Changes of vegetation in southern China

In order to reveal the changes of vegetation in southern China since the Last Glacial Maximum, we have established high-resolution time scales and palynological sequences of borehole profiles by drilling cores in some weak areas of the research to restore vegetation changes over the past 20,000 years on the basis of previous work. This paper gives the vegetation zoning maps of 18, 9 and 6 ka BP respectively in southern China, and describes the distribution characteristics of plants in different zones/subzones. The results show that the vegetation zonations around 18 ka BP were significantly different from that at present.It appeared in turn with Cold-temperate coniferous forest and alpine meadow steppe zone, and Temperate mixed coniferous and broad-leaved forest zone/warm temperate deciduous broad-leaved forest zone from northwest to southeast in the west, and Temperate mixed coniferous and broad-leaved forest zone, Warm temperate deciduous broad-leaved forest zone, and Northern subtropical mixed evergreen and deciduous broad-leaved forest zone from north to south in the central and east. The vegetation distribution around 9 ka BP changed distinctively. Except that the northwest part was located in Mountain temperate mixed coniferous and broad-leaved forest zone, the vegetation in other areas occurred in turn with North subtropical mixed evergreen and deciduous broad-leaved forest subzone, Mid-subtropical typical evergreen broad-leaved forest subzone, and South subtropical monsoon evergreen broad-leaved forest subzone/Tropical seasonal rainforest and rainforest zone from north to south.There was little change in the appearance of vegetation zonations between 6 and 9 ka BP, but the northern edge of each vegetation belt moved a little northward, reflecting that the overall climate became warmer around 6 ka BP. The vegetation changes in southern China over the past 20,000 years were largely driven by environmental changes. Climate change was the main factor affecting the vegetation distribution. The impact of human activities became more and more remarkable in the later period. In the lower reaches of the Yangtze River and the delta region, sea level changes also influenced the vegetation distribution.     

Pollen and spores from Lower Cretaceous in Guyang Basin of Inner Mongolia,China and their palaeoclimatic and paleoecological significance

Research on the climate and vegetation of the Cretaceous is fundamental to understanding the present environment. The present study focuses on the Lower Cretaceous Guyang Formation (Inner Mongolia), which yields unique macrofossils and diverse palynological assemblages that are used to understand the palaeoecology. In total, 56 genera are identified in the examined assemblage, which are dominated by spores and pollen of pteridophytes and gymnosperms. The gymnosperm pollen is dominated by Taxodiaceae, which belong to Coniferales, and a large proportion of pollen attributable to the Cycadophyta and Ginkgopsida. The pteridophyte spores are dominated by taxa attributable to the Lygodiaceae and Cyatheaceae. Quantitative analysis based on the geographical distribution of modern plant communities and the Sporomorph Ecogroup (SEG) model, the palynomorph associations are used to infer the presence of a closed coniferous forest dominated by Podozamitales, Picea and Podocarpus with understory vegetation comprising ferns prevailed. The fossil palyno flora indicates a warm and humid subtropical climate during Early Cretaceous of Inner Mongolia.     

Neogene palynological assemblages in the west slope of Songliao Basin and their geological implications

Abundant palynological fossils are found from the drill core in the west slope of Songliao Basin, the first full coring borehole that drilled throughout the Neogene. Two Palynological assemblages are recognized according to their vertical distributions, i.e., the late early Miocene–middle Miocene assemblage from the Da'an Formation named as Caryapollenites simplex-Momipites coryloides-Celtispollenites sp.-Tsugaepollenites igniculus, and the late Miocene-early Pliocene assemblage from the Taikang Formation named as Artemisiaepollenites minor-Betulaceoipollenites sp.-Carpinipites sp.-Polypodiaceaesporites sp. On the basis of the composition of each assemblage, we infer that the climate was warm-temperate to sub-tropic during the late early Miocene–middle Miocene and the vegetation was mainly deciduous broadleaved forest and subordinate coniferous and broad-leaved mixed forest with few understory ferns, and probably some shallow fresh water wetlands. The climate then turned cooler and drier in the late Miocene–early Pliocene, represented by the development of xerophytic herbs and temperate plants, although the canopy of the forest remained relatively stable. The results significantly improve the understanding of the Cenozoic palynostratigraphy in the Songliao Basin, and provide new data for both stratigraphical correlation and paleovegetational and paleoclimatical analysis in adjacent area.     

Evolution of vegetation and climate since the last glacial maximum recorded at Dahu peat site, South China

Sporopollen analysis on a 346 cm peat record at Dahu, Jiangxi, chronologically constrained by 16 AMS 14C datings, provides an opportunity to reconstruct the vegetation evolution stages responding to cli-mate change in South China since the last glacial maximum. The result shows that during 18330-15630 cal a B.P., broad-leaved forest dominated the area, corresponding to mild, cool and fairly humid climate. At the interval of 15630-11600 cal a B.P., several evergreen broad-leaved species appeared within the broad-leaved forest, indicating moderate and humid condition. During early Holocene, broad-leaved evergreen forest community was constructed as Castanopsis/Lithorcarpus principally developed, suggesting a warm and humid scenario until 6000 cal a B. P. Since 6000 cal a B. P., abrupt forest deterioration happened with an contemporary increase of fern and herb communities, repre-senting a turnover to relatively cool and dry condition and as well, possible impact from human activi-ties. Meanwhile, several relatively cool and dry events can be identified in the sporopollen record, they can be correlated to the North Atlantic Heinrich event, YD and Holocene millennial-scale oscillations, implying that the low latitude climate was coupled with high latitude influences. Moreover, the varia-tions of temperature and humidity since LGM at Dahu were much smaller when compared with the re-cords in north monsoonal China.     

A new pollen record of the last 2.8 Ma from the Co Ngoin,central Tibetan Plateau

A new pollen record from the lake of Co Ngoin in the central Tibetan Plateau provides information on the vegetation and climate changes during the last 2.8 Ma. Seven major significant changes in pollen associations indicate the processes of vegetation change and possible tectonic uplifts. The seven changes in vegetation succession include a temperate montane conifer and broad-leaved mixed forest, cold temperate montane dark conifer forest, alpine shrub-meadow and alpine desert, montane dark coniferous forest and alpine shrub meadow, montane dark coniferous forest and alpine shrub meadow, montane dark coniferous forest and alpine meadow, and alpine desert and meadow. The pollen record provides the evidence of at least five times tectonic uplifts occurring at about 2.58 Ma, 1.87 Ma, 1.17 Ma, 0.83 Ma, and 0.3 Ma ago, respectively. Before 0.8 Ma, this region maintained the altitude below 4000 m a.s.l. Larger amplitude of uplift occurring at about 0.8 Ma ago enforced the plateau rising into cryosphere, shaping the basic topographic pattern of modern plateau. The major successions in vegetation of this area were largely controlled by stepwise uplift of the Tibetan Plateau.

     

Late quaternary monsoon patterns on the Loess Plateau of China

China's Loess Plateau was formed under special conditions. The tectonic movement, topographical characteristics, and monsoon patterns combined to create a favourable environment for the accumulation of thick loessic deposits. The Loess Plateau itself is part of the ‘Monsoon Triangle’ of China, a region very susceptible to climatic changes. Throughout the Upper Pleistocene the palaeoenvironment on the Loess Plateau alternated from steppe, to deciduous forest and coniferous forest, in response to shifts in the atmospheric circulation. Three monsoon patterns appear to be indicated: (1) a full glacial monsoon pattern (18000–15000 yr BP) which induced a cold and dry climate favouring loess accumulation in steppe conditions; (2) an interglacial monsoon pattern (last interglacial and Holocene) in which a warm humid climate prevailed with deciduous forests, leaving palaeosols interbedded within the loess sequence; and (3) a transitional or interstadial monsoon pattern (50 000–23 000 yr BP) in which the climate was cold and humid in the Loess Plateau, encouraging the development of coniferous forest.     

Spatial patterns of vegetation and climate in the North China Plain during the Last Glacial Maximum and Holocene climatic optimum

Reconstructing the spatial patterns of regional climate and vegetation during specific intervals in the past is important for assessing the possible responses of the ecological environment under future global warming scenarios. In this study, we reconstructed the history of regional vegetation and climate based on six radiocarbon-dated pollen records from the North China Plain. Combining the results with existing pollen records, we reconstruct the paleoenvironment of the North China Plain during the Last Glacial Maximum(LGM) and the Holocene Climatic Optimum(HCO). The results show that changes in the regional vegetation since the LGM were primarily determined by climatic conditions, the geomorphic landscape and by human activity.During the LGM, the climate was cold and dry; mixed broadleaf-coniferous forest and deciduous-evergreen broadleaf forest developed in the southern mountains, and cold-resistant coniferous forest and mixed broadleaf-coniferous forest were present in the northern mountains. The forest cover was relatively low, with mesophytic and hygrophilous meadow occupying the southern part of the plain, and temperate grassland and desert steppe were distributed in the north; Chenopodiaceae-dominated halophytes grew on the exposed continental shelf of the Bohai Sea and Yellow Sea. During the HCO, the climate was warm and wet;deciduous broadleaf forest and deciduous-evergreen broadleaf forest, with subtropical species, developed in the southern mountains, and deciduous broadleaf forest with thermophilic species was present in northern mountains. Although the degree of forest cover was greater than during the LGM, the vegetation of the plain area was still dominated by herbs, while halophytes had migrated inland due to sea level rise. In addition, the expansion of human activities, especially the intensification of cultivation,had a significant influence on the natural vegetation. Our results provide data and a scientific basis for paleoclimate modelling and regional carbon cycle assessment in north China, with implications for predicting changes in the ecological environment under future global warming scenarios.     

Latest Middle Miocene fauna and flora from Kumkol Basin of northern Qinghai-Xizang Plateau and paleoenvironment

We report 7 mammalian and 16 pollen species from the top of the Shimagou Formation in Kumkol Basin of northern Qinghai-Xizang Plateau, whose age is latest Middle Miocene(about 12.5 Ma). We erect a new species of fossil rodent,Spermophilinus kumkolensis sp. nov. The micromammalian fauna from the Kumkol Basin shares high similarities with contemporary faunas from Europe and northern China, indicating the existence of active zoogeographic exchange between Europe and northern Asia. Trees are dominant in pollen fossils, and herbs and shrubs are minorities. Broadleaved Quercus and Fagus predominate in tree pollens. The flora reconstructed by pollens displays a mixture of evergreen broadleaved forest and dry and warm steppe landscape. Compared to the modern vegetation in Yunnan region, the latest Middle Miocene flora in the Kumkol Basin represents a distinct vertical distribution. The ecotypes of the latest Middle Miocene fauna and flora in the Kumkol Basin,as a whole, are markedly different from those of modern animals and vegetation, the past climate being more suitable than today.     

Palynostratigraphy and palaeoenvironments around the Albian-Cenomanian boundary interval(OAEld),North Bulgaria

The palynological assemblages from two Albian-Cenomanian boundary sections in North Bulgaria are described.The samples analyzed yielded a diverse palynological content including dinoflagellate cysts and miospores.Based on dinocyst nutrient and productivity indices a phase of enhanced nutrient availability and high primary productivity is inferred for the latest Albian interval.The pronounced predominance of peridinioid dinocysts in this interval,namely O.verrucosum,O.scabrosum and especially P.infusorioides is considered to reflect eutrophic conditions.It coincides with the increased phosphorus mass accumulation occurring at the top part of the Upper Albian Dekov Formation.OAE 1d is indicated in the Tolovitsa karst spring section,based on palynofacies dominated by high amounts of granular amorphous organic matter(AOM)related to anoxic environmental conditions.These sections serve as evidence suggesting a relationship between Cretaceous peridinioid cysts(including Palaeohystichphora infusorioides,Ovoidinium verrucosum,O.scabrosum)and anoxic/suboxic conditions and/or high primary productivity.The pollen spectrum inferred relatively stable vegetation patterns of surrounding continental areas during and after the Albian/Cenomanian boundary interval and the times of OAE 1d formation.The hinterland vegetation integrated mainly pteridophyte spores and gymnosperms.The area was part of the Southern Laurasian floral province which was characterized by warm temperate to subtropical humid climate.Angiosperms were still minor part of this vegetation.     

Palynostratigraphy and palaeoenvironments around the Albian-Cenomanian boundary interval (OAE1d), North Bulgaria

The palynological assemblages from two Albian-Cenomanian boundary sections in North Bulgaria are described. The samples analyzed yielded a diverse palynological content including dinoflagellate cysts and miospores. Based on dinocyst nutrient and productivity indices a phase of enhanced nutrient availability and high primary productivity is inferred for the latest Albian interval. The pronounced predominance of peridinioid dinocysts in this interval, namely O. verrucosum, O. scabrosum and especially P. infusorioides is considered to reflect eutrophic conditions. It coincides with the increased phosphorus mass accumulation occurring at the top part of the Upper Albian Dekov Formation. OAE 1d is indicated in the Tolovitsa karst spring section, based on palynofacies dominated by high amounts of granular amorphous organic matter (AOM) related to anoxic environmental conditions. These sections serve as evidence suggesting a relationship between Cretaceous peridinioid cysts (including Palaeohystichphora infusorioides, Ovoidinium verrucosum, O. scabrosum) and anoxic/suboxic conditions and/or high primary productivity. The pollen spectrum inferred relatively stable vegetation patterns of surrounding continental areas during and after the Albian/Cenomanian boundary interval and the times of OAE 1d formation. The hinterland vegetation integrated mainly pteridophyte spores and gymnosperms. The area was part of the Southern Laurasian floral province which was characterized by warm temperate to subtropical humid climate. Angiosperms were still minor part of this vegetation.     

云南鹤庆盆地中更新世以来的孢粉记录及其植被与气候变化

通过对“中国大陆环境钻探计划”首钻——云南鹤庆深钻前155 m约800 ka以来的岩芯进行孢粉研究,探讨了云南鹤庆盆地中更新世以来的植被演替与古气候变迁．研究表明鹤庆盆地周围山地的植被在约800 kaBP至6．98 kaBP之间经历了以松为主的针叶林、山地针阔叶混交林、寒温性针叶林的多次相互演替;从6．98 kaBP开始,植被发生了转折性变化,森林植被迅速退化,以草本为主,此时开始受到人类活动的影响,人类活动表现在砍伐森林和种植农作物等方面.与植被演替相应的古气候可划分为五个大的阶段,包含多次冷暖、干湿旋回．     

Vertical zonality of the water cycle and the impact of land-use change on runoff in the Qingshui River Basin of Wutai Mountain,China

ABSTRACT

Hydrological processes in hilly watersheds are significantly affected by variations in elevation; however, the hydrological functions of different vertical vegetation belts, have rarely been reported. The distributed hydrological model WEP-L (Water and Energy transfer Process in Large river basins) was applied to analyse vertical variations in the hydrological processes of Qingshui River basin (QRB), Wutai Mountain (altitude: 3058 m a.s.l.), China. The results show that the highest ratio of evapotranspiration to precipitation occurs at 1800 m a.s.l. Below 1800 m, evapotranspiration is mainly controlled by precipitation, and in regions above1800 m it is controlled by energy. The runoff coefficients for different vertical vegetation belts may be ranked as follows: farmland > grassland > subalpine meadow > evergreen coniferous shrub forest > deciduous broad-leaved forest. Grassland is the largest runoff production area, contributing approximately 39.10% to the annual water yield of the QRB. The runoff from forested land decreased to a greater extent than the grassland runoff. Increasing forest cover may increase evapotranspiration and reduce runoff. These results are important, not only for further understanding of the hydrological mechanisms in this basin, but also for implementing the sustainable management of water resources and ecosystems in other mountainous regions.     

A high-resolution late Pleistocene record of pollen vegetation and climate change from Jingning, NW China

During the late Pleistocene, a number of climatic fluctuations such as the Heinrich events were recorded in the climatic proxies in the Loess Plateau and in North China[1―7]. Most of these records were based on geophysical and geochemical evidence[1―4]. Therefore, more biologic evidence is necessary for explaining the regional ecosystems in response to climatic change in the Loess Plateau during this period since pollen re-cords in other areas presented strong evidence to cli-matic fluctu…     

西宁地区第四纪晚期孢粉组合及古环境

西宁地区位于黄土高原与青藏高原的接壤处,是环境和气候变迁的敏感地带。本文对西宁市北川河河谷地区黄土沉积的钻孔剖面进行了孢粉分析,获得了比较丰富的孢粉数据,结果呈现出以松、桦、蒿及藜等木本及草本植物花粉为主的孢粉组合。据各类植物花粉量在该剖面垂向上的明显变化,由下而上可划分为5个孢粉带。研究表明,该剖面的孢粉分析数据及资料不仅记录了75kaB.P以来大量的古地理及古环境的变迁,也揭示了西宁地区晚更新世以来古植被及古气候的演替及变化,其演变分别经历了5个阶段:第一阶段为森林型针叶林,反应了温爽轻湿的气候;第二阶段为针叶林,为温凉轻润的气候;第三阶段为针叶林夹稀树草原,属温和湿润夹温凉轻湿的气候;第四阶段为森林草原,反应了温凉轻爽的气候;第五阶段为针叶林,反应了温和湿润的气候。     

Palynological evidence for vegetational and climatic changes from the HQ deep drilling core in Yunnan Province, China

The high-resolution pollen study of a 737.72-m-long lake sediment core in the Heqing Basin of Yunnan Province shows that the vegetation and climate of mountains around the Heqing Basin went through six obvious changes since 2.780 Ma B.P. Namely, Pinus forest occupied most mountains around the studied area and the structure of vertical vegetational belt was simple between 2.780 and 2.729 Ma B.P., reflecting a relatively warm and dry climate. During 2.729―2.608 Ma B.P., the areas of cold-temperate conifer forest (CTCF) and Tsuga forest increased and the structure of vertical vegetational belt became clear. According to percentages of tropical and subtropical elements growing in low-altitude regions rifely increased, we speculate that the increase of CTCF and Tsuga forest areas mainly resulted from strong uplift of mountains which provided upward expanding space and growing condition for these plants. Thus, the climate of the low-altitude regions around the basin was relatively warm and humid. Between 2.608 and 1.553 Ma B.P., Pinus forest occupied most mountains around the studied area and forest line of CTCF rose, which reflects a moderately warm-dry climate on the whole. During 1.553―0.876 Ma B.P., the structure of vertical vegetational belt in mountains around the studied area became complicated and the amplitude of vegetational belts shifting up and down enlarged, which implies that the amplitude of climatic change increased, the climatic associational feature was more complex and the climate was moderately cold at a majority of the stage. During 0.876―0.252 Ma B.P., there were all vertical vegetational belts existing at present in mountains around the studied area. The elements of each belt were more abundant and complex than earlier. At different periods in the stage vertical vegetational belts occurred as expanding or shrinking, and alternated each other. The amplitude of vegetational belts shifting up and down was the maximum in the whole section. This change suggests that the amplitude of climatic change was evidently larger than earlier, but the frequency reduced and the climatic associational feature was more complex. From 0.252 Ma B.P. to the present, the most time was characteristic of the expanding of Pinus forest and semi-humid evergreen broad-leaved forest (SEBF) in mountains around the studied area, while expanding time of other vegetational belts was very short, which reflects a smaller amplitude of cold and warm fluctuation. On the basis of the six obvious cycles of vegetational and climatic changes, there were still many times of secondary vegetational successions and climatic oscillations. Based on the above analysis, the forcing mechanism of vegeta-tional succession and climatic change in the Heqing Basin is further discussed. It is primarily consid-ered that main influential factors were exterior factors such as orbital parameters, etc., but the uplift of the Qinghai-Tibet Plateau played a very important function for environmental changes in the Heqing Basin at two times obvious increase of vertical vegetational belts and three climatic transitions.     

Late Cretaceous palynology and paleoclimate change:Evidence from the SK1(South) core,Songliao Basin,NE China

Cretaceous climate was warmer than today.The Songliao Basin contains one of the most important Late Cretaceous non-marine deposits in China for the research of the paleoenvironment and paleoclimate.This research is based on core samples from the SK1(S)borehole.The strata sampled are the upper part of the Quantou Formation to member 2 of the Nenjiang Formation,where spores,pollen,dinoflagellates,and other microfossils are abundantly preserved.Based on analysis of the spores and pollen fossils from the core samples,the following six fossil assemblage zones have been recognized in ascending order:The Cicatricosisporites-Cyathidites-Pinuspollenites,Schizaeoisporites-Cyathidites-Classopollis,Cyathidites-Schizaeoisporites,Schizaeoisporites-Cyathidites-Proteacidites,Proteacidites-Cyathidites-Dictyotriletes,and the Lythraites-Callistipollenites-Schizaeoisporites zones.The six fossil zones range from the late Cenomanian to early Campanian.The Late Cretaceous dinoflagellate cysts in the Songliao Basin are of high abundance and low diversity.Specific phytoplankton types reflect salinity changes of the Songliao Lake.Paleoecology of the dinoflagellates suggests that sediments of members 2 and 3 of the Yaojia Formation(K2y2+3)were deposited in a freshwater environment,whereas members 2 and 3 of the Qingshankou Formation(K2q2+3)and members 1 and 2 of the Nenjiang Formation(K2n1+2)were deposited in freshwater to brackish water environments.Combined with the paleoecology of dinoflagellates and the palynomorph biozones,valuable information of the paleoclimate was provided.The quantitative analyses of spores and pollen fossils,such as vegetation type,climate type,and humidity type,diversity and dominance,indicate a relatively sub-humid,mid-subtropical paleoclimate,with slight climatic fluctuation and/or temporal change.     

Jianshangou Bed of the Yixian Formation in West Liaoning,China

The Jianshangou fossil locality was first found byChang Zhenglu and his colleagures in 1962, now thearea of Jianshangou, Sihetun and Huangbanjigou be-comes famous all over the world for its yielding feath-ered dinosaurs, Confuciusornis and Archaefructus. Thename of Jianshangou Bed was proposed by the firstauthor of present paper as an informal suggesting unitduring the research on Jehol fossils of western Liaon-ing in 1963 and 1964. The unit was named then asJianshan Bed[1], indicating th…     

黑龙江省连环湖孢粉记录揭示的约220年的环境变化与人类活动

通过210Pb测年建立年代标尺,利用黑龙江省连环湖阿木塔泡高分辨率的孢粉记录,探讨了研究区约220年的环境变化与人类活动.研究表明,1790-1820 AD期间,植被类型可能是以禾本科为主的草甸草原植被,沙地类型以固定沙地为主,气候相对较凉湿或环境几乎不受人类活动的破坏,湖泊营养较丰富.1820-1930 AD期间,草...     

New fossil eccoptarthrids (Coleoptera: Curculionoidea) from the Yixian Formation of western Liaoning, China

One new genus and three new species of the weevil family Eccoptarthridae (Curculionoidea), Leptocar polychaetus gen. et sp. nov., Abrocar macilentus sp. nov., Cretonanophyes punctatus sp. nov., are described and illustrated. They pertain to the Upper Jurassic or Lower Cretaceous Yixian Formation of western Liaoning Province, China. The host plants to the living eccoptarthrids and the floras in Yixian Formation indicate that those archaic eccoptarthrids possibly lived on conifers with a phylogenetic closeness to Cupressaceae. Besides, the early diversification of eccoptarthrids is discussed: origi- nated in Central or East Asia in the Late Jurassic, spread into Western Europe and South America during the Early Cretaceous, underwent a dramatic decline after the Early Cretaceous which likely was caused by competitive pressure and the displacement of their host plants.     

The vegetation feature and palaeoenvironment significance in the mountainous interior of southern China from the Last Glacial Maximum

Palynological records were selected from the profiles of three research sites in the mountainous interior of southern China(Dajiuhu at Shennongjia in the western part of Hubei Province, Dahu in the Nanling Mountains, and Gantang in the northern part of Fujian Province). It can be inferred that the forest vegetation growing in the south of the Qinling Mountains-Huaihe River was luxuriant during the late glaciation. The species succession with ecological significance in palaeoflora(Abies sp., Fagus sp. and Alnus sp.) revealed that there was a certain amount of precipitation and effective humidity in the mountain lands between Qinling Mountains-Huaihe River and Nanling Mountains. This ecological environment favored the zonal distribution of mountainous forest vegetation. The late glacial maximum featured a cold, wet climate that completely differed from the cold-dry climate on the Loess Plateau, and on the steppe and desert steppe of the Qinghai-Tibet Plateau. Besides being influenced by the predominant factors driving the Northern Hemisphere climate, the cold-wet climate feature of the mountainous interior of southern China was closely associated with some geographical factors such as the latitudinal position, proximity to the ocean, and the topography and landforms.