Spatiotemporal models for predicting high pollen concentration level of Corylus,Alnus, and Betula

Corylus, Alnus, and Betula trees are among the most important sources of allergic pollen in the temperate zone of the Northern Hemisphere and have a large impact on the quality of life and productivity of allergy sufferers. Therefore, it is important to predict high pollen concentrations, both in time and space. The aim of this study was to create and evaluate spatiotemporal models for predicting high Corylus, Alnus, and Betula pollen concentration levels, based on gridded meteorological data. Aerobiological monitoring was carried out in 11 cities in Poland and gathered, depending on the site, between 2 and 16 years of measurements. According to the first allergy symptoms during exposure, a high pollen count level was established for each taxon. An optimizing probability threshold technique was used for mitigation of the problem of imbalance in the pollen concentration levels. For each taxon, the model was built using a random forest method. The study revealed the possibility of moderately reliable prediction of Corylus and highly reliable prediction of Alnus and Betula high pollen concentration levels, using preprocessed gridded meteorological data. Cumulative growing degree days and potential evaporation proved to be two of the most important predictor variables in the models. The final models predicted not only for single locations but also for continuous areas. Furthermore, the proposed modeling framework could be used to predict high pollen concentrations of Corylus, Alnus, Betula, and other taxa, and in other countries.     

Spatial variations in the dynamics of the Alnus and Corylus pollen seasons in Poland

The objective of this study was to analyse the dynamics of the Alnus and Corylus pollen seasons in Poland with reference to spatial and seasonal differentiation. Aerobiological monitoring was performed in 10 cities, in 1994–2007. Five characteristics defining the pollen season were considered: 1. beginning and end dates of the season phases (5, 25, 50, 75, 95% of annual totals), 2. pollen season duration (90% method), 3. skewness and 4. kurtosis of airborne pollen curves, and 5. annual pollen totals. The beginning of the Corylus pollen season in Warsaw started on the 53rd day of a year. The Alnus pollen season started 9.5 days (SE = 1.4) later. The start of the season for both taxa was delayed by 3.3 (SE = 0.5) days for each 100 km towards the east. The Corylus pollen season lasted about 15 days longer than the Alnus season. Season duration for both taxa decreased towards the east by 3.5 days (SE = 0.7) and towards the north by 1.3 days (SE = 0.6) for each 100 km. Seasonal dynamics of both taxa are skewed to the right. In cities located west of Warsaw the dynamics are more skewed (except at Szczecin, Wroclaw). Asymmetry decreases towards the east by 0.16/100 km. Almost all kurtosis values of pollen-season dynamics were positive and higher for Alnus. Kurtosis values for both taxa increase together with delay of the pollen season beginning by 4% per day (p < 0.0001). Mean pollen total increases: for Corylus mainly towards the north (by 64%/100 km), for Alnus mainly towards the west (by 15%/100 km). Geographical location (longitude and latitude) determines: the start and duration of the pollen season, skewness of the pollen curve, and annual totals.     

The patterns of Corylus and Alnus pollen seasons and pollination periods in two Polish cities located in different climatic regions

This study compares phenological observations of Corylus (hazel) and Alnus (alder) flowering with airborne pollen counts of these taxa recorded using volumetric spore traps (2009–2011). The work was carried out in the Polish cities of Szczecin and Rzeszów that are located in different climatic regions. Correlations between pollen concentrations and meteorological data were investigated using Spearman’s rank correlation analysis. The timings of hazel and alder pollination and the occurrence of airborne pollen varied greatly and were significantly influenced by meteorological conditions (p < 0.05). The flowering synchronization of hazel and alder pollination in Szczecin and Rzeszów varied over the study period. Hazel and alder trees flowered notably earlier in stands located in places that were exposed to sunlight (insolated) and sheltered from the wind. On the other hand, a delay in the timing of pollination was observed in quite sunny but very windy sites. In Rzeszów, maximum hazel pollen concentrations did not coincide with the period of full pollination (defined as between 25 % hazel and alder and 75 % of flowers open). Conversely, in Szczecin, the highest hazel pollen concentrations were recorded during phenophases of the full pollination period. The period when the highest alder pollen concentrations were recorded varied between sites, with Rzeszów recording the highest concentrations at the beginning of pollination and Szczecin recording alder pollen throughout the full pollination period. Substantial amounts of hazel and alder pollen grains were recorded in the air of Rzeszów (but not Szczecin) before the onset of the respective pollen seasons.     

Substructure of spore and pollen grain exines in Lycopodium,Alnus, Betula,Fagus and Rhododendron

We have used atomic force microscopy and scanning tunnelling microscopy to extract new information about the substructure of the Alnus, Betula, Fagus, Lycopodium and Rhododendron pollen grain exine. Our scans of exines using atomic force microscopy and scanning tunnelling microscopy reveal somewhat similar substructures for Lycopodium spores and pollen of Alnus, Betula, Fagus and Rhododendron. They show various levels of alignment and clustering of substructure components. Except for Alnus, which showed polygonal clustering of spheroids and weak alignment, there is pronounced alignment of helical units. In Betula, Fagus, Lycopodium and Rhododendron the subunits appear to be helical or perhaps consisting of elongated spheroids, these spheroids are however arranged in a way that suggest that they are part of a helical structure. The diameter of these helical subunits range from 10–15 nm in Fagus, 20–25 nm in Lycopodium, 35–90 nm in Rhododendron up to 70–120 nm in Betula. Our preparations graded from intact or fractured fresh pollen to pollen that was acetolyzed, chemically fixed and epoxy resin embedded. While our knowledge of the exact radial/lateral orientation of most of our scans is less than perfect there were in all cases substructures or cross connections of exine units. We found results from scanning and transmission electron microscopy to be helpful in understanding images from Atomic Force- and Scanning Tunnelling Microscopy.     

Comparison of Glycolipids and Plastids in Callus Cells and Leaves of Alnus and Betula

The fine structure of plastids and fatty acid composition ofglycolipids (e.g. monogalactosyl diacylglycerides, MGDG; digalactosyldiacylglycerides, DGDG) in callus cells of Alnus glutinosa,A. incana and Betula pendula cultured in light was comparedwith that in intact leaves. The tissues were qualitatively verysimilar but a rather high amount oflignoceric acid (24:0) wascharacteristic for the callus of A. incana. This fatty acidwas found only in trace amount in other tissues. Linolenic (18:3)and palmitic (16:0) acids are the most abundant (25–65%and 17–27% respectively) fatty acids in all tissues studied.The proportion of 18:1 and 18:2 was much higher in the calluscompared with corresponding intact leaves, which are especiallyrich (48–65%) in 18:3. In callus cultures a higher proportion(17–19%) of linoleic acid (18:2) is found in both Alnusspecies than in the two callus strains of Betula (9–12%). All leaf and callus samples contained esterified steryl glycosidesand two cerebrosidelike spots in thin-layer chromatography,but they were more prominent in callus cultures than in leaves.The callus cells have plastids with rather well developed thylakoidswhich explains the similarity of the main glycolipid components(MGDG and DGDG) to that of leaves. (Received April 23, 1984; Accepted August 17, 1984)     

Climate change effect on Betula (birch) and Quercus (oak) pollen seasons in the United States

Climatic change is expected to affect the spatiotemporal patterns of airborne allergenic pollen, which has been found to act synergistically with common air pollutants, such as ozone, to cause allergic airway disease (AAD). Observed airborne pollen data from six stations from 1994 to 2011 at Fargo (North Dakota), College Station (Texas), Omaha (Nebraska), Pleasanton (California), Cherry Hill and Newark (New Jersey) in the US were studied to examine climate change effects on trends of annual mean and peak value of daily concentrations, annual production, season start, and season length of Betula (birch) and Quercus (oak) pollen. The growing degree hour (GDH) model was used to establish a relationship between start/end dates and differential temperature sums using observed hourly temperatures from surrounding meteorology stations. Optimum GDH models were then combined with meteorological information from the Weather Research and Forecasting (WRF) model, and land use land coverage data from the Biogenic Emissions Land use Database, version 3.1 (BELD3.1), to simulate start dates and season lengths of birch and oak pollen for both past and future years across the contiguous US (CONUS). For most of the studied stations, comparison of mean pollen indices between the periods of 1994–2000 and 2001–2011 showed that birch and oak trees were observed to flower 1–2 weeks earlier; annual mean and peak value of daily pollen concentrations tended to increase by 13.6 %–248 %. The observed pollen season lengths varied for birch and for oak across the different monitoring stations. Optimum initial date, base temperature, and threshold GDH for start date was found to be 1 March, 8 °C, and 1,879 h, respectively, for birch; 1 March, 5 °C, and 4,760 h, respectively, for oak. Simulation results indicated that responses of birch and oak pollen seasons to climate change are expected to vary for different regions.     

Responses in the start of Betula (birch) pollen seasons to recent changes in spring temperatures across Europe

A shift in the timing of birch pollen seasons is important because it is well known to be a significant aeroallergen, especially in NW Europe where it is a notable cause of hay fever and pollen-related asthma. The research reported in this paper aims to investigate temporal patterns in the start dates of Betula (birch) pollen seasons at selected sites across Europe. In particular it investigates relationships between the changes in start dates and changes in spring temperatures over approximately the last 20 years. Daily birch pollen counts were used from Kevo, Turku, London, Brussels, Zurich and Vienna, for the core period from 1982 to 1999 and, in some cases, from 1970 to 2000. The sites represent a range of biogeographical situations from just within the Arctic Circle through to North West Maritime and Continental Europe. Pollen samples were taken with Hirst-type volumetric spore traps. Weather data were obtained from the sites nearest to the pollen traps. The timing of birch pollen seasons is known to depend mostly on a non-linear balance between the winter chilling required to break dormancy, and spring temperatures. Pollen start dates and monthly mean temperatures for January through to May were compiled to 5-year running means to examine trends. The start dates for the next 10 years were calculated from regression equations for each site, on the speculative basis that the current trends would continue. The analyses show regional contrasts. Kevo shows a marked trend towards cooler springs and later starts. If this continues the mean start date will become about 6 days later over the next 10 years. Turku exhibits cyclic patterns in start dates. A current trend towards earlier starts is expected to continue until 2007, followed by another fluctuation. London, Brussels, Zurich and Vienna show very similar patterns in the trends towards earlier start dates. If the trend continues the mean start dates at these sites will advance by about 6 days over the next 10 years. Following this work, amendments will be needed to pollen calendars and local predictive models. It will also be important to assess the implications of earlier seasons for allergy sufferers.     

Quercetin 3-glucosylgalactoside from pollen of Corylus avellana

The main flavonoid glycoside from the pollen of Corylus avellana has been characterized as quercetin 3-O-(2″-O-β-d-glucopyranosyl)-β-d-galactopyranoside on the basis of UV, ¹H NMR, ¹³C NMR and mass spectral data and GLC sugar analysis.     

Differentiating pollen of Betula species from Iceland

Subfossil pollen from two co‐existing Betula species in Iceland, B. nana and B. pubescens, is frequently found in sediments and peat. Interpretation of the findings often depends on the ability to differentiate between the two species according to pollen size and structure. Fresh pollen samples were prepared from 70 individual trees/shrubs which had been identified to species by chromosome number. Grain diameters and pore depths were measured and ratios of grain diameter to pore depth (D/P ratios) were calculated. The mean grain diameters of pollen from diploid B. nana and tetraploid B. pubescens were 20.42 and 24.20?µm, whereas mean pore depths were 2.20 and 2.81?µm respectively. Mean D/P ratios were therefore 9.55 for B. nana and 8.85 for B. pubescens. The difference between species was statistically significant for all three pollen parameters. Grain diameter appeared to be the most useful parameter, as only about 20% of the samples were in the overlapping region of the species distributions. Pollen size (grain diameter) was also positively correlated to tree morphology, which was evaluated using species‐specific botanical characters. Pollen samples from different locations/populations in Iceland varied slightly in mean size and ratio. The size difference between pollen of B. nana and B. pubescens in this study is less than other papers have reported, which may be due to the effect of introgressive hybridisation between the two birch species in Iceland.     

Genetic transformation of 9 in vitro clones of Alnus and Betula by Agrobacterium tumefaciens

Crown gall tumorigenesis, integration and expression of T-DNA encoded genes from Agrobacterium tumefaciens were investigated in 9 clones of Alnus glutinosa, A. incana and Betula papyrifera. Tumor formation on in vitro shoots was frequent in all clones with strain Ach5 and present in 8 clones with strain C58. Tumors excised from shoots were selected for autotrophic growth in vitro and axenic cultures were established. Octopine or nopaline, respective of the strain type used for inoculation, was detected in tumorous cultures. Southern blot analyses demonstrated T-DNA integration by hybridization of DNA from tumors with tmr and nos gene probes. One clone of B. papyrifera produced tumors with a morphogenic character, unusual in calli of this species, generating viable shoots which did not synthesize opine.Abbreviations Cb Carbenicillin - Cf Cefotaxime - 2,4-D 2,4-Dichloro-phenoxyacetic acid     

Pollen–pollen interactions in Betula pendula in vitro

Direct pollen interactions, as well as interactions mediated by a recipient, can have a remarkable influence on pollen fertilization ability. Under conditions of pollen competition it could be advantageous if pollen grains interfered with the germination of other pollen. The aim of this study was to find out if there are direct negative or positive pollen–pollen interactions between pollen grains from genetically slightly different donors. The in vitro germinability of the pollen from several Betula pendula Roth clones was investigated. The pollen interactions between the clones were examined pairwise by using equal pollen mixtures. In three of the eight cases the germination percentage of the pollen mixture was significantly higher than the average germination percentage of the separate clones that formed the mixture, which indicates some type of interaction between the pollen populations. We found only positive interactions between the pollen of clones. This study also documented density-dependent germination of pollen grains in vitro (=pollen population effect). Adding an aqueous pollen extract to the incubation medium increased the germination percentages of poorly germinating pollen and small pollen populations. Germination-stimulating effects were found to exist both with fresh and dead pollen. Such direct pollen–pollen interactions could be explained by specific water-soluble substances diffusing from pollen grains.     

长白山毛赤杨和白桦-沼泽生态交错带群落生物量分布格局

采用样带网格、树干解析和经验模型方法,研究了长白山毛赤杨和白桦．沼泽交错群落生物量分布格局。揭示群落建群种生长过程、器官生物量分布、群落生物量水平分布和垂直分布规律性,结果表明,毛赤杨和白桦在生长过程及适宜生境方面存在差异．毛赤杨生长速度是白桦的2～3倍,随交错区环境梯度旱化。其生长呈减缓趋势,而白桦生长呈加快趋势,故白桦是耐水湿树种,毛赤杨是喜湿树种,毛赤杨和白桦个体营养器官生物量表现出相似的分布规律．两者营养器官生物量分布格局为树干1／2、树根1／4、树枝1／10、树皮1．5／20、树叶1／20,乔木层生物量占群落生物量的87％～90％、灌木层占7％～9％、草本层占2％～3％,群落生物量沿沼泽到森林交错区环境梯度呈显著线性递增趋势。     

Regional Differentiation in the Dynamics of the Pollen Seasons of Alnus, Corylus and Fraxinus in Poland (Preliminary Results)

In 1995–1996 a study of pollen concentrations of Corylus, Alnus and Fraxinus was performed at seven sites in regions of different climatic and natural conditions. The aim of the study was to determine whether regional differences in the course and duration of pollen seasons occur in Poland. The study was performed using a volumetric method. Several phases during the pollen season were defined for each taxon (1, 2.5, 5, 25, 50, 75, 95, 97.5, 99% of annual total) and duration of the pollen seasons was calculated using 98 and 90% methods. Dynamics and duration of the pollen seasons and a start of particular phases of the season were compared among sites. On the basis of the preliminary analysis it could be supposed that regional differences were most evident in the case of Corylus. The pollen season of this taxon started the earliest in Pozna where thermal conditions were most favourable and the latest in Gdask, a place at the furthest to the north ( ², 0.05). In montane regions (Zakopane, Rabka) last phases of the season were significant extended ( ², 0.05). Probably it results from secondary pollen deposition and a long-distance transport by montane wind. In case of Fraxinus the significant regional differences in the start of the pollen season were not found. The study supported that weather conditions have the substantial influence on the start of consecutive phases of the pollen season.     

Trends in pollen season characteristics of Alnus,Poaceae and Artemisia allergenic taxa in Bratislava,central Europe

Over the period 2002–2019, air temperature and precipitation significantly increased regionally for Bratislava, which could lead to phenological changes in some plant species. This study aimed to analyse the changes in the intensity, timing, and duration of pollen seasons of three allergological important plant taxa (Alnus, Poaceae, Artemisia) in the study area over 18 years. The pollen sampling was performed using a Hirst-type sampler. Mann–Kendall tau test was used to determine trends in pollen season characteristics, while Spearman’s correlation analysis was used to identify the relationships between the characteristics of pollen seasons and both air temperature and precipitation trends. The notable changes in the pollen-season-related features were observed for all analysed taxa. The Alnus pollen season now reaches the peak earlier and its intensity is rising in line with the summer-autumn temperature increasing trend, while unexpectedly intensity and duration of the Artemisia pollen season are declining in line with the increased precipitation and/or temperature trends. On the other hand, the intensity of the Poaceae pollen season is also declining, however, without statistically significant correlations with recorded increases in meteorological parameters considered. This phenomenon is probably related to both the reduction of the area of grasslands due to urbanization and the implementation of effective maintenance of urban green areas (e.g., timely mowing preventing the repeatedly flowering of grasses).

     

Characteristics of pollen from natural triploid Betula hybrids

Birch has a key role in the Holocene vegetation history of northern Europe and in sub‐arctic climates dwarf birch and tree birch co‐exist. In Iceland, triploid hybrids between diploid Betula nana (dwarf birch) and tetraploid B. pubescens (downy birch) are common and therefore likely to contribute to pollen deposition. Pollen from 22 triploid trees/shrubs from ten woodlands in Iceland was examined and its size and shape compared with pollen from the parental species. The mean diameter of pollen grains from the triploid hybrids was not statistically different from that of B. nana pollen, but was significantly smaller than the mean value of B. pubescens pollen. On the contrary, the size of the vestibulum was similar to that of B. pubescens, which was significantly greater than that of B. nana, and therefore the diameter‐pore depth ratio was lower than the values from either species. The pattern of size distribution within plants indicated that triploid hybrids might have produced two sizes of triporate pollen grains, but the small B. nana size was far more prevalent than the larger B. pubescens size. Several anomalies in pollen morphology were common among the hybrid pollen grains: four or more pores were the most frequent type of abnormality. Characteristics of the pollen of triploid Betula hybrids, especially structural anomalies, may provide a means to reveal periods of interspecific hybridisation in the analysis of sub‐fossil pollen.     

Sources,impact and exchange of early-spring birch pollen in the Moscow region and Finland

The paper presents an assessment of birch pollen seasons in Finland and Russia. The re-analysis covered the period from 1994 to 2005 and was focused on suspected long-range transport events that were recorded both in Moscow and at several Finnish sites. In order to trace the origin of airborne pollen before the onset of local pollination, we used both aerobiological and phenological observations combined with forward and adjoint (inverse) dispersion model simulations. It is shown that, although the Moscow region is surrounded by extensive birch forests, it still receives substantial amounts of foreign pollen before local pollination. In the Moscow region, the sources of long-range-transported pollen are in the south and south-west, sometimes even in the east. In Finland, there are frequently cases, before the local flowering season, in which Finnish territory receives Russian pollen; however in the opposite direction, from Finland to the Moscow region, no transport episodes were unequivocally registered. Analysis of the end of the seasons was more problematic, due to contributions to pollen observations from local sources; this results in difficulties in the reliable identification of the long-range transport episodes. Apart from its short-term effects on the pollen seasons, long-range transport can have substantial impacts on the exchange of genetic material within Europe. A quick atmospheric pathway for gene transport can be important for adaptation of plants to a changing climate.     

Incompatibility and pollen competition in Alnus glutinosa: Evidence from pollination experiments

Different types of incompatibility systems were found to operate simultaneously in alnus glutinosa in the course of numerous pollination experiments, including self-pollination and pollination with controlled pollen mixtures. Isozyme genetic markers were used to identify the pollen parent of each offspring from the mixed pollination experiments, thus allowing specification of the fertilization success of each pollen parent. In a first step, these results were compared with observations on in vitro pollen germination experiments. This comparison allows for exploration of the explanatory value of different germination media as models of germination conditions on stigmas. In most cases, the data suggest that the in vitro germination conditions resemble the fertilization conditions in vivo, at least in the sense that they favor the same pollen parents. By providing a generic and operable definition of the two basic types of incompatibility, eliminating (inability to fertilize ovules) and cryptic (resulting in lowered fertilization success of a pollen parent under competition), evidence was detected for the existence of both types of incompatibility in alnus glutinosa, where eliminating incompatibility occurred as self-incompatibility only. However, since this incompatibility seems to act primarily via pollen elimination, seed production is not likely to be negatively affected in natural populations, even for comparatively large amounts of self-pollination. This revised version was published online in July 2006 with corrections to the Cover Date.     

A comparison of 1978 and 2006 peak pollen seasons and sampling methods in Missoula, Montana

A study was conducted in Missoula, Montana to compare local pollen counts from 1978 with those measured nearly 30 years later in 2006 using two different measurement techniques (Durham gravimetric sampler and a Burkard volumetric sampler). Trends in peak pollen times measured during the spring, summer and autumn, respectively, were compared between the two years by Pearson's correlation and frequency of occurrence of plant genus. Meteorological conditions were also examined during each of the two study periods.In comparing the two years, there was a statistically significant linear association between the different counts for the months of April through August, with similar levels of pollen types for any given month. The five predominant pollen types (based on counts) identified in each study were Pinus, Poaceae, Populus, Alnus, and Betula for 2006 and Pinus, Poaceae, Populus, Acer and Artemisia for 1978. In summary most of the genera displayed similar peak pollination timing between the two years, suggesting that results from the Durham (gravimetric) and Burkard (volumetric) sampling methods are comparable when reporting relative frequency of occurrence.     

Genotype-environment interactions in pollen competitive ability in an anemophilous tree,Betula pendula Roth

This study describes genotype-environment interactions in pollen competitive ability expressed as pollen-tube growth rate and seed-siring success in Betula pendula Roth. A factorial crossing design was applied using the same maternal and paternal clones in two different environmental conditions, in a B. pendula seed orchard established in a greenhouse and at an outdoor clone collection. Both single donor and two-donor pollinations were employed. Female inflorescences were collected after a fixed time of germination, pollen-tube lengths were measured for each cross, and paternity of the seeds sired by two-donor pollen mixtures was analyzed using isozyme markers. The pollination site had a significant influence on pollen-tube growth rate and seed-siring success. Significant interactions between pollination site and pollen donor indicated genotype-environment interactions in pollen-tube growth rate and seed-siring success. A highly significant positive correlation between pollen-tube growth rate and seed-siring success was found in the greenhouse but not at the outdoor clone collection. These results suggest that the pollen-tube growth rate can be a predictor of seed-siring success in controlled greenhouse conditions, where differences among maternal plants are mainly of genetic origin, but not in more heterogeneous outdoor conditions. In natural birch stands, environmental maternal effects probably diminish the significance of pollen competition for sexual selection in Betula pendula. At seed orchards, the effects of environmental conditions on pollen competitive ability can have important consequences for the genetic composition of the seed crop.