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1.
Aim To reconstruct the Late Glacial and Holocene vegetation history of western Tasmania and to test the long‐held notion of a replacement of forest by moorland during the mid to late Holocene in western Tasmania, Australia. Location Western Tasmania, Australia. Methods Fossil pollen data were screened with a modern pollen dataset using detrended correspondence analysis and charcoal data were analysed using significance tests. Results At the landscape scale, the distribution of vegetation types in western Tasmania has remained remarkably stable through the post‐glacial period. Open moorland has dominated the landscape since the Late Glacial, while rain forest expanded at that time in to areas which it occupies today. Vegetation development in the Holocene is markedly different and charcoal values are significantly higher when compared with those in previous interglacial periods. Main conclusions The dominant paradigm of a replacement of rain forest by moorland across western Tasmania during the mid to late Holocene is not supported by this regional analysis. The arrival of humans in Tasmania during the Last Glacial Stage provided an ignition source that was independent of climate, and burning by humans through the Late Glacial period deflected vegetation development and facilitated the establishment of open moorland in regions occupied by rain forest during previous interglacial periods. It is concluded that the present dominance of the landscape of western Tasmania by open moorland is the direct result of human activity during the Late Glacial and that this region represents an ancient cultural landscape.  相似文献   

2.
Aim To present radiocarbon dated early Holocene pollen analytical data from two sites on the northern plain of the Isle of Man and to discuss the implications of the vegetation history in relation to severance of the island from the British Isles and to identify further evidence for divergent biogeographical development previously exemplified by the survival and apparent dwarfism of late glacial Megaloceros giganteus (Giant Deer). Location The Isle of Man, British Isles. Methods Pollen analysis and AMS radiocarbon dating of late glacial to early Holocene lake sequences at Pollies and Curragh‐y‐Cowle on the northern plain of the Isle of Man. Results The pollen data indicate a prolonged period of pre‐woodland vegetation after the late Glacial/Holocene transition, which lasted for most of the first post‐glacial millennium. This persistence of pre‐forest environments meant that the expansion of Betula woodland occurred later in this part of the Isle of Man than in adjacent areas of Britain and Ireland. Conclusions The Isle of Man, in the northern Irish Sea, was isolated from Britain during the late Glacial period perhaps explaining the delayed arrival of tree species. Delayed rise of the Holocene forest compared with surrounding regions probably reflects severance of the land‐bridge with Cumbria, but also could be a function of climate changes during the early Holocene and local environmental conditions. Late survival and the dwarfism of the Megaloceros giganteus (Giant Deer) fauna is another example of biogeographical divergence during the early Holocene/late Glacial of the Isle of Man. The delayed afforestation and absence of human hunters in the Manx early Holocene offers a permissive environmental context for the as yet unproven survival of Megaloceros into the early Holocene.  相似文献   

3.
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.  相似文献   

4.
Palynology of a thick quaternary succession in southern Spain   总被引:1,自引:0,他引:1  
This paper deals with the results of pollen analysis of a 70-m thick series of peat, calcareous mud and clay near Granada in southern Spain (Fig.1). The upper 20 m of the section represent the Holocene and Weichselian (last Glacial), the part below 20 m is believed to represent the Eemian (last Interglacial), the Saalian and part of the Holsteinian Interglacial.

During Glacial times the local type of vegetation corresponded with that of an open steppe with stands of Pinus. During Interglacial times a more oceanic Quercus-Pinus forest with Ericaceae was present. If the interpretation of the lower part is correct, Tsuga and Cedrus occurred in southern Spain as late as the Holsteinian.  相似文献   


5.
This paper reviews vegetation and climate reconstructions for different time scales based on palynological studies in China. It discusses examples of significant developments in palynological research topics within China: (1) Modern pollen—a modern pollen database (East Asia Surface Pollen Database) has been established through the collaboration of Chinese palynologists. Based on these data, modern pollen distributions and their quantitative relationship with vegetation and climate have been thoroughly studied. (2) Pre-Quaternary vegetation and climate dynamics—scientists have mapped pollen and palaeobotanical data from the Palaeogene. The vegetation distributions confirm a north–south zonal pattern during the Palaeogene that changed to an east–west monsoonal pattern during the Miocene and Pliocene. These results provide key evidence for understanding monsoon evolution. (3) Late-Quaternary vegetation—biome reconstructions based on fossil pollen data show spatial and temporal changes in vegetation since the Last Glacial Maximum, permitting a better understanding of climate change across China. (4) Quantitative climate reconstructions—some reconstructions have successfully detected Holocene climate variability thereby providing insights into monsoon history. At present, there are no comprehensive spatial reconstructions. Major possible future developments should focus on: (1) long-term vegetation reconstructions from lakes to study Asian monsoon dynamics at orbital scales; (2) quantitative reconstructions of vegetation and climate change to help stronger integration with palaeoclimate models and dynamic vegetation models; (3) land-cover and land-use change across China over the last 6,000 years to understand human impacts and provide empirical data for climate modellers; and (4) integration of pollen data with vegetation and climate modelling to understand the CO2-vegetation relationship and climate dynamics.  相似文献   

6.
In order to develop niche models for tree species characteristic of the cerrado vegetation (woody savannas) of central South America, and to hindcast their distributions during the Last Glacial Maximum and Last Inter‐Glacial, we compiled a dataset of tree species checklists for typical cerrado vegetation (n = 282) and other geographically co‐occurring vegetation types, e.g. seasonally dry tropical forest (n = 355). We then performed an indicator species analysis to select ten species that best characterize typical cerrado vegetation and developed niche models for them using the Maxent algorithm. We used these models to assess the probability of occurrence of each species across South America at the following time slices: Current (0 ka pre‐industrial), Holocene (6 ka BP), Last Glacial Maximum (LGM – 21 ka BP), and Last Interglacial (LIG – 130 ka BP). The niche models were robust for all species and showed the highest probability of occurrence in the core area of the Cerrado Domain. The palaeomodels suggested changes in the distributions of cerrado tree species throughout the Quaternary, with expansion during the LIG into the adjacent Amazonian and Atlantic moist forests, as well as connections with other South American savannas. The LGM models suggested a retraction of cerrado vegetation to inter‐tableland depressions and slopes of the Central Brazilian Highlands. Contrary to previous hypotheses, such as the Pleistocene refuge theory, we found that the widest expansion of cerrado tree species seems to have occurred during the LIG, most probably due to its warmer climate. On the other hand, the postulated retractions during the LGM were likely related to both decreased precipitation and temperature. These results are congruent with palynological and phylogeographic studies in the Cerrado Domain.  相似文献   

7.
In south-east Asia, during Quaternary glaciations, increased seasonality and sea level decreases of ~120 m caused considerable fragmentation of the rainforest. It is believed that most of the region's core was covered with savannah vegetation, and rainforest was confined to a few refugia. We investigated the geographical extent of the savannah vegetation and the positions of the refugia, using a combination of palynonlogical, geological, fossil and termite data. Our results show that during the Last Glacial Maximum, most of Thailand, Peninsula Malaysia, western and southern Borneo, eastern and southern Sumatra, and Java were probably covered by savannah. Rainforest refugia were probably present in northern and eastern Borneo, northern and western Sumatra and the Mentawai islands. We also discuss a possible complete history of the region. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society , 2002, 75 , 453–466.  相似文献   

8.
Studies on the dispersal mechanism and source areas of pollen from hemipelagic sediments recovered from the continental slopes of the South China Sea (SCS) reveal that vegetation existed on the exposed shelves at the Last Glacial Maximum (LGM) and the latter part of the Marine Isotope Stage 3. At the low sea level stand, Artemisia-dominated grassland covered the northern continental shelf and tropical lowland rainforest and mangroves grew on the southern shelf ‘Sunda Land’. Consequently, the climate in the northern SCS must have been much colder and drier during the last glacial period compared to the present. Sunda Land experienced only a marginally lower temperature but was not drier than today. The enhanced contrast between the northern and southern parts of the SCS in vegetation and climate during the LGM may be ascribed, at least partly, to the strengthening of Winter Monsoon during the last glacial period.  相似文献   

9.
This paper describes the present-day vegetation, stratigraphy and developmental history of the mire of Egelsee-Moor (Salzburg, Austria; 45°45′N, 13°8.5′E, 700 m a.s.l., 15 ha in area) since the early Late Glacial on the basis of 4 transects with 14 trial borings across the peatland. We present a vegetation map of the mire, a longitudinal section through the peat body based on six cores showing the peat types, overview macrofossil diagrams of six cores showing the local mire development and two pollen diagrams covering the Late Glacial and Holocene. The chronology of the diagrams depends on biostratigraphic dating for the Late Glacial and early Holocene and radiocarbon dating for the remaining Holocene. The northern part of the mire originated through terrestrialisation of nutrient-rich, mostly inundated fen and the southern part through paludification of wet soils. The very small lake of today was a reservoir until recently for providing water-power for timber rafting (‘Holztrift’). The mire vegetation today is a complex of forested parts (mainly planted Pinus sylvestris and Thuja occidentalis, but also spontaneous Picea abies, Betula pubescens and Frangula alnus), reed-lands (Phragmites) and litter meadows (Molinietum, Schoenetum, etc.). The central part has hummock-hollow complexes with regionally rare species of transitional mires (Drosera anglica, D. intermedia, Lycopodiella inundata, Scorpidium scorpioides, Sphagnum platyphyllum, S. subnitens). The results indicate that some of the mid-Holocene sediments may have been removed by the timber-rafting practices, and that water extraction from the hydrological catchment since 1967 has resulted in a partial shift of transitional mire to ombrotrophic bog. The latter potentially endangers the regionally rare species and was used as an argument to stop further water extraction.  相似文献   

10.
Assessing patterns of abundance and distribution of Amazonian species is still an overwhelming task that requires integration of multiple disciplines. This work is based on background information gathered from previous reconstructions of the geological history of the lower Amazon drainage basin, in order to analyse biodiversity patterns within the context of landscape transformation. A highly dynamic geological scenario is depicted for this area during the Plio‐Pleistocene and Holocene, which consisted of a large palaeovalley formed as a response of tectonic reactivation. This palaeovalley was filled with sediments transported by a north/northwest orientated palaeo‐Tocantins River. The palaeodrainage became abandoned as the main river course was deviated to the northeast, initiating the separation of Marajó Island from mainland. Geology had a direct impact on the modern physiognomy, with open vegetation dominating in areas with Holocene sedimentation, while closed forests prevailing in older Quaternary and, probably also, Pliocene terrains. Data from fossil and modern mammalian groups indicate the connection of Marajó Island to the mainland during the Last Glacial Maximum, when open vegetation seems to have dominated. Tectonic subsidence was responsible for the maintenance of this vegetation pattern on the eastern side of the Marajó Island, keeping it as a habitat favourable for savanna adapted faunal elements. Based on this kind of information, this work attempts to highlight the importance of integrating studies combining geological and biological events as the key to understand biodiversity patterns in Amazonia. It is expected to open new lines of research dealing with the comprehension of ecology, species and genetic diversity, biogeography, evolutionary scenarios, and speciation mechanisms.  相似文献   

11.
Aim To use surface pollen and vegetation relationships to aid the interpretation of a Holocene pollen record. Location South‐west Tasmania, Australia. Methods A survey was undertaken of surface‐pollen samples from the major regional vegetation types: alpine, rain forest and moorland. Relationships between vegetation type and surface‐pollen representation were analysed using twinspan classification and ordination. A core was retrieved from moorland vegetation, and interpretation of the fossil pollen sequence was aided using relationships detected in our surface‐pollen analysis. Results Regional vegetation types are reflected in the pollen rain of south‐west Tasmania, despite the over‐representation of important rain forest tree species in samples from non‐forest sites. twinspan classification of the surface‐pollen samples identified the following indicator pollen taxa for each vegetation type: Astelia alpina (alpine); Lagarostrobos franklinii (rain forest); Leptospermum and Melaleuca (moorland). Detrended correspondence analysis of the surface‐pollen samples clearly separates samples from each vegetation type. Correlation of the ordination axes with environmental data identified a dominant temperature/altitudinal gradient in the surface‐pollen data (R = 0.852/0.844). Application of the results of the surface‐pollen analysis to the fossil sequence revealed that fire‐promoted moorland has dominated the local environment around the core site for the entire Holocene. Changes in fossil pollen composition also suggest that temperatures increased through the Late Glacial to peak in the mid‐Holocene and declined thereafter, a trend consistent with other sites in the region. Main conclusions Pollen spectra can successfully be used to predict local vegetation in south‐west Tasmania. At least this part of inland south‐west Tasmania has remained forest‐free throughout the Holocene, conflicting with the dominant palaeoecological paradigm of a mid‐Holocene dominated by rain forest. A comparison with pollen records from moorland vegetation across the region suggests that fire‐promoted moorland has dominated the landscape since the Late Glacial. We suggest that burning by people through the Late Glacial (if not earlier) facilitated the spread of moorland throughout the region, greatly restricting the expansion of rain forest. The continued influence of fire throughout the Holocene in this perennially wet landscape argues for a revision of the dominant human‐occupation model that depicts an abandonment of the interior of south‐west Tasmania in the Late Glacial in response to the expansion of rain forest.  相似文献   

12.
Reconstruction of past climate change and ecosystem response is important to correctly assess the impacts of global warming. In this study, we provide a paleoenvironmental record of in-lake and catchment changes in northern Poland during the Late Glacial and early Holocene using various biotic proxies (pollen, macrofossils and Cladocera) preserved in the lake sedimentary record. Chronology was derived from palynological correlation with a well-dated pollen sequence from nearby-lying Lake Ostrowite and some well-dated events of vegetation history in Central Europe. Pollen analysis provided information on regional climate change affecting vegetation dynamics, whereas macrofossils supplied substantial information on the response of local flora and fauna to climatic, geomorphological and limnological changes. Data were supplemented by analysis of Cladocera remains, which are of special importance because of their quick response to changes in trophic conditions and climate (especially temperature). The bottom of the sediment core reflects an initial stage of the lake formed during the late Aller?d. The Younger Dryas cooling apparently resulted in forest recession and presence of cold tolerant Cladocera species. Due to amelioration of climate at the end of the Younger Dryas and melting of ice, the lake deepened. The beginning of the Holocene was characterised by forest shrinkage and induced clear changes in local flora and fauna communities. The regional vegetation development deduced from the lake’s core is generally consistent with the vegetation history of central Europe. Due to the location of the site near the seashore (oceanic climate and western wind), signals of warming came earlier than inland and in eastern Poland.  相似文献   

13.
Pleistocene mammalian communities display unique features which differ from present-day faunas. The paleocommunities were characterized by the extraordinarily large body size of herbivores and predators and by their unique structure consisting of species now inhabiting geographically and ecologically distinct natural zones. These features were probably the result of the unique environmental conditions of ice age ecosystems. To analyze the ecological structure of Last Glacial and Recent mammal communities we classified the species into biome and trophic-size categories, using Principal Component analysis. We found a marked similarity in ecological structure between Recent eastern Altai-Sayan mammalian assemblages and comparable Pleistocene faunas. The composition of Last Glacial and Recent eastern Altai-Sayan assemblages were characterized by the occurrence of large herbivore and predator species associated with steppe, desert and alpine biomes. These three modern biomes harbor most of the surviving Pleistocene mammals. None of the analyzed Palearctic Last Glacial faunas showed affinity to the temperate forest, taiga, or tundra biome. The Eastern part of the Altai-Sayan region could be considered a refugium of the Last Glacial-like mammalian assemblages. Glacial fauna seems to persist up to present in those areas where the forest belt does not separate alpine vegetation from the steppes and deserts.  相似文献   

14.
In 2016 the 100th birthday of palynology was celebrated: Lennart von Post introduced the scientific discipline in 1916 at lectures in Oslo and Stockholm. However, von Post was not the first to study pollen, and research dates back to the works of Nehemiah Grew and Marcello Malpighi in the late 17th century. Afterwards studies focussed mainly on the role of pollen for plant reproduction, and on pollen morphology. The first scientist who observed fossil pollen was Heinrich Göppert in 1836. However, it was not until the 1890s and 1900s that the study of pollen became a regular component in the reconstruction of past vegetation. Lennart von Post subsequently developed theoretical and practical concepts and methods of pollen analysis, and raised palynology from its infancy into the mature scientific discipline that flourished greatly during the century that followed.  相似文献   

15.
Libor Petr  Jan Novák 《Biologia》2014,69(7):847-862
The diversity of vegetation and the environment in the Late Glacial period in the Elbe region is illustrated by a comparison of three palynological localities. The localities differ in their history, profile lithology and position relative to the Elbe river. The Hrabanovská ?ernava profile holds a record of the development of a shallow lake, which was surrounded by a cold continental steppe in the Early Dryas. Evidence of a pine forest in the Late Glacial period is captured in the surroundings of the profile Chrást. The Mělnický úval — P?ívory locality is an interdune infill, where marl sediments redeposited in shallow water. The surrounding vegetation was diffuse and influenced by erosion. In the Early Holocene, the landscape was covered by an open birch-pine forest. Broad-leaved woody species appeared later. Localities in the Elbe region share a high proportion of Pinus throughout the Holocene as a result of the spread of drift and terrace sands. The human impact in the mid Holocene manifests as evidence of intensive charring of localities.  相似文献   

16.
As part of a new research programme, studies of peat bogs in Brittany are being carried out to trace the changes that have occurred in the course of time, and to determine the different regional stages related to the human activities of land clearance and agriculture. In this context, a palynological study of the Kerfontaine peat bog was undertaken to consider changes in local and regional vegetation dating from after about 7800 B.P. Local vegetation history from Neolithic times until the Middle Ages involved a succession of twelve pollen zones clearly related to variations in water level resulting from natural or anthropogenic influences. The dominant vegetation was alder carr, bog-myrtle mire and birch woods. Heath vegetation, which appeared at the end of the Iron Age, developed during the Gallo-Roman period, finally invading the entire bog in the Middle Ages. Regional vegetation history was characterised, among other things, by the presence of beech woods which developed after 3000 B.P. and then declined during the Middle Ages in conjunction with an increase of cultivation between the 8th and 11th centuries A.D., an indication of great activity during the Carolingian period. Human activity reached its peak around 1800 A.D. at the time of the first pine plantations.  相似文献   

17.
植被覆盖对风蚀地表保护作用研究的某些新进展   总被引:44,自引:0,他引:44       下载免费PDF全文
 植被覆盖在风蚀过程中可通过多种途径保护地表土壤,减少风蚀输沙,对此人们早已有所认识。然而,在植被覆盖防护效应的定量研究方面,却长期存在着严重不足。近年来,国外学术界在植被覆盖保护作用的机理和定量研究等多个方面取得了突破性进展,国内却仍处于起步阶段。在大量总结国内外最新文献基础上,从理论研究、观测实验和定量模型3个方面,就植被覆盖对风蚀地表保护作用研究的新进展进行了系统介绍和评述,并结合当前国内的研究状况和现实需要,提出了4个有待进一步深入研究的重点问题。  相似文献   

18.
As study area we selected the glacier foreland of Morteratsch (approx. 1900–2100 m a.s.l.) near Pontresina northwest of the Bernina pass, Upper Engadine, Grisons (Switzerland). The aim of this study is a multimethodological approach using floristic inventories, vegetation and soil mapping of the pro-glacial area in order to detect crucial parameters controlling plant resettlement in recently deglaciated areas as related to time, local microtopography and soil development.  相似文献   

19.
Rockshelter Baaz in the Damascus region of Syria provided a variety of botanical remains from the Late Pleistocene and Early Holocene period. These remains provide new information about the vegetation evolution in this region. The earliest occupational levels correspond with a moisture peak during the Late Pleistocene, between ca. 34–32 kyr b.p., when pine expanded. The next occupations took place during extreme arid conditions, ca. 23–21 kyr b.p., and probably during the Last Glacial Maximum when a steppe vegetation was established. The occupation level of the Younger Dryas, represented by Natufian remains, suggests that the area had been covered by almond-pistachio steppe, similar to later periods of the Early Holocene, and was probably located just outside the range of dense wild cereal stands. There is no drastic impact of the Younger Dryas visible on the vegetation in the botanical remains. The lack of fruits and seeds at Baaz indicates that the site was more likely to have been a temporary hunting post rather than a plant processing site for much of its history. It is ideally suited to this purpose because of its location over the Jaba′deen Pass and the associated springs. However, archaeological remains from the Natufian period, suggest that the site was more permanently occupied during this time. A. Dodonov deceased.  相似文献   

20.
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