Modern pollen-vegetation relationships along altitudinal vegetation belts in the Leigong Mountain of southwestern China

Understanding the distribution,dispersal,and correlation of modern pollen with vegetation in mountainous regions is essential for establishing accurate modern analogs for fossil pollen records.This study,conducted in Leigong Mountain on the YunnanGuizhou Plateau of southwestern China,involved the collection of 35 surface soil samples from diverse vegetation communities along an elevational gradient ranging from 1210 to 1875 meters.The results reveal a close correspondence between modern pollen assemblages and vegetation zones.Principal Component Analysis(PCA)results indicate that pollen assemblages can effectively distinguish between subtropical montane evergreen broad-leaved forest(SEBF)and subtropical montane deciduous broadleaved forest(SDBF).However,both SEBF and SDBF show significant overlap with subtropical montane evergreen-deciduous broad-leaved mixed forest(SEMF).Detrended Correspondence Analysis(DCA)results clearly distinguish the three vegetation zones,and the first axis of DCA shows a significant positive correlation with elevation(p<0.01,R=0.48).Discriminant Analysis(DA)successfully assigns 94.4%of the modern pollen samples to their respective vegetation zones.Pollen taxa such as Impatiens,Astertype,and Rosaceae exhibit significant indicative capabilities for the SEBF zone,effectively distinguishing this vegetation zone from others.Pinus and Alnus display overrepresentation in the Leigong Mountain region,while Quercus(D,deciduous-type)and Poaceae exhibit high representation in the SEBF zone.In the SEBF zone,both pollen diversity and richness are the lowest.Our study reveals the complex relationship between the richness and diversity of pollen and vegetation.The diversity and richness of tree and shrub pollen are found to be lower than those of the corresponding plants.The pollen-vegetation relationship elucidated in this study serves as a critical reference for reconstructing ancient environments from fossil pollen retrieved in this region.

Modern pollen assemblages from surface lake sediments in northwestern China and their importance as indicators of vegetation and climate

The modern pollen assemblages of surface lake sediments and topsoils in northwestern China were studied to understand the relationship of modem pollen data with contemporary vegetation and climate, and the differences between the pollen assem- blages of surface lake sediments and topsoils. The results show that Chenopodiaceae and Artemisia are dominant elements in the pollen assemblages of northwestern China. Additionally, Ephedra, Cyperaceae, Asteraceae, Poaceae, Picea, Pinus, and Betula are also important pollen taxa. Both pollen assemblages and principal component analysis indicate that pollen data from surface lake sediments and topsoils can be used to differentiate the main vegetation types of this region （desert, steppe, mead- ow and forest）. However, differences exist between modern pollen assemblages of the two types of sediments due to the dif- ferent relevant source areas of pollen and degrees of pollen preservation. For example, the larger relevant source area of sur- face lake sediment results in a higher abundance of Betula in pollen assemblage from surface lake sediment, whereas the ten- dency to disintegrate thin-walled pollen types in topsoil leads to a higher proportion of resistant pollen, such as Asteraceae. Linear regression analysis indicates that the Artemisia/Chenopodiaceae （A/C） ratio in pollen assemblages of surface lake sedi- ments can be used to indicate humidity changes in the study area. However, the A/C ratio in topsoils should be used carefully. Our results suggest that pollen data from surface lake sediments would be better references for interpreting the fossil pollen assemblages of lake cores or lacustrine profiles.

Characteristics of the modern pollen assemblages from different vegetation zones in Northeast China:Implications for pollen-based climate reconstruction

Northeast China is an essential area for studying the strength of East Asian Summer Monsoon(EASM), due to its northernmost location in EASM domain. However, the lack of sufficient modern pollen data in this region hinders an effective interpretation of fossil pollen records and quantitative vegetation/climate reconstructions. Here, 44 surface pollen samples from forest, steppe, and meadow were used to explore pollen-vegetation-climate relationships. Cluster analysis, species indicator analysis, and principal components analysis, were used to identify the discontinuous and continuous trends in pollen dataset. In addition, correlation analysis and boosted regression trees were used to investigate primary explanatory variables, while coinertia analysis and redundancy analysis to examine pollen-vegetation and pollen-climate correlations respectively. Our results show that:(1) vegetation can be well represented by surface pollen assemblages, i.e. forest is characterized by a high proportion of tree pollen(>70%) dominated by Betula(>40%) along with Alnus, Larix, and Pinus, whereas Steppe by herb pollen(>80%),dominated by Artemisia, Chenopodiaceae;(2) significant correlations exist between pollen assemblages and mean annual temperature and then mean annual precipitation;(3) pollen ratios of Artemisia/Chenopodiaceae and arboreal/non-arboreal can respectively be used as good indicators of humidity and temperature in Northeast China.

Modern pollen assemblages of the surface lake sediments from the steppe and desert zones of the Tibetan Plateau

Modern pollen analysis is the basis for revealing the palaeovegetation and palaeoclimate changes from fossil pollen spectra.Many studies pertaining to the modern pollen assemblages on the Tibetan Plateau have been conducted,but little attention has been paid to pollen assemblages of surface lake sediments.In this study,modern pollen assemblages of surface lake sediments from 34 lakes in the steppe and desert zones of the Tibetan Plateau are investigated and results indicate that the two vegetation zones are dominated by non-arboreal pollen taxa and show distinctive characteristics.The pollen assemblages from the desert zone contain substantially high relative abundance of Chenopodiaceae while those from the steppe zone are dominated by Cyperaceae.Pollen ratios show great potential in terms of separating different vegetation zones and to indicate climate changes on the Tibetan Plateau.The Artemisia/Chenopodiaceae ratio and arboreal/non-arboreal pollen ratio could be used as proxies for winter precipitation.Artemisia/Cyperaceae ratio and the sum of relative abundance of xerophilous elements increase with enhanced warming and aridity.When considering the vegetation coverage around the lakes,hierarchical cluster analysis suggests that the studied sites can be divided into four clusters:meadow,steppe,desert-steppe,and desert.The pollen-based vegetation classification models are established using a random forest algorithm.The random forest model can effectively separate the modern pollen assemblages of the steppe zone from those of the desert zone on the Tibetan Plateau.The model for distinguishing the four vegetation clusters shows a weaker but still valid classifying power.It is expected that the random forest model can provide a powerful tool to reconstruct the palaeovegetation succession on the Tibetan Plateau when more pollen data from surface lake sediments are included.

Modern pollen rain in the Lake Qinghai basin, China

Lake Qinghai is the largest inland brackish lake in China and lies within the NE Tibetan Plateau. Our study shows that pollen assemblages in each vegetation belt are significantly correlated with the vegetation types of this area. Among the herbaceous and shrubby pollen assemblages, Artemisia is over-represented, while Poaceae, Cyperaceae and Polygonaceae are under-represented. Artemisia/ Chenopodiaceae (A/C) ratios with the regional vegetation characteristic can be used as a proper index to reconstruct the history of vegetation and climate in Lake Qinghai basin. Modern pollen in the lake mainly comes from the nearby vegetation, controlled by the directions and velocity of the wind. The distribution of modern pollen in Lake Qinghai tends to be similar in most part of the lake. The difference of pollen sedimentation process in the lake can be potentially influenced by the focusing function of the lake, river streams, and lake current.

Modern pollen and vegetation relationships in the Yili Basin,Xinjiang, NW China

Fifty-six surface pollen samples from different vegetation zones in the Yili Basin,western Tianshan Mountains,Xinjiang were analyzed to examine the relationships between the surface pollen assemblages and the original vegetation.A pollen analysis and a vegetation investigation with a discriminant analysis show that the pollen assemblages greatly differ across disparate vegetation zones.Twelve pollen taxa can be used as significant types for vegetation reconstruction in the basin.These taxa were the most abundant in the surface pollen samples.Cupressaceae pollen percentages were greater than 1%in Cupressaceae shrubs.More than5%of Picea pollen indicates the growth of a Picea forest within 5 km.The subalpine meadow that is distributed widely in the basin is characterized by high content of Artemisia,Chenopodiaceae,Poaceae,Picea,Asteraceae,Taraxacum and Arenaria pollen types.The Artemisia-Chenopodiaceae-Poaceae-Cannabaceae pollen assemblages indicate the presence of montane steppe in the area.Artemisia and Chenopodiaceae pollen dominate the desert steppe and Populus forest.Artemisia pollen percentages were greater than 60%in the Artemisia desert,whereas Chenopodiaceae pollen percentages exceeded 65%in the Chenopodiaceae desert.The Artemisia/Chenopodiaceae(A/C)ratios reflect the vertical moisture changes in the Yili Basin.The mean A/C ratios were greater than 1.2 in the subalpine meadow and montane steppe that occupy the humid zone in the basin.These ratios were between1 and 1.2 in the Cupressaceae shrubs,desert steppe,Populus forest and floodplain meadow.The ratios were less than 0.5 in the Chenopodiaceae desert,which is an arid environment.

Modern pollen-vegetation relationship based on discriminant analysis across an altitudinal transect on Gongga Mountain,eastern Tibetan Plateau

Quantitative relationship between modern pollen assemblage and altitudinal vegetation belt is crucial for the reconstruction of paleovegetation in the mountain regions.Modern pollen analysis on 70 topsoil samples was conducted across an altitudinal transect(1100-4500 m) on the eastern slope of Gongga Mountain in the eastern Tibetan Plateau with an elevation interval of 50 m.Distributions of major pollen types along the transect indicated a weak correlation between Pinus pollen and the elevation.Distributions of Picea and Abies pollen(percentage sum of 2%-8%) could fairly indicate the elevation range of 2700-3700 m,as well as the subalpine dark coniferous forest and the timberline in the region.High percentage intervals of alpine types of Ericaceae,Cupressaceae and Cyperaceae were correlated to the high-elevation regions(3700-4500 m) dominated by alpine shrub meadow and alpine meadow.Seven altitudinal vegetation belts on the eastern slope of Gongga Mountain were well defined by discriminant analysis conducted on the modern pollen assemblages,as reflected by high values of probability of modern analog.Most of the modern pollen assemblages(88.5%) were typical for the vegetation types at their sampling locations.Thus,the relationship between the modern pollen assemblages and vegetation across the altitudinal transect based on discriminant analysis can be applied to the quantitative reconstruction of paleovegetation changes in the mountain regions of the eastern Tibetan Plateau.

Human impact gradients via anthropogenic pollen indicators:insights gleaned from a case study in the Rif Mountains(Northern Morocco)

Understanding the relationship between modern pollen and vegetation is crucial for interpreting fossil pollen records and assessing human impact on the environment,both of which are essential for effective environmental management strategies.Despite numerous studies on fossil pollen records in the Rif landscape,research specifically focusing on modern pollen and its implications for understanding human impact on the natural landscape is notably lacking.This paper presents novel anthropogenic pollen indicators for the Rif Mountains and seeks to evaluate the gradients of human impact on the southern Mediterranean landscape.We employed a combination of modern pollen analysis,vegetation survey,and ordination techniques,incorporating various environmental and land-use variables.Canonical correspondence analysis(CCA)allowed us to evaluate the relationships between pollen types and environmental variables,helping us identify key anthropogenic pollen indicators associated with land use and human activities:Poaceae,Cannabist,Olea-t,and Asteraceae for cultivation;Brassicaceae,Genista-t,Poaceae,Asteraceae and Plantago-t,for grazing;Apiaceae,Urtica-t and Genista-t for slashing and burning.Additionally,an anthropogenic index score(AIS)was calculated for each sampled location.Correspondence analysis(CA)was then used to correlate each specific pollen type with levels of human impact as follows(a)low(e.g.,Cedrus atlantica-t,Quercus canariensis-t),(b)moderate(e.g.,Erica-t,Arbutus unedo-t,Eucalyptus-t),and(c)high(e.g.,Cannabis-t,Brassicaceae,Olea-t,Nicotiana-t).This paper enhances our comprehension of land-use dynamics and impact levels,providing essential insights for evaluating anthropogenic impact trends and human-induced changes in the Rif Mountains landscape.

中药松花粉的化学成分及现代应用研究进展

目的综述松花粉的品种特点、分布、化学成分、药理作用及现代制剂应用研究进展,为其药食两用资源的深入开发利用提供参考。方法通过查阅书籍、Web of science、PubMed、CNKI等数据库以及CNIPA、SAMR、NMPA等网站中已发表松花粉相关文献进行分析和归纳总结。结果松花粉药食同源,含有多种化学成分,包括黄酮类、甾醇类、多糖类、脂肪类等。具有抗氧化、抗炎、增强免疫力等多种药理活性。结论松花粉具有广泛的药理作用和食用价值,其在药用、食用领域有待更深入的研究,应完善其质量标准、拓宽其临床应用以及研制开发成新制剂.

亚热带稻作区表土孢粉研究及其考古学应用

研究地点位于广东、湖南和湖北三省的华南双季稻分布区,纬度跨度为22.84°～32.51°N之间。沿纬度每30～50km间距取样,一共为26个样点,每个样点包含3～5个样品(稻田内、稻田外和附近地表或次生林表土样)。本研究采用了孢粉分析方法,在镜下共鉴定77种孢粉类型。研究结果表明,该区稻田耕土表层的禾本科花粉含量为36%～88%,其中水稻型花粉含量为30%～84%,平均含量为57.41%。而稻田外旱地样品禾本科总量降至26%～77%之间,而水稻型花粉平均值降低至38.52%。稻田内外样品和尘土花粉结果的对比分析表明,在人类强烈干扰的双季稻耕作区,禾本科含量达到36%以上时,很可能表明与稻作农业发展有关。上述表土孢粉结果为地层孢粉分析寻找农业和人类活动的证据提供了新的数据。番禺万顷沙钻孔孢粉研究表明,禾本科花粉在历史上出现一个快速增加的突变(从约10%增加至50%),反映了珠江三角洲稻作农业的迅速发展开始于秦朝,可能与当地人口快速增加和中原地区农耕技术的引入有关。而香港壕涌西区考古遗址地层的孢粉分析揭示出该地点的土地利用是从明清才开始作为耕地使用,而更早的唐宋时期并非原地种植水稻。

新疆地区表土孢粉空间分布规律研究

中国新疆地区表土花粉研究结果展示了干旱区主要孢粉的空间分布规律,大部分表土花粉属种的地理空间分布与含量与相应植物的分布区域基本一致,藜科、蒿属、麻黄属及木本植物云杉属、桦木属等花粉普遍呈超代表性,柽柳属花粉呈低代表性。干旱区主要草灌木表土花粉数据的聚类分析结果可以基本反映本区植物群落的主要生态组合类型。主成分分析进一步表明该区草本和灌木花粉分布主要受水文和湿度等因素控制。

东祁连山南坡现代花粉雨与植被

东祁连山南坡位于青藏高原、黄土高原和西北干旱区的过渡地带 ,植被类型具有多样性、复杂性和过渡性的特点 ,植被垂直分异十分明显 .以该区主要植被类型下的表土花粉百分含量为数据源 ,采用DCA排序方法定量研究表土花粉的组合特征及其与环境的关系 .结果表明 :主要的植被类型可以由他们的表土花粉谱区分开来———杨桦林、云杉林、高寒灌丛、高寒草甸 .花粉谱的变化也反映了植被随海拔高度和温度的变化 .但杨桦花粉在林中的代表性有待进一步研究 ;氧化作用对花粉的破坏作用最大 ,花粉浓度随pH值升高呈指数递减 ,pH值 7 6以上 ,花粉浓度迅速降低 .

热带雨林的孢粉垂直分布规律——以海南岛现代孢粉雨为例(英文)

热带地区环境变化对研究全球气候变化显得越来越重要,热带地区的古环境记录,特别是孢粉记录是恢复过去气候的重要方法。东亚热带地区在冰期—间冰期的气候影响下,生态环境主要表现为山地植被带的垂直升降。因此,定量恢复热带地区第四纪植被垂直移动的幅度,以及作为古气候的替代性指标进行数量化转换是热带地区孢粉研究的关键。然而,我国热带地区现代孢粉雨和植被的关系研究程度较低,给热带第四纪孢粉古生态的恢复和对比带来困难。本研究较系统地总结了海南岛从低地平原到五指山1860m的垂直植被带表土的孢粉散布规律,为热带地区孢粉古环境的重建提供了新的基础数据。 研究结果表明,孢粉组合的变化与垂直植被带紧密相关,孢粉的多样性随海拔升高而降低,其中针叶类随海拔升高而增加,蕨类孢子则相应减少。在低地和低山丘陵,孢粉组合显示出人为干扰的影响,如防风林的主要树种木麻黄(Casuarina)、行道树台湾相思(Acacia richii)和人为砍伐后大面积生长的芒箕(Dicranopteris)群落等在一些孢粉谱中特别高。尽管如此,孢粉组合反映的垂直植被带变化仍然是清楚的,海南岛由下至上可划分出5个表土孢粉组合带: -低地人类强烈干扰带(<400m):Mallotus,Casuarina,Pinus,Myrica,Palmae,Poaceae,Dicranopteris; -低地丘陵地?

江苏海州湾海区表层沉积物的孢粉研究

对江苏海州湾近岸海区的表层沉积物进行孢粉分析 ,总结该研究区的孢粉分布规律及成因。笔者认为该区的松花粉主要来自西北部胶东半岛 ;落叶阔叶乔木花粉来源于连云港市云台山 ;草本植物花粉与陆缘植被相应 ,以盐生的蒿、藜科花粉占优势 ,表明花粉沉积与当地及周边地区植被密切相关。蕨类孢子是从陆地由水流携带搬运而来 ,百分含量的高低可能是受补偿率的影响。

西藏扎布耶盐湖地区现代花粉雨的初步研究

从扎布耶盐湖和藏南地区采集的２１块表土花粉分析结果，提供了花粉与植被，花粉与亚环境上间的定性关系。在扎布耶盐湖，ａ．泉水沼泽，以莎草科（Ｃｙｐｅｒａｃｅａｅ）花粉占优势。ｂ．盐盘、藜科（Ｃｈｅｎｏｐｏｄｉａｃｅａｅ）和麻黄属（Ｅｐｈｅｄｒａ）花粉含量高。ｃ．山坡，分布变色锦鸡儿灌丛，表土花粉以蒿属（Ａｒｌｅｍｉｓｉａ）和藜科为优势。ｄ．河流沙滩，以蒿属和禾本科（Ｇｒａｍｉｎｅａｅ）花粉为主。ｅ．常年盐湖，以蒿属占优势，松属（Ｐｉｎｕｓ）、云杉属（Ｐｉｃｅａ）、冷杉属（Ａｂｉｅｓ）、铁杉属（Ｔｓｕｇａ）、桦属（Ｂｅｔｕｌａ）和桤木属（Ａｌｎｕｓ）等乔木植物花粉在表土中普遍存在。以松粉百分含量最高（平均２６．５％）。同藏南８个表土样花粉分析结果相比较，现代花粉雨反映了森林和草原植被的不同。在西藏高原影响松粉分布的主要因素是大气环流。

三江平原沼泽区的现代花粉雨

应用库尔式花粉收集器收集三江平原沼泽区１９９６年６月至１９９７年７月现代花粉雨滤网样品６０块（其中对照滤网样品２３块）。通过计算空气中各种花粉浓度，对照当地气象记录和现代植被景观，讨论三江平原沼泽区现代植被与花粉组成及传播的关系，从而为应用现代表土和化石孢粉谱对古植被、古环境的恢复提供更为可靠的参考。

基于遥感数据对中国表土花粉进行植被覆盖度定量估算的研究

本文主要探讨利用现代类比法将表土花粉数据定量转换为植被覆盖度的方法,以及该方法在中国复杂地貌和气候环境中应用的可行性和可信度。陆地植被覆盖使用了卫星遥感MODIS500×500m分辨率的栅格数据,覆盖度分类为乔木、草地和裸地三种。使用的表土花粉数据共1127个样点,其地理分布基本能够覆盖中国的各种植被类型。用于现代类比法定量计算的花粉变量类型共64个。研究结果表明,计算获得的每个样点的植被覆盖度与MODIS实际观测值具有很好的对应性,基于花粉的覆盖度估算值与遥感实际观测值之间的相关性很高,其中裸地达到0.99,乔木达到0.97,草地为0.95。从空间分布看,利用花粉定量转换的植被覆盖样点可以清楚地识别从裸地向草地和乔木的变化区间,并且与植被分布的实际情况吻合。本研究证明,基于中国表土花粉数据对植被覆盖度的定量恢复是可行的。此外,研究发现乔木覆盖度较高的对应特征花粉较多,主要是松属、栲属、栎属(含青冈栎)、桦属、桤木属、杨梅属、冷杉属、云杉属等,而草地的对应特征花粉类型有莎草科、禾本科、蒿属、蔷薇科、豆科等,裸地主要为麻黄属和藜科等。

现代松粉热模拟产物的碳氢同位素特征及其地质意义

对现代松粉在热模拟过程中生成的甲烷、乙烷、丙烷及干酪根碳同位素分析表明，低温阶段（250℃以下）松粉热模拟生成的甲烷相对较高温阶段生成的甲烷更富集13C，松粉热模拟残余干酪根较松粉原样稍微富集12C，反映低温阶段的热模拟产物主要来源于相对富集13C的松粉原生质。高温阶段（300℃以上）松粉热模拟生成的甲烷、乙烷、丙烷的13C值随温度升高而富集13C，松粉热模拟残余干酪根的碳同位素组成没有显著变化，与烃源岩干酪根热模拟成烃过程中的变化具有相似特征。在同一温度下，松粉热模拟生成的甲烷、乙烷、丙烷依次富集13C，与油伴生气中甲烷、乙烷、丙烷的碳同位素组成特征一致。松粉热模拟生成的甲烷的氢同位素组成特征与产自淡水沉积源岩的甲烷相似。高温阶段的热模拟产物主要来源于与干酪根具有相似结构及组成的孢粉素。

典型喀斯特石漠化地区表土孢粉与现代植被关系

喀斯特石漠化地区6个不同植被类型的25个表土和苔藓样品的孢粉分析表明:(1)研究区植物孢粉共由47科属组成,以草本和蕨类植物占据优势,含量为23.62%～76.47%,其次是乔木[主要为马尾松(Pinus masso-niana)],含量为17.73%～74.05%,灌木植物花粉含量最低,为0～12.50%,显示该区植被退化严重;(2)研究区不同植被类型的表土孢粉组合差别明显,与其相应的实际植被情况大致相同,基本反映了石漠化地区现代植被的基本状况,表明孢粉可以为该区恢复和重建自然生态环境提供参考性依据。

青藏高原全新世1月和7月气温序列重建

青藏高原自然环境受人类干扰相对较小,为利用古孢粉记录重建气候因子提供了可能,高原过去气候因子的重建对于预测未来气候变化趋势有重要意义.通过选取的29条高原化石孢粉记录,利用现代类比法和化石孢粉点与高原气温的函数关系,把化石孢粉点古气温转化为青藏高原古气温,重建了高原全新世1月和7月古气温序列.结果表明：对于1月和7月气温而言,全新世早期（11.5~8.5ka BP）为气温波动上升期;全新世中期（8.5~4.6 ka BP）为全新世大暖期,气温整体高于现代;全新世晚期（4.6 ka BP~至今）又可分为两个阶段,一个是4.6~2.4 ka BP,在此阶段1月和7月气温都有减小的趋势,另一个阶段则是2.4 ka BP至今,气温出现反常的趋势.