山西西部吕梁山中北段现代花粉散布特征

山西西部吕梁山中北段关帝山和芦芽山地区7个不同植被类型共计15个表土样品和7个捕捉器样品表土花粉组合特征和花粉通量研究表明:(1)表土和捕捉器样品花粉组合中主要类型与植被组成中优势类型一致.(2)关帝山与芦芽山现代花粉组合特征差异明显,芦芽山地区花粉组合中草本花粉占优势,百分比多高于50%,乔木花粉百分比多低于50%,花粉通量平均为27194 grains/(cm2 · a);关帝山乔木花粉占优势, 百分比多高于50%,草本花粉多低于30%,花粉通量平均为57961 grains/(cm2 · a).(3)松属、云杉属和蒿属花粉在表土样品中的百分比远高于捕捉器样品,显示较强的保存能力;落叶松属、桦属和栎属花粉在表土样品中的百分比明显低于捕捉器样品,显示花粉保存能力相对较差.(4)样品聚类分析和DCA分析结果显示:二者分析结果具有很好的一致性,花粉组合最主要的控制因子是温度.     

南京低山丘陵区表土及捕捉器花粉谱的差异探究

选取南京丘陵地区29处样点,分别搜集表土及捕捉器样品,开展两种采样方式下孢粉组合与植被关系研究。结果表明,南京低山丘陵地区花粉类型以松属、栎属、枫杨属、榆属、蔷薇科、菊科、禾本科为主,表土花粉组合较好地反映了现代植被特征。主成分分析可以大致区分人工草坪区、农田区以及森林区的样品。农田区表土花粉浓度最低,每克仅为4 964粒,农田的翻耕以及微生物环境是造成其花粉浓度低的重要原因;森林区花粉浓度(每克29 176粒)及花粉通量(49 358粒/平方厘米/年)均很高。人类活动的增强可能会造成孢粉浓度的下降。在探究本地区历史时期人类活动时,可运用孢粉浓度以及与农作物相关的孢粉类型的变化来分析。所有捕捉器样品的乔木花粉百分比均低于其对应的表土样品,其中以松属尤为明显。     

长白山针阔叶混交林带花粉通量及垂直散布年际对比

长白山针阔叶混交林一号样地2005和2006年气象塔不同高度捕捉器样品花粉分析对比表明:连续两年花粉组成都足以乔木花粉为主,但存在差异,06年乔木花粉百分比较高,灌木、草本较低,同时06年花粉通量也较高,可能与05年花期降水较多,温度较低,花粉产量低有关.连续两年花粉通量在垂直高度上具有较高的一致性,特别是主要乔木花粉类型(白蜡属、桦、栎、松属花粉).这一结果有助于更好理解表土花粉对植被的指示性,森林表土样品中的草本、低矮灌木花粉类型,应主要来自样品点附近的植物;样品中的乔木、较高灌丛花粉类型,可能来自样品点附近或更大范围植物;区域性植物对花粉组合也有一定影响.     

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.     

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     

太白山表土花粉和气孔器与植物类型的关系研究

通过陕西太白山13个样点表土花粉组合特征和气孔器及其与植物类型之间关系的分析,结果发现:针阔混交林花粉组合能很好地反映植物类型特征,落叶阔叶林和针叶林花粉组合能较好地与植物类型相对应,高山灌丛草甸花粉组合未能反映植物类型数量特征;主要花粉类型松属、铁杉属和桦属花粉具超代表性,胡桃属和榆属花粉具适宜代表性,落叶松属、冷杉属、杜鹃花科和槭属花粉具低代表性;DCA(Detrended Correspondence Analysis)分析表明,通过花粉数据能够较好区分不同植被类型,结合气孔器特征能够准确反映植被特征。     

青藏高原南部米拉山东、西坡表土花粉与现代植被关系研究

本文通过分析西藏米拉山东、西坡不同植被类型23个表土花粉样品,结合现代植被样方调查资料,探讨了米拉山地区表土花粉组合与现代植被的关系。结果显示,米拉山地区的表土花粉组合特征基本上能够反映出现代植被类型特征,但是在科属类别,组成方面又存在一定的差异性。同时,米拉山地区主要花粉类型代表性R值分析结果表明,灌木植物花粉杜鹃属具有低代表性,草本植物花粉蒿属、禾本科具有超代表性,而莎草科与蓼属则具有低代表性,这为本地区及相似地区古气候重建提供了基础和验证资料。     

燕山南部花粉散布特征

燕山南部花９粉用布特性研究表明,空气中的花粉反映的是植物花期的季节性变化,表 粉是植物多年花粉散布的混合,冲积物花粉与空气中和表土花粉显著不同,是取样点上游表土花粉的混合,与取样点周围植被关系较小。因此,根据冲积物花粉恢复古植被,反映的是整个流域的植被面貌,而不是某一点的植被特征。     

样地尺度现代表土花粉与植物群落的定量关系

建立现代植被与表土花粉的精确关系,是基于孢粉记录定量重建古植被与古气候的基础与关键。截止目前,植物群落样方记录较少参与到现代植被与花粉的统计分析中,限制了其精确关系的定量表达。本文通过中国东北样带的森林、草甸草原、典型草原和荒漠草原33个表土样品分析及植被样方调查,基于Bray-Curtis相异系数,研究了东北样带现代表土花粉与植物群落组成和数量之间的定量关系。结果表明: 由于花粉传播距离和花粉产量大小的不同,单个样点的所有科属、优势和常见科属、少见和稀有科属,在组成和数量上的关系存在差异。不同植被类型间差异显著,草甸草原在组成上差异较大,而所有科属、优势和常见科属的数量关系在森林中差异较大,少见和稀有科属的数量关系则在草甸草原中差异较大。不同科属的植被-花粉关系在组成和数量上的趋势基本一致,根据Bray-Curtis相异系数可将该地区花粉类群划分为3类: 超代表性类型、低代表性类型和适中代表性类型。该系数可以获得样方水平和物种水平上植被-花粉的物种组成和数量关系,是定量描述植被-花粉关系的有效指标之一。     

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     

Pollen input to, and incorporation in, two crater lakes in tropical northeast Australia

Pollen input to the water surfaces of maar crater lakes Barrine and Eacham (1km(2) and 0.5km(2) respectively, ca. 720m a.s.l.), surrounded by rainforest in northeastern Australia, were measured in floating Tauber traps for a variety of periods spanning the years 1978 to 1985. The mean weekly total pollen catch is 75% of that estimated for the surrounding region of varied vegetation. Regardless of their sources, the influxes of pollen taxa are unevenly distributed over the lakes' surfaces. There is similar variation through time, with some indication that this might be smoothed over periods of 5years or more. There are no inflow streams and pollen input down surrounding slopes is negligible. Mean total pollen influx to seston traps close to the lakes' bottoms (1979 to 1988) is <5% of that to the Tauber traps, a discrepancy attributed to trap design. In contrast, mean annual influx measured by the Tauber traps is similar to that estimated from dated sediment samples younger than 1966 AD at Lake Barrine. The proportions of different pollen taxa are less affected by trap position or period of exposure than are their influxes; their mean percentages for Tauber traps, seston traps and sediment samples are all rather similar.The similarity between the mean contribution of exclusively rainforest pollen to the lakes' surfaces (56%) and to Oldfield traps in rainforest interiors (51%) emphasizes the importance of the rainforests, which clothe the crater walls, as sources of pollen to the lakes. The impact of pollen from other vegetation in the region, although present, is much smaller than at interfaces between rainforest and other vegetation types. All this pollen is mixed within and above the crater and delivered to the lakes' surfaces by gravity and frequent rainfall. Limnological processes redistribute it in the water body before it is incorporated into the deep-lake sediments.The value and limitations of current pollen transport and accumulation theory are noted in relation to sites with morphologies similar to these two crater lakes and to the irregular flowering and floristic inhomogeneity of tropical rainforest. The potential for the use of modern pollen input data in the interpretation of pollen analyses from the sediments of such sites is explored.     

Holocene tree‐line fluctuations and climate in central troms,Northern Norway

Based mainly on pollen influx data, an attempt is made at reconstructing Holocene tree‐line fluctuations and palaeotemperatures in central Troms, North Norway. Both past and present‐day (Tauber trap) pollen influx data suggest that influx rates exceeding 250–300 pollen/cm²/year for each of the major arboreal taxa (Betula pubescens and Pinus sylvestris) are only found at sites with corresponding forest types in the immediate surroundings. High influx rates, raised tree‐lines and favourable climatic periods are recorded at 7500–4500 and 3000–2600 B.P. Betula and Pinus woodlands may have reached more than 200 m above their present altitude limits, suggesting a July mean temperature 2°C higher than at present during the Holocene optimum.     

Modern pollen samples from alpine vegetation on the Tibetan Plateau

• 1 A set of 316 modern surface pollen samples, sampling all the alpine vegetation types that occur on the Tibetan Plateau, has been compiled and analysed. Between 82 and 92% of the pollen present in these samples is derived from only 28 major taxa. These 28 taxa include examples of both tree (AP) and herb (NAP) pollen types.
• 2 Most of the modern surface pollen samples accurately reflect the composition of the modern vegetation in the sampling region. However, airborne dust‐trap pollen samples do not provide a reliable assessment of the modern vegetation. Dust‐trap samples contain much higher percentages of tree pollen than non‐dust‐trap samples, and many of the taxa present are exotic. In the extremely windy environments of the Tibetan Plateau, contamination of dust‐trap samples by long‐distance transport of exotic pollen is a serious problem.
• 3 The most characteristic vegetation types present on the Tibetan Plateau are alpine meadows, steppe and desert. Non‐arboreal pollen (NAP) therefore dominates the pollen samples in most regions. Percentages of arboreal pollen (AP) are high in samples from the southern and eastern Tibetan Plateau, where alpine forests are an important component of the vegetation. The relative importance of forest and non‐forest vegetation across the Plateau clearly follows climatic gradients: forests occur on the southern and eastern margins of the Plateau, supported by the penetration of moisture‐bearing airmasses associated with the Indian and Pacific summer monsoons; open, treeless vegetation is dominant in the interior and northern margins of the Plateau, far from these moisture sources.
• 4 The different types of non‐forest vegetation are characterized by different modern pollen assemblages. Thus, alpine deserts are characterized by high percentages of Chenopodiaceae and Artemisia, with Ephedra and Nitraria. Alpine meadows are characterized by high percentages of Cyperaceae and Artemisia, with Ranunculaceae and Polygonaceae. Alpine steppe is characterized by high abundances of Artemisia, with Compositae, Cruciferae and Chenopodiaceae. Although Artemisia is a common component of all non‐forest vegetation types on the Tibetan Plateau, the presence of other taxa makes it possible to discriminate between the different vegetation types.
• 5 The good agreement between modern vegetation and modern surface pollen samples across the Tibetan Plateau provides a measure of the reliability of using pollen data to reconstruct past vegetation patterns in non‐forested areas.

     

Comparison of pollen sampling with a Burkard Spore Trap and a Tauber Trap in a warm temperate climate

Aerobiological data have been widely used by many scientists, including those that study modern flora as well as those wishing to reconstruct past vegetational associations. Burkard (Hirst-type) volumetric spore traps are widely used instruments for studying airborne pollen, while Tauber traps are typically used to analyze pollen deposition. The present study compared the pollen collected by these two methods in Tulsa, Oklahoma a warm temperate area with year-round pollen. There was a strong correlation between the pollen influx from the Tauber traps and cumulative sum of average daily airborne pollen concentrations recorded with the Burkard spore trap over the course of 12 months from 1 Feb 1997 through 1 Feb 1998. The correlation coefficient between all taxa over the 12 months was 0.914; while the correlation coefficient for the monthly totals was 0.972. The data showed that both methods reflected local anemophilous vegetation although variations occurred in the prevalence recorded by both samplers.     

Pollen Analysis of Forest Surface Samples in Kunming Area

Pollen analysis of surface samples is one of the major means in study of pollen representation. The results of palynolopical study on 46 surface samples collected from plots with different vegetation types show that pollen assemblages in surface samples do not reflect major characteristics of vegetation within 20m radius of the surface samples, which is commonly accepted in forest surface sample studies. This is due to general low vegetation cover and broad distribution of pine forest in the study area. In order to avoid possible effects of large amounts of pollen from outside plots, it is considered necessary to test whether pollen in surface samples is mostly from within plots unler consideration or to choose areas with relatively evenly distributed vegetation before calculation of quantitative correction factors is attempted.     

Comparing pollen spectra from modified Tauber traps and moss samples: examples from a selection of woodlands across Europe

This paper compares pollen spectra derived from modified Tauber traps and moss samples from a selection of woodland types from Bulgaria, the Czech Republic, Georgia, Greece, Poland, Switzerland and Wales. The study examines the representation of individual taxa in the two sampling media and aims to ascertain the duration of pollen deposition captured by a moss. The latter aim was pursued through the calculation of dissimilarity indexes to assess how many years of pollen deposited in a pollen trap yield percentage values that are most similar to those obtained from the moss. The results are broadly scattered; the majority of moss samples being most similar to several years of pollen deposition in the adjacent trap. For a selection of samples, a comparison of the pollen accumulation rate in pollen traps with the pollen concentration in the moss per unit surface indicates that the entrapment and/or preservation of individual pollen types in the moss differ from that in the pollen trap. A comparison of the proportion of different taxa in the moss with the pollen spectrum of 2 years of pollen deposition in the trap also revealed large differences. There is a tendency for bisaccate grains such as Pinus and Picea to have a higher representation in moss than in traps but there is considerable regional variation. The results indicate that pollen proportions from moss samples often represent the pollen deposition of one area over several years. However, bisaccate pollen grains tend to be over-represented in moss samples compared to both pollen traps and, potentially, lake sediments.