的气候波动, 3.8~0.5 cal ka BP气候向冷干方向发展, 0.5 cal ka BP以来气候又逐渐转向暖湿. 这一特征与中国东部季风区的气候变化有很好的一致性. 此外, 区域全新世气候变化过程中存在10次千年尺度的寒冷事件, 并与高原冰芯、 湖泊、 泥炭和风成沉积记录的古气候变化, 甚至与北半球高低纬度的气候变化都具有良好的可比性. 因此, 认为区域全新世气候变化具有"季风模式"与"千年尺度震荡"的双重特点.     

安徽巢湖湖泊沉积物孢粉-炭屑组合记录的全新世以来植被与气候演变

利用湖泊钻孔的孢粉及炭屑分析资料,探讨了安徽巢湖湖泊沉积物孢粉-炭屑组合记录的全新世以来植被与气候演变。孢粉-炭屑记录表明：本区9870-6040 cal.{a BP},植被是以壳斗科的落叶、常绿属种为主的落叶阔叶、常绿阔叶混交林,气候呈现温和略干的特点;6040-4860 cal.{a BP},植被是以落叶栎类、栗属、青冈属和栲/石栎属为主的落叶阔叶、常绿阔叶混交林,气候由前一阶段的温和略干变为温暖湿润,进入全新世最适宜气候期;4860-2170 cal.{a BP},植被是以落叶栎类占绝对优势的落叶阔叶、常绿阔叶混交林,气温逐渐降低、湿度下降,气候温和干燥,环境整体向着干旱趋势转化,2170 cal.{a BP}左右出现一次明显的干旱事件;2170-1040 cal.{a BP},森林退缩,落叶阔叶、常绿阔叶混交林迅速被破坏,演替成以禾本科为主的草地,气候处于转型时期,总体上温和湿润;1040-200 cal.{a BP},木本植物仅零星分布,可能存在针叶阔叶混交林植被,植被类型逐渐演替成以禾本科、蒿属和蓼属等为主的草丛,其中包括较多的农作物,气候温凉稍湿;200 cal.{a BP}以来,湖区周围零星分布有阔叶乔木,松林在远处可能有分布,植被仍是以禾本科、蒿属和蓼属等为主的草丛,气候相对温暖湿润,但也有若干变凉干的波动,湖泊富营养化水平逐渐增加,人类活动已经对环境变化产生了较大的影响。     

鲁北平原东部巨淀湖岩心沉积物记录的全新世环境演变

鲁北平原东部巨淀湖处于中国北方季风区,对全球气候变化响应敏感,为研究海岸带地区过去的气候环境演变提供了丰富的湖泊沉积资料。通过对巨淀湖钻孔岩心沉积物孢粉鉴定、粒度分析和AMS¹⁴C年代测定,探讨了鲁北平原地区8900 cal a BP以来的气候环境演变过程。结果表明: 8900—7625 cal a BP,气温较高,降水丰沛,气候较暖湿;7625—6810 cal a BP,气候整体呈变凉变干的趋势;6810—4435 cal a BP,温度回升,降水增加,显示了全新世中期整体温暖湿润的气候特征;4435—3150 cal a BP,气候整体寒冷湿润,其间也存在小幅的冷暖波动。中全新世期间5450—5280 cal a BP和4160—4090 cal a BP出现了明显冷干事件,这与中国乃至全球范围内的地质气候记录存在一致性,究其原因可能是受到太阳辐射变化导致的赤道辐合带南移、大洋海表温度变化以及地表植被的反馈作用的共同影响。     

内蒙古克什克腾旗浩来呼热古湖泊全新世以来的环境演变

利用位于中国北方季风尾闾区的浩来呼热古湖泊沉积物中的硅藻化石重建了全新世以来的环境演变历史。根据硅藻组合的变化,可将浩来呼热古湖泊全新世以来的环境演变过程划分为6个阶段:阶段Ⅰ(12.1～11.5cal ka BP),气候以寒冷为主;阶段Ⅱ(11.5～8.6cal ka BP),温度有所回升,但存在一定的冷暖波动;阶段Ⅲ(8.6～6.7cal ka BP),气候仍相对偏凉,且比较干燥;阶段Ⅳ(6.7～5.8cal ka BP),气候开始转温;阶段Ⅴ(5.8～2.9cal ka BP),气候温暖偏湿,为全新世气候最适宜期;阶段Ⅵ(2.9～0.2cal ka BP),气候趋于凉干,湖水也越来越浅,最终在0.2cal ka BP前后干涸消失。     

中-晚全新世以来安固里淖气候演变的植硅体记录

河北坝上地区位于东亚季风边缘区和农牧交错带,季风强弱的变化深刻影响着该地区人类文明的发展.为了重建河北坝上地区中-晚全新世以来的气候演化过程,剖析气候变化与人类文明发展的关系,以坝上地区安固里淖湖为研究对象,通过对该湖沉积剖面植硅体的分析,并结合孢粉组合特征,恢复了安固里淖地区5 000 cal.a BP以来的气候演变历史.结果显示,在千年尺度上该区域气候总体呈冷干趋势,但在5 030~3 070 cal.a BP时期气候相对湿润,千年尺度上气候的变化主要受控于北半球太阳辐射量的变化.在百年尺度上安固里淖地区经历了7次冷干事件,分别发生于4 500 cal.a BP、4 100~3 800 cal.a BP、3 500 cal.a BP、3 000 cal.a BP、2 100 cal.a BP、1 100 cal.a BP和800~270 cal.a BP左右,这7次冷干事件对应于东亚季风减弱阶段,主要受到了北半球高纬气候和太阳活动的共同影响.该区人类文明的演化敏感响应于气候变化,气候温湿期以农业文明为主,气候冷干期以草原文明为主.      

黄河源区距今13万年来古气候演化

综合分析黄河源区-青海玛多地区斗格涌盆地钻孔剖面的孢粉及易溶盐等气候代用指标,揭示了该区130ka B P以来的古气候演变规律。即:130.0-110.0ka B P寒冷干旱;110.0-82.0ka B P寒温较湿;82.0-10.4ka B P寒冷干旱;10.4ka B P至现代(即全新世)温湿冷干交替。全新世古气候又可划分为3期:早全新世升温期(10.4-7.5ka B P)(Anathermal);中全新世大暖期(7.5-3.5ka B P)(Megathermal);晚全新世降温期(3.5ka B P至今)(Katathermal)。本区古气候总的规律是:冷期长且比全球其它地方提前,暖期短且开始时期滞后。全新世以来气候波动具有千年尺度的振荡规律,晚全新世至今,气温有逐渐降低,湿度逐渐变干的趋势。      

河北省丰宁地区全新世风沙活动及其对古文化的影响

在滦河上游,全新世时期曾有过气候相对湿润阶段,具体表现是:就地起沙的风沙层内,形成了2层特殊的古土壤———黑沙土。黑沙土层分布的厚度不均匀,但具有明显的有机质半固结现象。2层黑沙土之间为黄色风沙层,上层黑沙土又为晚近风沙层覆盖。在下层黑沙土中散布着一些古文化遗存,石片、石核、石斧等石器主要见于下部,陶片数量则以近顶部居多。对黑沙土中的有机质进行14C测年,结果表明,下层黑沙土形成于约7990±150～3200±125aB·P·（cal·）之间,上层黑沙土形成于约3055±170aB·P·（cal·）以后。由这个遗址附近的环境分析证明,古代人类在此活动时期,当地气候处于相对湿润阶段,风沙活动虽依然存在,但可以断定黑沙土的成壤速度大于风沙物质堆积速度,使这里的先民能够依靠农耕、渔猎而生存。大约3200±125aB·P·（cal·）后,风沙堆积速度骤然加快,使黑沙土成土过程一度完全停止,在大约100多年的时间里,风沙活动强烈,形成黑沙土层之间的黄色风沙层堆积。这一时期恶劣的环境使得当时当地的先民无法生存,被迫迁移,从此出现新石器遗址的缺失。该遗址所在的丰宁地区,是影响北京沙尘暴的上源地区之一。因此,该地区环境考古学问题的研究,对了解北京地区沙尘暴变化历史有直接佐证的价值。     

Vegetation and climate changes over the last 30 000 years on the Leizhou Peninsula,southern China,inferred from the pollen record of Huguangyan Maar Lake

A pollen record from Huguangyan Maar Lake documents regional palaeovegetation and palaeoclimate changes in southern China over the last 30 000 years. Huguangyan Maar Lake is located close to the South China Sea (SCS) coastline and is influenced by the East Asian Monsoon (EAM). The pollen assemblages show a succession of vegetation and climate changes. During the Last Glaciation, 30–15.8 cal. ka BP, the Huguangyan area was dominated by subtropical evergreen‐deciduous forest with grassland surrounding the lake, indicating a colder and drier climate than today. During 15.8–11 cal. ka BP, the study area experienced several climatic fluctuations. From 11 to 2 cal. ka BP, the climate shifted to warmer and wetter conditions. After the Holocene Optimum in the early Holocene, the temperature and precipitation decreased. The sediment record of the last 2000 years cannot be used to interpret natural palaeoclimate changes due to the intense anthropogenic influences. Overall, however, the Huguangyan pollen archive highlights the rapid responses of subtropical vegetation to insolation changes in southern China.     

Holocene environmental evolution recorded by core sediments of Judian Lake in the east of Lubei Plain,Shandong Province

Judian Lake in the east of Lubei Plain is located in the monsoon area of northern China,which is sensitive to global climate change and provides abundant lake sedimentary data for the study of the past climate and environment evolution in the land-sea interaction area. Based on the sporopollen identification,grain size analysis and AMS¹⁴C dating of core sediments from the drilling hole of the Judian Lake,the evolutional process of climate and environment since 8900 cal a BP in the northern Lubei Plain was discussed. The results show that: 8900-7625cal a BP,the temperature and precipitation increased and the climate changed from cold-dry to warm-wet;7625—6810 cal a BP,the overall climate was becoming cooler and drier;6810—4435cal a BP,the temperature rose and the precipitation increased,showing an overall warm and humid climate in the middle Holocene;4435—3150cal a BP,the climate was generally cold and humid with some low-amplitude fluctuations of cold and warm. During the middle Holocene,there were two obvious cold and dry events in 5450—5280cal a BP and 4160—4090cal a BP,which was consistent with the geological and climatic records in China and even in the world. It may be due to the southward movement of the equatorial convergence zone caused by the change of solar radiation,the change of ocean surface temperature and the feedback of surface vegetation.     

A Preliminary Study of Holocene Climate Change and Human Adaptation in the Horqin Region

Abstract: Human activity during the Holocene in the Horqin region, northeastern China, has been widely documented. As an important proxy record of human activity, black carbon (BC) in sediments has been linked to climate change and human adaptation. A loess-paleosol section located in south Horqin was chosen for this study. Holocene climate change and human adaptation to the environment were discussed by analyzing BC, organic carbon (OC) and other proxies. The conclusions included: (1) before 3900 cal BP, human activity was closely related to the natural environment and cultural development was dominated by climate change. For example, the rapid decline of the agrarian Hongshan culture was caused by a slight decrease in temperature at ~5000 cal BP; (2) during 3900-3200 cal BP, the heavy dependence of human societies on nature gradually lessened and the ability of those human societies to adapt to the environment was enhanced. However, the farming-dominated Lower Xiajiadian culture was nonetheless replaced by the pastoralist Upper Xiajiadian culture due to an extremely cooling event at ~3200 cal BP; (3) during the late Holocene period, the marked influence of climate change on human activity might have lessened as a result of a clear improvement in human labor skills. After this, human living styles were influenced by cultural developments rather than climate change because humans had mastered more powerful means of productivity.     

An improved methodology of the modern analogues technique for palaeoclimate reconstruction in arid and semi-arid regions

Jiang, W., Guiot, J., Chu, G., Wu, H., Yuan, B., Hatté, C. & Guo, Z. 2009: An improved methodology of the modern analogues technique for palaeoclimate reconstruction in arid and semi-arid regions. Boreas , 10.1111/j.1502-3885.2009.00115.x. ISSN 0300-9483.
This study presents an improved method of the plant functional type modern analogues technique (PFT-MAT) in which environmental proxies and a moisture index (α, i.e. ratio of actual evapotranspiration to potential evapotranspiration) are used to constrain the selection of modern analogues. The method is tested using high-resolution, precisely dated palaeorecords (pollen, Pediastrum and δ¹⁸O of authigenic carbonate) from Lake Bayanchagan, northern China. The unconstrained and constrained PFT-MAT produces general agreement for Holocene climate changes, with a wet period between 11 000 and 5500 cal. yr BP and a warm interval between 11 000 and 8000 cal. yr BP. However, there are significant differences in the details of their reconstruction. The constrained PFT-MAT generally yields smaller error bars for the reconstructed climate parameters than the unconstrained PFT-MAT. In addition, three prominent climatic events are identified from the constrained reconstructions; namely, a cold event around 8400 cal. yr BP and two warm events around 6000 and 2000 cal. yr BP, which is consistent with other regional palaeoclimatic records. Our data show that changes in tree components correlate well with α variations during the entire Holocene, with the highest tree components and highest α values between 8000 and 5500 cal. yr BP, indicating the dominant role of α in the growth of trees in northern China rather than single temperature or precipitation. The improved PFT-MAT is therefore an efficient method for quantitative reconstructions of palaeoclimate in arid and semi-arid regions.     

Holocene temperatures in Bohuslän, southwest Sweden: a quantitative reconstruction from fossil pollen data

Inferred mean annual temperatures (Tann) from a radiocarbon-dated fossil pollen stratigraphy obtained from Lake Trehörningen, southwest Sweden, provide evidence of climate variability during the Holocene in the boreal-nemoral zone of Sweden. The record indicates low early Holocene temperatures, followed by a rising trend and maximum temperature values from about 7000 to 4000 cal. yr BP. During the later part of the Holocene until present day, a cooling trend is reflected in the temperature record. At about 8200 cal. yr BP, temperatures temporarily drop, and at 8000 cal. yr BP the rising temperature trend is recovered. Inferred mid-Holocene temperatures are about 2.5-3°C higher than at present, and also higher than other pollen-inferred mid-Holocene temperatures of 1.5-2.5°C further to the north and east in Scandinavia. The reconstructed long-term climate pattern in Trehörningen has an overall consistency with temperature reconstructions from Scandinavia, suggesting a regional climate link for the Holocene variability in Sweden. Holocene climate trends in Trehörningen also show a remarkably similar pattern with the classic work on postglacial climate change by Sernander (1893, Sernander 1909), Andersson (1909) and von Post (1924).