Fossil pollen as a record of past biodiversity

Quaternary pollen records may contribute uniquely to the understanding of present plant diversity. Pollen assemblages can reflect diversity at community and landscape scales but the time resolution of most studies does not match that of modern ecological studies. Because of the complicating effects of differential pollen productivity and dispersal, pollen records do not directly reflect equitability aspects of vegetation diversity. Vegetation diversity indices other than S (the total number of taxa) are therefore not appropriate for pollen assemblages. As a measure of the species richness palynological richness is biased by the lack of taxonomic precision, by a possible interference on pollen dispersal from vegetation structure and by pollen representation. The nonlinear relationship between species richness and pollen-taxa richness may be used in attempts to estimate past floristic richness from fossil pollen assemblages. Using a hypothetical example the strong effect of cover shifts in the vegetation affecting taxa with different representation (R_rel) values on observed palynological richness is demonstrated. It is suggested that estimates of relative pollen productivity should be used to guide the pollen sum on which pollen-type richness is estimated by rarefaction techniques and this approach is illustrated using a paired site study of late Holocene diversity dynamics. The need for a modern training set relating pollen-type richness to species richness, pollen productivity and vegetation structure is emphasized.     

Coastal dune vegetation and pollen representation in south Buenos Aires Province, Argentina

Aim To establish the relationship between coastal dune vegetation and its pollen representation as an aid to interpret Holocene vegetation dynamics and environmental changes from pollen assemblages. Location The study area is situated on the temperate Atlantic coast of south Buenos Aires Province, Argentina (c. 39° S and 61°20′ W). Methods The vegetation of the active dune area adjacent to the beach was described on the basis of its floristic composition from 25 plots. Classification of the vegetation into distinct zones was carried out by cluster analysis. Surface samples were collected from each vegetation stand and analysed for their pollen composition. Pollen percentage data were analysed using principal components analysis in order to investigate the degree to which the different vegetation units can be distinguished by their pollen spectra. Pollen–vegetation relationships for selected taxa were explored using simple scatter plots and indices of association, under‐ and over‐representation. Indices of floristic diversity and palynological richness were used to assess the representation of the vegetation in the pollen spectra. Results and conclusions Five vegetation zones are defined on the basis of species composition and their quantitative variation: back shore, mobile dunes, slacks, semi‐fixed and fixed dunes. Pollen assemblages from back shore, mobile dunes and slacks are clearly differentiated from semi‐fixed and fixed dunes. Pollen assemblages differ considerably from the associated vegetation composition. Major discrepancies are caused by large differences in pollen and vegetation proportion of Hyalis argentea and Discaria americana. There is a considerable proportion of non‐local pollen in every spectrum. Pollen representation in the coastal dunes at Monte Hermoso is influenced by differences in pollen production, dispersal and preservation of individual taxa as well as by the spatial distribution of the vegetation, the topography of the dune system and the wind pattern. The pollen–vegetation relationship established in this study has important implication for understanding and interpreting fossil pollen records from coastal dune environments.     

On the interpretation of fossil Poaceae pollen in the lowland humid neotropics

Poaceae pollen is abundant in fossil records and is often used as a paleoclimatic indicator. A common interpretation is to link increases in Poaceae pollen abundance to increased regional aridity. However, the representation of Poaceae pollen is influenced by a number of factors, such as the proportion of other plants in the flora that are anemophilous, the size of local marshes, and the influence of humans on the landscape. Abundant anemophilous trees are likely to mask the contribution of Poaceae pollen, whereas floras that are primarily entomophilous are likely to produce a pollen spectrum containing an over-representation of Poaceae. As most fossil pollen data are drawn from flooded settings, it is critically important that palynologists recognize the Poaceae pollen contribution derived from floating grasses and marshes that surround their coring site. Interpretations that ignore changes in effective lake size and assume that Poaceae percentage is a simple indicator of regional vegetation change are likely to overstate ‘dry’ episodes and transitions from wet forest to scrub environments. Human occupation of a site is sometimes manifested in increased Poaceae pollen abundance in lake sediments. The duration, intensity and land-use associated with occupation are all variables that influence Poaceae pollen representation. Very high (50–90%) abundances of Poaceae pollen provide a strong indicator of savanna habitats, but trying to determine transitional vegetation types between savanna and wet forest is best determined using other taxa. Indeed, reliance on Poaceae abundance as an indicator of paleoprecipitation is potentially very misleading when it is in the fossil record at moderate abundances.     

热带雨林的孢粉垂直分布规律——以海南岛现代孢粉雨为例

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,孢粉组合显示出为干扰的影响,如防风雨的主要树种木麻黄（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,Poaceaae,Dicranopteris:--低地质陵地带（400－800m):Quercus,Castanopsis,Mallotus,Myrica,Platea,Meliaceae和大量孢子（包括Dicranopteris);--山地下带（800-1200m):Castanopsis,Quercus,Podocarpus,Dacrydium,Cyathea和单缝孢子;－－山地上带（1200-1600m):Dacrydium,Pinus,Altingia,Quercus,Castanopsis;－－山顶带（＞1600m):Pinus,Rhododendron,Dacrydium,Symplocos.     

Cretaceous diversification of angiosperms in the western part of the Iberian Peninsula

The classic leaf fossil floras from the Cretaceous of the Lusitanian Basin, Portugal, which were first described more than one hundred years ago, have played an important role in the development of ideas on the early evolution of angiosperms. Insights into the nature of vegetational change in the Lusitanian Basin through the Cretaceous have also come from studies of fossil pollen and spores, but the discovery of a series of mesofossil floras containing well-preserved angiosperm reproductive structures has provided a new basis for understanding the systematic relationships and biology of angiosperms at several stratigraphic levels through the Cretaceous. In the earliest mesofossil floras from the Torres Vedras locality, which are of probable Late Barremian-Early Aptian age, angiosperms are surprisingly diverse with about 50 different taxa. In slightly later mesofossil floras, which are of probable Late Aptian-Early Albian age, the diversity of angiosperms is still more substantial with more than hundred different kinds of angiosperm reproductive structures recognized from the Famalicão locality alone. However, this early diversity is largely among angiosperm lineages that produced monoaperturate pollen (e.g., Chloranthaceae, Nymphaeales) and early diverging monocots (Alismatales). Eudicots are rare in these Early Cretaceous mesofossil floras, but already by the Late Cenomanian the vegetation of the western Iberian Peninsula is dominated by angiosperms belonging to various groups of core eudicots. The Normapolles complex is a particularly conspicuous element in both mesofossil floras and in palynological assemblages. In the Late Cretaceous mesofossil floras from Esgueira and Mira, which are of Campanian-Maastrichtian age, core eudicots are also floristically dominant and flowers show great organisational similarity to fossil flowers from other Late Cretaceous floras described from other localities in Asia, Europe and North America.     

The role of landscape structure in determining palynological and floristic richness

The associations between floristic and palynological richness and landscape structure were studied based on modern pollen?Cvegetation data from a patchy cultural landscape in southern Estonia (northern temperate vegetation zone). Nine study sites (small lakes and their surrounding vegetation) represent land cover gradient from closed forest to semi-open vegetation. Floristic richness (number of species) and floristic richness of pollen types (number of pollen-equivalent taxa) were used to describe the vegetation within the radius of 250?m from the pollen sampling sites. Palynological richness was calculated to describe the modern pollen samples diversity. Landscape structure was estimated on the basis of landscape openness and three landscape diversity measures: richness of community patches, Simpson evenness of community patches and Simpson diversity of community patches. To study the effect of the spatial scale of landscapes on the vegetation?Clandscape and pollen?Clandscape associations, landscape structure was estimated within eight radii (250?C2,000?m) around each lake. The results showed that landscape openness was the most important determinant of both floristic richness and palynological richness in southern Estonia and that landscape diversity estimated by Simpson diversity index was also significantly associated with the richness estimates. Floristic and palynological richness were significantly positively correlated with landscape structure within the radii greater than 1,000?m from the pollen sampling sites, which is similar to the estimated Relevant Source Area of Pollen in southern Estonia. We conclude that within one floristic or climatic region, palynological richness gives reliable estimates about the variation in floristic richness and landscape structure; however, caution must be taken when comparing pollen-inferred vegetation diversities from different regions or when interpreting fossil pollen records from times with highly different vegetation associations.     

ADDITIONS TO THE MIOCENE SUCKER CREEK FLORA OF OREGON AND IDAHO

Study of plant microfossils and additional macrofossils collected from sediments in the vicinity of Sucker Creek along the Oregon-Idaho boundary has provided additional data on the composition of this fossil flora. A total of seven taxa new to the flora have been recognized. These include colonies of Botryococcus; pollen of Podocarpus, Pachysandra, and the Onagraceae; and leaves of Cephalotaxus californica and Vaccinium sophoroides. The occurrence of Podocarpus in this mid-Miocene flora is particularly significant in view of the limited number of records of this genus in the Tertiary of North America. In addition to these new records, the presence of three additional taxa—Castanea, Nyssa, and Ilex—previously recognized on the basis of leaf remains, is further substantiated by the occurrence of fossil pollen in the sediments.     

A brief review of the fossil history of the family Rosaceae with a focus on the Eocene Okanogan Highlands of eastern Washington State, USA, and British Columbia, Canada

Many of the oldest definitive members of the Rosaceae are present in the Eocene upland floras of the Okanogan Highlands of northeastern Washington State and British Columbia, Canada. Over a dozen rosaceous taxa representing extant and extinct genera of all four traditionally recognized subfamilies are known from flowers, fruits, wood, pollen, and especially leaves. The complexity seen in Eocene Rosaceae suggests that hybridization and polyploidy may have played a pivotal role in the early evolution of the family. Increased species diversity and the first appearance of additional modern taxa occur during the Late Paleogene in North America and Europe. The Rosaceae become increasingly important components of fossil floras during the Neogene, with taxa adapted to many habitats.     

History of the development of the temperate forest flora in Kazakhstan,U.S.S.R. from the Oligocene to the Early Miocene

Exact dating of the floras existing in western Kazakhstan during the Oligocene and Early Miocene permits a detailed examination of the formation of a temperate flora during the Rupelian (Early Oligocene), Chattian (Late Oligocene), Aquitanian (the beginning of Early Miocene) and the Burdigalian (end of Early Miocene) Ages and at the same time an establishment of the sequence in the origin and the disappearance of a flora of Turgayan type (the “Turgayan flora” of Kryshtofovich) in Kazakhstan. The most important aspects (composition and terminology) of a previous subtropical flora of a Drevlyanian (possibly Volynian) ecological type (the “Poltavian” flora of Kryshtofovich), which had developed in Kazakhstan and the Ukraine during the Eocene, are also discussed. The text is intended for botanists of various special interests, e.g., paleobotanists, phytogeographers and floristicians, as well as for geologists, especially stratigraphers and paleogeographers. The bibliography comprises more than 200 references and there are seven tables.     

The interpretation of fen carr pollen diagrams: pollen–vegetation relationships within the fen carr

Sediments deposited in fen carr environments are frequently used in pollen-based reconstructions of vegetation history, although few studies of modern pollen–vegetation relationships in fen carr have been undertaken to aid the interpretation of fossil assemblages. It is often assumed that the wetland pollen signal will reflect the overall composition of the fen carr system although, given the closed canopy context, it may actually be dominated by local vegetation elements. This paper seeks to determine whether the vegetation heterogeneity within a modern fen carr is reflected in the pollen signal of the wetland taxa. Vegetation composition was recorded around a series of moss polster sample points at Calthorpe and Wheatfen, two areas of fen carr in the Norfolk Broadland, UK. The spatial interrelationship between the wetland components of the vegetation and their palynological equivalents in the moss polster pollen assemblages is explored through trend surfaces and a correlation based statistical test (the Mantel Test). The representation of the major vegetation components in the pollen record is highly variable. Values for Alnus glutinosa, a dominant canopy species, range from 5.3% to 73% of total land pollen (TLP) at Calthorpe and 2.5–61% TLP at Wheatfen. In part, this variation reflects the enhanced input of pollen from dry land sources close to the wetland edge although the variation recorded at points equidistant from the dry land margin suggests that other processes are also influential. The strongest positive associations in the Mantel Test are for under-storey and ground flora elements that are poorly represented in the pollen record. Taxa for which there is no association include those with few vegetation occurrences and those for which a large proportion of the pollen appears to have been derived from outside the study areas. We conclude that modern pollen samples collected from fen carr broadly reflect the vegetation composition of the study areas. However, the input of pollen from fen carr species is spatially inconsistent. Differences between the sample points can be attributed to the distribution and pollination biology of the under-storey and ground flora elements and the structure of the vegetation around sites. The results caution against assuming that changes in the pollen representation of wetland taxa, in fossil sequences constructed from fen carr deposits, necessarily reflect changes in the overall composition of the community.     

Modern vegetation–pollen–climate relationships for the Pampa grasslands of Argentina

Aim To analyse the relationships between potential natural vegetation, pollen and climate in order to improve the interpretation of fossil pollen records and provide the background for future quantitative palaeoclimatic reconstructions. Location Pampa grasslands of Argentina, between 33–41° S and 56–67° W. Methods Modern pollen data were obtained from a pollen data base developed by the Grupo de Investigación de Paleoecología y Palinología, Universidad Nacional de Mar del Plata, Argentina (143 surface samples and 17 pollen types). Analysis of pollen and climate data involved multivariate statistics (cluster analysis and principal components analysis), scatter diagrams, Pearson’s correlation and isopoll mapping. Results Vegetation patterns at regional scales (grasslands and xerophytic woodlands) and local scales (edaphic communities) were identified by cluster analysis of pollen surface samples. The main climatic variables that appear to constrain the vegetation distribution and abundance of taxa are mean annual precipitation, annual effective precipitation and summer temperature. Individual pollen types such as Chenopodiaceae, Apiaceae, Cyperaceae, Prosopis, Schinus, Condalia microphylla and other xerophytic taxa are good indicators of moisture regime. Many pollen types are significantly correlated with summer temperature. The modern vegetation–pollen–climate relationships vary in a broadly predictable manner, supporting the contention that fossil pollen assemblages can be related to particular climatic characteristics. Main conclusions An expanded suite of modern analogues facilitated new insights into vegetation–pollen–climate relationships at the regional scale in Pampa grasslands. Relationships between individual pollen types and climate are appraised at a regional scale and new modern analogues are presented. The results provide the basis for improved vegetation and climate reconstruction from fossil records of the study area.     

Early Miocene repetitive vegetation and climatic changes in the lacustrine deposits of the Rubielos de Mora Basin (Teruel, NE Spain)

Pollen analysis of a Lower Miocene succession from the Rubielos de Mora Basin (NE Spain) has been carried out with the aim of reconstructing the flora, vegetation and climatic changes. Previous paleobotanical studies on these sedimentary rocks and adjacent areas interpreted very diverse climates for the Early Miocene: from humid temperate to dry subtropical. In this study, a rich thermophilous pollen spectrum and a diverse subarid flora including Nitraria, Caesalpiniaceae, Ephedra and Acacia, indicative of a dry subtropical climate are identified. On the other hand, mesothermic taxa with high water requirements are also abundant. Therefore, the pollen assemblages evidence the juxtaposition of very contrasted environments: the presence of subdesertic taxa, typical of plants growing in the lowlands and conditioned by a long warm, dry season, together with others with very high water requirements, needing constant water. This can be explained by the presence of the Rubielos de Mora Lake providing local conditions for developing riparian forests. The vegetation was clearly controlled by the water availability under a subtropical and dry-seasonal climate. Pollen changes along the succession, which coincide with sedimentological changes, are related to climatic variations. Alternation in pollen taxa (thermophilous–dry vs. mesothermic–riparian) reflects the influence of the cyclicity of temperature and precipitation on the lake level and vegetation.     

中国现代花粉数据集

孢粉是重建古植被、古气候的重要基础数据。孢粉数据库对研究样点至区域和全球尺度上的古环境演变规律、古气候变化特征反演和古生物地球化学循环模拟等具有重要意义。该文收集整理了中国1960-2020年间发表和部分未发表的现代花粉数据记录, 包括样品编号、采样位置、采样地经纬度和海拔高度、样品类型、数据来源、数据类型、周边植被信息、参考文献、花粉类群及其含量等信息; 并对数据进行筛选和标准化等处理, 由此整合为中国现代花粉数据集。该数据集由4 497个现代花粉采样点的数据信息组成, 包括660个来自中国第四纪孢粉数据库数据, 1 763个前期整理发表的数据和2 074个近期收集的数据, 涵盖772个花粉类群。样品类型以土壤表层样品(3 332个)为主, 苔藓样品以及湖泊、海洋表层样品等为辅, 广泛分布于全国不同地理区域和植被类型中, 其中以温带荒漠区域(24.91%)和亚热带常绿阔叶林区域(24.02%)最丰富, 其次为温带草原区域(16.14%)和青藏高原高寒植被区域(15.83%)。数据按照来源可分为原始数据(58%)和数值化数据(42%); 按照数据类型可分为原始统计粒数的样点(59%)和以花粉百分比表达的样点(41%)。半个多世纪以来, 科研人员开展了大量的表层现代花粉取样和研究。本数据集虽然仅获取部分记录, 但样点覆盖了我国绝大多数地区, 可有效地用于古植被与古气候重建的现代孢粉与现代植被校验, 并将为中国孢粉数据库的建立与更深入的孢粉研究提供数据支撑。     

云南元谋盆地上新世甘棠组植物和孢粉组合及其古气候意义

云南元谋盆地湾堡甘棠组植物群的叶化石和孢粉化石合计107种类型,分属86属,47科。植物叶化石包括18科,24属,35种。除一种裸子植物外,其它均为被子植物。被子植物中,榆科、桦木科、豆科无论属种或者化石数量都是最多;杨柳科、槭科、蔷薇科次之;壳斗科、樟科、杨梅科、鼠李科、忍冬科、胡颓子科、杜鹃科、香蒲料、禾本科均有代表。甘棠组的孢粉植物群也相当丰富,合计97个类型,分属72属,44科。以松科、榆科、禾本科及蕨类植物的水龙骨科最为丰富,胡桃科、壳斗科、金缕梅科及蕨类植物的凤尾蕨属也很常见。被子植物花粉占孢粉总数的50%--60%,以禾本科和榆属花粉含量最高,多在10%以上。裸子植物绝大部分为松科花粉,占孢粉总数的20%-30%。孢子以水龙骨科和凤尾蕨属为主,二者各占孢粉总数的5%-10%。发现于元谋盆地湾堡甘棠组的植物叶化石以及孢子花粉组合在成分上都是混合的类群。组合中既有相当多的湿润亚热带常绿阔叶林成分,也有耐干旱的胡颓子、杨梅、旱蕨等灌木、小乔木或草本分子,同时还有含量很高的、在半干旱环境下也能生存的禾本科、榆科花粉。据此推测甘棠组的植物群和孢粉组合反映了上新世时元谋地区的植被已经分化,盆地的周围山地生长有松科、壳斗科、樟科、胡桃科、金缕梅科为主的常绿和落叶阔叶树木或林块,可能有少许杜鹃科小乔木混杂其中,属于地带性植被。而在盆地内则是以禾本科、蔷薇科等为主,杂以大戟科、豆科、忍冬科、杨梅科等灌木或草本植物以及榆科、桦木科等树木组成的稀树灌丛草原型植被。盆地内的植被所反映的气候和周边地区相比,显得明显干旱。因此推测元谋盆地在2-3百万年前的中晚上新世已经发育成为金沙江流域的干热河谷盆地之一。     

Eocene plant diversity at Laguna del Hunco and Río Pichileufú, Patagonia, Argentina

The origins of South America's exceptional plant diversity are poorly known from the fossil record. We report on unbiased quantitative collections of fossil floras from Laguna del Hunco (LH) and Río Pichileufú (RP) in Patagonia, Argentina. These sites represent a frost-free humid biome in South American middle latitudes of the globally warm Eocene. At LH, from 4,303 identified specimens, we recognize 186 species of plant organs and 152 species of leaves. Adjusted for sample size, the LH flora is more diverse than comparable Eocene floras known from other continents. The RP flora shares several taxa with LH and appears to be as rich, although sampling is preliminary. The two floras were previously considered coeval. However, (40)Ar/(39)Ar dating of three ash-fall tuff beds in close stratigraphic association with the RP flora indicates an age of 47.46+/-0.05 Ma, 4.5 million years younger than LH, for which one tuff is reanalyzed here as 51.91+/-0.22 Ma. Thus, diverse floral associations in Patagonia evolved by the Eocene, possibly in response to global warming, and were persistent and areally extensive. This suggests extraordinary richness at low latitudes via the latitudinal diversity gradient, corroborated by published palynological data from the Eocene of Colombia.     

Response of pollen diversity to the climate-driven altitudinal shift of vegetation in the Colombian Andes

Change in diversity of fossil pollen through time is used as a surrogate for biodiversity history. However, there have been few studies to explore the sensitivity of the measured pollen diversity to vegetation changes and the relationship between pollen diversity and plant diversity. This paper presents results of a study to assess the relationship between pollen diversity and relative abundance of pollen from different altitudinal vegetation belts (subandean forest, Andean forest, subparamo and grassparamo) in three records from the tropical Andes in Colombia. The results indicated that plant diversity in the vegetation declined with altitude and pollen diversity is positively correlated to the abundance of pollen from lower altitude vegetation belts and negatively correlated to that from the grassparamo. These results, therefore, suggest that pollen diversity coarsely reflects the diversity of the surrounding vegetation. Using this interpretation, we were able to predict changes in plant diversity over the past 430000 years in the Colombian Andes. Results indicated that under warmer climatic conditions, more species-diverse vegetation of low elevation moved upslope to contribute more pollen diversity to the study sites, and under colder conditions, species-poor grassparamo moved downslope and observed pollen diversity was lower. This study concludes that fossil pollen diversity may provide an important proxy to reconstruct the temporal changes in plant diversity.     

Extent and timing of floristic exchange between Australian and Asian rain forests

Aim We tested an entrenched concept – that the Australian rain forest flora is essentially a Gondwanan relict. We also assessed the role of regional‐level source–sink dynamics in the assembly of this flora. Location Eastern Australia. Methods To avoid potential biases inherent in selective studies undertaken to date, we used an analytical, whole‐of‐flora approach integrated with the fossil record. We identified disjunctions between woody Australian rain forest plant taxa and relatives on other land masses. To test the strength of the fossil evidence for the regional antiquity of this flora, we evaluated the proportion of these disjunct clades represented in the Australian fossil record, and to minimize the effects of biases in this record, we compared late Quaternary (i.e. late Pleistocene and Holocene, 126–0 ka), Pliocene and late Oligocene–early Miocene Australian pollen records interpreted as tropical rain forest. Using within‐species disjunctions as a proxy, we assessed the role of recent immigration from Asia into Australia. To assess the role of source–sink dynamics, we performed comparative analyses of disjunctions in major rain forest categories representing a north–south/climatic gradient. Results Southern Australian, cool temperate (microthermal) rain forests contain many floristic disjunctions with Gondwanan fragments and most of these clades have Gondwanan fossils. Disjunct clades in Australian mesothermal rain forest mostly occur in Asia/Malesia and a low proportion of these clades show pre‐Neogene records. Many clades in lowland tropical and ‘dry’ rain forest show disjunctions with Asia/Malesia and few have Australian fossil records. Rates of recent immigration from Asia/Malesia are high in these northern forests, and outweigh rates of recent emigration approximately nine‐fold. The late Quaternary fossil record has many more rain forest angiosperms than Oligocene–Miocene and Pliocene floras, consistent with extensive late Cenozoic immigration. Main conclusions The microthermal rain forests are largely Gondwanan relicts, but there is progressively greater, and more recent contribution from Asia/Malesia into more northern, and more lowland tropical rain forests. This variation reflects a strong gradient in geographic and ecological proximity between these forests and source floras in Asia/Malesia, and is consistent with a source–sink size model of immigration driven by late Cenozoic contractions and expansions of Australian rain forest.     

Airborne Pollen Sampling in Trieste (Italy)

A qualitative and quantitative analysis of airborne pollen in Trieste City is presented, with special attention being paid to allergenic species. A trap constructed according to Cour (1974) was located on top of a building in the middle of the town. Pollen was collected weekly for three years. Separate records were kept for 16 taxa which are particularly relevant, either as allergenic factors, or as major components in the local vegetation. Cupressaceae and Gramineae are found to be the most abundant in the atmosphere. Genera of waste land such as Artemisia, Rumex and Parietaria are also frequent. The pollen composition largely reflects the man-made environment as vegetation of gardens, parks and roadsides; the natural vegetation of the surrounding country is scarcely represented.     

Herb pollen representation in surface moss samples from mown meadows and pastures in western Norway

Grazed and mown vegetation types in western Norway were investigated with the aim of describing their modern pollen/vegetation relationships as an aid to the interpretation of fossil pollen diagrams. Pollen surface samples and vegetation data were obtained from 186 square metre plots within 39 different sites of 10×10 m. Scatter plots that show the relationship between pollen percentages and vegetation percentages are presented forTrifolium pratense-type,Trifolium rcpens-type,Lotus, Campanula-type,Succisa, Ranunculus acris-type,Cirsium-type, Asteraceae Cichorioideae,Achillea-type,Potentilla-type, Apiaceae,Rumex sect.Acetosa, Galium-type, Cyperaceae,Calluna, Plantago lanceolata and Poaceae. Pollen representation factors relative to Poaceae (R_rel) are calculated for 54 pollen taxa. Differences in the values from different geographical areas were found in the case of some taxa, due to either different genera or species being included in the pollen taxa and/or to the different representation of high pollen producers in the different regional vegetation types. Background pollen influences the estimates for taxa such asR. sect.Acetosa, P. lanceolata, Poaceae, Cyperaceae, andCalluna, and an extended R-value (ERV) model was used to investigate the magnitude of this pollen component. Groups of roughly similar pollen representation were identified and factors to convert pollen percentages to vegetation abundances are suggested.     

Studies in Neotropical paleobotany. XI. Late Tertiaryvegetation and environments of southeastern Guatemala: palynofloras fromthe Mio-Pliocene Padre Miguel Group and the Pliocene HerreriaFormation

Plant microfossils are reported from the late Tertiary Padre MiguelGroup and the Pliocene Herrería Formation of southeasternGuatemala. The most abundant palynomorphs are cf. Acrostichum(maximum 45%), Cyperaceae (29%), cf. Antrophyum(27%), monolete fern spores (16%), and Pinus(11%). Pollen grains of Picea, Juglans,Quercus, and Ulmus, primarily from the Padre Miguelflora, reveal the presence of a northern cool-temperate element. Theyounger Herrería flora is more lowland and warm temperate. Inthe absence of evidence for substantially higher elevations, thedifferences between the Neogene and modern vegetation are attributedmostly to climate. MAT (mean annual temperature) is estimated2°-3°C cooler than at present for the Padre Miguel flora,and ～3.5°C warmer for the Herrería flora. There islittle evidence for arid vegetation, and the tropical rain forest wasabsent or poorly represented. These data are consistent with those ofother fossil floras in the region and with trends suggested by isotopicpaleotemperature analysis and global sea-level changes. The Guatemalaassemblages further provide evidence that the current version of thetropical rain forest is recent in origin and has undergone considerablechange in its range and composition throughout the lateCenozoic.