Preliminary study on pollen distribution in the surface soil of the Turpan region in the southern slope of Tianshan Mountains,Xinjiang, China

Aims Our main purposes were to analyze the relationship between vegetation and pollen in the surface soil of the Turpan region, which is located in the southern slope of the eastern Tianshan Mountains, and to compare different pollen assemblages between the Turpan region and the northern slope of the Tianshan Mountains.Methods We collected 36 modern pollen samples and carried out modern vegetation survey in the Turpan region along an altitudinal gradient from 2 000 m to -154 m. Detrended correspondence analysis and Redundancy analysis were applied to analyze the distribution pattern of pollen in surface soils. Important findings We divided the pollen spectra into four pollen assemblage zones (mountain desert-steppe and desert, Gobi gravel, typical desert and salt mash vegetation), corresponding to the major vegetation types in the Turpan region. When compared with the northern slope, the characteristics of pollen assemblages in the mountain desert-steppe and desert were similar to those in the forest-steppe on the northern slope of the Tianshan Mountains; the pollen assemblages in the Gobi gravel and the typical desert seemed to be more consistent with those in the typical desert on the northern slope; however, no analogue was found in the salt mash vegetation. Obviously, the vertical pollen spectra in Turpan region were incomplete, lacking typical forest and Artemisia desert pollen zones. Besides, similar pollen zones in the Turpan region were found at an elevation of about 300 m higher than those in the northern slope. It is remarkable that the typical tree pollen, such as Picea and Pinus, showed their extra representation in the Turpan region. On one hand, the valley forest on the southern slope of the Tianshan mountains played an important role in pollen dispersal. On the other hand, with the cold air on the northern slope over the Tianshan Mountains, pollen may be carried and deposited in the Turpan region. The rivers feeding into Aiding Lake in the Turpan region may also contribute to the distribution of Picea and Pinuspollen. Lots of pollen studies have shown that the ratio of Artemisia to Chenopodiaceae (A/C) can be used as a good indicator of the degree of humidity in the semi-arid and arid areas. Our study revealed that A/C can roughly reflect the characteristics of the desert zone in the study area. The results of Redundancy Analysis ordination on pollen assemblages and environmental factors (mean annual temperature (MAT), mean annual precipitation (MAP) and altitude (ALT)) revealed that MAP was the main environmental factor affecting the pollen assemblages in the surface soil in the Turpan region and had more significant effects on the distribution of Nitraria pollen than on the distribution of Artemisia and Chenopodiaceae.     

西天山南坡表土花粉分析

通过对西天山南坡不同植被带52个表土花粉样品的鉴定,研究表土花粉组合与现代植被分布的关系,分析蒿属/藜科比值(A/C)在该区域的指示意义.结果表明:山顶至山底可以划分为5个植被带,分别为高山荒漠带、高山草甸带、草甸草原带、山地荒漠带、典型荒漠带,代表性科属为蒿属、藜科、禾本科和麻黄属,该区域不同植被类型表土样品花粉组合差异明显.西天山南坡表土花粉在一定程度上受到北坡的影响,海拔越高影响越大.A/C值随海拔升高而先升高再降低,在高山草甸区域达到最高,可以作为反映山地垂直方向气候干湿变化的有效指标.由于A/C值波动较大,利用该比值进行气候环境重建时,需注意受人类活动等因素影响所产生的高值可能带来误判.     

Anthropogenic and climatic impacts on surface pollen assemblages along a precipitation gradient in north‐eastern China

Aim To understand the scenarios of ‘anthropogenic biomes’ that integrate human and ecological systems, we need to explore the impacts of climate and human disturbance on vegetation in the past and present. Interactions among surface pollen, modern vegetation and human activities along climate and land‐use gradients are tested to evaluate the natural and anthropogenic forces shaping the modern vegetation, and hence to aid the reconstruction of vegetation and climate in the past. This in turn will help with future predictions. Location The North‐east China Transect (NECT) in north‐eastern China. Methods We analysed 33 surface pollen samples and 213 quadrats across four vegetation zones along the moisture/land‐use gradients of the NECT. Detrended correspondence analysis (DCA) and redundancy analysis (RDA) of 52 pollen taxa and three environmental variables were used to distinguish anthropogenic and climatic factors that affect surface pollen assemblages along the NECT. Results The 33 surface samples are divided into four pollen zones (forest, meadow steppe, typical steppe and desert steppe) corresponding to major vegetation types in the NECT. Variations in pollen ratios of fern/herb (F/H), Artemisia/Chenopodiaceae (A/C) and arboreal pollen/non‐arboreal pollen (AP/NAP) represent the vegetation and precipitation gradient along the NECT. DCA and RDA analyses suggest that surface pollen assemblages are significantly influenced by the precipitation gradient. Changes in the abundance of Chenopodiaceae pollen are related to both human activities and precipitation. Main conclusions Surface pollen assemblages, fossil pollen records, archaeological evidence and historical documents in northern China show that a large increase of Chenopodiaceae pollen indicates human‐caused vegetation degradation in sandy habitats. The A/C ratio is a good indicator of climatic aridity, but should be used in conjunction with multiple proxies of human activities and climate change in the pollen‐based reconstruction of anthropogenic biomes.     

Numerical Characteristics of Pollen Assemblages of Surface Samples from the West Kunlun Mountains

A total of 31 suface sediment samples were collected from West Kunlun Mountain in south Xinjiang Autonomous Region in northwest China. These samples are from seven types of vegetation: Picea schrenkiana Fisch. et Mey. forest, Sabina Spach. woodland, sub-alpine steppe, alpine meadow, desert vegetion, cushion-vegetation and vegetation adjancent to glaciers. Pollen percentages and pollen concentrations were calculated in all samples. The dominant pollen types in the region are Chenopodiaceae, Artemisia, Picea, Ephedra, Gramineae, Cyperaceae, Rosaceae, Leguminosae, Compositae etc. In order to reveal the relationship between pollen composition and the vegetation type from which the soil sample was collected, principal component analysis and group average cluster analysis were employed on the pollen data. The results revealed that the major vegetation types in this region could be distinguished by pollen composition: a. Samples from desert vegetation were dominated by pollen of Chenopodiaceae (about 60195%). The percentages of all other pollen types were low. b. Picea forest samples were rich in Picea pollen (about 20%) Sabina forest had more Sabina pollen grains than other vegetation types (about 5%, others <1%). Pollen percentages of Artemisia, Chenopodiaceae and Ephedra were comparatively higher (each about 20%) in these samples from the two types of vegetations. C. Pollen percentages of Artemisia, Cyperaceae, Gramineae and Chenopodiaceae were high in both sub-alpine steppe and alpine meadow. But steppe containal more Artemisia and Chenopodiaceae (steppe 33.75% and 32.30%, meadow 15.57% and 19.48% in average), less Cyperaceae and Gramineae (steppe 2.58% and 7.60%, meadow 22.35% and 12.93% in average) than meadow. d. Samples from cushion-vegetation and vegetation adjacent to glaciers were mainly composed of pollen grains transported from other sites. It was not easy to distinguish them from other vegetation types. Principal component analysis and cluster analysis distinguish samples from Picea forest, Sabina woodland, sub-alpine steppe, alpine meadow and desert vegetation. Therefore we think it will be possible to apply the module to reconstruct past vegetation in this region and other similar regions. Regression analysis was also applied to reveal the relationships between pollen and plant percentages of Artemisia, Chenopodiaceae, Cyperaceae and Gramineae. The results indicated that a linear relationship existed between pollen and plant percentages for Artemisia, Chenopodiaceae and Cyperaeeae.     

Modern pollen representation of source vegetation in the Qaidam Basin and surrounding mountains, north-eastern Tibetan Plateau

We use a data set of 35 surface pollen samples from lake sediments, moss polsters and top soils on the north-eastern Tibetan Plateau to explore the relationship between modern pollen assemblages and contemporary vegetation patterns. The surface pollen transect spanned four vegetation zones––alpine meadow, steppe, steppe desert and desert––under different climatic/elevational conditions. Relative representation (R _rel) values and Principal Components Analysis (PCA) were used to determine the relationships between modern pollen and vegetation and regional climate gradients. The results show that the main vegetation zones along the regional and elevational transects can be distinguished by their modern pollen spectra. Relative to Poaceae, a high representation of Artemisia, Nitraria and Chenopodiaceae was found, while Cyperaceae and Gentiana showed values in the middle range, and Ranunculaceae, Asteraceae, Ephedra and Fabaceae had low relative representation values. PCA results indicate a high correlation between the biogeoclimatic zones and annual precipitation and annual temperature and July temperature. The Artemisia/Chenopodiaceae ratio and the Artemisia/Cyperaceae ratio are useful tools for qualitative and semi-quantitative palaeoenvironmental reconstruction on the north-eastern Tibetan Plateau. Surface lake sediments are found to have different palynomorph spectra from moss cushion and soil samples, reflecting the larger pollen source area in the contemporary vegetation for lakes.     

内蒙古中部表土花粉研究

采用花粉百分含量分析和主成分分析方法对内蒙古中部表土花粉与植被的关系进行了对比研究 ,探讨了草原花粉组合的特点及其形成原因。研究发现 ,草原区表土花粉以藜科和蒿属 ( Artemisia)为主 ,并以前者占优势地位 ,麻黄属 ( Ephedra)亦较常见。草原区植被的 A/C(蒿属 /藜科 )值较干旱区草原植被为低 ,分布规律也较干旱区复杂 ,但仍能反应干旱程度的差别 ,而且还反映了草原植被的退化程度。松属 ( Pinus)和桦属 ( Betula)的花粉在个别样品中占有较大比例 ,是环境噪音 (指外源性的、超代表性的花粉 )的主要来源。不同植被类型在花粉组合上各有特点 ,可以从花粉百分含量的数量特征上进行区分。在研究中还发现草原区的严重退化在花粉组合上具有明显表现     

Study on Surface Pollen in Middle Inner Mongolia,China

The paper deals with features of pollen assemblages and their relationship to vegetation by comparing the results from surface pollen analysis with that from sample determination. It showed that Chenopodiaceae dominate with some Artemisia and a few Ephedra in steppe area. Although A/C (Artemisia/Chenopodiaceae) value was lower and more complicated than arid steppe area, it could reflect the humidity and the level of grass degeneration. The much more Pinus and Betula pollen percentage might be the main environmental noise source produced as statistical error. There were no obvious difference on pollen assemblage among the steppe types as Stipa gobica, S. krylovii, Peganum-Achnatherum except Artemisia and Chenopodiaceae pollen. However, there were some difference among meadow steppe, viz. sparse Ulmus pumila and Salisc tree, Aneurolepidium chinense and also the types like Salisc flavida, Stipa gobica, S. krylovii, Peganum-Achnatherum. Features of pollen assemblage in steppe degeneration and applications of PCA (principal component analysis) and method on surface pollen analysis were discussed.     

Late Holocene palaeoenvironment change in central Tianshan of Xinjiang,northwest China

The northern slopes of central Tianshan Mountains in Xinjiang, northwestern China can provide an ideal database to research palaeoclimate as disturbance by human impact is relatively low and the vegetation zones reflect climatic gradients. In order to establish the correlation between modern climatic factors and surface pollen assemblages and to reconstruct palaeoclimate on the northern slope of central Tianshan Mountains, three Holocene sections in Daxigou, Huashuwozi and Sichanghu located at different elevations and vegetation zones were chosen for study. A total of 80 surface pollen samples in 86 vegetation quadrats were collected for pollen‐vegetation relationship analysis. The Warmth Index (WI) and Moisture Index (MI) were calculated based on averaged modern climate data during 1951 – 2000 at eight weather stations in the study area. Pollen percentages of Picea, Artemisia, Chenopodiaceae, Ephedra, and Tamarix, as well as A/C (Artemisia/Chenopodiaceae) and AP/NAP (arboreal/nonarboreal pollen) ratio were selected as pollen variables and WI and MI were chosen as climatic variables. The relationship between pollen percentages (Picea, Artemisia, Chenopodiaceae and Tamarix), A/C, AP/NAP ratio, WI and MI values were estimated (95% confidence interval) using stepwise multiple linear regression analysis. WI and MI values for the three sections were calculated using these regression equations, and palaeoclimate for the study area could be reconstructed. The results showed periods of both cool‐humid and warm‐dry conditions on the northern slopes of Tianshan Mountain during the late Holocene.     

Modern pollen and land-use relationships in the Taihang mountains, Hebei province, northern China—a first step towards quantitative reconstruction of human-induced land cover changes

Studies of the modern relationship between pollen, vegetation and land-use are essential to infer past human impact on vegetation from pollen records. Nevertheless, such investigations are relatively few in China. We present here a study of pollen assemblages from sediment samples collected from irrigation pools in the Tuoliang and Qipanshan catchments in northern China. Pollen and spores from natural vegetation such as Artemisia, Chenopodiaceae, Pinus and Selaginella sinensis dominate the pollen assemblages, while pollen types which could be from crops such as cereals, Brassicaceae, Fabaceae, Solanaceae, Apiaceae and Cucurbitaceae are common but not abundant. Pollen percentages of Artemisia and Chenopodiaceae become less with decreasing altitude, while Pinus and S. sinensis percentages increase, indicating that saccate Pinus pollen and S. sinensis spores are transported further than non-saccate Artemisia and Chenopodiaceae pollen, and differential sorting of pollen is occurring during transport in river water. Proportions of pollen from farmland and crops increase with decreasing altitude, showing that pollen percentages of crops might be a good indicator of the extent of farmland. A linear correlation analysis between pollen percentages and vegetation proportions shows that pollen percentages of crops are positively correlated with proportions of farmland, while correlation between pollen percentages of trees, shrubs and herbs and proportions of woodland, scrubland and grassland respectively is poor. This study indicates that the relationship between pollen percentages and vegetation proportions can be explained by the differences of pollen productivity, dispersal and deposition, and might be the basis for a modelling approach to infer past vegetation cover in northern China.     

华北泥河湾盆地植被、气候与早期人类生存环境研究进展

中国北方泥河湾盆地可以与非洲奥杜威峡谷相媲美, 它们具有十分相似的地质演化过程, 这里河湖相沉积发育, 并且蕴藏着丰富的古生物化石和大量古人类遗迹, 是研究东亚早期人类生存环境变化的重要区域。基于前人积累的晚上新世以来植被、气候及早期人类生存环境的大量研究资料, 经分析发现在大约2.6 Ma (百万年), 泥河湾盆地的植被由阔叶林转变为以针叶林为主; 大约1.92 Ma以后, 植被以温带森林-草原(主要是松属、蒿属及藜科)/温带草原(主要是蒿属和禾本科等)为主。通过对比发现, 晚上新世以来中国北方从西部到中部, 由森林转变为以森林-草原为主的植被类型出现的时段呈现明显的阶梯型。此外, 泥河湾盆地气候出现了13个冷暖旋回, 15个干湿旋回, 显著的冷干事件发生在2.8 Ma、2.6 Ma、1.92 Ma及143.8 ka (千年), 湿润事件发生在43、32和6.6 ka。早期人类生活在森林-草原或以草原为主的植被环境中, 气候冷暖干湿波动较大, 水源丰富, 大量哺乳动物共存。建议在建立泥河湾人类遗址更为精细地层的年代框架下, 开展古气候温度与降水参数的定量化研究, 将有助于精准重建古人类生存环境及揭示其变化规律。     

新疆阿尔泰红山嘴地区的表土孢粉与现代植被

在新疆阿尔泰山中段的红山嘴地区选取一条沿海拔745-2 413 m的不同植被带群落样方进行调查, 对应采集37个表土样品进行孢粉统计和排序分析, 初步探究了红山嘴地区的植被与表土孢粉之间的对应关系, 并将之与新疆阿尔泰西部的喀纳斯西坡孢粉垂直带进行对比。结果表明, 红山嘴地区表土孢粉谱依照海拔高度自上而下划分为4个孢粉组合类型, 分别对应亚高山草甸、山地森林、灌丛草原和荒漠草原。乔木植物中云杉属(Picea)和松属(Pinus)花粉, 灌木植物中麻黄属(Ephedra)及草本植物中的苋科和蒿属(Artemisia)因受到自然风力、水流及人为活动的影响, 表现出明显的超代表性; 乔木植物中的落叶松属(Larix)花粉, 草本植物中的禾本科及莎草科花粉, 却在其自身为优势种的群落中呈现低代表性; 蒿属与苋科花粉百分含量的比值(Ar/Am)能较好地反映该区气候垂直带的干湿状况, 灌丛草原带的Ar/Am低, 在一定程度上反映了人类活动对草原灌丛化的影响。与新疆阿尔泰西部的喀纳斯西坡孢粉垂直带相比, 红山嘴垂直带的孢粉类型偏少, 同时相似的孢粉带在该区的分布高度比喀纳斯西坡高。此外, 排序分析(RDA)结果表明, 年降水量是影响该区表土孢粉组合的主要环境因子。     

Reassessment of Holocene vegetation change on the upper Tibetan Plateau using the pollen-based REVEALS model

Previous studies based on fossil pollen data have reported significant changes in vegetation on the alpine Tibetan Plateau during the Holocene. However, since the relative proportions of fossil pollen taxa are largely influenced by individual pollen productivities and the dispersal characteristics, such inferences on vegetation have the potential to be considerably biased. We therefore examined the modern pollen–vegetation relationships for four common pollen species on the Tibetan Plateau, using Extended R-value (ERV) models. Assuming an average radius of 100 m for the sampled lakes, we estimated the relevant source area of pollen (RSAP) to be 2200 m (which represents the distance from the lake). Using Poaceae as the reference taxa (Pollen Productivity Estimate, PPE = 1), ERV Submodel 2 derived relative high PPEs for the steppe and desert taxa: 2.079 ± 0.432 for Artemisia and 5.379 ± 1.077 for Chenopodiaceae. Low PPEs were estimated for the Cyperaceae (1.036 ± 0.012), whose plants are characteristic of the alpine Kobresia meadows. Applying these PPEs to four fossil pollen sequences since the Late Glacial, the plant abundances on the central and north-eastern Tibetan Plateau were quantified using the “Regional Estimates of Vegetation Abundance from Large Sites” (REVEALS) model. The proportions of Artemisia and Chenopodiaceae were greatly reduced compared to their original pollen percentages in the reconstructed vegetation, owing to their high productivities and their dispersal characteristics, while Cyperaceae showed a relative increase in the vegetation reconstruction. The reconstructed vegetation assemblages of the four pollen sequence sites always yielded smaller compositional species turnovers than suggested by the pollen spectra, as revealed by Detrended Canonical Correspondence Analyses (DCCA) of the Holocene sections. The strength of the previously reported vegetation changes may therefore have been overestimated, which indicates the importance of taking into account pollen–vegetation relationships when discussing the potential drivers (such as climate, land use, atmospheric CO₂ concentrations) and implications (such as for land surface–climate feedbacks, carbon storage, and biodiversity) of vegetation change.     

中国草原区主要群落类型花粉组合特征

现代表土花粉组合与植被关系研究是推断过去植被演化的基础。对中国草原区 39个样点进行植被调查及表土花粉分析的研究结果表明 ,表土花粉组合可反映出草原植被的总体特征。大多数样品中乔木花粉百分比低于 5 %。蒿属、藜科是草原区所有样品花粉组合中最主要的成分 ,两者在花粉组合中所占比例多大于 5 0 % ,且人类活动越强或气候越干旱 ,蒿属、藜科花粉所占百分比越高。花粉组合不能反映群落结构特征 ,如建群种、结构、盖度等的差异在花粉组合中表现不出来。即使以禾本科为建群种的草原群落 ,禾本科花粉所占比例也多低于 10 %。花粉浓度在草原区花粉与植被关系研究中意义不明确。典型草原与荒漠草原花粉组合存在明显区别 ,无倾向性对应分析 (DCA)分析表明 ,典型草原区样品在第一排序轴的排序值多高于 0 ,荒漠草原区样品的排序值小于 0 ;典型草原区藜科花粉百分比一般低于 2 5 % ,花粉类型多样性指数大于 2 ,当蒿藜占花粉总数的 5 0 %以上时 ,蒿藜比值大于 2。荒漠草原区藜科花粉含量多高于 2 5 % ,蒿藜比值多为 0 .5～ 2 ,花粉类型多样性指数多为 1～ 2。蒿属花粉属超代表性 ,但在蒿类建群的群落中 ,蒿属花粉多低于其在植被中的百分比     

毛乌素沙地海流兔河流域植被净初级生产力估算

采用CASA(Carnegie-Ames-Stanford Approach)模型,结合TERRA MODIS卫星数据和气象数据,对毛乌素沙地海流兔河流域2015年各月的植被净初级生产力(NPP)进行估算,并对植被NPP月平均值的时空分布规律及其与气象因子和地下水位埋深的关系进行了分析.结果表明:毛乌素沙地海流兔河流域2015年植被NPP总量为2.88×1011 g,生长季(4月份至10月份)的植被NPP总量达2.81×1011 g,占全年植被NPP总量的97.57%.随着时间推移,植被NPP月平均值和归一化差分植被指数(NDVI)月平均值呈"缓慢增加—急剧增加—急剧下降"的变化趋势.植被NPP月平均值季节变化明显,春季、夏季、秋季和冬季植被NPP月平均值之和分别为20.55、69.39、20.46和0.48 g·m-2.从空间分布上看,中部河谷和滩地的植被NPP月平均值总体上高于东南部、西部和西北部等沙丘荒漠区.月平均气温对植被NPP月平均值变化的影响最大,其次为平均实际日蒸散发量和地表月太阳辐射.植被NPP月平均值随着地下水位埋深的增加而减小,最大值出现在地下水位埋深1~2 m之间.上述研究结果显示:采用CASA模型可以较好地估算毛乌素沙地海流兔河流域植被NPP值,月平均气温和地下水位埋深对该流域植被NPP值的影响较大.     

A survey of modern pollen and vegetation along a south–north transect in Mongolia

Aim This modern pollen‐rain study documents the spatial and quantitative relationships between modern pollen and vegetation in Mongolia, and explores the potential for using this relationship in palaeoclimatic reconstructions. Location East‐central Mongolia. Methods We collected 104 pollen surface samples along a south–north transect across five vegetation zones in Mongolia. Discriminant analysis was used to classify the modern pollen spectra into five pollen assemblages corresponding to the five vegetation zones. Hierarchical cluster analysis was used to divide the main pollen taxa into two major groups and seven subgroups representing the dry and moist vegetation types and the main vegetation communities within them. Results Each vegetation zone along the transect can be characterized by a distinctive modern pollen assemblage as follows: (1) desert zone: Chenopodiaceae–Zygophyllaceae–Nitraria–Poaceae pollen assemblage; (2) desert‐steppe zone: Poaceae–Chenopodiaceae pollen assemblage; (3) steppe zone: Artemisia–Aster‐type–Poaceae–Pinus Haploxylon‐type pollen assemblage; (4) forest‐steppe zone: Pinus Haploxylon‐type–Picea–Artemisia–Betula, montane forb/shrub and pteridophyte pollen assemblage; and (5) mountain taiga zone: Pinus Haploxylon‐type–Picea–Poaceae–Cyperaceae, montane forb/shrub and Pteridophyte pollen assemblage. Main conclusions Based on the ratio between the major pollen taxon groups and subgroups, we propose two pollen–climate indices that represent the precipitation and temperature conditions in the study region. When plotted along our south–north transect, the moisture indices (M) and temperature indices (T) mimic the regional gradients of precipitation and temperature across Mongolia very closely. These pollen–climate indices can be used for palaeoclimatic reconstruction based on fossil pollen data.     

新疆巴里坤湖8.8cal.kaBP以来植被演替的花粉记录

本文利用新疆东部巴里坤盆地内巴里坤湖的地层孢粉记录,结合14C定年,重建了该地区8.8cal.kaBP以来植被的演化历史.结果表明在8.8-8.0cal.kaBP、8.0-4.3cal.kaBP、4.3-3.8cal.kaBP、3.8-0.6cal.kaBP以及0.6cal kaBP至今,植被分别经历了荒漠、荒漠草原/草原、荒漠、荒漠草原/草原再到荒漠的演化过程.研究区中全新世以来的这种植被变化模式与亚洲中部干旱区的其它研究记录具有很好的一致性.     

黑龙江青冈地区晚更新世猛犸象-披毛犀动物群生存的环境背景

更新世晚期大型哺乳动物消亡一直是科学界关注的热点科学问题,其消亡的环境背景和影响机制仍没有形成一致观点。我国东北地区晚更新世地层中保存有丰富的猛犸象-披毛犀动物群(Mammuthus-Coelodonta Fauna)化石记录,是研究更新世晚期大型哺乳动物生存环境及消亡过程的理想区域。黑龙江省青冈地区出土有典型的晚更新世哺乳动物化石种类,如真猛犸象(Mammuthus primigenius)、披毛犀(Coelodonta antiquitatis)等。本文以青冈县英贤村化石出土剖面为研究对象,通过孢粉分析,重建猛犸象-披毛犀动物群的生存环境背景。青冈地区猛犸象-披毛犀动物群出土于湖沼相沉积中,研究发现其生存环境的主要植被成分是蒿属、菊科、禾本科、莎草科和云杉属,指示草甸草原为主,局地生长有针叶林的植被景观。欧亚大陆晚更新世高纬度地区广泛分布的猛犸象草原植被曾延伸到我国东北地区。     

塔落岩黄芪主要传粉蜂的传粉效率研究

塔落岩黄芪 (Hedysarum laeve)是毛乌素沙地重要豆科植物, 在我国西部生态系统恢复与重建中起着重要作用, 但其自交率非常低, 必须依靠传粉昆虫授粉才能结实。野生传粉蜂是其主要传粉者。为了明确塔落岩黄芪的主要传粉蜂组成及优势传粉蜂的传粉效率, 2004–2006年, 我们设置了4个2 m×2 m样方观测访花昆虫的组成并对主要传粉蜂的访花频率、花粉移出率和柱头花粉沉降数目及单花停留时间进行了观测。结果表明白脸条蜂(Anthophora albifronella)、海切叶蜂(Megachile maritima)和散熊蜂(Bombus sporsdicus)是塔落岩黄芪的主要传粉蜂, 其中白脸条蜂在数量和访花频率上占有明显优势, 但其花粉移出率比海切叶蜂和散熊蜂的低, 3种蜂的柱头花粉沉降数目没有显著区别。通过对这3种蜂的花粉移出率、柱头花粉沉降数目和访花频率综合分析后, 我们认为白脸条蜂是塔落岩黄芪最有效的传粉蜂。     

半干旱区气候变化和人类活动的孢粉指示

中国半干旱区是季风气候影响的边缘地区,气候波动性明显,文明的演化表现为农牧业交替,而当前的土地利用则表现为农牧交错.用孢粉学证据复原这一地区复杂的气候变化和人类活动历史的前提是区分不同孢粉类群的指示意义,并提出在景观和区域尺度上复原植被演化历史的模式.本文通过中国半干旱区不同地点沉积剖面的对比分析,结合表土花粉和现代植被地理研究,从孢粉来源的角度对以上科学问题进行了探讨,结果表明:1)桦属、蔷薇科、石竹科和白刺属的花粉最能反映降水量和湿度变化;云杉和冷杉属花粉是温度变化的良好指示体;藜科、蒿属、菊科等的花粉含量与气候和人类活动均有密切的关系;禾本科植物的峰值,在低人为干扰和高人为干扰的情况下都有出现,其花粉含量较多地反映了人类活动的影响;车前属植物主要出现在低湿地点,低的车前属花粉含量(5%以内)在半干旱区对气候干湿变化的指示意义更明显;高的榛属花粉含量(10%以上)更多地指示森林破坏之后的灌丛化.2)藜科植物常在干涸湖泊周边形成盐化草甸,可以导致沉积物中藜科花粉含量的富集.3)地形条件导致了森林-草原交错带林草植被的镶嵌分布,森林一般分布在陡阴坡,由于温度升高导致蒸发加强,区域气候变暖湿可能使得阴坡更湿而阳坡更旱,从而出现更喜湿的乔木与更耐旱的草本植物共存.     

内蒙古中部四子王旗荒漠草原过渡带表土花粉分析

通过研究内蒙古中部四子王旗地区的表土花粉,试图揭示荒漠草原地区小尺度范围中表土花粉的植被和气侯指示意义.源自4个不同植物群落的19块表土花粉显示:研究区表土花粉组合主要以草本植物蒿属(Artemisia)、藜科(Chenopodiaceae)花粉占优势,两者百分含量一般在60%以上;禾本科(Poaceae)花粉具低代表性,平均含量在5%左右;另含有一定数量的白刺属(Nitraria)、麻黄属(Ephedra)、菊科(Asteraceae)和葱属(Allium)等花粉为特征.笔者首次提出的(蒿属+禾本科+菊科)/(白刺属+麻黄属+藜科)百分比值,有效地揭示了研究区北部较南部要干旱,与A/C比值及当地现生植被生境和气候因子相吻合.研究结果对我国内陆干旱、半干旱荒漠草原区第四纪古植被的恢复,以及古气候的重建提供了参照依据.