Pollen–vegetation relationships along steep climatic gradients in western Amazonia

Question: How accurately do Amazonian montane forest pollen spectra reflect the vegetation? Can compositional changes observed in the vegetation along environmental gradients be identified in the pollen spectra? How well do herbarium collection data and bioclimatic envelopes represent abundance changes along elevation gradients? Location: Amazonian montane forests, Peru. Methods: Moss polsters collected along five altitudinal transects spanning over 3000 m a.s.l. were used to characterize pollen spectra. Vegetation plot data from a network of 15 1‐ha permanent plots were used to correlate pollen spectra with present‐day vegetation. Probability density functions (PDFs) fitted to pollen and plot data allowed comparisons using Spearman correlation coefficients. Ordination analyses were used to summarize changes in pollen spectra. Correlations between pollen‐based PDFs and previously‐published herbarium collection PDFs were also evaluated. Results: Pollen spectra closely reflected changes in species composition along elevation gradients. A mid‐elevation shift in pollen spectra was identified using ordination analyses. Pollen spectra from the driest forest in our data set were statistically different from those of wet forests. Pollen abundance PDFs along the altitudinal gradient were significantly correlated (P<0.01) with PDFs fitted to plot abundance, basal area and herbarium collection data for ten out of 11 taxa analysed. Conclusions: Pollen spectra closely reflected the vegetation composition of Amazonian montane forests. The differentiation of pollen spectra from dry localities showed the potential of genus‐level pollen data to reflect precipitation gradients. Pollen spectra also reflected mid‐elevation compositional changes well along the lower elevation limit of ground cloud formation. Despite collection biases, herbarium‐based bioclimatic envelope PDFs also represented well forest compositional changes along elevation gradients.     

Pollen flow in Eucalyptus grandis determined by paternity analysis using microsatellite markers

Gene flow by pollen dispersal from forestry plantations containing introduced species, provenances or selected elite breeding material may impact on local native forest by changing the genetic diversity, introducing new genes or gene combinations, or causing the extinction of rare genotypes in adjacent native forest areas. Patterns of pollen flow can be used to assess the risk of genetic pollution of native forest areas from nearby plantations. Pollen flow in an artificial population of Eucalyptus grandis was estimated using molecular markers and paternity analysis. Microsatellite genotyping was used to identify pollen parents of progeny arrays from six mother trees. Of 329 progeny analysed, 178 (54%) were assigned to pollen parents within the population. Pollen parents located within the population were between 0–192 m from the respective mother trees, with an average pollination distance of 57.96 m. Pollination of mother trees was outcrossed, not by nearest neighbours, and displayed a preference for inter-provenance matings within the population. Progeny that could not be assigned pollen parents within the population (46%) were assumed to have resulted from pollen immigration from external sources. These pollen flow parameters provide useful information about the dynamics of pollen movement within E. grandis populations and may be used in risk assessment of gene flow from plantations to adjacent areas of native forest.     

Analysis of protein content in pollen loads produced in north-west Spain

An analysis was made of the protein content of pollen loads produced by the bees in a hive situated in Viana do Bolo (Ourense, north-west Spain), to establish whether or not the relative quantity of protein in the pollen of each plant species influences the preference made by the bee of the flowers that supply pollen to the hive. This analysis was performed on all types of pollen that formed more than 5% of the pollen spectrum. Pollen load samples were collected directly from the hive from March to September. Pollen loads were separated by colour, and their specific homogeneity was confirmed microscopically. The Bradford method has been used for protein extraction and spectrophotometry was used for the determination of protein content. The results show that the different pollen loads have high protein content. Pollen of the plant species that reached relatively higher percentages in the pollen spectrum are also those that have the highest protein content. These were Cytisus scoparius type, uncultivated Poaceae, Quercus robur type, Sanguisorba minor, Salix fragilis and Spergularia rubra type. The pollen of the systematic units, which had pollen loads that could be identified at the level of species, maintained a constant value of protein content independently of the date the samples were obtained. The pollen of the systematic units, which had pollen loads that could be identified at the level of pollen type, has varied in protein content in the analyses performed on samples obtained on different dates. This result is due to the fact that the different species that integrate the pollen type flower on different dates, and thus have a pollenkitt with different characteristics.     

不同群落中四川大头茶（Gordonia acuminata）花粉游离脯氨酸含 …

四川大头茶（Ｇｏｒｄｏｎｉａ ａｃｕｍｉｎａｔａ）是缙云山亚热带常绿阔叶林的优势树种之一,对缙云山３种不同群落中四川大头茶的花粉游离脯氨酸含量和果实的种子产量进行了研究,发现花粉游离脯氨酸含量和每果种子产量在同一群落中的不同龄级四川大头茶个体间没有差异,但在不同群落间表现差异,常绿阔叶林中的四川大头茶个体具有最高的花粉游离脯氨酸含量和每果种子产量,四川大头茶纯林中的次之,针阔混交林中的最低。分析发     

不同群落中四川大头茶 (Gordonia acuminata)花粉游离脯氨酸含量与种子产量

 四川大头茶(Gordonia acuminata)是缙云山亚热带常绿阔叶林的优势树种之一。对缙云山3种不同群落中四川大头茶的花粉游离脯氨酸含量和果实的种子产量进行了研究,发现花粉游离脯氨酸含量和每果种子产量在同一群落中的不同龄级四川大头茶个体间没有差异,但在不同群落间表现出差异。常绿阔叶林中的四川大头茶个体具有最高的花粉游离脯氨酸含量和每果种子产量,四川大头茶纯林中的次之,针阔混交林中的最低。分析发现,四川大头茶花粉游离脯氨酸含量与果实的种子产量有密切的正相关关系,花粉中的游离脯氨酸含量可以作为一种预测和比较相同地区不同生态环境中四川大头茶种子产量的指标。     

Holocene forest development along the Setesdal valley, southern Norway, reconstructed from macrofossil and pollen evidence

The Setesdal valley in South Norway runs north to south for 200 km, from alpine vegetation at 1200 m, passing the tree-line at around 1000 m, through Boreal forests, to Nemoral forest at sea level. The Holocene vegetation history and its altitudinal differentiation were reconstructed using pollen percentages and influx and plant macrofossil concentration records from four lakes along an altitudinal transect. During the early Holocene (c. 10500–8000 cal b.p.) Betula pubescens, Pinus sylvestris, Alnus, and Corylus expanded in the lowlands. Only Pinus and B. pubescens reached 1000 m asl (Lille Kjelavatn). Only B. pubescens reached Holebudalen (1144 m asl) at about the same time as it arrived in the lowlands. Between c. 8000–3000 cal b.p. mixed deciduous forest developed around Dalane (40 m asl) and to a lesser extent around Grostjørna (180 m asl), birch woodland with pine surrounded Lille Kjelavatn and birch woodland occurred at Holebudalen. From c. 3000 cal b.p. to present, the vegetation at Dalane hardly changed except for slight human impact and the immigration of Picea abies. At Grostjørna Pinus expanded. At Lille Kjelavatn Pinus disappeared and Betula became sparse as at the tree-line today. Betula retreated from Holebudalen thus leaving it above the tree-line in low-alpine vegetation. The strengths and weaknesses of pollen and plant macrofossil data were assessed for forest reconstructions. Where local pollen production is low, as near the tree-line, percentages of long-distance tree pollen can be misleadingly high. Pollen influxes of Betula and Pinus were much smaller near their altitudinal limits than at lower altitudes, although their macrofossils were equally abundant. The limited dispersal capacity of macrofossils documents the local presence of species and the character of the local vegetation, although macrofossils of some tree taxa are rarely found. Pollen and plant macrofossil evidence complement each other to provide a more complete reconstruction of Holocene tree-limits and tree-lines and hence climate changes, than either form of evidence alone.     

Pollen from tree and shrub taxa in the atmosphere of Caxias do Sul (Rio Grande do Sul, Brazil)

An aerobiological study has been carried out in the region of Caxias do Sul in southern Brazil. Pollen monitoring was performed from January 1, 2001 through to December 31, 2002. A total of 30,469 pollen grains were collected during this period, and 40 pollen types were identified; of these, 23,389 pollen grains, representing 29 pollen types, originated from tree and shrub taxa. The maximum pollen concentration was registered in August 2001 and October 2002. In the study area, the pollen type Mimosa scabrella (18.8%) was much more abundant than all of the pollen types from tree and shrub taxa, such as: Urticaceae (18.4%), Myrtaceae (10.2%), Cupressaceae (7.7%), Myrsine (4.8%), Sorocea (3.9%), Pinaceae (2.9%), Asteraceae (2.2%) and Ricinus (2.1%). These nine pollen types accounted for the largest pollen concentrations of all the tree and shrub taxa. The pollen types Carya, Melastomataceae, Mimosa scabrella, Myrsine and Sorocea are reported for the first time in an aerobiological study in Brazil.     

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.     

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.     

泽泻科的花粉形态研究

本文对泽泻科11属27种代表植物的花粉进行了光学显微镜、扫描电镜和透射电镜观察。在系统描述了该科及各属植物花粉形态的基础上,将泽泻科植物的花粉划分为3种类型,即少果泽苔草型、慈菇型和泽泻型。根据花粉形态特征的比较,并依据泽泻科植物祖先类群的花粉具有船形、具单沟萌发孔、花粉外壁具明显的刺状纹饰、覆盖层完整无通道等特征,作者认为泽泻科植物花粉形态的如下演化趋势是明显的：由船形演化为卵球形、球形和多面体球形;由单沟萌发孔经过一无孔的中间类型演化为散孔类型;孔膜由光滑演化为具颗粒和小刺;萌发孔不内陷进化到内陷;花粉粒外壁的刺状纹饰逐渐过渡为颗粒状纹饰或者消失,以及覆盖层由无通道到具细通道和通道。     

Pollination success in a population of dioecious rain forest trees

Pollination success in female trees was determined for a population of Neolitsea dealbata (R. Br.) Merr., a locally abundant dioecious tree pollinated by small, unspecialized insects in northern Queensland rain forest, Australia. The population consisted of a clustered group of trees with a mean male-to-female distance of 4.5 m and more isolated individuals, including females more than 90 m away from the nearest pollen source. A map of all reproductive trees was produced to determine accurate male-to-female distances. The size of the pollen source available to females was defined as a function of the distance to the nearest ten male trees and their sizes (male neighbourhood index). The rate of pollen movement to females was measured by counting pollen tubes (and the number of tubes per style) in female trees 6 days after the commencement of population flowering. The pollination rate decreased steeply to less than half when the nearest male was only 6.5 m away. Although pollen reached a female 330 m away from the nearest pollen source, only 10% of receptive flowers had been pollinated. The short flowering period (2–3 weeks) combined with the the slow rate of pollen movement means that a large proportion of flowers in isolated trees are unpollinated, confirming an earlier finding that isolated females set fewer fruits than gregarious females. The reliability of pollen transfer to females was determined by quantifying insects and their pollen loads trapped at female trees with a range of male neighbourhood indices. Quantities of insects and pollen were significantly correlated with the size of the male neighbourhood index, indicating a strong density-dependent response by vectors to flowering. Pollen was also collected from insect visitors to non-flowering trees. Females with large male neighbourhood indices received more pollen than non-flowering trees with equivalent male neighbourhood indices. However, when the male neighbourhood indices were small for both female and non-flowering trees, the changces of pollinators encountering female and non-flowering trees were similar, suggesting random movements of pollinators in sparse-flowering sub-populations. The dioecious breeding system, brief, synchronous flowering period, clustered population structure and random, opportunistic foraging behaviour of vectors interacted in a way that reduced reproduction in relatively isolated trees. These results demonstrate a mechanism for differential breeding success between trees in natural populations and emphasize the possible impact of logging regimes on pollen flow between trees. Large interconspecific distances in species-rich environments may have been a factor in the selection for synchronous flowering between trees in outcrossing tree species with generalist insect pollinators.     

The Pollen Morphology in Relation to the Taxonomy and Phylogeny of Fagaceae

The present paper deals with the pollen morphology of 103 species belonging to sixgenera-Castanea, Castanopsis, Lithocarpus, Quercus, Fagus and Trigonobalanus in threesubfamilies-Castaneoideae, Quercoideae and Fagoideae. All pollen grains were examinedunder light microscope and scanning electron microscope, and those of some species were ex-amined under transmission electron microscope. The results may be summarised as follows:1. Pollen morphology of Fagaceae, seems to support division of the family into threesubfamilies. Fagoideae, Castaneoideae and Quercoideae.2. Four types of pollen grains are recognized in Fagaceae:1) Fagus-type (representative genus: Fagus): pollen granis are oblate-sphaeroidal,(31.5-39.9) x (35.7 46.2) μm in size, 3(-4)-colporate, peritreme or goniotreme, granulate-ornate under LM., granulate or verrucate under SEM.2) Trigonobalanus-type (T. doichangensis): pollen grains are suboblate-sphaeroidal,(23.1-29.4) ×(25.2-29.4) μm in size, 3-colporate, goniotreme, obscurely granulate-ornateunder LM, densely granulate or verrucate under SEM.3) Quercus-type (Quercus): pollen grains are subspheroidal-subprolate, (21-44.3)× (16.8-39.9) μm in size. 3-colporoidate (-3-colpate), peritreme, crassgranulate or finely-gra-nulate under LM, tuberculate verrucate or spinate under SEM.4) Castanea-type (including Castanea, Castanopsis, Lithocarpus): Pollen grains areprolate-supraprolate, (14.7-23.1)×(10.5-16.8)μm in size; 3-colporate, peritreme, obscu-rely ornate or subpsilate, under LM, rugulose, striate-rugulate or crass-striate under SEM.3. Pollen grains of Cyclobalanopsis age very similar to those of Quercus, and there-fore we support the treatment of Cyclobalanopsis as a subgenus of Quercus.4. On the basis of shape, type of aperture and exine structure, pollen of Trigonobalanusis distinguishable from those of the other genera in Fagaceae and it may be a new type of Fagaceae;5. On the basis of pollen morphology, morphological characters and geological stratification a scheme of phylogeny of Fagaceae is here presented.     

罗布泊地区第四纪环境演化

新疆罗后干涸湖盆中的Ｋ１钻孔揭示,１００、２ｍ的沉积剖面共有９２个宙积层,划归１６同积旋回,包括了早更新世以来的各时期沉积。据划分的１５个孢粉组这及古地磁、１４＾Ｃ、岩石地层资料综合分析,早更新世该区曾发育森林－草原植被,早更民末,强烈的构造运动保留我下更充变形,上覆的中更统与下更新统间呈不整合接触。中更新世,荒漠和荒漠草原交替出现,地层中有大量膏质泥岩和石膏。晚更新世以来,在干旱气候的控制之下,     

Effects of pollen competitive environment on pollen performance in Mirabilis jalapa (Nyctaginaceae)

 We examined the influence of pollen competitive environment on pollen performance in Mirabilis jalapa. We used the number of pollen grains and the number of pollen tubes per pistil as measures of pollen competition. Pollen germination, pollen tube penetration into the style, and pollen tube growth rates were used as measures of pollen performance. All three measures of pollen performance were affected by the competitive environment. Pollen germination was greatest at intermediate pollen load sizes. The percentage of germinated pollen grains that penetrated the stigma and grew into the style decreased with pollen load size. Pollen tube growth rate in the style was greater and more variable with larger numbers of pollen tubes in the style. Controlling for the degree of selection at the stigma indicated that pollen-pollen or pollen-style interactions were the likely causes of increased growth rates. Received: 28 October 1996 / Revision accepted: 24 January 1997     

A Palynological Survey of Neogene Strata in Xiaolongtan Basin,Yunnan Province of South China

A palynological investigation of 24 samples from the representative Neogene strata of the Xiaolongtan Basin (23°48′N, 103°ll′E) were novelly carried out. Pollen samples were collected from the strata of N1 (clay, sandstone and conglomerate), N2 (clay intercalated with thin bedded lignite at the lower part, and coal bed at the upper part), N3 (marl), and N4 (clay intercalated with thin bedded lignite) in ascending order respectively. Pollen flora was characterized by the predominant appearance of angiospermous elements, representing the parent plants of evergreen broad-leafed types. Variations in the pollen flora were recognized between sample 15 and 16, as more herbaceous pollen of the Compositae types increasing upward in the strata, while certain woody types were minimized or even disappeared, thus dividing the pollen flora into two subzones. According to the current study, the geological age of the flora was suggested to be Middle-Late Miocene (Subzone A) to Early Pliocene (Subzone B), and the inferred vegetational type was evergreen broad-leafed forest, accompanied by a few deciduous elements.     

Pollen survival and spore dispersal on altitudinal clines: the case of the Popocatepetl volcano,Mexico

Pollen grains are abundant micro-organisms in the summer or dry season outdoor atmosphere. Moreover, they are fragile organisms, living for only a few days and their constant chemical interactions with their surrounding environment makes them prime candidates as biological indicators of ambient conditions. Volumetric samples were taken at different altitudes (3900–4400 m) on the Popocatepetl volcano (5452 m), 70 km south-east of Mexico City (2240 m). Results from September–October 1992 show that: (1) Local airborne pollen emission is negligible, most plant species found along the altitudinal transect being entomophilous. Indeed, maximum in vivo pollen viability was found at 4100 m a.s.l., where very few total airborne pollens were collected. (2) Regional pollen transport is found under 4000 m a.s.l., where pollen viability is discontinuous, being either below 50% or over 75%. (3) There is a long distance transport layer of pollen and spore dispersal below Mean Cloud Base, but over maximum wind speed, at a height of 4200–4300 m a.s.l., where pollen were found highly viable (>80%). (4) Pollen concentration or viability were not correlated with wind speed, relative humidity or temperature. However, the same factors were all significant regarding spore concentrations.     

Pollen morphology of the genus Nothofagus and its taxonomic significance

The present paper describes the pollen morphology of 26 species and 2 varieties in Nothofagus from Australia, New Zealand, New Caledonia, New Guinea and South America. Pollen grains were all examined with light microscope (LM), scanning electron microscope ( SEM ) and transmission electron microscope(TEM). A comparative analysis of pollen exine ultrastructure was made for some species. The results are summarised as follows: Pollen grains are oblate to peroblate, 5～8-short-colpate, rarely 4- or 9-colpate; colpi generally thickened at margins; pollen surface spinulose. The exine ultrastructure of Nothofagus differs considerably from that of the other genera in the Fagaceae. The pollen grains of the species examined here show great differences in shape, size, colpal number and characteristics of colpi at margins and could be divided into three distinct types, i.e. N. brassii type; N. menziesii type and N. fusca type.     

阴山山脉东段花粉通量及其与表土花粉比较研究

阴山山脉东段蛮汉山和大青山山顶草甸、桦木林、虎榛子灌丛、人工油松林及杂草草原5个植被类型花粉通量与表土花粉对比研究发现,不同植被类型及同一植被类型不同样点花粉通量和花粉浓度差异明显,捕捉器样品花粉源区面积小于表土样品,能较好地反映样品点周围植被组成,但受虫媒植物和局地植物花粉影响,与表土样品花粉组合差异明显;表土样品中松属、桦属、蒿属及藜科花粉含量多高于捕捉器样品,表明这些花粉不仅易于传播,而且在表土中具有较强的保存能力;禾本科花粉具低代表性,花粉保存能力较低.地层花粉分析中应引起注意.     

东北杜鹃花属植物花粉形态的研究

利用光学显微镜和扫描电子显微镜对东北杜鹃花属(Rhododendron Linn.)6种, 1变种, 1变型的花粉形态进行了观察和比较研究。该属花粉粒均为四合花粉。四合花粉呈正四面体排列。花粉粒近球形。每粒花粉均具3沟,在四合花粉粒上,相邻花粉粒上的沟相接,有些种可见沟内的萌发孔。光镜下可见花粉外壁为内外两层,厚度约相等。不同的种在花粉粒大小上有区别。在扫描电镜下观察可见不同的种花粉表面具有不同的纹饰。即该属在花粉形态上具有种的特性。     

Holocene forest development in the central Scandes Mountains, Sweden

Pollen analyses of sediment cores from two small lakes within the boreal forest in the central Scandes Mountains help to elucidate the Holocene forest dynamics of the region. Analyses of pore/pollen grain diameter ratios of Alnus grains indicate the early Holocene presence of Alnus glutinosa in the study area. The results are discussed in conjunction with available pollen records to evaluate the importance of thermophilous trees during the early Holocene and to deduce the regional spread of Picea abies. Corylus avellana, Alnus glutinosa and Ulmus glabra were probably common constituents of the early Holocene forest. Tilia cordata may have occurred there as a rare tree. Pollen stratigraphies from the region do not indicate the occurrence of Quercus robur. The regional spread of Picea abies can be separated into two phases: a mid-Holocene establishment or first expansion of small outpost populations and a late-Holocene population expansion. The mid-Holocene shift in vegetation composition may have been caused by changes in the westerly airflow.