Major Pollen Types Research Articles

Relationships between pollen assemblages and modern vegetation of the southern Gaoligong Mountains region, southwest China

Comprehensive understanding of the modern pollen–vegetation relationship is crucial for utilizing fossil pollen to reconstruct palaeovegetation, especially in mountainous areas of southwestern China. In this study, we present forty-five modern surface samples collected from five different vegetation communities of the southern Gaoligong Mountains region, and the vegetation composition was investigated at each sample site. The modern pollen assemblages were analyzed through multivariate analysis to evaluate the relationships between vegetation types and pollen assemblages, and to investigate the representation of major pollen types in different vegetation types. The results indicate that the surface pollen assemblages of different vegetation types reliably represent the modern vegetation. The median R-values of dominant pollen taxa in the Gaoligong Mountains region can be ordered as follows: Pinus > Alnus > Poaceae > evergreen Quercus. The over-representation of Pinus pollen, attributed to its high productivity and strong dispersal ability, makes it the dominant component of exotic pollen. Conversely, the under-representation of evergreen Quercus suggests that the presence of its pollen within a sample might indicate the growth of the local parent plant in the study area. The human activities in the region have a recognizable effect on the surface pollen spectra and also exert a significant negative impact on pollen diversity. Our study supplements the modern pollen database of the mountain regions in southwestern China, and provides representative modern pollen analogues to interpret fossil pollen records from southwestern China and similar regions.

The South African Pollen Monitoring Network: Insights from 2years of national aerospora sampling (2019-2021).

Pollen monitoring has been discontinuously undertaken in South Africa, a country with high biodiversity, a seasonal rainfall gradient, and nine biomes from arid to subtropical. The South African Pollen Monitoring Network was set up in 2019 to conduct the first long-term national aerospora monitoring across multiple biomes, providing weekly reports to allergy sufferers and healthcare providers. Daily airborne pollen concentrations were measured from August 2019 to August 2021 in seven cities across South Africa. Updated pollen calendars were created for the major pollen types (>3%), the average Annual Pollen Index over 12 months was calculated, and the results were compared to available historical data. The main pollen types were from exotic vegetation. The most abundant taxa were Poaceae, Cupressaceae, Moraceae and Buddleja. The pollen season start, peak and end varied widely according to the biome and suite of pollen taxa. The main tree season started in the last week of August, peaked in September and ended in early December. Grass seasons followed rainfall patterns: September-January and January-April for summer and winter rainfall areas, respectively. Major urban centres, for example, Johannesburg and Pretoria in the same biome with similar rainfall, showed substantive differences in pollen taxa and abundance. Some major differences in pollen spectra were detected compared with historical data. However, we are cognisant that we are describing only 2years of data that may be skewed by short-term weather patterns. Differences in pollen spectra and concentrations were noted across biomes and between geographically close urban centres. Comparison with historical data suggests pollen spectra and seasons may be changing due to anthropogenic climate change and landscaping. These data stress the importance of regional and continuous pollen monitoring for informed care of pollinosis.

Melıssopalynologıcal study of Apıs Mellıfera L. honey sourced from dıfferent localıtıes in the mıddle belt of Nıgerıa

Melissopalynological studies are useful to determine the floral contents and geographical origin of honey samples. The great diversity of plants allows bees to produce honey that is highly valuable to the consumers. This study was aimed to determine pollen types in honey samples collected from the Middle Belt region to provide information on botanical origin of honeys. Six honey samples were collected from Benue and Kogi States in North Central, Nigeria. According to their pollen spectra, they were multiflora honeys. The honey samples collected from Benue State had a total pollen count of 8, 932, thirty nine pollen types in twenty five (25) families of plant and samples from Kogi State recorded 3,859 pollen, 29 pollen types in nineteen 19 plant families. A total of thirteen pollen types were identified to generic level, fifteen to species and nine to family level in honey samples collected from Benue State whereas in Kogi State samples, eleven pollen types were identified to generic level, eight to species and nine to family level. The major pollen types in Benue honey samples were Sarcocephalus latifolius, Phyllanthus sp., Lannea sp., Hymenocardia acida, Syzygium guineense, Solanum sp., Parkia biglobosa, members of Anacardiaceae, Combretaceae/Melastomataceae, Euphorbiaceae and Sapindaceae whereas Hymenocardia acida, Elaeis guineensis, Solanum sp., Cassia sp., Sarcocephalus latifolius, members of Combretaeaeceae/Melastomataceae and Fabaceae were dominant in samples from Kogi State. The pollen analyses provided important information on the floral source preferences of bees and on honey contents, which can be used by traditional beekeepers and the public in general in promoting the production and consumption of high quality honey in the Middle Belt region of Nigeria.

Airborne Pollens and Their Association with Meteorological Parameters in the Atmosphere of Shiraz, Southwest Iran.

Airborne pollen is considered one of the causative agents of hay fever, allergic rhinitis, conjunctivitis, and asthma. We aimed to investigate airborne pollens in the context of Shiraz located in the southwest of Iran and find their association with meteorological parameters. The survey was conducted from October 2017 to September 2018, using seven days of volumetric Burkard spore trap, located in the center of the city. A total of 5810 pollen grains/m3 belonging to 15 taxa were identified and recorded. Among them, 73.8% was the tree, while the grass, shrub, and weed constituted 13.56%, 3.5%, and 9.2% of total reported pollens, respectively. The major pollen types were Platanaceae (28.39%), Oleaceae (21.17%), Pinaceae (15.11%), Amaranthaceae (9.29%), and Brassicaceae (8.02%). A higher number of pollen counts and types were recorded in March, followed by September, while it was lower in May. Meteorological parameters were correlated with the monthly pollen counts. Wind speed was found to have a positive correlation with Platanaceae concentration. The significant correlation between pollen concentration and the temperature was positive for Poaceae, Amaranthaceae, and Plantaginaceae and negative for Rosaceae, Oleaceae, and Ulmaceae. Poaceae and Amaranthaceae were negatively correlated with humidity and positively with Rosaceae, Oleaceae, and Plantaginaceae. A negative correlation was found between rainfall and Poaceae and Amaranthaceae, while Plantaginaceae had a positive correlation with this parameter. The results of this study may be helpful for allergologists in the diagnosis and treatment of airborne allergic disorders due to pollen grains.

Pollen-based mapping of Holocene vegetation on the Qinghai-Tibetan Plateau in response to climate change

Improved studies of past vegetation change are required to better understand the variation of alpine ecosystems on the Qinghai-Tibetan Plateau (QTP) in response to future climate change. Spatial and temporal variations of past vegetation can be traced by fossil pollen data mapping. In this paper, we synthesized 57 continuous pollen records on the QTP covering the past 15 kyr to depict large-scale vegetation change and its response to climate variations. In order to minimize potential chronological biases, age-depth models were revised using a state-of-the-art and consistent method for all the records. The spatial and temporal variation of major pollen taxa were examined based on interpolated pollen maps at 1000-year intervals. The arboreal pollen (AP, mainly of Pinus, Betula and Abies/Picea) content expressed significant climate signals over a broad spatial and temporal gradient. During the late glacial period, high proportions of AP widely occurred in regions that are presently unforested owing to the sparse local vegetation coverage. For the Holocene period, AP showed relatively high contributions in records from the southeastern margin of the QTP, with a decreasing gradient in abundance towards the northwest. The transportation of AP to unforested regions corresponds closely to the intensity of monsoon wind, which can be used to track the Holocene evolution of the summer monsoon. The dominant shrub and herbaceous taxa (including Artemisia, Chenopodiaceae, Cyperaceae, Poaceae and Ephedra) generally represent developments of local vegetation responding to climate variations. In addition, the persistent increase in Poaceae pollen during the mid to late Holocene correlates possibly to regional human activities. The inferred spatial and temporal patterns of major pollen types on the QTP provide significant knowledge about long-term vegetation change and its potential response to climate variations.

Relationship between airborne pollen assemblages and major meteorological parameters in Zhanjiang, South China.

Pollen is an important component of bioaerosol and the distribution of pollen and its relationship with meteorological parameters can be analyzed to better prevent hay fever. Pollen assemblages can also provide basic data for analyzing the relationship between bioaerosol and PM. We collected 82 samples of airborne pollen using a TSP large flow pollen collector from June 1, 2015 to June 1, 2016, from central Zhanjiang city in South China. We also conducted a survey of the nearby vegetation at the same time, in order to characterize the major plant types and their flowering times. We then used data on daily temperature, relative humidity, precipitation, vapor pressure and wind speed from a meteorological station in the center of Zhanjiang City to assess the relationship between the distribution of airborne pollen and meteorological parameters. Our main findings and conclusions are as follows: (1) We identified 15 major pollen types, including Pinus, Castanopsis, Myrica, Euphorbiaceae, Compositae, Gramineae, Microlepia and Polypodiaceae. From the vegetation survey, we found that the pollen from these taxa represented more than 75% of local pollen, while the pollen of Podocarpus, Dacrydium and other regional pollen types represented less than 25%. (2) The pollen concentrations varied significantly in different seasons. The pollen concentrations were at a maximum in spring, consisting mainly of tree pollen; the pollen concentrations were at an intermediate level in autumn and winter, consisting mainly of herb pollen and fern spores; and the pollen concentrations in summer were the lowest, consisting mainly of fern spores. (3) Analysis of the relationship between airborne pollen concentrations and meteorological parameters showed that variations in the pollen concentrations were mainly affected by temperature and relative humidity. In addition, there were substantial differences in these relationships in different seasons. In spring, pollen concentrations were mainly affected by temperature; in summer, they were mainly affected by the direction of the maximum wind speed; in autumn, they were mainly affected by relative humidity and temperature; and in winter, they were mainly affected by relative humidity and wind speed. Temperature and relative humidity promote plant growth and flowering. Notably, the variable wind direction in summer and the increased wind speed in winter and spring are conductive to pollen transmission. (4) Of the 15 major pollen types, Moraceae, Artemisia and Gramineae are the main allergenic pollen types, with peaks in concentration during April-May, August-September, and October-December, respectively. (5) Atypical weather conditions have substantial effects on pollen dispersal. In South China, the pollen concentrations in the sunny day were usually significantly higher than that of the rainy day. The pollen concentrations increased in short rainy days, which usually came from the Herb and Fern pollen. The pollen concentrations decreased in continuous rainy days especially for the Tree and Shrub pollen. the pollen concentrations in the sunny days were usually significantly higher than that in the rainy days. The pollen concentrations increased in short and strong rainfall.

A study on modern pollen rain and pollen morphology in the tropical western Malay Peninsula and its implications for paleoenvironmental reconstructions in the Sunda region

The tropical Southeast Asia area is rich in plant diversity, and the current environment conditions, especially the vegetation, were formed through a series of complicated processes, both geological and biological, in the past. One of the most powerful tools to reveal these processes is pollen analysis. However, so far, it is still poorly understood in the modern pollen rain, hindering further palynological exploration of ecological and environmental evolutions in the region. Here we analyzed 84 surface pollen samples from the western Malay Peninsula and illustrated a high level of pollen and spore diversity by photographic images of 328 types. The results also revealed that all the regional vegetation types are distinguished by a few major characteristic pollen and spore types in the assemblages. For montane rainforests, Podocarpaceae, Ericaceae, cf. Distichostemon, Borreria, Myrica, Rapanea, Ophioglossaceae and Ilex type1 are characteristic. For lowland dipterocarp rainforests, Bursaraceae, Sapotaceae, Mallotus/Macaranga, Eugeissona, Anacardiaceae, Asystasia, Ilex type2/3, Hamamelidaceae, Dicranopteris, etc. are good indicators. The coastal rainforests are distinguished by relatively abundant Casuarina, cf. Pittosporum, Styracaceae, Ulmus, Alstonia and Schoutenia, and the mangrove forest by abundant Rhizophora, Sonneratiaceae, Xylocarpus and Lygodiaceae. Detrended Correspondence Analysis (DCA) of pollen percentages shows strong correlations of plant communities with the distribution elevation and the substrate gradients. Our results demonstrate the potential for detailed paleoecological reconstructions of both montane and lowland communities in the study region, and also suggest a pollen sorting of marine samples after a long-distance transport to the deposition sites.

Pollen Diversity in the Atmosphere of Karacabey (Bursa), Turkey

Pollen grains are known as important bio-allergens for sensitive individuals because of their presence in the air we breathe. Therefore, it is important to know the pollen load, major pollen types and sesonal variations of them for each populated region. The aim of this study was to determine the pollen types, densities and the pollen seasons of main pollen producers in Karacabey area. Pollen quantities and diversity studies were carried out by the gravimetric method in Karacabey (Bursa) atmosphere for two years, between 1 January 2015 and 31 December 2016. During sampling, the slides were changed weekly and examined by light microscopy. Annually 14226 pollen grains (15281 in 2015 and 13171 in 2016) belonging to 59 plant taxa (32 woody and 27 herbaceous taxa) were identified and pollen grains of woody taxa represented 72.63% (77.00% in 2015 and 68.27% in 2016) and herbaceous taxa represented 26.69% (22.30% in 2015 and 31.09% in 2016) of the annual pollen index (API) which was concordant and evaluated as a reflection of the dominant flora and maquis vegetation of the area. Types of pollen identified belonged to Cupressaceae/Taxaceae, Pinus, Poaceae, Quercus, Platanus, Ambrosia, Olea, Plantago, Amaranthaceae, Salix, and Fraxinus which were classified as dominant pollen types for the region and the the total amount for them was 88.21% of the annual pollen index. In this regard, April-May and August-September can be thought of as a risky period for sensitive individuals living in or visiting the region. One of the most exciting findings of this study was the high dominance of highly allergenic Ambrosia pollen in the atmosphere.

Preliminary study of the atmospheric pollen in Sierra de las Nieves Natural Park (Southern Spain)

Sierra de las Nieves is a Natural Park and a Biosphere Reserve located in Southern Spain. This protected area has a high diversity of ecosystems with abundant endangered species which has led to be proposed as a National Park. In January 2018, a pollen trap was installed inside this Natural Park in order to determine the atmospheric pollen behaviour of the main taxa registered during a whole year. Additionally, the results were compared with those registered in the urban and rural stations of Malaga and Ronda, respectively, during the same period. The samplings were made by means of a Hirst-type volumetric pollen trap, and the samples obtained were mounted and counted according to the methodology proposed by the Spanish Aerobiology Network. The highest amount and diversity of atmospheric pollen in the Natural Park was detected during the spring months. Statistical significant differences were found, regarding daily total pollen concentrations, between Sierra de las Nieves (Natural Park) and Malaga (urban city), and between Ronda (rural city) and Malaga. These differences were particularly detected for some pollen types such as Quercus. In general, the start of the main pollen season and the maximum concentration peak of the major pollen types occurred later in Sierra de las Nieves than in Ronda and Malaga. The qualitative and quantitative differences between Sierra de las Nieves and the others nearby locations can be explained by the differences in land use, altitude, climatic characteristics, as well as the distance between the aerobiological stations and the pollen emission sources.

A Revision of Cuphea section Amazoniana s. s. (Lythraceae)

Abstract—Cuphea section Amazoniana, one of 13 sections in Cuphea, comprises 20 species, mostly narrow endemics in Colombia, Ecuador, and the Guiana Shield region of Venezuela, Guyana, French Guiana, and Brazil. The species inhabit river margins, tepuis, scrubland, savanna, and low montane forests in tropical to cold temperate climates. They are subshrubs defined by the common presence of a strigose indumentum of bifid (malpighiaceous) trichomes; small elliptic to narrowly lanceolate or linear coriaceous leaves; and tubular flowers to 9 mm long with 11 deeply inserted stamens included in the floral tube. In morphology, they are similar to or partially overlap species currently classified in Cuphea sections Trispermum and Heteranthus. The revision provides a new key, comparative morphological descriptions, first descriptions and illustrations of pollen and seed morphology, and distribution maps. Cuphea saxatilis S. A. Graham, sp. nov. from Colombia and Cuphea trisperma S. A. Graham, sp. nov. from Venezuela are newly described. Cuphea killipii Lourteig is placed in synonomy of C. philombria Lourteig. Presence or absence of a floral spur, position and shape of a nectary-like floral organ, the “disc”, and presence of two major pollen types suggest the section is not monophyletic, but consists of a minimum of two phylogenetic lineages, one in the Guiana Shield region in Venezuela and eastward, the other in low montane forests and on outliers of the Guiana Shield in Colombia and northern Ecuador. Fossilized Cuphea pollen grains resembling two types of pollen known in sect. Amazoniana, establish the presence of the genus in the Mio-Pliocene to Holocene of northern South America in areas occupied today by members of the section.

Pollen morphology of Trigonostemon and its relatives (Euphorbiaceae)

The pollen of Trigonostemon and the related genera Dimorphocalyx, Ostodes, Tritaxis and Jatropha (outgroup) has been studied with light microscopy, and scanning and transmission electron microscopy. The two major pollen types within Trigonostemon correlate well with macromorphological characters. Species belonging to the Trigonostemon reidioides type have pollen with ‘croton pattern’ ornamentation, a pistil with deeply divided stigmas (to at least half the length of the stigma arm) and stamens with a protruding appendage on the connective, while species of the Trigonostemon verrucosus type have verrucate (to almost gemmate) pollen, stigmas that are shortly cleft and stamens without an appendage on the connective. Dimorphocalyx, Ostodes, Tritaxis and Jatropha (outgroup) have similar pollen morphology, while Trigonostemon deviates from these genera in the absence of the ‘vertically’ striate ornamentation on the subunits. Therefore, when compared with an existing phylogeny of the Euphorbiaceae, the pollen characters of Trigonostemon appear to be derived. Moreover, because the ‘croton pattern’ ornamentation itself is widely shared by the ‘inaperturate crotonoids’, the loss of that structure in the Trigonostemon verrucosus type pollen is considered a further apomorphy.

Botanical origin and geographic differentiation of bee-pollen produced in high mountains from the Colombian eastern Andes

In the high mountains of the Colombian Eastern Cordillera (~2000–3000 m above sea level), at the Altiplano Cundiboyacense region and surroundings, beekeepers have specialised in pollen production with substantial harvests all year round. Despite this productive advantage, the knowledge about plants used by honeybees as pollen resources is still limited. Hence, the aim of this work was to identify the botanical origin of bee pollen from this region and to examine differences between five distinguished sub-regions: Sabana de Bogotá, Fúquene, Márquez, Tundama and Norte-Gutiérrez. By means of palynological analyses of 86 pollen samples produced between 2008 and 2010, we found a total amount of 126 pollen types, most of them belonging to the families Asteraceae and Fabaceae. Major pollen types correspond to the exotic taxa Hypochaeris radicata, Brassicaceae, Eucalyptus globulus, Trifolium repens, Trifolium pratense and the native taxa Quercus humboldtii and Weinmannia sp. Differences between sample groups from the five sub-regions were mainly associated to variations in pollen abundance and frequency of native plant species. This result highlights the potential for commercialising bee-pollen from the Colombian Eastern Cordillera with geographical origin differentiation, as well as the importance for beekeeping in promoting the conservation of the natural ecosystems from the region.

Pollen morphology of the tribeHemimerideae: possible evidence of ancestral pollen types and parallel evolution in the basalmost clade ofScrophulariaceaes.str.

Abstract: Pollen morphology of nine species belonging to six genera of tribe Hemimerideae (representing the basalmost clade of Scrophulariaceae s.str.) was studied and illustrated with light microscopy (LM) and scanning electron microscopy (SEM). Pollen grains in Hemimerideae are 3- or 6–8-colpate or 3- or 5–8-colporate, prolate, spheroidal or oblate-spheroidal in shape; they are mainly medium-sized or occasionally small. The outline in polar view is 3-lobed, rounded-3-lobed or 5–8-lobed; the outline in equatorial view is elliptic or orbicular. Exine sculpture is rough, rough-foveolate, foveolate, microreticulate, rugulate, rugulate-foveolate or rugulate-microreticulate. Four major pollen types are recognized, based on original data: 3-colpate (Alonsoa), 6–8-colpate (Diclis, Hemimeris), 3-colporate (Colpias) and 5–8-colporate (Diascia, Nemesia). Within two of these pollen types, two subtypes can be further distinguished based on pollen size, exine sculpture, details of the colpi and endoapertures. Based o...

Comparison between the counting methods used by two aerobiology networks in southern Europe (Spain and Italy)

Aerobiology studies the biological particles suspended in the atmosphere in order to know what types are present in the air and how their concentrations vary spatially or seasonally. The measurement of airborne pollen concentration requires a standardized methodology. Normally, the analysis of the slides obtained after samplings is carried out according to national network procedures. Different networks use different slide counting methods (longitudinal sweeps, transverse sweeps or random fields), and a different number of lines/fields are routinely read. In this study, we compared two slide counting methods adopted by two monitoring centres belonging to different aerobiology networks that operate in southern Europe, the University of Malaga (Spanish Aerobiology Network, the REA) and the University of Roma Tor Vergata (Rete Italiana di Monitoraggio in Aerobiologia, the RIMA). For that, the same samples were counted following the two methodologies consisting on the reading of four (REA) and six (RIMA), respectively, longitudinal sweeps at a magnification of 400X (REA). Statistical analysis was performed in order to search the degree of association between the two series of data obtained, as well as whether or not there were significant differences between them. The results showed highly significant correlation and regression coefficients. On the other hand, Wilcoxon tests, in general, did not showed significant differences between the series for the total pollen as well as for the major pollen types. This confirms that the two methods can be used indistinctly although it would be convenient for the different networks to standardize and unify methodologies in order to follow the same operating procedures.

Small-scale moisture availability increase during the 8.2-ka climatic event inferred from biotic proxy records in the South Carpathians (SE Romania)

In this paper, we present high-resolution early Holocene pollen, plant macrofossil, charcoal, diatom, biogenic silica, and loss-on-ignition records from a mountain lake in the South Carpathians in order to reveal ecosystem response to the 8.2-ka climatic oscillation. We found significant changes both in terrestrial vegetation and lake diatom assemblages in the northern slope of the Retezat Mts between c. 8300 and 8000 cal. yr BP. Rapid changes in relative frequencies and pollen accumulation rates of the major deciduous pollen types associated with peaks in microcharcoal accumulation rates suggested that vegetation disturbance mainly took place in the mixed-deciduous forest zone, where woodland fires partially destroyed the populations of Fraxinus excelsior, Quercus, and Corylus avellana and facilitated the establishment of Carpinus betulus in the forest openings. The diatom record furthermore showed the spread of a planktonic diatom species, Aulacoseira valida, at 8150 cal. yr BP, coincidently with a short-lived expansion of C. betulus. Since diatom blooms mainly occur in spring in the Retezat Mts, increased spring water depth and increased water turbulence were inferred from these data. The expansion of C. betulus against F. excelsior and C. avellana at the same time suggested a modest increase in available moisture during the growing season. Taken together, these data imply that during the 8.2-ka event, winter and spring season available moisture increased, while summers were characterized by alternating moist/cool and dry/warm conditions.

Pollen morphology of the southern African tribeTeedieae, an early-branching lineage of crownScrophulariaceae

Mosyakin S. L. & Tsymbalyuk Z. M.: Pollen morphology of the southern African tribe Teedieae, an early-branching lineage of crown Scrophulariaceae. — Willdenowia 45: 65–75. 2015. — Version of record first published online on 13 March 2015 ahead of inclusion in April 2015 issue; ISSN 1868-6397; © 2015 BGBM Berlin-Dahlem.DOI: http://dx.doi.org/10.3372/wi.45.45107The pollen morphology of seven species representing four genera of the tribe Teedieae (Scrophulariaceae) is described and illustrated using light microscopy (LM) and scanning electron microscopy (SEM). Two major pollen types, 3-colporate and 4-colporate, are recognized by aperture types. Within these pollen types, subtypes are distinguished based on exine sculpture, colpi, colpus membrane, and endoaperture characters. Within type I (3-colporate), three subtypes are recognized: Ia — sculpture psilate, rarely with microperforations; Ib — sculpture microperforate and microreticulate; and Ic — sculpture macroreticulate. Type II (4-colporate) is represented by only one subtype IIa — sculpture psilate, rough, and foveolate. The revealed characteristics of pollen grains are taxonomically significant at the generic and specific levels. Our palynomorphological data are consistent with the results of molecular phylogenetic studies. Pollen grains in Teedieae are typically characterized by the colporate aperture type (probably ancestral in Scrophulariaceae) and rather primitive characters of surface and sculpture of colpi membranes. Similar palynomorphological patterns in Teedieae and Buddlejeae can be viewed as ancestral for pollen characters observed in more advanced clades of Scrophulariaceae.

Taxonomic Revision of <i>Cuphea</i> sect. <i>Euandra</i> subsect. <i>Oidemation</i> (Lythraceae)

Cuphea sect. Euandra subsect. Oidemation comprises a non-monophyletic group of species defined by possession of a fire-resistant xylopodium. The xylopodium is a frequent feature of plants occurring in the seasonally and ecologically dry cerrados and savannas of South America. Subsect. Oidemation has diversified particularly in these habitats in eastern Brazil and adjacent Paraguay. Twenty species and five varieties are recognised: eleven species are endemic to Brazil; one each is endemic to Paraguay and Florida, USA; and seven are distributed in Brazil and adjacent areas of Bolivia, Paraguay, Uruguay and/or Argentina. Their morphology, including pollen and seed morphology, and chromosome numbers are reviewed. The presence of at least three major pollen types and two base chromosome numbers suggests the subsection is para- or polyphyletic; phylogenetic information based on molecular data for species of the subsection is limited. Diverse diploid, tetraploid, and hexaploid chromosome numbers point to polyploidy as an important mechanism of speciation in this group. A key to the species is accompanied by descriptions, illustrations and distribution maps.The subsection is lectotypified by C. retrorsicapilla and lectotypes are designated for C. acicularis, C. aspera, C. confertiflora, C. crulsiana, C. emarginata, C. enneanthera, C. excoriata, C. ferruginea, C. ferruginea var. acuminata, C. hyssopoides, C. remotifolia, C. retrorsicapilla, C. sperguloides, C. spermacoce var. angustata, and C. spermacoce var. elongata. A new combination is made for C. retrorsicapilla var. enneanthera.

Pollen assemblages and their environmental implications in the Qaidam Basin, NW China

The Qaidam Basin is one of the most sensitive areas to climate change in China, owing to its unique geographical position and ecological condition. In this study, 32 surface‐soil pollen samples were collected to reveal the relationship between modern pollen assemblages, vegetation and precipitation in the eastern region of the Qaidam Basin. The results show that Chenopodiaceae (3.8–87%, average 48%), Artemisia (1.7–64.2%, average 17.5%) and Ephedra (0–90%, average 16.3%) are the dominant pollen types in all samples, and that different pollen assemblages correspond to different vegetation types. DCA and CCA of major pollen types demonstrate that precipitation is an important factor in the control of the distribution of vegetation in the study area. The content and concentration of the three major pollen types (Artemisia, Chenopodiaceae and Ephedra) change with the mean annual precipitation, and the optimum mean annual precipitation for Ephedra, Chenopodiaceae and Artemisia is <80, 80–200 and >160 mm, respectively. Correlation analysis between the variation in grain size of the three major pollen types and the main environmental variables shows that the grain size of the three pollen types is positively correlated with precipitation in the Qaidam Basin. The results confirm that precipitation is the most important environmental factor in the Qaidam Basin, and that it has an important effect on pollen grain size in the study area.

Modern pollen-vegetation relationship based on discriminant analysis across an altitudinal transect on Gongga Mountain, eastern Tibetan Plateau

Quantitative relationship between modern pollen assemblage and altitudinal vegetation belt is crucial for the reconstruction of paleovegetation in the mountain regions. Modern pollen analysis on 70 topsoil samples was conducted across an altitudinal transect (1100-4500 m) on the eastern slope of Gongga Mountain in the eastern Tibetan Plateau with an elevation interval of 50 m. Distributions of major pollen types along the transect indicated a weak correlation between Pinus pollen and the elevation. Distributions of Picea and Abies pollen (percentage sum of 2%-8%) could fairly indicate the elevation range of 2700-3700 m, as well as the subalpine dark coniferous forest and the timberline in the region. High percentage intervals of alpine types of Ericaceae, Cupressaceae and Cyperaceae were correlated to the high-elevation regions (3700-4500 m) dominated by alpine shrub meadow and alpine meadow. Seven altitudinal vegetation belts on the eastern slope of Gongga Mountain were well defined by discriminant analysis conducted on the modern pollen assemblages, as reflected by high values of probability of modern analog. Most of the modern pollen assemblages (88.5%) were typical for the vegetation types at their sampling locations. Thus, the relationship between the modern pollen assemblages and vegetation across the altitudinal transect based on discriminant analysis can be applied to the quantitative reconstruction of paleovegetation changes in the mountain regions of the eastern Tibetan Plateau.

Estimating pollen productivity and relevant source area of pollen using lake sediments in Norway: How does lake size variation affect the estimates?

This study aims to estimate relative pollen productivity (PPEs) of major pollen types and the relevant source area of pollen (RSAP) in a semi-open landscape in western Norway. Extended R-value (ERV) models are used to analyse a data set consisting of surface pollen assemblages from 34 lakes and vegetation survey around each site. Ordination techniques indicate relatively short gradients (<2.3 SD) both in the vegetation and pollen data sets. The lake sizes vary from 0.4 ha to 19.0 ha (mean=5.7 ha, sd=4.3 ha) but follow a normal distribution – a departure from the assumption of the ERV models that the lake size should be constant among sites. Simulations demonstrate that, if the sizes of circular-shaped lakes follow a normal distribution, the ERV model-based methods provide the expected PPE and RSAP values using a standardized lake radius. If the distribution is highly skewed or equally random around the mean, the results are not reliable. We apply the analytical strategy implied from the simulations to obtain relative PPEs and the RSAP in western Norway. PPEs for ten taxa ( Alnus, Fagus, Picea, Pinus, Quercus, Juniperus, Salix, Calluna, Cyperaceae, Rumex) relative to Poaceae are comparable with some of those previously obtained in different parts of Europe, indicating that there are general patterns of high and low pollen producers that will be useful for reconstruction purposes. The RSAP estimate is the area within a radius of 900–1100 m. This study demonstrates the importance of careful evaluation of the extent to which the departures from the model assumptions affect the outcomes from the ERV model-based analysis.