Individual Pollen Types Research Articles

Towards European automatic bioaerosol monitoring: Comparison of 9 automatic pollen observational instruments with classic Hirst-type traps

To benefit allergy patients and the medical practitioners, pollen information should be available in both a reliable and timely manner; the latter is only recently possible due to automatic monitoring. To evaluate the performance of all currently available automatic instruments, an international intercomparison campaign was jointly organised by the EUMETNET AutoPollen Programme and the ADOPT COST Action in Munich, Germany (March–July 2021).The automatic systems (hardware plus identification algorithms) were compared with manual Hirst-type traps. Measurements were aggregated into 3-hourly or daily values to allow comparison across all devices. We report results for total pollen as well as for Betula, Fraxinus, Poaceae, and Quercus, for all instruments that provided these data. The results for daily averages compared better with Hirst observations than the 3-hourly values. For total pollen, there was a considerable spread among systems, with some reaching R2 > 0.6 (3 h) and R2 > 0.75 (daily) compared with Hirst-type traps, whilst other systems were not suitable to sample total pollen efficiently (R2 < 0.3). For individual pollen types, results similar to the Hirst were frequently shown by a small group of systems. For Betula, almost all systems performed well (R2 > 0.75 for 9 systems for 3-hourly data). Results for Fraxinus and Quercus were not as good for most systems, while for Poaceae (with some exceptions), the performance was weakest. For all pollen types and for most measurement systems, false positive classifications were observed outside of the main pollen season. Different algorithms applied to the same device also showed different results, highlighting the importance of this aspect of the measurement system. Overall, given the 30 % error on daily concentrations that is currently accepted for Hirst-type traps, several automatic systems are currently capable of being used operationally to provide real-time observations at high temporal resolutions. They provide distinct advantages compared to the manual Hirst-type measurements.

Why should we care about high temporal resolution monitoring of bioaerosols in ambient air?

This is the first time that atmospheric concentrations of individual pollen types have been recorded by an automatic sampler with 1-hour and sub-hourly resolution (i.e. 1-minute and 1-second data). The data were collected by traditional Hirst type methods and state-of the art Rapid-E real-time bioaerosol detector. Airborne pollen data from 7 taxa, i.e. Acer negundo, Ambrosia, Broussonetia papyrifera, Cupressales (Taxaceae and Cupressaceae families), Platanus, Salix and Ulmus, were collected during the 2019 pollen season in Novi Sad, Serbia. Pollen data with daily, hourly and sub-hourly temporal resolution were analysed in terms of their temporal variability. The impact of turbulence kinetic energy (TKE) on pollen cloud homogeneity was investigated. Variations in Seasonal Pollen Integrals produced by Hirst and Rapid-E show that scaling factors are required to make data comparable. Daily average and hourly measurements recorded by the Rapid-E and Hirst were highly correlated and so examining Rapid-E measurements with sub-hourly resolution is assumed meaningful from the perspective of identification accuracy. Sub-hourly data provided an insight into the heterogenous nature of pollen in the air, with distinct peaks lasting ~5–10 min, and mostly single pollen grains recorded per second. Short term variations in 1-minute pollen concentrations could not be wholly explained by TKE. The new generation of automatic devices has the potential to increase our understanding of the distribution of bioaerosols in the air, provide insights into biological processes such as pollen release and dispersal mechanisms, and have the potential for us to conduct investigations into dose-response relationships and personal exposure to aeroallergens.

Holocene vegetation history of the Jeseníky Mts: Deepening elevational contrast in pollen assemblages since late prehistory

AbstractQuestionsHow did the vegetation of a Central European mountain region with a fragmented alpine zone develop during the Holocene? When did human land use start to alter summit grasslands? Which gradient in pollen assemblages was strongest and was it consistent through time?LocationJeseníky Mountains, Czech Republic.MethodsSixteen pollen records were subjected to DCA in order to explore patterns of compositional similarities in the fossil pollen data. Because only the last 6,000 years were recorded in the study sites from mountain summits, we restricted further analysis to this period. Twelve radiocarbon‐dated pollen records were subjected to DCCA constrained by modelled calibrated age. Responses of individual pollen types to the principal DCCA gradients were tested with GAMs.ResultsIn the DCA, Early Holocene samples were located close to recent ones due to abundant pollen of herbs, Poaceae, Betula, Pinus sylvestris type and rare pollen of climax deciduous trees. In the DCCA for the last 6,000 years, the sorting of sites along the first unconstrained axis correlated with altitude, which is a complex factor corresponding to temperature and geomorphology (flat summits vs alluvia of mountain rivulets). This elevational differentiation became more pronounced after 2,250 cal BP when summit peatlands started to contain more Vaccinium, Calluna vulgaris, Amaranthaceae, Plantago lanceolata and Rumex acetosa type pollen. In contrast, mid‐elevation pollen spectra started to contain more meadow herbs (Caltha, Potentilla type, Cirsium/Carduus). Picea pollen was surprisingly more associated with mid‐elevation than high‐elevation sites, unlike Fagus.ConclusionIncreasing contrast between summits and middle elevation alluvia seems to be a major feature of vegetation development over the last 6,000 years. While alluvial areas were encroached by Alnus–Picea forests, and later locally transformed into wet grasslands, grazing and forest burning at summits gradually increased abundance of acidophytic dwarf shrubs and peatlands, especially since the Iron Age. Human impact might facilitate beech expansion at high elevations, with Picea‐dominated forests being restricted to alluvia and around mid‐elevation basin peatlands prior to establishment of modern Picea plantations.

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

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

A potential of pollen-based climate reconstruction using a modern pollen–climate dataset from arid northern and western China

To improve the interpretation of fossil pollen records, we analyzed the relationships between modern pollen taxa and climate data and established a pollen–climate calibration using the northern and western Chinese modern pollen dataset to demonstrate its potential for the reconstruction of past climate dynamics in the semi-arid and arid regions of China. Analysis of pollen and climate data involved Pearson's correlation ceofficient and other transfer functions, as well as the "best modern analogues" method. We also applied a technique for error estimation to calibrate reconstructed values into a probability distribution and a confidence interval for the observed values. The percentage representations of 24 pollen taxa in 546 surface pollen samples collected in northern and western China were correlated with modern climate characteristics. The relationships between individual pollen types and climate were appraised over a large spatial scale in the study area. Of investigated taxa, 41.7% had linear, 45.8% had unimodal (orthogonal polynomial), and 12.5% had monotonic (Log) distribution in response to annual precipitation. Both taxa and plant functional types (PFTs) provided similar results using the best modern analogues method for modern pollen and climate data at the 546 sites in northern and western China. Precipitation reconstructions were more accurate than climate reconstructions of any thermal parameters, suggesting that available moisture was the most important factor controlling plant distribution in the primarily semi-arid to arid study region. Climate reconstruction performed using the modern analogues technique for 112 taxa was not significantly better than reconstruction with only 37 selected taxa. Climate reconstruction based on PFTs was more accurate when using only the main pollen taxa than when using most of the taxa. Our test of the best modern analogues method with the northern and western Chinese surface pollen dataset demonstrated its reliability for reconstructing modern climate variables.

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

AbstractAim 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.

Modern climate–vegetation–pollen relations in Africa and adjacent areas

The pollen–climate and pollen–vegetation relation in Africa, Madagascar and Arabia has been investigated using 1170 modern pollen samples presently available in the African Pollen Database. Data are collected from different sedimentary environments (soil, lake, river, traps, midden, etc.). In spite of an irregular spatial distribution, there are representatives in all of the major vegetation and climate zones. Accounting for the different trapping efficiency of the different sediment types, large-scale patterns can be determined from the pollen assemblages. Maps and response-surfaces depicting the distribution in geographic and climate space of the main pollen types distinguish the major phytogeographic regions. Computing dissimilarities among the African pollen spectra using squared chord distance demonstrates that pollen spectra within a particular vegetation zone are more similar to one another that they are to pollen samples from other vegetation zones. Using the method of modern analogs, we find significant correlations between modern temperature and precipitation reconstructed using the best modern analog, which suggests the potential of this database for quantitative climate reconstructions. The study of individual pollen types provides an alternative method to the biomization to characterize and quantify the land-surface conditions at a continental scale.

A palynological study of surface and suspended sediments on a tidal flat: implications for pollen transport and deposition in coastal waters

This study examines patterns of pollen deposition and resuspension on a tidal flat of the Dollard, a tidal basin near the mouth of the Ems River, at the border of Germany and The Netherlands (Fig. 1). Sediment samples were collected during three sequential low tides at the spring stage of the lunar tidal cycle when the greatest area of the flat would be exposed and, with the exception of storm events, when maximum scour and redeposition would be expected to occur. Fifteen sample stations were selected along a 5 km transect, with paired ripple crest and trough samples collected at three stations. Water samples were collected hourly during two tidal cycles, from a single location on the flat. Both numbers and condition of pollen and spore taxa were determined for all samples. Grain size and LOI of suspended matter were also determined. The same eight types of pollen and spores were important in both water and sediment samples: Ericaceae, Alnus, Betula, Chenopodiaceae, Corylus, Gramineae and Polypodiaceae. In water samples the lack of a relationship between concentrations of some pollen types and mineral fractions is assumed to be evidence that certain pollen types are preferentially incorporated into floccules suspended in local waters. Analysis of tidal flat sediments indicates that pollen concentrations increase in troughs between ripples and at lower elevations where finer grain sizes accumulate. There is minimal evidence of selective sorting of pollen types. Ordination (using Principal Components Analysis) of pollen percentages and concentrations in sediments indicates that both elevation and distance from the estuary mouth influence concentrations of all abundant pollen types. These parameters, however, have minimal influence on pollen percentages. Incorporation of pollen into fecal pellets, which have relatively high settling velocities, is assumed to be a critical control on pollen deposition in this environment. Analysis of stomach contents of locally common bivalves supports this hypothesis. Transport and deposition of individual pollen types cannot be predicted as floccules and pellets have varying densities and settling velocities. Some pollen and spores may be deposited in coarser sediments than would be predicted based on the size and density of individual grains, but in general display predicted patterns of deposition of fine-grained clastic sediments.

Contemporary pollen assemblages from the Vosges (France)

This paper comprises a comparative study of the recent relative regional pollen deposition and the forest vegetation in a 70 km long transect across the Vosges. The forest vegetation was mapped with the aid of the qualitative data from individual forest lots, available from the “Office National des Forêts”. Eight landscape regions were established and defined on the basis of forest vegetation, geology, topography and precipitation. Pollen was analysed from surface samples and the ranges, frequencies and median values of the individual pollen types were calculated for each of the landscape regions and compared with the distribution of forest vegetation types and the relative abundancies of Abies alba, Castanea sativa, Fagus sylvatica, Larix decidua, Picea abies, Pinus sylvestris, Pseudotsuga menziesii, and Quercus sp. Next to tree pollen types, all the pollen types of herbs and shrubs were fully accounted for in order to establish the relation between the pollen values and the regional and local occurrence of the relevant taxa. In general the major vegetation sequence of the forest dominants, from west to east across the mountains, viz. Quercus—Pinus, Fagus—Abies—Picea, Fagus and again Fagus—Abies—Picea and Quercus—Pinus is well reflected in the pollen deposition. It is concluded that the landscape regions can be characterized by their regional pollen assemblages, mainly by the values of the tree pollen types; to a lesser extent by those of herbs and shrubs. Herb pollen types that characterize landscape regions include Genista, Pteridium and Dryopteris type. The degre of aforestation an d cultivation is reflected in the pollen values of Anthemis type, Chenopodiaceae, Plantago lanceolata, Cerealia and by Corylus, Betula and Alnus. Three additional landscape regions were recognized on the basis of vegetation only.

Allergenic factors and symptomatology of respiratory allergy patients*

An attempt has been made in the present study to find out the relationship between the symptomatology of nasobronchial allergy patients of Delhi with markedly positive skin reactions and prevalence of total pollen concentration in the atmosphere, concentration of major individual pollen types, total fungal spores and house dust mites together with climatic factors such as mean monthly temperature and relative humidity. A statistically significant correlation was not found between symptomatology of the patients of Delhi and mean monthly relatively humidity, atmospheric concentration of pollen, fungal spores and house dust mites. A significant negative correlation was observed between symptomatology of patients and mean monthly temperature. Except for the pollen of prospis which showed significant positive correlation with the symptomatology of Delhi patients, a significant positive correlation was absent with respect to other individual pollen types.

The pollen‐vegetation relationship in southern Michigan: An application of isopolls and principal components analysis

Abstract Maps of the modern pollen from southern Michigan show that the patterns in the vegetation are derivable from pollen data. The pollen maps reveal the differences at the formation level, i.e., between the deciduous forests and the mixed conifer‐hardwood forests, and the differences at the forest‐type level, i.e., between the pine forests and the northern hardwoods and between the oak‐hickory forests and beech‐maple forests. Maps showing the isopolls for individual pollen types and the distribution of principal components derived from the pollen data are used to illustrate these results.