中国黑龙江省嘉荫地区乌云组古果实学研究

白垩纪末至第三纪初（K/T界限，距今约65Ma），恐龙大规模灭绝，爬行类的优势地位被哺乳动物所取代;裸子植物和蕨类急剧衰退，被子植物蓬勃发展，并逐渐成为地表植被的主体，研究这一时期的植物群的结构和特征进而揭示植物演化和环境变迁的规律及其相互关系是当今地球科学、生命科学和环境科学的重要研究内容。黑龙江省嘉荫地区的乌云组产有丰富的植物化石，其地质时代虽未定论，但不超出晚白垩世马斯特里赫特期至早第三纪古新世的范围，处于K/T界限，对其植物群的研究意义重大。乌云植物群以往的研究在古果实学研究方面明显不足、在植物群的性质的认识及乌云组时代的确定等方面存在很大争议。本文重点研究了乌云组的果实和种子化石，增添了新的植物类群，丰富了此植物群的研究内容，对乌云组的时代问题的确定提供了新的证据。 本文研究了乌云组的Nordenskioldia borealis（昆兰树科）、Nyssidium jianyinense sp. nov. （连香树科）、Hypericum zhuii sp. nov. （金丝桃科）、Amersinia obtrullate（广义山茱萸科）、Acer wuyunense sp. nov.（槭树科）等5种果实和种子化石。Nordenskioldia borealis的果无柄、为分果、小果瓣环绕中央柱轮状排列。Nyssidium jianyinense的果序为圆锥果序、蓇葖对生、蓇葖腹缝相对、果皮三层。Hypericum zhuii的种子外形呈长椭圆形、端部具乳突、表面网状、种脊明显、种皮两层、外种皮细胞的垂周壁明显加厚。Amersinia obtrullate果序头状、果镘形、3果室。Acer wuyunense果为翅果、小坚果被明显侧翼、翅强烈下延，包围小坚果。经修订和补充，乌云植物群目前共有维管植物48属60种，其中，蕨类植物4属6种、裸子植物7属7种、被子植物37属48种，被子植物占总种数的80%、占总属数的77%，被子植物占绝对优势。当时的群落类型湿生群落和中生群落类型为主，湿生群落主要有：由Sequoia、Metasequoia、Taxodium、Glyptostrobus等组成的针叶林;以Nyssidium、Trochodendroides占优势的阔叶林。 以Metasequoia占优势的针叶林和以Nyssidium、Trochodendroides等占优势的阔叶林。乌云植物群中热带和亚热带成分占种子植物总属数的54%，而温带成分则占36%，亚热带成分占优势，当时的气候-植被类型为亚热带常绿林或常绿夏绿混交林。Nordenskioldia、Nyssidium、Amersinia、Acer化石的地质分布不早于古新世的地层，这—证据不支持乌云组的地质时代划为晚白垩世，而支持划归古新世的观点。

云南中西部地区晚第三纪孢粉植物群及其古植被和古气候研究

晚第三纪是云南地区环境演变过程中的关键地质历史时段，本论文以晚第三纪晚中新世（吕合）、晚上新世（羊邑和龙陵）地层中的孢粉为研究对象，结合同层位大化石植物证据，参照现代植被，恢复了云南三个化石出产地区的古植被垂直分布景观，并定性地描述了古气候;同时运用共存分析方法（The Co-existence Approach）定量化地重建了三个地区的古气候参数值;初步推测了沉积地可能的古海拔。 吕合晚中新世孢粉植物群含52个孢粉类型，隶属38科，其中25个类型鉴定到属级。植物群中被子植物占73.1%，裸子植物占11.5%，蕨类植物占15.4%。 吕合孢粉植物群的组成反映该地区在沉积时期植被具有垂直分带特征，沉积地附近分布有常绿阔叶林，包括壳斗科的青冈属、栲属、石栎属和漆树科等植物，以及多种亚热带和温带阔叶成分;林中混生少量针叶树（如松属和杉科等）;林内蕨类植物较少;距沉积地较远的海拔较高的地区分布由铁杉属、冷杉属、雪松属和云杉属组成的针阔混交林或针叶林。 吕合地区晚中新世的气候参数：年均温：13.3-20.9℃，最热月均温：22.5-27.5℃，最冷月均温：2.5-12.6℃，年较差：12.1-24.8℃，年降雨量：803.6-1254.7mm，最大月降雨量：179.4-281.9mm，最小月降雨量：10.2-18.5mm。 羊邑晚上新世孢粉植物群含52个孢粉类型，隶属32科，其中36个类型鉴定到属级。植物群中被子植物占61.5%，裸子植物占9.6%，蕨类植物占25.0%，藻类植物占3.9%。 羊邑孢粉植物群的组成反映在沉积时期该地区的植被具有明显垂直分带特征。湿性常绿阔叶林分布在沉积地附近，以壳斗科的石栎属、青冈属和栲属为主，混生漆树科、桃金娘科、蓼科、大戟科和金缕梅科的枫香属等植物，林内蕨类植物丰富;针阔叶混交林分布在距沉积地较远海拔较高的山地，主要包括松属，铁杉属，罗汉松属和一些阔叶植物类群;云杉林、冷杉林和铁杉林分布在更高海拔的地区。 根据植物群的组成推测羊邑沉积地的古海拔不高于2000m。 羊邑地区晚上新世的气候参数：年均温：13.3-20.9℃，最热月均温：22.5-27.5℃，最冷月均温：1.9-12.6℃，年较差：12.3-25.8℃，年降雨量：797.5-1254.7mm，最大月降雨量：172.4-249.6mm，最小月降雨量：7.2-12.7mm。 龙陵晚上新世孢粉植物群含86个孢粉类型，隶属61科，其中45个类型鉴定到属级。植物群中被子植物占69.0%，裸子植物占4.6%，蕨类植物占24.1%，藻类植物占2.3%。 龙陵孢粉植物群反映当时沉积地区的植被具有明显垂直分带特征。沉积地附近分布有湿润常绿阔叶林，以壳斗科的青冈属、栲属和石栎属为主，混生杜鹃花科、藤黄科、漆树科和无患子科等植物，林内蕨类植物丰富;在距沉积地较远的高海拔的山地上分布有针阔混交林和针叶林，以松属、云杉属、冷杉属和铁杉属植物为主。 龙陵地区晚上新世的气候参数：年均温 18.6-22.1℃，最热月均温：22.8-27.5℃，最冷月均温：9.7-15.1℃，年较差：12.3-18.1℃，年降雨量：815.8-1254.7mm，最大月降雨量：172.4-249.6mm，最小月降雨量：9.8-11.3mm。 综合吕合、羊邑和龙陵孢粉植物群新研究资料和云南地区已有的第三纪孢粉学资料，云南地区晚第三纪时期孢粉植物群组成相对稳定，均已经反映常绿阔叶林、针阔混交林或针叶林垂直分布的植被景观，具有湿润的山地亚热带气候特点。与我国北方晚第三纪孢粉植物群相比，在对全球气候变化的响应上，云南地区晚第三纪孢粉植物群的变化不如北方显著;与我国南方其它地区晚第三纪孢粉植物群相比，虽然在对全球气候变化的响应均表现出不明显，但云南地区在植物区系组成上更为丰富。

云南中新世和山西上新世果实和种子的研究

研究化石果实和种子的古果实学在欧洲和北美开展较早，近年来发展迅速，我国在这个领域的研究相对薄弱，迄今为止尚没有专项的研究工作。本论文首次对我国云南和山西晚第三纪的果实和种子进行专门研究，并根据它们对应的现存最近亲缘植物的分布及生态特征分析和重建了当时当地的吉植被、古环境和古气候。 1．云南省西部陇川盆地芒旦地区早一中中新世被子植物果实和种子植物群，包括果实和种子29种，详细研究了14种，隶属于ll科12属：壳斗科的石栎属、金缕梅科的蜡瓣花属、金丝桃科的金丝桃属、樟科的木姜子属、木兰科的木兰属和鹅掌楸属、桑科的榕属、杨梅科的杨梅属、蓝果树科的蓝果树属、芸香科的花椒属、清风藤科的清风藤属以及山矾科的山矾属。所有这些果实和种子的化石在中国均为首次报道，其中蜡瓣花属、鹅掌楸属、蓝果树属、清风藤属和山矾属还是该属在中国的首次大化石记录。在植物群组成中，石栎属占绝对优势，其他主要类群有蜡瓣花属、木姜子属、木兰属、花椒属和山矾属等。芒旦果实和种子植物群反映当时当地为亚热带常绿阔叶林的森林面貌和温暖湿润的亚热带气候条件。 2．山西省榆社盆地张村地区晚上新世( 2.3 Ma-3.5 Ma)水生植物川蔓藻属(Ruppia)果实和种子的大量发现及其与川蔓藻属2个化石种和5个现代种的比较表明，这些果实和种子属于一个新种—榆社川蔓藻Ruppia yushensis sp. nov。该新种的主要特征为内果皮卵形、表面光滑、侧面具两个显著的窄椭圆形凹陷、顶端具一个明显的小尖突，以及种子顶端具显著的球形膨大的种脐。榆社川蔓藻将川蔓藻属的第三纪地理分布范围从欧洲延伸到了东亚，并且填补了它在上新世地层的空缺。榆社川蔓藻作为榆社盆地晚新生代水生植物的发现，指示了当时当地的咸水环境。根据川蔓藻属植物的现代生态资料并结合其它矿物学和生物学指标，可以推测晚上新世张村地区为一个浅而平静的微咸水湖。榆社川蔓藻果实和种子的大量出现说明该植物可能在该水域形成了单一的优势类群，其光滑的内果皮表面指示当时当地为暖温带或温带气候。

浙江嵊州早上新世植物群重建和古气候定量研究

上新世时期是地球环境发展变化过程中由温暖的中新世向冰期-间冰期交替出现的更新世的过渡时期，研究上新世的气候有助于研究现代全球气候变化趋势。我国上新世植物群研究不多，尤其缺乏早上新世植物群的研究。在研究化石植物群的过程中，叶角质层的信息通常被忽视。迄今，我国古气候的定量研究主要集中在山东山旺和云南地区，研究的主要是中新世和晚上新世的古气候，早上新世气候的定量研究国内外都未见报道。 本论文以采自浙江中部嵊州地区硅藻土中的植物叶和果实为材料，通过光学显微镜、荧光显微镜和扫描电镜观察，对提取的化石叶角质层和叶结构进行研究，对比研究现代相关类群植物的叶片，确定了化石植物类群计15科24属（或亚科）34种。同时参照现代植物分布，恢复了早上新世嵊州地区古植被情况，进一步运用共存分析（Co-existence Approch）定量重建了当时的古气候，得到古年均温、古年较差和古年降水量等7个参数。 研究表明，叶结构和叶角质层可以应用于化石植物类群的鉴定。光学显微镜和荧光显微镜下可以获得的信息有：气孔、表皮细胞形状及大小、表皮细胞垂周壁、分泌结构、表皮毛或毛基等。扫描电镜观察的是叶表皮细胞表面的情况，如细胞外壁是否被蜡质以及蜡质的交结情况，气孔外壁是否增厚呈环等。 经化石植物类群鉴定，早上新世（约4Ma）嵊州地区植被属亚热带常绿阔叶林。推测：该地区当时存在一个较大的湖泊，湖泊边缘水中生长有菱角，湖泊周边可能有海拔超过1400m的山地。 常绿阔叶林主要成分是壳斗科植物，其中青冈属植物可能是建群植物。自低海拔到高海拔地区都有分布的是：栎属、栗属、桤木属植物，青杨梅。低海拔地区（<600m）分布的植物有：海南锥，樟。中低海拔地区（300-1000m）分布着：柯属、黄杨属植物，水青冈，海南油丹，江南油杉，福建柏。中高海拔地区（>700m）分布有：高山栎、黄肉楠属植物，米心水青冈，榉树，建始槭，天台鹅耳枥和昌化鹅耳枥。除了上述类群，林中还散布着鼠李属、杜鹃花属和冬青属的植物，豆科崖豆藤属植物则缠绕一些较大乔木生长。另外，在一些土壤、有机质易堆积的洼地生长有竹林，山地贫瘠的地方生长着柏属植物。 嵊州早上新世化石植物群反映的植被同浙江地区现代植被相似。第三纪浙江地区从针叶林或阔叶树为主的针-阔叶混交林过渡到常绿-落叶阔叶林，再发展为常绿阔叶林。 依据23个植物类群分析获得7个古气候参数：年均温17.7-21.4°C，最热月均温22.2-27°C，最冷月均温8.4-13.4°C，年较差12.1-15.3°C，年降水量1136-1869.9mm，最大月降水量211.8-283.3mm，最小月降水量20.3-36.8mm。 对比现代嵊州地区气候参数，早上新世嵊州地区年降水量略高于现代，年均温比现代高1.3-5°C，年较差为12.1-15.3°C。早上新世期嵊州地区四季气温比现代平稳。

中国黄土高原洛川剖面 630 kyr 以来的孢粉记录

It is known that global climate changed from the early Tertiary “Green House” to the Quaternary “Ice House” of cyclic glacial-interglacial climatic changes. Since the middle Pleistocene, the climate cycles changed from 40 kyr to 100 kyr, and the amplitudes of climatic fluctuations increased significantly. Therefore, it is important to study the climate changes since the middle Pleistocene. The loess-paleosol sequence in China is considered as one of the most continuous continental records of the last 2.58 Ma. Paleoclimatic and environmental changes have been widely extracted through various climatic parameters. However, the history of paleovegetation on the Loess Plateau still remains unclear. Did an extensive broadleaf forest ever exist on the Loess Plateau? Pollen preserved in the loess and paleosol provides a direct record for vegetation and paleoenvironmental change on the Plateau. However, because it is difficult to extract sufficient pollen grains from loess, the pollen record since the middle Pleistocene especially in the central part of the Chinese Loess Plateau has not been well studied. So we preliminarily focus on the palynological records of the loess-paleosol sequence spanning the last 630 kyr at Luochuan and aim to understand the evolution of vegetation and climate change on the Chinese Loess Plateau. The main results and conclusions are as follows: 1. The palynological results show that the grassland has been a dominant vegetation in the Luochuan area since 630 kyr, even during the intervals of relatively warm and wet climatic conditions. 2. The pollen concentration of Luochuan section sharply decreases from the bottom of S1 to downward depth. This decrease can be attributed to depositional environment rather than climate change. In loess, not only oxidation, but also the PH of deposits and bacteria or fungi have been able to degrade sporopollenin. 3. The paleoclimatic condition during S4 stage, characterized with warmer condition during the early stage, was warmer and wetter than that during S5 in Luochuan area. Paleoclimate was warmer and wetter during the early stage of S5 and became colder and drier later. The special pedogenic features of S5-I can be attributed to a prolonged pedogenic duration rather than a warm-wet climate. 4. Evidence from pollen assemblage suggests that the Holocene vegetation has been affected by human impacts, especially after the Yangshao Culture. 5. The present steppe environment on the loess plateau is mainly due to natural conditions. Temperature, seasonal precipitation and soil structure are three important factors which control the vegetation type. 6. The vegetation on the loess plateau is characterized with zonal or azonal distribution. So local conditions should be taken into account when recover natural vegetation. Finally, the restoration and reconstruction of ecosystem on the loess plateau area should be focused on planting grassland rather than forests.

湛江湖光岩玛珥湖55ka以来植硅体化石记录及古环境变迁

The study of biogenic proxy of tropical and subtropical regions provides important evidence about the process and history of vegetation and environmental changes, and is of globally importance for understanding the dynamic mechanism of paleoclimatic and paleoenvironmental changes. The sediments from the Huguangyan Maar lake in Guangdong Province offer a continuous high-resolution record of the past 55 ka about environmental and vegetational changes. The studies of chronology, and physical, chemical environmental proxies have provided much important information about the paleoenvironmental and paleoclimatic histories. The phytolith, a new biogenicl proxy, has been used to determine the nature and types of plants in this area since the last 55 ka. This study presents a preliminary result about the characteristics of phytolith shapes, the variations of the fossils assemblages, and their significance for environmental changes. Moreover, the author probes the process of special specie evolution and their relationship to climatic parameters. The history of fire has been reconstructed based on the variations in charcoals. The main results and conclusions include: 28 types of phytoliths from 233 samples have been identified. Their environmental meanings are investigated in detail. Based on the variations in phytolith associations, the history and process of climatic and environmental changes in the last 55 kaBP have been established for this region. Climatic changes experienced eight intervals during this period, showing the variations of hot-humid to cool-try climate in the ten thousands years scale, and a shorter dry-hot climate condition in millennial scale. The history of palm plant has been established in this region. Two peaks appeared from 55-39 ka and since the Holocene. Plants in Bambusoideae have been growing in this area all the period, representing the impact of the East Asian summer monsoon. Bamboo plants have similar tendency in their abundance to palm plants, but with a lag of 1-2 ka BP. Panicoideae plants, the representative of C4 plants, have 6 flourishing periods occurred at 54.5, 44, 41.5, 32.5, 14, and 10 kaBP, respectively, reflecting 6 times short-term arid events. Charcoal record from the Huguang Marr lake reveals the history of nature fire, that mostly happened in dry period of last glacial from 55-10 kaBP, centered at 50-45, 40-35, 30-25, and 20-15kaBP, showing about a cycle of 10,000 years.

The impact of sea ice dynamics on the Arctic climate system

Five paired global climate model experiments, one with an ice pack that only responds thermodynamically (TI) and one including sea-ice dynamics (DI), were used to investigate the sensitivity of Arctic climates to sea-ice motion. The sequence of experiments includes situations in which the Arctic was both considerably colder (Glacial Inception, ca 115,000 years ago) and considerably warmer (3 × CO2) than today. Sea-ice motion produces cooler anomalies year-round than simulations without ice dynamics, resulting in reduced Arctic warming in warm scenarios and increased Arctic cooling in cold scenarios. These changes reflect changes in atmospheric circulation patterns: the DI simulations favor outflow of Arctic air and sea ice into the North Atlantic by promoting cyclonic circulation centered over northern Eurasia, whereas the TI simulations favor southerly inflow of much warmer air from the North Atlantic by promoting cyclonic circulation centered over Greenland. The differences between the paired simulations are sufficiently large to produce different vegetation cover over >19% of the land area north of 55°N, resulting in changes in land-surface characteristics large enough to have an additional impact on climate. Comparison of the DI and TI experiments for the mid-Holocene (6000 years ago) with paleovegetation reconstructions suggests the incorporation of sea-ice dynamics yields a more realistic simulation of high-latitude climates. The spatial pattern of sea-ice anomalies in the warmer-than-modern DI experiments strongly resembles the observed Arctic Ocean sea-ice dipole structure in recent decades, consistent with the idea that greenhouse warming is already impacting the high-northern latitudes.

Late Quaternary vegetation dynamics from central parts of the Madeira River in Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

LGM Summer Climate on the Southern Margin of the Laurentide Ice Sheet: Wet Or Dry?

Regional climate simulations are conducted using the Polar fifth-generation Pennsylvania State University (PSU)-NCAR Mesoscale Model (MM5) with a 60-km horizontal resolution domain over North America to explore the summer climate of the Last Glacial Maximum (LGM: 21 000 calendar years ago), when much of the continent was covered by the Laurentide Ice Sheet (LIS). Output from a tailored NCAR Community Climate Model version 3 (CCM3) simulation of the LGM climate is used to provide the initial and lateral boundary conditions for Polar MM5. LGM boundary conditions include continental ice sheets, appropriate orbital forcing, reduced CO2 concentration, paleovegetation, modified sea surface temperatures, and lowered sea level. The simulated LGM summer climate is characterized by a pronounced low-level thermal gradient along the southern margin of the LIS resulting from the juxtaposition of the cold ice sheet and adjacent warm ice-free land surface. This sharp thermal gradient anchors the midtropospheric jet stream and facilitates the development of synoptic cyclones that track over the ice sheet, some of which produce copious liquid precipitation along and south of the LIS terminus. Precipitation on the southern margin is orographically enhanced as moist southerly low-level flow (resembling a contemporary, Great Plains low-level jet configuration) in advance of the cyclone is drawn up the ice sheet slope. Composites of wet and dry periods on the LIS southern margin illustrate two distinctly different atmospheric flow regimes. Given the episodic nature of the summer rain events, it may be possible to reconcile the model depiction of wet conditions on the LIS southern margin during the LGM summer with the widely accepted interpretation of aridity across the Great Plains based on geological proxy evidence.

Polar MM5 Simulations of the Winter Climate of the Laurentide Ice Sheet at the LGM

Optimized regional climate simulations are conducted using the Polar MM5, a version of the fifth-generation Pennsylvania State University-NCAR Mesoscale Model (MM5), with a 60-km horizontal resolution domain over North America during the Last Glacial Maximum (LGM, 21 000 calendar years ago), when much of the continent was covered by the Laurentide Ice Sheet (LIS). The objective is to describe the LGM annual cycle at high spatial resolution with an emphasis on the winter atmospheric circulation. Output from a tailored NCAR Community Climate Model version 3 (CCM3) simulation of the LGM climate is used to provide the initial and lateral boundary conditions for Polar MM5. LGM boundary conditions include continental ice sheets, appropriate orbital forcing, reduced CO2 concentration, paleovegetation, modified sea surface temperatures, and lowered sea level. Polar MM5 produces a substantially different atmospheric response to the LGM boundary conditions than CCM3 and other recent GCM simulations. In particular, from November to April the upper-level flow is split around a blocking anticyclone over the LIS, with a northern branch over the Canadian Arctic and a southern branch impacting southern North America. The split flow pattern is most pronounced in January and transitions into a single, consolidated jet stream that migrates northward over the LIS during summer. Sensitivity experiments indicate that the winter split flow in Polar MM5 is primarily due to mechanical forcing by LIS, although model physics and resolution also contribute to the simulated flow configuration. Polar MM5 LGM results are generally consistent with proxy climate estimates in the western United States, Alaska, and the Canadian Arctic and may help resolve some long-standing discrepancies between proxy data and previous simulations of the LGM climate.