川北若尔盖高原玛曲-红原一带表土中孢粉组合的特征

通过对四川若尔盖高原玛曲—红原一带20个表土孢粉样的分析,研究了该区域表土孢粉组合与现代植被的关系。结果显示,玛曲—红原一带表土的孢粉组合基本反映了现代植被的整体特征,与现代植被在植被类型、植被带的空间排列、主要建群种属和优势种属等方面基本一致。依据孢粉的百分含量,可以划分为亚高山灌丛植被区,亚高山灌丛、亚高山草甸植被区和高寒草甸、草原植被区3个植被带。表土花粉的代表性因种属的不同而各有差异,松属和菊科花粉具超代表性,云杉属花粉的代表性较好,禾本科和莎草科具低代表性,而桦木属则不具有超代表性,可能与桦木属花粉不易搬运有关。3个植被区中的表土孢粉的种类、比例与现代植被均存在一定的差别,这可能与植被退化有关。     

Pollen distribution in large freshwater lake of arid region: a case study on the surface sediments from Bosten Lake,Xinjiang, China

The interpretation of the pollen records from lake sediments is always hampered by a lack of information relating to different pollen production, transportation, deposition, and preservation. It is important to understand the modern process of pollen sedimentation and its climatic implications. This paper presents results from a palynological study on 61 surface sediments samples from Bosten Lake, the largest inland freshwater lake in China. Our results suggest that Chenopodiaceae and Artemisia dominate the modern pollen assemblages and have stable percentages at most sites of the lake basin except for the estuary area. Pollen Artemisia/Chenopodiaceae ratio is about 0.5, indicating the dry climate of the region. Principle Components Analysis (PCA) of pollen data can identify the pollen samples as several ecological groups from different parts of the lake. Pollen transportation dynamics and the mixing effect of lake currents and waves on pollen deposition have affected the pollen assemblages. The distribution of Typha pollen seems to be affected by the location where the parent plants grow. Picea pollen has higher percentages at estuary area, suggesting fluvial transport. Pollen concentration has high values at the central part of the lake basin due to the sedimentation focusing process effect. Our results suggest that the pollen assemblages of the sediment core from the central part of the lake can potentially record the regional vegetation history.     

The REVEALS model,a new tool to estimate past regional plant abundance from pollen data in large lakes: validation in southern Sweden

The REVEALS model was developed to reconstruct quantitatively regional vegetation abundance (in a 10⁴–10⁵ km² area) from pollen assemblages in large lakes (≥100–500 ha). This model corrects for biases in pollen percentages caused by inter‐taxonomic differences in pollen productivity and dispersal. This paper presents the first case study to validate REVEALS, using empirical data from southern Sweden. Percentage cover of modern regional vegetation in Skåne and Småland, two contrasting vegetation regions, was predicted with REVEALS for 26 key taxa, using pollen assemblages from surface sediments in 10 large lakes, and compared to the actual vegetation within 10⁴ km² compiled from satellite data, forestry inventories, crop statistics, aerial photographs, and vegetation inventories. REVEALS works well in predicting the percentage cover of large vegetation units such as total trees (wooded land), total herbs (open land), total conifers and total broad‐leaved trees, and it provides reasonable estimates for individual taxa, including Pinus, Picea, Betula, Corylus, Alnus, Tilia, Salix spp., Juniperus, Poaceae, Cyperaceae, Cerealia and Secale. The results show great potential for REVEALS applications, including (1) quantitative reconstructions of past regional land cover important for palaeoclimatology and nature conservation, and (2) local‐scale reconstruction of vegetation (<1 km² up to ～ 5 km² area) relevant for palaeoecology and archaeology. Copyright © 2007 John Wiley & Sons, Ltd.     

A late Wisconsin and Holocene vegetation history from the central brooks range: Implications for Alaskan palaeoecology

Five pollen diagrams reveal late Wisconsin and Holocene vegetation changes in the Walker Lake/Alatna Valley region of the central Brooks Range, approximately 100 km west of the area studied by D. A. Livingstone (1955, Ecology36, 587–600). New insights into the vegetation history of this region are provided by calculations of pollen influx and by the use of linear discriminant analysis to separate Picea glauca and P. mariana pollen. Three major pollen zones are identified: (1) a basal herb zone, characterized by high percentages of Cyperaceae, Gramineae, Salix, and Artemisia, and low total pollen influx; (2) a shrub Betula zone with increased total pollen influx and very high percentages of Betula pollen, predominantly in the size range of B. nana and B. glandulosa; and (3) and Alnus zone dominated by Alnus pollen. Lakes currently within the boreal forest or near tree line show relatively high percentages of Picea pollen in the Alnus zone. Several striking vegetation changes occurred between ca. 10,000 and 7000 yr B.P. Between ca. 11,000 and 10,000 yr B.P., Populus balsamifera pollen percentages as great as 30% indicate that this species was present at low-elevation sites near Walker Lake. These populations declined abruptly ca. 10,000 yr ago and have never regained prominence. About 8500 yr B.P., Picea glauca pollen reached 10–15%, indicating the arrival of P. glauca in or near the study area. P. glauca populations evidently decreased ca. 8000 yr ago, when Picea pollen percentages and influx fell to low values. About 7000 yr B.P., Alnus pollen percentages and influx rose sharply as alder shrubs became established widely. Picea once more expanded ca. 5000 yr ago, but these populations were dominated by P. mariana rather than P. glauca, which increased slowly at this time and may still be advancing northward. Some vegetation changes have been remarkably synchronous over wide areas of interior Alaska, and probably reflect responses of in situ vegetation to environmental changes, but others may reflect the lagged responses of species migrating into new areas.     

Relationship of Pollen-Vegetation-Land Use in Small Watersheds of Mountain Area: A Tentative Study of Quantitative Detecting Human Activities on Environment

With the progress of study on global climate change and the sensitivity simulation of various climate systems, human activities might be one of important factors driving climate change in historical periods. Therefore, since the beginning of this century, Land Cover Change has become the currently hot topic of global change research and climate simulation. The establishment of pollen-vegetation-land use relationship may be one of the effective ways to obtain quantitative estimates of human impact on natural environment. Therefore, in the Taihang Mountains,two small watersheds were selected to detect the relationships quantitatively among pollen, vegetation and land-use of small watershed by using pollen data. There are natural vegetation components and crop pollen types in pollen assemblages, which well reflect the relationships among pollen, vegetation and land-use in small watershed. As altitude decreases, the area of farmland, the intensity of human activities and the cereal, vegetable pollen percentages increases. The regression analysis of pollen percentages and land-use indicate that a linear positive relationship exists between the percentages of cereals, vegetables pollens and the area of farmland, which has a significance for human activities.     

Absolute pollen productivity and pollen–vegetation relationships in northern Finland

Pollen productivity is one of the most critical parameters for pollen–vegetation relationships, and thus for vegetation reconstruction, in either pollen percentages or pollen accumulation rates. We obtain absolute pollen productivity of three major tree types in northern Finland: pine (Pinus sylvestris), spruce (Picea abies) and birch (Betula pubescens ssp. pubescens and B. pubescens ssp. czerepanovii treated as one taxon). Long‐term monitoring records of pollen traps from 15 sites (duration: 5–23 years) and tree volume estimates within a 14 km radius of each trap were compared to estimate pollen productivity (grains m^?3 a^?1) of these trees using a regression method. The slope of the linear relationship between pollen loading and distance‐weighted plant abundance represents pollen productivity. Estimated productivities of pollen (×10⁸ grains m^?3 a^?1) for pine, spruce and birch are 128.7 (SE 31.5), 341.9 (SE 81.3) and 411.4 (SE 307.7), respectively. The birch estimate (P > 0.05) is not as good as the others and should be used with caution. Pollen productivities of pine, spruce and birch in northern Finland are, in general, comparable to those of congeneric species in other regions of Europe and Japan. Although the year‐to‐year variations are significant, our volume‐based estimates of pollen productivity for pine and spruce will be essential for quantitative reconstruction of vegetation in the region. Copyright © 2009 John Wiley & Sons, Ltd.     

晋冀低山丘陵区人工扰动植被花粉组合特征

54个晋冀低山丘陵区人工和人工扰动植被表土花粉样品分析表明:花粉组合以草本植物花粉(74.5％)为主,乔木花粉含量低于20％。人类活动较强的农田以谷物禾本科、蒿属和藜科花粉为主,人类活动较弱的荒地以蒿属、藜科和杂草禾本科花粉为主。人类活动强度不同,指示种不同,孢粉浓度亦不同;农田指示种为谷物禾本科、葡萄科和胡桃科,孢粉浓度约4380粒/g;而蒿属、蓼科和蔷薇科则为荒地指示种,孢粉浓度约10983粒/g。农作物种植方式不同,谷物禾本科花粉含量不同,单一禾本科作物种植区谷物禾本科花粉含量(40.2％)高于多种作物混作区(18.8％)和荒地(3.8％)的含量。谷物禾本科含量的变化可以为利用化石花粉提取和检测人类活动信息提供依据,也可为利用地层中谷物禾本科花粉判断古代农业活动提供依据。     

Relative pollen productivities of the major plant taxa of subtropical evergreen–deciduous mixed woodland in China

Quantifying the relationship between pollen and vegetation is an essential step in the pollen-based quantitative reconstruction of past vegetation cover. In this study, we use the Extended R-Value (ERV) model and a modern dataset of pollen (collected from moss polsters) and related vegetation from 50 sites in the Daba Mountains (subtropical China) to (i) estimate the relevant source area of pollen (RSAP) of the moss samples and the relative pollen productivities (RPPs) of nine major plant taxa-characteristic of the region, and (ii) evaluate the obtained RPPs. The RSAP estimates of moss polsters vary between 225 and 610 m depending on the ERV submodels and models of pollen dispersal and deposition used. The RPP estimates are different from values published in previous studies from temperate and subtropical China. This may be explained by differences in methodology, climate and vegetation (species composition and spatial distribution), of which vegetation is probably the most important factor. The ranking of the RPP estimates for the nine taxa is Pinus > Juglandaceae > D − Quercus (deciduous Quercus) > Poaceae > Rosaceae > Cyperaceae > Anacardiaceae > Castanea > Fabaceae. We use a ‘leave-one-out’ cross-validation strategy and the Landscape Reconstruction Algorithm (LRA) for pollen-based reconstruction of regional and local plant cover to evaluate the ERV model-based RPP estimates. Both the REVEALS (Regional Estimates of VEgetation Abundance from Large Sites)-based and the LOVE (LOcal Vegetation Estimates)-based plant cover using the RPP estimates are closer to the modern vegetation composition than pollen percentages, thus confirming the applicability of the ERV model and the LRA approach in subtropical China.     

Younger Dryas cold stage vegetation patterns of central Europe – climate,soil and relief controls

In the north Atlantic region the final period of the last ice age saw abrupt shifts between near present‐day warm and near ice age cold conditions, ending with the cold Younger Dryas. The effects of the cold periods may have been more severe in the vicinity of the Atlantic Ocean than in continental Europe. We use pollen percentage and influx data combined with data on substrate and relief to reconstruct spatially explicit vegetation composition, patterns and development during the Younger Dryas, with special focus on to the forest/non‐forest transition across NE Germany. Opposing trends, such as birch pollen percentages sharply increasing but accumulation rates sharply decreasing northwards, underline pitfalls in the interpretation of pollen percentage data in tree‐line situations. The combined approach reveals a sharp ecotone. Pine declined on northern sites, possibly because of permafrost formation, but was hardly affected in the south. Birch also declined in the south, possibly because of the severe winter cold. Cold‐adapted trees did not enter forest gaps. The cooling had little impact on herbal vegetation. Steppe elements (grasses, Artemisia) were largely restricted to south‐exposed slopes and did not benefit from the cooling – patches of steppe vegetation were even less abundant than during the preceding warm periods. The approach of combining fossil pollen data, including accumulation rates, with data on the contemporary distribution of substrate and relief allowed unprecedented spatial resolution to be reached in the reconstruction of Younger Dryas vegetation patterns.     

European vegetation during Marine Oxygen Isotope Stage-3

European vegetation during representative “warm” and “cold” intervals of stage-3 was inferred from pollen analytical data. The inferred vegetation differs in character and spatial pattern from that of both fully glacial and fully interglacial conditions and exhibits contrasts between warm and cold intervals, consistent with other evidence for stage-3 palaeoenvironmental fluctuations. European vegetation thus appears to have been an integral component of millennial environmental fluctuations during stage-3; vegetation responded to this scale of environmental change and through feedback mechanisms may have had effects upon the environment. The pollen-inferred vegetation was compared with vegetation simulated using the BIOME 3.5 vegetation model for climatic conditions simulated using a regional climate model (RegCM2) nested within a coupled global climate and vegetation model (GENESIS-BIOME). Despite some discrepancies in detail, both approaches capture the principal features of the present vegetation of Europe. The simulated vegetation for stage-3 differs markedly from that inferred from pollen analytical data, implying substantial discrepancy between the simulated climate and that actually prevailing. Sensitivity analyses indicate that the simulated climate is too warm and probably has too short a winter season. These discrepancies may reflect incorrect specification of sea surface temperature or sea-ice conditions and may be exacerbated by vegetation-climate feedback in the coupled global model.     

Pollen taphonomy in a canyon stream

Surface soil samples from the forested Chuska Mountains to the arid steppe of the Chinle Valley, Northeastern Arizona, show close correlation between modern pollen rain and vegetation. In contrast, modern alluvium is dominated by Pinus pollen throughout the canyon; it reflects neither the surrounding floodplain nor plateau vegetation. Pollen in surface soils is deposited by wind; pollen grains in alluvium are deposited by a stream as sedimentary particles. Clay-size particles correlate significantly with Pinus, Quercus, and Populus pollen. These pollen types settle, as clay does, in slack water. Chenopodiaceae-Amaranthus, Artemisia, other Tubuliflorae, and indeterminate pollen types correlate with sand-size particles, and are deposited by more turbulent water. Fluctuating pollen frequencies in alluvial deposits are related to sedimentology and do not reflect the local or regional vegetation where the sediments were deposited. Alluvial pollen is unreliable for reconstruction of paleoenvironments.     

Stick-Nest Rat Middens as Sources of Paleoecological Data in Australian Deserts

The existing paleoenvironmental data from the Australian arid zone lack sensitivity and come from only a few sites. Macrofossils and pollen from four dated middens of the stick-nest rat (Leporillus spp.) were analyzed from two sites in Western Australia. Animal and plant macrofossil remains were well preserved and provided evidence of change in species distribution within the last 1150 yr. Brush-tail possum and golden bandicoot have contracted their ranges in the recent past, possibly since the introduction of cats into Australia. An undescribed lacewing was also a significant find. Pollen preserved in parts of the same midden and in middens from different sites indicates that records are sensitive to the composition of the local vegetation when the midden was built. Pollen spectra are quite different from playa lakes, which record largely regional vegetation. Pollen preserved in the fecal pellets, desiccated urine, and grass mat nesting material provided similar information but some differences were apparent, suggesting dietary preferences were reflected in the fecal component. The pollen record suggested a trend to less-wooded vegetation cover in central Australia between 900 and 300 yr B.P.     

A Holocene vegetation record from the Mississippi River Valley, southeastern Missouri

Pollen preserved in a peat deposit from a large swamp, the Old Field in the Mississippi River Valley near Advance, Missouri, records radiocarbon-dated vegetation changes between 9000 and about 3000 years ago. The principal feature of both the percentage and influx pollen diagrams is the replacement of arboreal pollen, primarily Quercus, Fraxinus, and Cephalanthus, with Gramineae and NAP between 8700 and 5000 years BP. This vegetation shift is interpreted as reflecting a decrease in the extent of the Old Field swamp and its associated bottomland forest species along with the expansion of a grass-dominated herb community, as a result of a reduction in available ground water. The desiccation of the swamp during this period indicates a reduction in precipitation within the ground-water source area and a shift to a drier climate in the southern Midwest. The pollen suggests that the lowest water levels and driest climate in southeastern Missouri lasted from 8700 to 6500 years BP, at which time there is a partial reappearance of swamp species. Relatively dry conditions, however, continued until at least 5000 years BP. Although pollen influx data are lacking from the upper part of the profile, the relative pollen frequencies suggest an increase in trees after 5000 BP. The replacement of the arboreal vegetation by grasses and herbs between 8700 and 5000 years BP reflects the period of maximum expansion of the Prairie Peninsula in southeastern Missouri. The Old Field swamp provides the first pollen evidence that the vegetational changes along the southern border of the Prairie Peninsula were chronologically similar to those on the northern and northeastern margins.     

Charcoal analysis for paleoenvironmental interpretation: A chemical assay

Pollen and charcoal analysis of radiocarbon-dated sediment cores from Duck Pond in the Cape Cod National Seashore provide a continuous 12,000-yr vegetation and climate history of outer Cape Cod. A Picea-Hudsonia parkland and then a Picea-Pinus banksiana-Alnus crispa boreal forest association grew near the site between 12,000 and 10,000 yr B.P. This vegetation was replaced by a northern conifer forest of Pinus strobus-P. banksiana, and, subsequently, by a more mesophytic forest (Pinus strobus, Tsuga, Quercus, Fagus, Acer, Ulmus, Fraxinus, Ostrya) as the climate became warmer and wetter by 9500 yr B.P. By 9000 yr B.P. a Pinus rigida-Quercus association dominated the landscape. High charcoal frequencies from this and subsequent levels suggest that the pine barrens association developed during a warmer and drier climate that lasted from 9000 to about 5000 yr B.P. Increased percentages of Pinus strobus pollen indicate a return to moister and cooler conditions by about 3500 yr B.P. A doubled sedimentation rate, increased charcoal, and increased herb pollen suggest land disturbance near the pond before European settlement. These results suggest a rapid warming in the northeast in the early Holocene and support a hypothesis of a rapid sea level rise at that time. Comparison of the pollen results from Duck Pond with those from Rogers Lake, Connecticut, illustrates the importance of edaphic factors in determining the disturbance frequency and vegetation history of an area.     

呼伦湖表层沉积物花粉空间分布特征及影响因素探讨

对呼伦湖29个表层沉积物花粉组合和环境影响因子进行主成分分析(PCA)和冗余分析(RDA),探讨呼伦湖表层沉积物花粉组合的空间分布特征及造成空间分异的现代过程机制.研究结果表明,呼伦湖表层沉积物花粉组合空间分布差异显著,藜科和松属等花粉在湖泊东侧近岸地带百分含量较高,蒿属与桦属花粉在湖泊中部和西部百分含量较高.呼伦湖东岸盐生非地带性植被、主导风向形成的漂流、与水深相关的二次悬移再沉积过程以及河流搬运作用是影响呼伦湖表层沉积物花粉空间分异的主要因素,其中湖泊东岸盐生非地带性植被造成了藜科花粉百分含量在近东岸地带偏高,主导风向形成的由西向东的漂流作用可能导致了松属花粉百分含量在近东岸地带偏高.     

Middle Pleistocene temperate deposits at Dingé, Ille-et-Vilaine,northwest France: pollen,plant and insect macrofossil analysis

Nine cores were taken from a damp depression at Dingé, Ille-et-Vilaine, northwest France. Analyses of the pollen, plant macrofossil and Coleoptera remains preserved in the same organic samples of two profiles suggest a temperate vegetation characterised by a mixed deciduous forest with mesophilous taxa (Carpinus, Fagus, Quercus) followed by a coniferous forest with Pinus and Picea. The determination of plant taxa to species was made either directly through the identification of plant macrofossil remains and pollen or indirectly through the identification of phytophagous Coleoptera specifically related to certain plants. Stratigraphical information derived from pollen, plant macrofossil and insect data indicates that this sequence may be correlated with a temperate episode older than the Eemian and younger than the Holsteinian, possibly the Bouchet 2 (Oxygen Isotope Stage 7c) or Bouchet 3 (Oxygen Isotope Stage 7a) temperate periods or the Landos Interglacial (Oxygen Isotope Stage 9 pro parte). © 1997 John Wiley & Sons, Ltd.     

青藏高原东北部典型花粉类型埋藏特征及其与植被关系的研究

取自青藏高原东北部不同植被类型的6个土壤剖面花粉与植被关系研究表明,表土花粉较好地代表当地植被的组成,区域外花粉百分比低于30％,但桦、杨花粉在植被中的代表性较差;土壤剖面典型花粉类型的埋藏特征表明：在土壤表层8cm以下,花粉总浓度迅速降低。氧化作用对花粉的破坏性最大,花粉浓度随土壤的pH值升高呈指数形式递减,pH值7．6以上,花粉浓度迅速降低,花粉在土壤中的运移作用不明显。     

Comparison of climate model results with European vegetation and permafrost during oxygen isotope stage three

Oxygen isotope stage 3 (OIS3), an interstade between approximately 60,000 and 25,000 yr B.P., presents an ideal opportunity to compare high-resolution climate simulations with the geologic record. To facilitate this comparison, the results of a mesoscale climate model (RegCM2) embedded in the GENESIS GCM are utilized to drive a vegetation model (BIOME 3.5). The BIOME output is then compared with OIS3 compilations derived from pollen. The simulated biomes agree well with the pollen-based biomes in southern Europe; however, disagreements occur in the northern part of the domain. The most striking mismatch involves the distribution of tundra. The models fail to have tundra extend to its observed position as far south as 50°N in central Europe during OIS3. The model also fails to have permafrost extend southward to its observed position between 50°N and 55°N in western Europe during OIS3. A variety of sensitivity experiments are performed to investigate these mismatches. These experiments demonstrate the importance of annual and summer temperatures and the length of the winter season in creating improved matches between the model results and the inferred distributions of vegetation and permafrost in northern Europe.     

黄河兰州段河水搬运花粉与累积花粉组合特征初步研究*

对从2011年9月至2012年6月在黄河兰州段采集的24个水样进行了孢粉分析,并探讨了河流搬运花粉组合随时间变化的特征以及累积花粉的组合状况。结果表明,河流中花粉组合和花粉浓度随时间具有明显的变化,春夏时段花粉组合以榆属、杨属、柳属和桦属等乔木花粉为主,秋冬时段以蒿属、藜科等草本花粉为主,且花粉浓度和河流含沙量有较好的正相关关系。根据河水流量与花粉浓度积分计算得出样品采集时段的累积花粉通量,其组合特征与各时间点的花粉组合具有明显的差异,表明单个时间节点花粉组合由于影响因素较多不能够反映流域植被状况,而累积花粉组合可以指示泥沙和花粉源区的植被状况。本研究中黄河兰州段河水搬运花粉可能指示黄河兰州段以上至刘家峡水库之间黄土区的植被情况。     

青藏高原东北部典型花粉类型埋藏特征及其与植被关系的研究

取自青藏高原东北部不同植被类型的 6个土壤剖面花粉与植被关系研究表明，表土花粉较好地代表当地植被的组成，区域外花粉百分比低于30％，但桦、杨花粉在植被中的代表性较差；土壤剖面典型花粉类型的埋藏特征表明：在土壤表层 8cm以下，花粉总浓度迅速降低。氧化作用对花粉的破坏性最大，花粉浓度随土壤的pH值升高呈指数形式递减，pH值 7．6以上，花粉浓度迅速降低，花粉在土壤中的运移作用不明显。