Conifer Pollen Research Articles

Three-dimensional label-free imaging and analysis of Pinus pollen grains using optical diffraction tomography

The structure of pollen grains is related to the reproductive function of the plants. Here, three-dimensional (3D) refractive index maps were obtained for individual conifer pollen grains using optical diffraction tomography (ODT). The 3D morphological features of pollen grains from pine trees were investigated using measured refractive index maps, in which distinct substructures were clearly distinguished and analyzed. Morphological and physiochemical parameters of the pollen grains were quantified from the obtained refractive index (RI) maps and used to quantitatively study the interspecific differences of pollen grains from different strains. Our results demonstrate that ODT can assess the structure of pollen grains. This label-free and rapid 3D imaging approach may provide a new platform for understanding the physiology of pollen grains.

Dinosaur-plant interactions within a Middle Jurassic ecosystem\u2014palynology of the Burniston Bay dinosaur footprint locality, Yorkshire, UK

Dinosaur footprints are abundant in the Middle Jurassic Ravenscar Group of North Yorkshire, UK. Footprints are particularly common within the Bathonian Long Nab Member of the Scalby Formation and more so within the so-called ‘Burniston footprint bed’ at Burniston Bay. The Yorkshire Jurassic is also famous for its exceptional plant macrofossil and spore-pollen assemblages. Here we investigate the spore-pollen record from the dinosaur footprint-bearing successions in order to reconstruct the vegetation and assess possible dinosaur-plant interactions. We also compare the spore-pollen assemblages with the macroflora of the Scalby Ness Plant Bed, which occurs within the same geological member as the Burniston succession. The spore-pollen assemblages are dominated by Deltoidospora spp., the majority of which were probably produced by Coniopteris. Lycophyte spores (including megaspores) are common in the Yorkshire Jurassic, but lycophyte parent plants are extremely poorly represented in the macroflora. Seed ferns, represented by Alisporites spp., are moderately abundant. Conifer pollen assemblages are dominated by Araucariacites australis (probably produced by Brachyphyllum mamillare), Perinopollenites elatoides and Classopollis spp., with additional bisaccate pollen taxa. Abundant Ginkgo huttonii in the macroflora suggests that much of the monosulcate pollen was produced by ginkgoes. The diverse vegetation of the Cleveland Basin presumably represented an attractive food source for herbivorous dinosaurs. The dinosaurs probably gathered at the flood plains for fresh-water and also used the non-vegetated plains and coastline as pathways. Although assigning specific makers to footprints is difficult, it is clear that a range of theropod, ornithopod and sauropod dinosaurs inhabited the area.

Extensive wildfires, climate change, and an abrupt state change in subalpine ribbon forests, Colorado.

Ecosystems may shift abruptly when the effects of climate change and disturbance interact, and landscapes with regularly patterned vegetation may be especially vulnerable to abrupt shifts. Here we use a fossil pollen record from a regularly patterned ribbon forest (alternating bands of forests and meadows) in Colorado to examine whether past changes in wildfire and climate produced abrupt vegetation shifts. Comparing the percentages of conifer pollen with sedimentary δ18 O data (interpreted as an indicator of temperature or snow accumulation) indicates a first-order linear relationship between vegetation composition and climate change with no detectable lags over the past 2,500yr (r=0.55, P<0.001). Additionally, however, we find that the vegetation changed abruptly within a century of extensive wildfires, which were recognized in a previous study to have burned approximately 80% of the surrounding 1,000km2 landscape 1,000yr ago when temperatures rose ~0.5°C. The vegetation change was larger than expected from the effects of climate change alone. Pollen assemblages changed from a composition associated with closed subalpine forests to one similar to modern ribbon forests. Fossil pollen assemblages then remained like those from modern ribbon forests for the following ~1,000yr, providing a clear example of how extensive disturbances can trigger persistent new vegetation states and alter how vegetation responds to climate.

Fossil record of Ephedra in the Lower Cretaceous (Aptian), Argentina.

Fossil plants from the Lower Cretaceous (upper Aptian) of the La Cantera Formation, Argentina, are described. The fossils studied represent a leafy shooting system with several orders of articulated and striated axes and attached leaves with unequivocal ephedroid affinity. We also found associated remains of ovulate cones with four whorls of sterile bracts, which contain two female reproductive units (FRU). Ovulate cone characters fit well within the genus Ephedra. Special characters in the ovulate cones including an outer seed envelope with two types of trichomes, allowed us to consider our remains as a new Ephedra species. Abundant dispersed ephedroid pollen obtained from the macrofossil-bearing strata also confirms the abundance of Ephedraceae in the basin. The co-occurrence of abundant fossil of Ephedra (adapted to dry habitats) associated with thermophilic cheirolepideacean conifer pollen (Classopollis) in the unit would suggest marked seasonality at the locality during the Early Cretaceous. Furthermore, the floristic association is linked to dry sensitive rocks in the entire section. The macro- and microflora from San Luis Basin are similar in composition to several Early Cretaceous floras from the Northern Gondwana floristic province, but it may represent one of the southernmost records of an arid biome in South America.

Eocene–early Oligocene climate and vegetation change in southern China: Evidence from the Maoming Basin

Although the Eocene-Oligocene climate transition marks a critical point in the development of the ‘icehouse’ global climate of the present little is known about this important change in the terrestrial realm at low latitudes. Our palynological study of the Shangcun Formation shows it to be early Oligocene in age: palyno-assemblages in the lower part of the formation indicate a cool interval dominated by conifer pollen in the earliest Oligocene followed by a warmer regime in the second half of the early Oligocene. To quantify middle Eocene to late early Oligocene climate conditions at low (~20°N) palaeolatitudes in southern Asia several thousand leaf fossil specimens from the Maoming Basin, southern China, were subjected to a multivariate (CLAMP) analysis of leaf form. For terrestrial palaeoclimate comparisons to be valid the palaeoaltitude at which the proxy data are obtained must be known. We find that leaves preserved in the Youganwo (middle Eocene), Huangniuling (late Eocene) and Shangcun (early Oligocene) formations were likely to have been deposited well above sea level at different palaeoelevations. In the Youganwo Formation fine-grained sediments were deposited at an altitude of ~1.5km, after which the basin dropped to ~0.5km by the time the upper Huangniuling sediments were deposited. The basin floor then rose again by 0.5km reaching an altitude of approximately 1km in which the Shangcun Formation fine-grained sediments were accumulated. Within the context of these elevation changes the prevailing climates experienced by the Youganwo, Lower Huangniuling, Upper Huangniuling and Shangcun fossil floras were humid subtropical with hot summers and warm winters, but witnessed a progressive increase in rainfall seasonality. By the early Oligocene rainfall seasonality was similar to that of the modern monsoonal climate of Guangdong Province, southern China. All floras show leaf physiognomic spectra most similar to those growing under the influence of the modern Indonesia-Australia Monsoon, but with no evidence of any adaptation to today's South or East Asia Monsoon regimes. The Upper Huangniuling Flora, rich in dipterocarp plant megafossils, grew in the warmest conditions with the highest cold month mean temperature and at the lowest altitude.

Palynology and terrestrial ecosystem change of the Middle Triassic to lowermost Jurassic succession of the eastern Danish Basin

The pre-Rhaetian Triassic succession in the Danish Basin is generally dominated by red bed deposits unsuitable for preservation of organic material. However, during the late Middle Triassic a temporary change to wetter conditions resulted in preservation of diverse palynofloral assemblages, dominated by corystospermous seed fern pollen of Alisporites/Falcisporites and characterized by high abundances of the conifer pollen Protodiploxypinus gracilis, as well as common to abundant lycophyte spores assigned to Aratrisporites spp. A mid-Ladinian to early Carnian (earliest Julian) age is inferred for this interval based on the presence of the probable gymnosperm pollen Staurosaccites quadrifidus, rare Retisulcites perforatus (of unknown affinity) and Enzonalasporites vigens of probably voltzialean affinity. No marine palynomorphs were recorded, only rare specimens of Ovoidites sp. and Plaesiodictyon mosellanum. Thus, together with previously recorded other fossils (a fish microfauna, an ostracod, plant remains and characeans) the recorded palynoflora indicates semi-arid conditions and deposition in a terrestrial to marginal fresh- or brackish water environment. After this, red bed deposition resumed in the area, and it is not until the mid-Rhaetian that well preserved and diverse palynofloras are again encountered in the succession. The Rhaetian palynofloras are significantly different to the Ladinian–early Carnian assemblages, being dominated by tree fern spores (Deltoidospora spp.), taxodiacean/cupressacean pollen (Perinopollenites elatoides), and the enigmatic gymnosperm pollen assigned to Ricciisporites tuberculatus. As much as 62% of the mid-Ladinian to Early Carnian spore-pollen taxa were not recorded in the Rhaetian, suggesting that major restructuring of the terrestrial ecosystem took place in this area during the Carnian and Norian. In comparison, 34% of the Rhaetian spore-pollen taxa recorded in this study, e.g. R. tuberculatus, Polypodiisporites polymicroforatus, Limbosporites lundbladiae and Cingulizonates rhaeticus, disappeared during the well-recognized end-Triassic event. The extinction interval is also characterized by a dramatic increase in the number of reworked palynomorphs, indicating erosion of the hinterland at this time. There is a marked drop in diversity from the Late Triassic to the earliest Jurassic. The palynology indicates that the established post-extinction vegetation was dominated by tree ferns (Deltoidospora) and pinacean conifers (Pinuspollenites minimus), along with common taxodiacean/cupressacean conifers, ginkgos/cycads and corystospermous seed ferns, and that it remained relatively stable during the Hettangian to early Sinemurian.

Diet and environment 1.2 million years ago revealed through analysis of dental calculus from Europe's oldest hominin at Sima del Elefante, Spain.

Sima del Elefante, Atapuerca, Spain contains one of the earliest hominin fragments yet known in Europe, dating to 1.2Ma. Dental calculus from a hominin molar was removed, degraded and analysed to recover entrapped remains. Evidence for plant use at this time is very limited and this study has revealed the earliest direct evidence for foods consumed in the genus Homo. This comprises starchy carbohydrates from two plants, including a species of grass from the Triticeae or Bromideae tribe, meat and plant fibres. All food was eaten raw, and there is no evidence for processing of the starch granules which are intact and undamaged. Additional biographical detail includes fragments of non-edible wood found adjacent to an interproximal groove suggesting oral hygiene activities, while plant fibres may be linked to raw material processing. Environmental evidence comprises spores, insect fragments and conifer pollen grains which are consistent with a forested environment.

Pollen grains associated with gymnospermous mesofossils from the Jurassic of Uzbekistan

Pollen grains were studied which are associated with supposed ginkgoalean seeds and leaves from the Middle Jurassic locality of Angren in Uzbekistan. The fine morphology of the pollen grains was observed with the help of light, confocal laser scanning, scanning electron, and transmission electron microscopes. The morphology and ultrastructure of the pollen grains show that although some of them belong to ginkgoaleans, others belong to conifers and cycadaleans. Bisaccate conifer pollen grains were found in the pollen chambers of seeds of Allicospermum sp. and A. angrenicum. Non-saccate boat-shaped pollen grains that can be ascribed to the genus Cycadopites were found in association with a seed of Ginkgo gomolitzkyana, leaves of Sphenobaiera angrenica, and in pollen chambers of seeds of A. angrenicum. These Cycadopites pollen grains show several types of exine, which allowed us to draw conclusions about their botanical affinities. The Cycadopites pollen associated with a seed of Ginkgo gomolitzkyana shows a ginkgoalean exine ultrastructure. Of interest is that its ultrastructure shows some dissimilarities from that of pollen grains of the ginkgoalean morphology and ultrastructure, which were earlier studied from the pollen chamber of a seed of A. budantsevii from the same locality. We think on this basis that at least two members of the ginkgoaleans grew in the cenose. The Cycadopites pollen grains from leaves of S. angrenica and from pollen chambers of seeds of A. angrenicum show a cycadalean exine ultrastructure. In sum, the morphological studies revealed pollen grains of two members of ginkgoaleans associated with the ginkgoalean remains and pollen grains of conifers that are most probably alien to the enclosing seeds. As to the cycadalean pollen from the seeds of A. angrenicum, the seeds were either contaminated by cycad pollen or produced by a cycadalean parent plant rather than a ginkgoalean plant. The revealed pollen diversity is an argument to be more careful while reconstructing whole plants on the basis of such materials.

A 23,000-year microscopic charcoal record from Anderson Pond, Tennessee, USA

ABSTRACTCharcoal records of past fires are important for reconstruction of palaeoenvironments and palaeoclimate, particularly when compared with pollen records of past vegetation, but such records are scarce in the southeastern US. To address the question of how fire activity changed from the Last Glacial Maximum (LGM) into the Holocene as vegetation changed, we chose a site in central Tennessee for which a pollen record exists back to 23,000 cal yr BP. We developed a new microscopic charcoal record based on point counting of microscopic charcoal fragments on pollen slides from Anderson Pond studied by Hazel Delcourt (1979). The record we produced spans the interval from the LGM to recent and is directly tied to the original pollen record. Charcoal:pollen ratios and charcoal area concentrations are high during the late glacial and track the coniferous pollen record from the LGM to the late glacial, at which point spruce and jack pine pollen markedly diminished along with fire activity. From around 15,000 cal yr BP to the beginning of the middle Holocene, charcoal indices are low. High fire activity began around 8200 cal yr BP, and remained high from ca. 8200–5000 cal yr BP, an interval broadly corresponding to the Mid-Holocene Warm Period (MHWP). The evidence of higher fire activity during the MHWP is coincident with increased percentages of indeterminate pollen grains that are interpreted to signal drier conditions. Charcoal area concentrations declined following the MHWP. Viewed against the original pollen record, the patterns in microscopic charcoal abundance from the LGM to recent at Anderson Pond argue for the strong influence of vegetation as well as climate in driving fire occurrence in eastern temperate North America.

Prevalence of allergic sensitization to conifer pollen in a high cypress exposure area.

Background:Sensitization to Pinales (Cupressaceae and Pinaceae) has increased dramatically in recent years. The prevalence of sensitization in different geographic areas is related to exposure to specific pollens.Objectives:To investigate the prevalence of allergy to different conifer pollens, describe the characteristics of patients with such allergy, and identify the involved allergens.Methods:Patients were recruited at five hospitals near Madrid. Extracts from conifer pollen were prepared and used in skin-prick testing. Wheal sizes were recorded, and serum samples obtained from patients with positive reactions to Cupressus arizonica and/or Pinus pinea. The specific immunoglobulin E value to C. arizonica and Cup a 1 was determined. Individual immunoblots for each patient and with a pool of sera were performed. Allergenic proteins were sequenced by using liquid chromatography-tandem mass spectrometry.Results:Of 499 individuals included in the study, 17 (14%) had positive skin-prick test results to some conifer pollen extracts. Sixty-four patients had positive results to C. arizonica (prevalence 12.8%) and 11 had positive results to P. pinea (2.2%). All the patients had respiratory symptoms (61.4% during the C. arizonica pollination period), and 62.9% had asthma. Approximately 86% of the patients had positive specific immunoglobulin E results to C. arizonica and 92.3% had positive results to Cup a 1. Fourteen different bands were recognized by immunoblot; the most frequent bands were those detected at 43, 18, 16, and 14 kDa. All sequenced proteins corresponded to Cup a 1.Conclusion:Allergy to conifer pollen could be considered a relevant cause of respiratory allergy in central Spain. Asthma was more frequent than in other studies. We only identified Cup a 1 as involved in sensitization.

Late Cretaceous (Campanian) leaf and palynoflora from southern Skåne, Sweden

Abstract A Late Cretaceous (Campanian) leaf megaflora from the Vomb Trough in southern Skåne, Sweden, has been investigated on the basis of collections held at the Swedish Museum of Natural History. The main plant-bearing locality is Köpinge, but single specimens originate from Högestad, Ingelstorp, Rödmölla, Svenstorps mölla and Tosterup. The fossil flora is dominated by the angiosperm (eudicot) Debeya ( Dewalquea ) haldemiana (Debey ex de Saporta &amp; Marion) Halamski. Other dicots are cf. Dryophyllum sp., Ettingshausenia sp., Rarytkinia ? sp., Dicotylophyllum friesii (Nilsson) comb. nov. and Salicites wahlbergii (Nilsson) Hisinger. Conifers are represented by cf. Aachenia sp. (cone scales), Pagiophyllum sp. and Cyparissidium sp. (leaves). Single poorly preserved specimens of ferns and monocots have also been identified. The terrestrial palynomorphs (the focus herein) clearly link to the megaflora, although with different relative abundances. The fern spore Cyathidites dominates along with the conifer pollen Perinopollenites elatoides and Classopollis . Angiosperm pollen comprise up to 15% of the assemblage, represented by monocolpate, tricolpate and periporate pollen and the extinct Normapolles group. The spores in the kerogen residue show a thermal alteration index (TAI) of 2+. The flora probably represents mainly a coastal lowland Debeya /conifer forest, and is similar to approximately coeval assemblages from analogous palaeo-communities described from eastern Poland, western Ukraine and Westphalia.

Longitudinal Investigation on Allergenic Conifer Pollen in Japan for Successful Prevention and Treatment against Japanese Cedar Pollinosis

Longitudinal Investigation on Allergenic Conifer Pollen in Japan for Successful Prevention and Treatment against Japanese Cedar Pollinosis In Japan allergic people has been recognized increasing according to the increase of Japanese cedar, Cryptomeria japonica (JC) pollinosis since first reported in 1964. We have detected allergenic airborne pollen when Japanese government has begun to investigate the background and treatment on JC pollinosis as a serious social problem since July1986. Urgently the gravitational method with Durham’s sampler has been adopted to know huge number of JC and cypress family, Cupressaceae family (Cypress) pollen grains as causative agent. The area of national artificial forest of over 31 years old has become about 7 times from1970. We have estimated annual fluctuation of Japanese important allergenic pollen, with climatic factor during about 30 years for successful treatment of pollinosis in near future. There are institutions in fifteen locations monitoring airborne pollen by Durham’s sampler in Japan between the latitude of 30 to 40 degrees north. Airborne pollen samples were collected at each institute and were sent to our hospital on a daily basis. We counted pollen grains per cm2 through microscope, classifying and summarizing them. From 1986 to 2014 we have referred to the change in meteorological condition at the close to 9 of the pollen monitoring locations and estimated statically. JC and Cypress pollen counts have shown huge but remarkable annual fluctuation and they have been increasing gradually according to over 31 y-old conifer planting area expanding. The mean temperature in summer time, JC male flower formation, has a significant correlation with next year pollen counts. The pollination season has started earlier in north and later in central Japan gradually through a changing on mean temperature. In Japan allergenic conifer pollen counts have been increasing because of over 31 y-old conifer plantations area increase through the climate change about 30 years. Moreover, it has changed the start of pollination season.

Vibrational microspectroscopy enables chemical characterization of single pollen grains as well as comparative analysis of plant species based on pollen ultrastructure.

Chemical imaging of pollen by vibrational microspectroscopy enables characterization of pollen ultrastructure, in particular phenylpropanoid components in grain wall for comparative study of extant and extinct plant species. A detailed characterization of conifer (Pinales) pollen by vibrational microspectroscopy is presented. The main problems that arise during vibrational measurements were scatter and saturation issues in Fourier transform infrared (FTIR), and fluorescence and penetration depth issues in Raman. Single pollen grains larger than approx. 15 µm can be measured by FTIR microspectroscopy using conventional light sources, while smaller grains may be measured by employing synchrotron light sources. Pollen grains that were larger than 50 µm were too thick for FTIR imaging since the grain constituents absorbed almost all infrared light. Chemical images of pollen were obtained on sectioned samples, unveiling the distribution and concentration of proteins, carbohydrates, sporopollenins and lipids within pollen substructures. The comparative analysis of pollen species revealed that, compared with other Pinales pollens, Cedrus atlantica has a higher relative amount of lipid nutrients, as well as different chemical composition of grain wall sporopollenin. The pre-processing and data analysis, namely extended multiplicative signal correction and principal component analysis, offer simple estimate of imaging spectral data and indirect estimation of physical properties of pollen. The vibrational microspectroscopy study demonstrates that detailed chemical characterization of pollen can be obtained by measurement of an individual grain and pollen ultrastructure. Measurement of phenylpropanoid components in pollen grain wall could be used, not only for the reconstruction of past environments, but for assessment of diversity of plant species as well. Therefore, analysis of extant and extinct pollen species by vibrational spectroscopies is suggested as a valuable tool in biology, ecology and palaeosciences.

Palynomorph assemblages and paleoclimate records from the Zhuanchengzi Bed of the Yixian Formation, western Liaoning Province, China

We collected, processed, identified, and analyzed the spores and pollen samples from the Zhuanchengzi Bed of the Yixian Formation in the Yingwoshan area of western Liaoning. As a result, we confirm a palynomorph assemblage of Cicatricosisporites-Protoconiferus. The pollen was primarily from gymnosperms, dominated especially by conifer pollen. Pteridophyte spores were less common and some questionable angiosperm pollen occurred occasionally. The age of the palynomorph assemblage is dated as the late Valanginian or Hauterivian-Barremian stage, the Early Cretaceous. The study applies the concept of Palynological Vegetation based on palynological spectra and the paleoecological characteristics of palynological taxa for the first time. Palynological vegetation type, climatic zone type, and humidity type are divided quantitatively for the Zhuanchengzi Bed in the Yixian Formation of western Liaoning. We then obtained the evolutionary trends. The results showed that the overall climate was warm and humid during the deposition period of the Zhuanchengzi Bed in the Yixian Formation. Palynological vegetation types are various and include coniferous forest, deciduous broadleaf forest, evergreen broad-leaved forest, grass, and shrubs. The local temperature changed from warm to much warmer and from a semi-humid to humid climate. Palynological vegetation types are always dominated by coniferous forest. The coexistence of deciduous broad-leaved forest, evergreen broad-leaved forest, shrubs, grass, and some xerophytic plants indicates vertical zonation and seasonal climate change The vertical vegetation types and the warm humid climate may imply a large geomorphological contrast in the Yixian Formation of western Liaoning.

Late Holocene environment of subalpine northeastern Taiwan from pollen and diatom analysis of lake sediments

We used multi-decadal pollen and diatom records from sediment core TFL-1 from Tsuifong Lake to reconstruct the vegetation dynamics and hydroclimate in northeastern Taiwan during the past 3500cal BP. Coarse grained sediments in association with higher percentages of wetland pollen (Cyperaceae) and upper conifer pollen (Tsuga and Pinus) in the lower part of the core indicate low lake levels and a relatively cold/dry climate between 3500 and 2030cal BP, reflecting a decline of the East Asian summer monsoon (EASM). Muddy sediments coupled with reduction of wetland pollen represent the rise of lake levels, implying the re-strengthening of the EASM during the past 2000years. Paleotemperature was inferred from the variation of pollen origin from the upper and lower mountain forest, indicating the global temperature anomalies of the Medieval Warm Period (MWP) and the Little Ice Age (LIA). In comparison to the main climate forces in the North Pacific, we suggest that the long-term climatic trend in Taiwan was controlled by variations in EASM intensity, while increased precipitation over the past 2000years may also be linked to warmer sea surface temperature (SST) of the western Pacific Warm Pool (WPWP) and increased El Niño-Southern Oscillation (ENSO) events, which increased typhoon intensity. Higher diatom-inferred pH during 2930–2030cal BP and the LIA suggest strong hydrological disturbances, reflecting more typhoons passing over Taiwan. The frequent typhoon events could be linked by an abrupt shift of typhoon track, due to the reduction of the WPWP and expansion of the Northwestern Pacific High, which move typhoons in a more westerly direction.

The pollen complex from postglacial sediments of the Laptev Sea as a bioindicator

The first results of comparison of palynological analysis (pollen of terrestrial plants), SEM analysis of pollen morphology, and radiocarbon age dating (AMS14C) of sediments of the eastern shelf of the Laptev Sea show that the diverse taxonomic composition of pollen spectra provides an integrated idea of the vegetation and climate of the region over 11.2 calendar kiloyears. It is found that phases of the tree and shrub vegetation development (maxima of pollen of Betula sect. Nanae and Pinus s/g Haploxylon) correspond to the warm epochs in the Holocene. It is obvious that birch phytocoenoses first settled in the southern tundra subzone with increasing temperature, and then coniferous communities of forest tundra. An occurrence of pollen of shrubby birches (Nanae) suggests compliance of permafrost landscapes with cold climate conditions, i.e., with an annual average temperature of −2°C and amount of precipitation of less than 500 mm. Owing to a progressive increase in summer temperatures, dwarf cedar and pine communities advanced toward the seashore. The SEM analysis results show that a significant proportion of regional coniferous pollen belongs to representatives of Pinus pumila (Pall.) and P. sylvestris L. In addition, the SEM study of the exine of Pinus sylvestris L. and P. pumila (Pall.) Regel pollen grains confirmed polymorphism in coniferous pollen. According to the inverse relationship between climate and vegetation, frequent climate fluctuations that are typical of progressive and differential postglacial transgression were revealed. An increase in arboreal pollen transfer onto the shelf later than 9.1 cal. ka coincides with the time of forest boundary migration to the north due to the warming of the Earth’s climate. At that time, the tundra vegetation was replaced by forest-tundra vegetation, the maximum stage of sea transgression began, and there appeared a trend of increasing temperature and moisture.

Aberrant Classopollis pollen reveals evidence for unreduced (2n) pollen in the conifer family Cheirolepidiaceae during the Triassic-Jurassic transition.

Polyploidy (or whole-genome doubling) is a key mechanism for plant speciation leading to new evolutionary lineages. Several lines of evidence show that most species among flowering plants had polyploidy ancestry, but it is virtually unknown for conifers. Here, we study variability in pollen tetrad morphology and the size of the conifer pollen type Classopollis extracted from sediments of the Triassic-Jurassic transition, 200 Ma. Classopollis producing Cheirolepidiaceae were one of the most dominant and diverse groups of conifers during the Mesozoic. We show that aberrant pollen Classopollis tetrads, triads and dyads, and the large variation in pollen size indicates the presence of unreduced (2n) pollen, which is one of the main mechanisms in modern polyploid formation. Polyploid speciation may explain the high variability of growth forms and adaptation of these conifers to different environments and their resistance to extreme growth conditions. We suggest that polyploidy may have also reduced the extinction risk of these conifers during the End-Triassic biotic crisis.

Dunkard Group coal beds: Palynology, coal petrography and geochemistry

Coal beds that occur in the Dunkard Group are typically thin (avg. 0.3m), and are high in ash yield (avg. 27.8%) and total sulfur content (avg. 5.1%). Petrographically, Dunkard coals are high in vitrinite (avg. 83.1%, mmf), with correspondingly low to moderate amounts of liptinite (avg. 2.1%, mmf) and inertinite (avg. 13.8%, mmf). Palynologically, Dunkard coal beds are all dominated by tree fern spore taxa (avg. 96.3%), especially Punctatisporites minutus (avg. 82.8%). Calamite spores are the second most abundant plant group (avg. 2.4%), with others (lycopods, small ferns, Cordaites and other gymnosperms) having very minor representation. Overall, the coal palynofloras are strongly dominated by lowland plants (ferns and Calamites), with only rare occurrences of bisaccate–striate conifer pollen.Coal beds of the underlying Monongahela Group (Pittsburgh, Redstone, Sewickley and Waynesburg) are thicker (avg. 1.6m), and are lower in ash (avg. 13.4%) and sulfur (avg. 3.3%) than their Dunkard counterparts. Petrographically, Monongahela Group coals are very similar to Dunkard Group coals, when compared on a mineral matter free basis; coal beds that occur in both groups are strongly dominated by vitrinite macerals. Monongahela Group coals are also palynologically very similar to Dunkard Group coals, with tree fern spore taxa dominating. A coal bed of early Permian age from west-central Texas is also similar, petrographically and palynologically, to Dunkard and Monongahela coals, being vitrinite and tree fern spore dominant.The almost complete lack of coniferous pollen in Dunkard coals led earlier workers to conclude that the Dunkard was entirely Late Pennsylvanian, and not Permian, in age. However, it is now known that Late Pennsylvania lowland floras persisted into the Dunkard, especially during wet intervals. As earlier interpretations were based primarily on spore and pollen floras from coal beds, the lack of conifer pollen in Dunkard coals is probably the result of a sampling bias. Because of this ecological bias, coal palynology is a poor proxy for age dating Dunkard Group coals.Collectively, Dunkard swamps were all planar and topogenous, their formation being controlled by topography and moisture availability. A progressive decrease in wet intervals, both in terms of frequency and duration, during the Dunkard was the major control on peat accumulation and preservation. Collectively, moisture limitation appears to be the principle factor that controlled the formation of Dunkard Group coals.

Vegetational composition of the Early Cretaceous Chicalhão flora (Lusitanian Basin, western Portugal) based on palynological and mesofossil assemblages

A new Early Cretaceous flora is described from the Lusitanian Basin in the Estremadura region (western Portugal) based on a combined study of mesofossils and palynomorphs. The fossil specimens were extracted from samples collected in the Chicalhão clay pit complex, near the village of Juncal from sediments belonging to the Figueira da Foz Formation. The plant bearing sequence is considered to be of Late Aptian–Early Albian age. Palynomorphs and mesofossils are generally well-preserved and include about 63 taxa. The palynoflora is dominated by conifer pollen and fern spores. Angiosperm pollen is also present, but subordinate among the palynomorphs. In contrast, angiosperms completely dominate the mesofossil flora and are mainly represented by fruits and seeds. Four taxa of angiosperm flowers were also identified. The combined palaeobotanical and sedimentological evidence indicates seasonally dry climate and an open vegetation consisting of a mixed conifer forest with an understorey and ground cover of ferns and angiosperms and with patchy occurrences of lycophytes and plants of the Bennettitales–Erdtmanithecales–Gnetales (BEG) group. Angiosperms probably inhabited moister areas bordering rivers and lakes.

Late Cenozoic continuous aridification in the western Qaidam Basin: evidence from sporopollen records

Abstract. Cenozoic climate changes in inner Asia provide a basis for understanding linkages between global cooling, the Tibetan Plateau uplift, and possibly the development of the East Asian monsoon. Based on a compilation of palynological results from the western Qaidam Basin, this study reconstructed a 15-million-year (Ma) record of changing vegetation and paleoclimates spanning the middle Miocene to present (comprising two series: ~ 18–5 Ma and ~ 3.1–0 Ma, respectively). The thermophilic percentages were highest between 18 and 14 Ma, and decreased after 14 Ma, closely corresponding to the Middle Miocene Climatic Optimum (MMCO) between 18 and 14 Ma and the following global climatic cooling between 14 and 5 Ma. At the same time, decreases in the xerophytic and coniferous taxa percentages, and the increasing logarithmic ratio of non-arboreal pollen to arboreal pollen (ln (NAP/AP)), reveal the continuous aridification across both the basin and surrounding mountains. Between ~ 3.1 and 0 Ma, the percentages of the thermophilic, xerophytic and coniferous pollen as well as the ln (NAP/AP) imply further cooling and drying in this region since 3.1 Ma. We argue that these vegetation and climate patterns during the late Cenozoic western Qaidam Basin are primarily a result of the global cooling, with the Tibetan Plateau uplift and East Asian summer monsoon having contributions of lesser importance.