鄂尔多斯盆地西南部甘肃西峰地区延长组孢粉组合及古气候研究

鄂尔多斯盆地西南部西峰油田中上三叠统延长组长8段和长7段钻井岩心中发现丰富的孢粉化石,分别命名为Aratisporites-Punctatisporites组合和Asseretospora-Walchiites组合,组合特征分别与盆地东南部发现的铜川组孢粉组合和延长组孢粉组合相似,地质时代分别为中三叠世晚期Ladinian期与晚三叠世早期Carnian期。通过孢粉植物群类型地层分布特征及其生态环境讨论,推测盆地区中晚三叠世气候温暖潮湿,雨量充沛,植被茂盛。孢粉植物群所反映的古气候为温带—亚热带暖湿或湿热气候。这是由于本地区当时处于较低的纬度,且濒临大型湖泊,而长8—长7段沉积时期正处于湖泊扩张的鼎盛期。     

内蒙古乌达煤田下二叠统山西组4,5号煤层底板植物群研究北大核心CSCD

基于对内蒙古乌达煤田下二叠统山西组4,5号煤层底板的野外工作,系统采集、鉴定植物化石18属26种,其中以华夏植物群的特有属种或常见分子占绝对优势。沉积环境及植物古生态学分析表明,5号煤底板植物群主要由Lepidodendron posthumii Jongm. and Goth.和Cathaysiodendron cf.incertum(Sze and Lee) Lee等组成,代表了三角洲平原上碎屑沼泽植被景观。4号煤底板植物群主要由成煤沼泽植物和碎屑沼泽植物混合而成,原位埋藏的Stigmaria ficoides(Sternb.) Brongn.为成煤沼泽植被类群,代表了上覆4号煤的成煤植物;由Tingia carbonica(Schenk) Halle和Pecopteris arborescens(Schloth.) Sternb.等组成的碎屑沼泽植被类群,代表了三角洲平原上的碎屑沼泽植被景观。综合相关研究资料和当前植物化石分析表明,煤层底板植物群主要代表了地质历史时期中的湿地植被,按照其与形成上覆煤层植物之间的关系可主要分为:上覆煤层形成初期的泥炭沼泽植物群、与成煤作用无关的碎屑沼泽植物群和两者的混合类型。底板植物群的深入研究必须要结合沉积岩石学、地层学以及埋藏学的分析。当前研究显示乌达地区早二叠世沉积时期,湿地植被组成较为稳定,其中石松类植物一直都是重要的成煤泥炭沼泽植被类型;碎屑沼泽植被与成煤沼泽植被多数情况下成分类似,仅存在种一级别的差异。     

内蒙古大青山调角海了地区全新世气候与环境重建研究

以全封闭湖泊调角海子湖相沉积的高分辨率采样为基本分析材料,采用孢粉分析,沉积地球化学分析,14C测年等多种分析手段,对调角海子地区全新世气候与环境进行了综合研究,结果表明：全新世气候与环境演化可划分为5个阶段,其中后两个阶段又可分为3个亚段;全新世大暖期的时代为9400－3800aBP;全新世大暖期具有二分性;6900－6300aBP为全新世气候最适宜的鼎盛期,当时气温比现在高2－3度,降水量至少高于现代150－200mm,植被为针阔叶混交林。     

末次盛冰期以来沙漠-黄土过渡带植被演替及其对气候变化的响应

末次盛冰期(LGM)以来的增温期和全新世高温期是人类古文化进步的重要时期。黄土高原北部沙漠-黄土过渡带两个自然剖面高分辨率花粉分析结果显示,该区LGM以来为草原植被景观,但优势群落和伴生植物随气候变化而有所不同,温度和降水变化对植被演替有着重要的控制作用。气候干冷时,以耐干旱的草本植物种属为主,群落成分单一,植被盖度低;增温期和高温期,出现少量暖温带乔木植物如胡桃科、栎属等,植被盖度高,群落发育良好。全新世暖期是植被发育良好、植被盖度高的适宜期。本研究为黄土高原地区未来增温下植被响应的分析提供了历史相似型。     

江苏句容宝华山全新世中晚期的花粉与环境

根据宝华山华山口和官塘头两个剖面的花粉、地层资料,结合植物大化石和＾１４Ｃ年代资料,提示该地区从＞６７００－５６００ａＢＰ为稳定的温暖湿润时期;自５６００－５１００ａＢＰ为全新世中期气候的转型时期,冷暖干湿变化较大,前期转凉,旱涝频繁,中期暖湿,后期转冷;大约从４４００－４０００ａＢＰ又变为稳定的暖湿气候。还根据自然保护区现代植被与花粉的关系和与植物大化石共生的沉积物花粉,阐明长江下游新石器时代以     

北京地区全新世植被和气候变化研究进展

该文综述了北京地区全新世以来植被演替和气候变化的相关研究资料,这些资料反映了当前阶段对该地区该时段植被与气候环境格局特征的认识。北京地区全新世早期(约12 000–8 000 cal a B.P.)植被为森林草地和/或针叶树占主导的针阔混交林,森林中阔叶树类群逐渐增多,指示了气候由寒冷干燥转为温暖湿润;全新世中期(约8 000–2 000 cal a B.P.前后)植被为暖温带针阔混交林,指示暖湿气候;全新世晚期(约2 000 cal a B.P.以来)转为森林草地和/或针叶树占主导的针阔混交林,气候转向凉干。植被演替反映的湿润度变化与季风区其它地区变化趋势一致。值得注意的是,前人研究揭示北京地区山区与平原中植被类型和类群组成已经出现空间分异。今后如能深入开展定量古气候重建研究,有可能精确描述其气候变化的过程,增进中国不同地理单元同时期气候变化的对比。     

依据Altingiaceae和Juglandaceae孢粉化石探讨我国第三纪植物群及气候特征

依据化石花粉Caryapollenites和Liquidambarpollenites的现存对应植物的生态特征 ,探讨我国第三纪一些孢粉组合的植物群及其所反映的古气候特征。得出 :1)我国第三纪植被 ,从第三纪初至末 ,东西部就有明显区别 ;2 )我国第三纪的孢粉组合所反映的古植被可以和我国现存的植被进行比较 ,从而获得气候特征 ;3)从孢粉资料判断 ,Carya属和Altingiaceae科植物从第三纪初至今 ,生长地带纬向南移了 10°多。     

内蒙北部晚白垩世马斯特里赫特期(Maastrichtian)的孢粉组合

1.在内蒙北部首次发现含有山龙眼粉、正型粉的晚白垩世马斯特里赫特期的孢粉组合。2.孢粉组合反映了沉积时期内蒙北部地形较现在起伏大,曾有低山及平原,生长有亚热带山地针叶林、亚热带常绿落叶阔叶和常绿针叶混交林及沼泽湖滨盐碱地植物,气候温暖,稍干旱。3.内蒙北部马斯特里赫特期孢粉区系与当时西伯利亚、北美西部太平洋区系有密切联系,而与欧洲及北美大西洋联系较弱。     

内蒙古乌达煤田早二叠世山西组湿地植被群落演替序列

基于对内蒙古乌达地区早二叠世山西组2号煤相邻地层的野外工作,系统采集植物化石12属、14种。根据沉积环境及植物古生态学分析,识别出生长于该地区早二叠世三角洲平原环境下的植被群落演替序列,包括由早及晚5个群落,即:1)Lepidodendron incertum Sze et Lee群落,代表最初开始形成2号煤层的植被;2)Lepidodendron incertum-Lepidodendron posthumii Jongm.et Goth.群落,反映2号煤下段煤层在停止成煤作用之前的沼泽植被;3)Stigmaria ficoides(Sternb.)Brongn.-Calamites suckowii Brongn.群落,反映泛滥平原上碎屑沼泽与河流之间的广大湿地所生长的植被;4)Lepidodendron incertum-Calamites suckowii群落,代表该区泛滥平原上碎屑沼泽植被;5)Pecopteris taiyuanensis Halle-Emplectopteris triangularis Halle-Taeniopteris serrulata Halle群落,反映天然堤及河流上游泛滥平原中的植被生态群落。植物群落整体面貌为典型的华夏植物群(如织羊齿、大量的带羊齿以及东方鳞木类)。当前群落演替序列反映了二叠纪华夏植物群成煤向碎屑景观的演替状况,以及华夏区成煤植被的稳定性。     

长江三角洲锦溪地区全新世气候适宜期孢粉组合及其环境意义

通过对长江三角洲锦溪地区白莲湖附近人工剖面的孢粉研究,重建该地区7 230cal a BP前后的植被和气候。孢粉植物群反映当时气候略有波动,但整体上与全新世气候适宜期的温暖环境相一致。孢粉自下而上可以细分为4个组合带:Zone 1青冈栎含量丰富,反映温暖气候;Zone 2落叶栎有所增多,气候稍有转凉;Zone 3青冈栎含量再度增高,气候变暖;Zone 4松属和落叶栎明显增多,气候再度转凉。从沟鞭藻和相关孢粉类型的分布分析,除底部12号样品因孢粉含量低而未予考虑外,其它样品都指示沉积时期当地受到海水的影响。其中Zone 1和Zone 2孢粉植物群指示两次海水的进退过程。当前孢粉研究结果很好地反映出长江三角洲地区全新世大暖期的气候变化特征,以及与当时海平面变化的关联。     

Natural age and size of Pinus sylvestris and Picea abies on a mire in the inland part of northern Sweden

The investigation was carried out on a sparsely forest covered poor fen 350 m a.s.l. in the inland pan of northern Sweden (64°32'N, 18°55'E). On the investigated mire the natural regeneration of pine Pinus sylvestris has been relatively successful from the 1920's up to the beginning of the 1970's. Natural regeneration of spruce Picea abies has taken place throughout the period 1938-1970, whereafter no establishment at all has occurred. The age and size structures of the pine and spruce stands on the mire vary in pattern according to the particular type of vegetation in which they are growing. Both the climatic amelioration during the first half of the present century and the successional stage of the mire vegetation were found to be important in regard to present-day age and size structures of the pine and spruce. Root competition and snow conditions arc probably important determinants of the size structure of pine stands in the mire environment.     

The Discussion on the Border Line of Vegetational Regions of Xinganling Mountain in China

The present paper described the border line of vegetation regions of Xinganling Mts. in China. The border line between the larch (Larix dahurica) forest region and pine (Pinus koraiensis) broalleaved mixed forest region determined according to the materials of survey of field work are Aihui-Naheko-Menluhe. The main reasons for the line are as follows: (1) pine broal-leaved mixed forest as the zonal vegetation of lesser Xinganling Mrs. is mainly covering in the south of the line, but Oak (Quereus mongolica)-larch forest in the north of the line; (2) Though Oak forest is widely distributed in both the south and the north of the line, there are well-marked differences in constitutions, structures, originations as well as growth between them; (3) differences in floristic compositions between the south and the north of the line; (4) different artificial vegetation between to regions. Such differences are caused by climatic, earth elevation and glacial activity, etc.     

Sensitivity of Bolivian seasonally-dry tropical forest to precipitation and temperature changes over glacial–interglacial timescales

We used fossil pollen to investigate the response of the eastern Chiquitano seasonally-dry tropical forest (SDTF), lowland Bolivia, to high-amplitude climate change associated with glacial–interglacial cycles. Changes in the structure, composition and diversity of the past vegetation are compared with palaeoclimate data previously reconstructed from the same record, and these results shed light on the biogeographic history of today’s highly disjunct blocks of SDTF across South America. We demonstrate that lower glacial temperatures limited tropical forest in the Chiquitanía region, and suggest that SDTF was absent or restricted at latitudes below 17°S, the proposed location of the majority of the hypothesized ‘Pleistocene dry forest arc’ (PDFA). At 19500 yrs b.p., warming supported the establishment of a floristically-distinct SDTF, which showed little change throughout the glacial–Holocene transition, despite a shift to significantly wetter conditions beginning ca. 12500–12200 yrs b.p. Anadenanthera colubrina, a key SDTF taxon, arrived at 10000 yrs b.p., which coincides with the onset of drought associated with an extended dry season. Lasting until 3000 yrs b.p., Holocene drought caused a floristic shift to more drought-tolerant taxa and a reduction in α-diversity (shown by declining palynological richness), but closed-canopy forest was maintained throughout. In contrast to the PDFA, the modern distribution of SDTF most likely represents the greatest spatial coverage of these forests in southern South America since glacial times. We find that temperature is a key climatic control upon the distribution of lowland South American SDTF over glacial-interglacial timescales, and seasonality of rainfall exerts a strong control on their floristic composition.     

Features of Species and Structural Diversity of Artificial Pine Stands on Soddy–Podzolic Loam Soils

The method of ecological transects was used for studying plant-species composition in an aged artificial pine stand created on a composite spruce forest on soddy–podzolic soil (underlain by blanket loams) in the broadleaved–spruce forest subzone (Moscow oblast). The change of edificatory tree species was followed by changes in the ecological conditions and, as a consequence, in the species composition, abundance, and cenotic significance of vegetation. Changes in the pattern of restoration of floristic diversity in different soil-geochemical facies of the transect were observed.     

Vegetationsverhältnisse und Naturumwelt des Beckens Jestřebská kotlina am Ende des Spätglazials und im Holozän (Doksy-Gebiet)

The method of pollen analysis was used to study a profile sample taken from the Jest?ebské blato mire, the Doksy District (northern Bohemia). The aim of the palacobotanical analyses was to perform a reconstruction of vegetation and environment for geobotanical and archaeological research purposes. Sediments dating back to the end of the Late Glacial and to both the Early and Middle Holocene were pollenanalytically studied. The results of the pollen analyses recorded the development of vegetation during the end of the Late Glacial, Preboreal, Boreal and Atlantic Periods. Parkline pine stands of the end of the Late Glacial developed to closed pine forests, during the Preboreal. Even during the Boreal, the dominant pine formed forest communities were typical of the area under study, though trees with greater demands on temperature and moisture conditions continued to penetrate the existing communities. During the Lower and the first half of the Upper Atlantic Period, spruce forests and alder woods formed the dominant forest communities in mire. Nevertheless,Pinus was still dominant on extreme sites (both from the edaphic and geomorphological points of view). An early occurrence ofAlnus andPicea is another characteristic feature of the studied area. The conclusions drawn from pollenanalytical results were used for the reconstruction of the past environment of the Mesolithic and Neolithic Ages.     

Holocene altitudinal shifts in vegetation belts and environmental changes in the Sierra Madre Occidental, Northwestern Mexico, based on modern and fossil pollen data

A modern pollen rain study was performed in a 300 km-long altitudinal transect (~ 28° N latitude) from 300 to 2300 m elevation. The higher elevation modern communities: epithermal oak–pines, pine–oak forest, pine forest, and mixed conifer forest were easy to distinguish from their pollen content. In contrast, lower elevation subtropical communities: thornscrub and tropical deciduous forest were difficult to separate, because they share many pollen taxa. Nevertheless we identify high frequencies of Bursera laxiflora as an important component of the tropical deciduous forest.Additionally, fossil pollen was analyzed at three sites located between 1700 and 1950 m altitude at ~ 28° latitude north in the Sierra Madre Occidental of northwestern Mexico. The sites were in pine–oak (Pinus–Quercus), pine, and mixed-conifer forests respectively. Shifts in the altitudinal distribution of vegetation belts were recorded for the last 12,849 cal yr BP, and climate changes were inferred. The lowest site (pine–oak forest) was surrounded by pine forest between 12,849 and 11,900 cal yr BP, suggesting a cold and relatively dry Younger Dryas period. The early Holocene was also cold but wetter, with mixed conifer forest with Abies (fir) growing at the same site, at 1700 m elevation, 300 m lower than today. After 9200 cal yr BP, a change to warmer/drier conditions caused fir migration to higher elevations and the expansion of Quercus at 1700 m. At 5600 cal yr BP Abies was growing above 1800 m and Picea (spruce) that is absent today, was recorded at 1950 m elevation. Fir and spruce disappeared from the 1950 m site and reached their present distribution (scattered, above 2000 m) after 1000 cal yr BP; we infer an episodic Holocene migration rate to higher elevations for Abies of 23.8 m/1000 cal yr and for Picea of 39.2 m/1000 cal yr. The late Holocene reflects frequent climate oscillations, with variations in the representation of forest trees. A tendency towards an openness of the forest is recorded for the last 2000 yrs, possibly reflecting human activities along with short-term climate change.     

Floristic variation in ecotonal areas: Patterns,determinants and biogeographic origins of subtropical forests in South America

We present the first quantification of forest community composition and its relationship with environmental factors in South American subtropical Atlantic Forests. In this region, rain, seasonally dry and mixed forests form an ecotonal zone near the parallel of latitude 30°S. To investigate how well current knowledge on climatic effects and biogeographic distribution apply to subtropical ecotones, we tested the following expectations: (i) there is a floristic longitudinal gradient correlated to altitudinal and climatic gradients; (ii) climatic variables are more important than soil factors in shaping floristic composition; and (iii) there are three floristic regions in the southernmost limit of the Atlantic Forest biome that are expected to be distinct in composition, structure and biogeographical origin. We examined floristic composition and its relationship with environmental factors across 52 1‐ha permanent study areas in subtropical Brazil, containing in total 269 tree species ≥ 9.5 dbh (diameter at breast height). Climatic data, related to rainfall seasonality and temperature, as well as soil properties, were compiled from published sources or global data banks. Expectations one and two were confirmed, but expectation three was only partially met. Hierarchical cluster analysis divided the southernmost Atlantic Forests into four major groups (Rain, Seasonally Dry, Western Mixed and Eastern Mixed Forests). Overall, the tested environmental variables differed significantly among the four regions. Using indicator species analysis, we distinguished 46 indicator species, which had significant environmental preferences for one floristic region. These species can be used as indicators of environmental conditions or to determine to which floristic region a certain forest belongs. Biogeographic distributions differed between floristic groups, supporting the interpretation that Eastern Mixed Forests are relict forests of a temperate forest of Andean origin that occurred during colder palaeoclimates. Western Mixed Forests represent the main floristic ecotone between Seasonally dry and Eastern Mixed Forests.     

Long-term forest composition and its drivers in taiga forest in NW Russia

Understanding the processes behind long-term boreal forest dynamics can provide information that assists in predicting future boreal vegetation under changing environmental conditions. Here, we examine Holocene stand-scale vegetation dynamics and its drivers at the western boundary of the Russian taiga forest in NW Russia. Fossil pollen and conifer stomata records from four small hollow sites and two lake sites are used to reconstruct local vegetation dynamics during the Holocene. Variation partitioning is used to assess the relative importance of the potential drivers (temperature, forest fires and growing site wetness) to the long-term stand-scale dynamics in taiga forest. All the main tree taxa, including the boreal keystone species Picea abies (Norway spruce) and Larix sibirica (Siberian larch), have been locally present since 10,000 cal yr bp. The constant Holocene presence of L. sibirica at three small hollow sites suggests a fast postglacial immigration of the species in northern Europe. Picea was present but not dominant at all study sites until its expansion between 8,000 and 7,000 cal yr bp markedly changed the forest structure through the suppression of Betula (birch), Pinus (pine) and Larix. Our results demonstrate that in general, the Holocene forest dynamics in our study region have been driven by temperature, but during short intervals the role of local factors, especially forest fires, has been prominent. The comparison between sites reveals the importance of local factors in stand-scale dynamics in taiga forests. Therefore, the future responses of taiga forest to climate change will be predominantly modulated by the local characteristics at the site.     

不列颠·哥伦比亚省北部小杆松及白云杉立地指数与生态立地质量的关系

为在ＰｒｉｎｃｅＲｕｐｅｒｔ林区的“亚北方”部分建立生态立地质量与森林生产力的联系,对从９３个小杆松林分和７７个白云杉林分获得的数据进行了分析．所研究的林分处于两个气候状况、８个土壤水分状况以及５个土壤养分状况．这些气候、土壤水分和养分状况被视为等级变量用于林地分类和回归分析．小杆松和白云杉的立地指数随土壤水分和养分状况变化而变化,但不依赖于气候变化．与土壤水分相关的变化格局对两个种来说很相似,但与土壤养分相关的变化格局则全然不同．在所建立的５类回归模型中,土壤小区模型对于两个种都显示出立地指数与土壤水分和养分状况具有很强的相互关系（Ｒ２＞０．８０,ＳＥＥ≤１．６ｍ）．可以认为土壤水分和养分的等级度量在大范围内可作为小杆松和白云杉立地指数的预测预报因子．     

Relating postglacial relict plants and Holocene vegetation dynamics in the Balearic Islands through field surveys,pollen analysis and GIS modeling

Abstract

An inventory of the current Balearic plants occurring in mesophyllous environments, with climatic conditions similar to those in the first half of the Holocene, was compiled. The presence of these floristic elements, extending mainly into the postglacial time, has been related to pollen records of different localities in the Balearic Islands. GIS techniques have been applied in order to map the past and the present-day vegetation suitability of some of these mesophyllous species using pollen surface samples, forest inventory data and Digital Climatic Models. We integrated the information provided by field survey, pollen records and suitability mapping in order to discuss the vegetation dynamics of different habitats. We focused on the nature and the possible causes of the vegetation landscape change that occurred approximately 5000 – 6000 uncal. years BP, when Fagus, Corylus and Buxus formations were replaced by xeric-type formations with Olea dominance.