25000年以来勃海湾西岸古环境探讨

本文依据孢粉,微体古生物,放射性碳测年,因子分析等资料,表明25000a,BP以来渤海湾西岸的古植被,古地理环境演变既受气候冷暖变化的影响,又受海平面变化的制约,25000－23000a,BP为高 平面时期,古植被为森林草甸植被,23000－12000a,BP气候冷干,为低海平面时期,以草原植被为主,前期和后期为沼泽草甸植,被12000－5000a,BP气候温凉或温暖湿润为海平面上升时期,为阔叶林草甸或沼泽草佃植被,5000a,BP以来,气候迹凉变干,为海退时期,古植被由沼泽草甸演为盐生草甸。     

根据孢粉资料推论长江三角洲地区12000年以来的环境变迁

根据长江三角洲地区全新世９个具代表性钻孔的孢粉分析结果讨论了本区约自１２０００年以来的环境变迁。孢粉序列表明,本区约在距今１２０００年前就已发育了亚热带性质的落叶常绿阔叶林,约在９０００－５０００ａＢ．Ｐ．常绿阔叶林获得大发展,孢粉序列良好地记录了古季风盛衰的历史,表现在：１２０００－１０８００ａＢ．Ｐ．较温湿 ,东南季风强度加强,１０８００（或１１０００）－１００００（或１０３００）ａＢ．Ｐ．偏     

贵州大干坝孢粉分析与古环境探讨

大干坝洼地发育了一套晚更新世河湖相地层,富含孢粉,明显可分两段：两万三千多年前为茂密的亚热带山地森林,水青冈属一度占优势;两万三千多年后森林稀化,蕨类植物生长,尔后阳性树种恢复,这反映该地从大理间冰段（阶）向盛冰期过渡时,环境条件发生了跳跃式的变化。     

甘肃小陇山林区全新世中期以来古植被演替的研究

采用花粉孢子分析和＾１４Ｃ测定年代的方法,来研究小陇山林区植被的历史演根据小陇山林区不同地点３个剖面的孢粉资料和＾１４Ｃ数据,首次推断该区自全新世中期以来,古植被和古气候经历了３个演替阶段;距今７５００－５０００年,为以栎类为主的落叶阔叶林和局部为针阔混交林,气候温度湿润;距今５０００－２５００年,为以栎类为主的针阔混交林,气候温和略干;２５００年至今,早期为栎林和针阔昆交林,晚期是以栎类占优势的     

11000年以来太湖地区的植被气候变化

根据太湖盆地３个钻孔,约自１１０００年以来的孢粉分析结果将其划分为３个阶段;１）１１０００－９０００ａＢ．Ｐ．该段虽以Ｐｉｎｕｓ为主的针叶植物占有一定的优势,但起主导作用的仍以壳斗科为主的阔叶乔木种类,尤其是其间尚含有不少的亚热带成分,推测当时该区地带性植被已为亚热带落叶常绿阔叶林,鉴于植被中尚含有少量耐寒的Ａｂｉｅｓ和Ｐｉｃｅａ,推测当时气温可能较今略低;２）９０００－５０００（５４００）ａＢ．     

11000年以来太湖地区的植被气候变化

根据太湖盆地３个钻孔,约自１１０００年以来的孢粉分析结果将其划分为３个阶段;１）１１０００－９０００ａＢ．Ｐ．该段虽以Ｐｉｎｕｓ为主的针叶植物占有一定的优势,但起主导作用的仍以壳斗科为主的阔叶乔木种类,尤其是其间尚含有不少的亚热带成分,推测当时该区地带性植被已为亚热带落叶常绿阔叶林,鉴于植被中尚含有少量耐寒的Ａｂｉｅｓ和Ｐｉｃｅａ,推测当时气温可能较今略低;２）９０００－５０００（５４００）ａＢ．     

贵州大干坝孢粉分析与古环境探讨

大干坝洼地发育了一套晚更新世河湖相地层,富含孢粉,明显可分两段：两万三千多年前为茂密的亚热带山地森林,水青冈属一度占优势;两万三千多年后森林稀化,蕨类植物生长,尔后阳性树种恢复,这反映该地从大理间冰段（阶）向盛冰期过渡时,环境条件发生了跳跃式的变化。     

青海湖QH85—14C钻孔孢粉分析及其古气候古环境的初步探讨

本文主要依据青海湖具有~(14)C 年龄数据的 QH 85-14C 钻孔系统孢粉分析资料,将井深4.5m 岩芯所做的孢粉图式从下至上分为五个区域性孢粉带,进而论述了青海湖区11,000年来的植被曾经历了疏林草原(11,000—10,000年 BP)、森林草原(10,000年 BP)、森林(8,000—3,500年 BP)、森林草原(3,500—1,500竿 BP)和疏林草原(1500年前至今),反映的气候序列为凉干→温湿→温干阶段。     

松柏类木化石生长轮的定量研究方法与应用

树木生长轮记录了植物生长期的气候环境信息及其生理响应过程,而这些信息可以通过定量分析生长轮的解剖学特征获得,因此生长轮的定量分析被广泛应用于林学、地理学、古气候学和古生物学等研究领域.我国虽然保存了丰富的木化石,但前人多从系统分类学角度研究木化石,而较少利用木化石生长轮定量分析方法开展古气候环境的研究.本文主要结合松柏...     

A contribution towards the reconstruction of Eemian vegetation and climate in central Europe: First results of pollen and oxygen-isotope investigations from Mondsee, Austria

In this paper, the results of pollen analysis and oxygen-isotope investigations of two new cores from Mondsee are discussed. The climatic progression from the end of the penultimate glaciation to the end of the Eemian interglacial is compared with reconstructions from Bispingen and Gräbern, northern Germany. The rise in temperature, between thePinus phase and the climate optimum in theCorylus phase, appears to have occurred in two steps. Evidence for climatic deterioration is first recorded during thePicea-Pinus phase, i.e. after theCarpinus phase. These reconstructions are in agreement with those based on the Gräbern pollen data, but contrast with recent reconstructions based on the Bispingen pollen profile and the GRIP ice core from Greenland.     

Late Glacial and early Holocene environment in the middle Lahn river valley (Hessen,central-west Germany) and the local impact of early Mesolithic people—pollen and macrofossil evidence

The Late Glacial to early Holocene river valley landscape of the middle Lahntal in Hessen, central-west Germany, is reconstructed by means of pollen and macrofossil analyses. AMS ¹⁴C dating combined with pollen, macrofossil and geomorphological mapping provide a detailed chronology of the floodplain sediments of the river Lahn. Archaeological evidence for early Mesolithic settlements in the middle Lahntal is backed up by pollen and macrofossil evidence, which indicates an increase in light demanding plants, together with ones indicating nutrient-rich and disturbed environments and more macroscopic charcoal and charred pieces of pine. Different phases of human impact were dated; a first phase was dated at ca. 9,270 uncal b.p. and a second phase at ca. 9,120 uncal b.p. Comparison of the palynological data from different fluvial channel fills demonstrates that during this second phase, between ca. 9,120–8,700 uncal b.p., there were several cycles of woodland clearance. The outcome of combined archaeological, palynological and macrofossil data is discussed in terms of the impact of early Mesolithic people using fire on the vegetation during the early Holocene in the middle Lahntal.     

Vegetation history of Lago Battaglia (eastern Gargano coast,Apulia, Italy) during the middle-late Holocene

A pollen and charcoal record from Gargano (southern Italy) provides new information on the vegetation history and environmental change in southern Italy during the middle to late Holocene. The chronological framework is provided by six AMS radiocarbon dates carried out on plant macroremains. Pollen diagrams record a Mediterranean vegetation along the coastland and a stable mixed oak forest at higher elevations between ca. 5900 and 4200 cal b.p. A sharp and dramatic fall of tree pollen concentrations and a change in fire frequencies occurred from approximately 4200 cal b.p. suggesting a climate change towards drier conditions. This event is coherent with regional and extra-regional palaeoclimatic records that suggest that a mid-Holocene dry period was experienced in southern Italy, southern Spain, and perhaps further afield. Human impact on vegetation seems to have occurred since about 2700 cal b.p.     

The Messinian event: What happened to the peri-Mediterranean mammalian communities and local climate?

What truly happened in the terrestrial ecosystems in response to the famous Messinian salinity crisis is still the matter of extensive discussions. Did mammals record any faunal and/or a climatic or environmental fluctuation is a question that still remains open. Our objective is to investigate mammalian faunas before, during and after the crisis within different terrestrial basins surrounding the Mediterranean Sea. We therefore apply here two methods, the cenogram method and a transfer function based on murine (rodents) species richness to better understand if our proxies can record any qualitative or quantitative climatic or environmental change. The results indicate that mammal faunas do not record any particular shift in climate or environment at the scale of the whole peri-Mediterranean area. The trend is different at the regional scale of terrestrial basins as temperatures increase (Calatayud-Daroca-Teruel Basin) or decrease (Languedoc-Roussillon region) punctually occurs just after the crisis; stable conditions in different areas (e.g. Greece) contradict these trends. Biases in the fossil record or in the methodologies could produce such discrepancies.     

Linking past cultural developments to palaeoenvironmental changes in Estonia

Connections between environmental and cultural changes are analysed in Estonia during the past c. 4,500 years. Records of cereal-type pollen as (agri)cultural indices are compared with high-resolution palaeohydrological and annual mean temperature reconstructions from a selection of Estonian bogs and lakes (and Lake Igelsjön in Sweden). A broad-scale comparison shows increases in the percentage of cereal-type pollen during a decreasing trend in annual mean temperatures over the past c. 4,300 years, suggesting a certain independence of agrarian activities from environmental conditions at the regional level. The first cereal-type pollen in the region is found from a period with a warm and dry climate. A slow increase in pollen of cultivated land is seen around the beginning of the late Bronze Age, a slight increase at the end of the Roman Iron Age and a significant increase at the beginning of the Middle Ages. In a few cases increases in agricultural pollen percentages occur in the periods of warming. Stagnation and regression occurs in the periods of cooling, but regression at individual sites may also be related to warmer climate episodes. The cooling at c. 400–300 cal b.p., during the ‘Little Ice Age’ coincides with declines in cereal-type and herb pollen curves. These may not, however, be directly related to the climate change, because they coincide with war activities in the region.     

Chronological and environmental context of the Middle Pleistocene human tooth from Mollet Cave (Serinyà, NE Iberian Peninsula)

Mollet Cave is a small cave situated in Serinyà (north-east Iberian Peninsula). It was excavated in 1947-48, 1958 and 1972 by Josep M. Corominas. An archaic human molar comes from its base layer (Layer 5). Up till now, this layer has only been dated based on a relative and imprecise chronology of macromammals and the archaeostratigraphic evidence from the early excavations. Recent excavations, conducted between 2001 and 2005, have made it possible to ascertain more precisely the archaeological and palaeontological contents of Mollet Cave, gather microvertebrates, and collect samples for radiometric dating. The aim of this paper is to present the absolute dating of Layer 5, as well as its palaeo environmental and climatic characterisation. The macromammal assemblage seems to have been the result of accumulations produced by the most abundant carnivore, the hyena, which would have used the cave as a den. The results obtained using uranium-series disequilibrium dating ascribe to Layer 5 an age of ca. 215 ka (thousands of years ago), which would correspond to MIS 7. The faunal association suggests a landscape formed by an open and humid woodland characteristic of an interstadial phase, which would have been an environment well suited to sustaining both hyenas and human groups.     

A 200-ka pollen and oxygen-isotopic record from two sediment cores from the eastern Arabian Sea

We present here a pollen record from the northern Indian Ocean that goes back to 200 ka, the boundary between marine isotopic stages (MIS) 7 and 6. Pollen, oxygen-isotopic composition and organic carbon have been examined for two sediment cores from the eastern Arabian Sea (15°02′N and 71°41′E, 13°16′N and 71°00′E), to reconstruct the long-term palaeoclimate and palaeovegetation of the Indian subcontinent. Oxygen-isotope data suggest that glacial periods (MIS 2, 4 and 6) are characterised by low precipitation because of a weak southwest monsoon and a strong northeast monsoon. In contrast, interglacial periods (MIS 1, 3 and 5) are marked by high fresh water input resulting from a strong southwest monsoon. During the last glacial-interglacial cycle, sea-surface temperature and surface salinity changed as a result of variations in the evaporation-precipitation (E-P) balance. Throughout the core, the dominant pollen types are Poaceae and Chenopodiaceae and/or Amaranthaceae (>50%). Their dominance during glacial periods (MIS 2, 4 and 6) suggests that the climate was cold and dry. This dominance is also suggestive of salinity-tolerant vegetation colonizing large areas near seashore due to lower sea level or high E-P conditions. During interglacial periods (MIS 1, 3 and 5) when there was high precipitation, the arid taxa were sparse, whereas Poaceae and Piperaceae were abundant. Hence, Chenopodiaceae and/or Amaranthaceae and Artemisia are suggestive of cold and arid/semi-arid climate, and Poaceae and Piperaceae of warm and wet conditions. Mangrove pollen is not well represented in the cores.     

Meteorological variables connected with airborne ragweed pollen in Southern Hungary

About 30% of the Hungarian population has some type of allergy, 65% of them have pollen sensitivity, and at least 60% of this pollen sensitivity is caused by ragweed. The short (or common) ragweed (Ambrosia artemisiifolia = Ambrosia elatior) has the most aggressive pollen of all. Clinical investigations prove that its allergenic pollen is the main reason for the most massive, most serious and most long-lasting pollinosis. The air in the Carpathian Basin is the most polluted with ragweed pollen in Europe. The aim of the study is to analyse how ragweed pollen concentration is influenced by meteorological elements in a medium-sized city, Szeged, Southern Hungary. The data basis consists of daily ragweed pollen counts and averages of 11 meteorological parameters for the 5-year daily data set, between 1997 and 2001. The study considers some of the ragweed pollen characteristics for Szeged. Application of the Makra test indicates the same period for the highest pollen concentration as that established by the main pollination period. After performing factor analysis for the daily ragweed pollen counts and the 11 meteorological variables examined, four factors were retained that explain 84.4% of the total variance of the original 12 variables. Assessment of the daily pollen number was performed by multiple regression analysis and results based on deseasonalised and original data were compared.