Seasonal fluctuations of the airborne pollen spectrum in Murcia (SE Spain)

During six consecutive years (1993–1998), aBurkard volumetric pollen trap was continuouslyoperated to sample pollen from the air of thecity of Murcia. The aim of the study was toelucidate the spectra of airborne pollen andthe variations during the year, and toelaborate a pollen calendar. This time spanincludes the end of the period with severedrought from 1990–1995, which particularly affected the south-eastern region of Spain.The total sum of daily average pollenconcentrations amounted to 148,645 pollen grainsbelonging to 93 different taxa. A daily averageof 74 pollen grains/m³ and 11 taxa wererecorded, with maxima of 1157 and 27respectively. The total pollen amountregistered in a year correlated with yearlyrainfall, but there was no relation with meanannual temperature. As for annual fluctuations,there seemed to be no influence by totalrainfall or temperature. Spring and winter werethe seasons with the highest pollen counts andpollen diversity.From the 93 identified taxa, 36 are included inthe pollen calendar. Noteworthy findings are:(i) the presence of Thymelaeaceae,Robinia, Betula, Castanea,Zygophyllum, Caryophyllaceae andCannabis, (ii) a long pollen season ofChenopodiaceae/Amaranthaceae, Urticaceae,Poaceae, Arecaceae and Plantago, (iii)the occurrence of summer, autumn and winterflowering of Artemisia, (iv) the lateappearance of Corylus pollen, and (v) theminor presence of Casuarina pollen duringthe mid winter and late spring.     

A pollen-analytical investigation at Threepwood Moss

Summary

Absolute and relative pollen analyses from Threepwood Moss in south-east Scotland are presented. Three local pollen assemblage zones with sub-divisions, together with stratigraphic evidence, indicate the mire succession from minerotrophy to ombrotrophy and the vegetational history of the area during the mid-Flandrian period to present-day. The landscape was initially shrub dominated, chiefly by Corylus, with a subsequent inspread of Betula which retained its importance in the tree cover and was never displaced by Alnus while mixed oakwood taxa are poorly represented. Consequent on deforestation due to anthropogenic activities, open habitat communities replaced the woodland.

Comparisons are drawn between Threepwood Moss and other sites in Britain to establish chronozones and to illustrate the vegetational variation due to latitude and altitude.     

Comparative study of different methods for capturing airborne pollen,and effects of vegetation and meteorological variables

The atmosphere of Mar del Plata city (Argentina) was monitored using three different pollen traps—Burkard, Rotorod, and Tauber—during a flowering season (mid-winter to springtime) in order to compare the diversity and amounts of pollen grains collected in each trap. Sixty three percent of taxa diversity was simultaneously recorded by all three apparatuses. The five most abundant types of pollen in the three traps were Platanus, Ulmus, Quercus, Poaceae, and Fraxinus. The Tauber trap contained the most pollen from taxa with the largest grains, and exclusively trapped ten pollen types with entomophilous characteristics. The amount of pollen in each trap and local/extra-local plant abundance were compared to elucidate the effect of the method used on the pollen–vegetation relationship. The correlation coefficients for total pollen were positive and significant between all pairs of traps. The maximum peak was observed first in the Burkard trap, in agreement with an increase in temperature, but the general pattern in the three traps was similar, with a maximum in early spring. Opposite deviations from the mean value were observed for the Burkard and Tauber data; these deviations were associated negatively with wind speed and relative humidity, respectively. This paper discusses whether in some cases the pollen records could be used in an equivalent manner, although with some limitations.     

Annual pollen spectrum variations in the air of Bratislava (Slovakia): years 2002–2009

Pollen grains in the atmosphere of Bratislava were quantitatively and qualitatively analysed during an 8-year period (2002–2009) using a Burkard volumetric pollen trap. The mean annual total pollen grain count recorded during this period was 36,608, belonging to 34 higher plant taxa (22 trees and/or shrubs and 12 herbaceous species). The maximum annual total pollen grain count (50,563) was recorded in 2003 and the minimum (14,172) in 2009. The taxa contributing the highest concentration of pollen grains were Betula, Urticaceae, Cupressaceae-Taxaceae, Populus, Pinus, Poaceae and Ambrosia. During the study period, there was a remarkable increase in the number of pollen grains from February to April, with the highest daily mean pollen counts recorded in April. Total pollen concentration began to decrease markedly in May, but there was a second increase between July and August, followed by a decrease in September. The timing and length of the pollen seasons varied. Betula and Poaceae showed a rather constant 2-year fluctuating rhythm. The relationships between airborne pollen concentration and meteorological variables were assessed. Based on these results, the first pollen calendar in Slovakia has been constructed for the area of Bratislava, which provides a great deal of useful and important information.     

Fluctuations and trends in airborne concentrations of some abundant pollen types,monitored at Vienna,Leiden, and Brussels

The annual sums of daily airborne pollen concentrations fluctuate from year to year. It has been suggested that for some taxa there is a regular or alternating pattern in these fluctuations. On the other hand, environmental changes may lead to decreasing or increasing trends in airborne pollen concentrations. These two phenomena can only be studied reliably on the basis of long-term volumetric observations of abundantly occurring pollen types. For this study two arboreal (Betula and Quercus) and two herbaceous (Poaceae and Urtica) types were chosen.

For some of these pollen types a weak but significant trend is observed. For the arboreal types (Quercus and Betula) there appears to be a rather constant biennial fluctuating rhythm.     

Correlation between airborne pollen incidence,skin prick tests and serum immunoglobulins in allergic people in cracowm,poland

Fifty patients suffering from pollen allergy were observed during the period 1988–1989. At the same airborne pollen content was examined using volumetric and gravimetric sampling methods.

The mean daily symptom scores and percentages of patients with symptoms of allergy during the pollen season correlated positively with the airborne pollen content of wild Gramincae and Cerealia (Secale cereale).

Skin prick test results and elevated levels of specific serum IgE confirmed the presence of allergy to these taxa in the patients observed. Allergy to tree pollen and herb pollen was confirmed in only 3 cases.

Elevated levels of specific serum IgE for Dactylis glomerata, Pltleum pratense, and Secale cereale appeared in 70–80% of patients. Specific serum IgE levels correlated more with skin prick reactions (especially with late phase reactions) than with total serum IgE levels. Airborne pollen concentrations evaluated by volumetric sampling (Burckard trap) ad by a gravimetric method differ in so many details, that their results are not comparable. However, both methods provide largely similar information about the presence of airborne pollen presence.     

Studies in Montia L. and Claytonia L. and Allied Genera

The pollen morphology of several genera in Portulacaceae is described. Particular attention has been paid to the genera of the subfamily Montioideae, as a stage of continued monographical studies. Among genera especially dealt with are Claytonia, Montia, Crunocallis, Naiocrene, Neopaxia, Mona, Maxia, Limnalsine, and Montiastrum. In the taxonomical treatment of these genera the pollen morphology has proved to afford many important additional characters.

The pollen grains of Claytonia are distinguished from those of the remainder in being 3-colpate. The grains of the Claytonia-type have many similarities with those of Lewisia, a genus of the subfamily Portulacoideae. The other genera of Montioideae have pantocolpate pollen grains. Among these genera several different pollen types are distinguished, chiefly with regard to the sexine structures and the aperture membranes. The Montiastrum-type is especially interesting, with tholate grains, a particular pollen type not met with in any other genus in the family. The pollen morphology of some genera in the Portulacoideae is also treated. In some species in Calandrina and Talinum pantotreme pollen grains are observed with apertures transitional between pori and colpi. The apertures of the pantotreme grains are arranged in characteristic patterns.

Particular attention has been given to the variation of the pollen morphological characters. This variation has been examined with regard to the differences between different populations of the same species as well as between different species. The greatest variation has been observed in the shape and size of the grains. The structure and sculpture and thickness of the sexine and the aperture membranes are less variable. Some polyploid taxa are connected with the occurrence of pollen grains with divergent and varying aperture numbers.

In a survey of the genera the taxonomical results of the investigation are presented with particular regard to the pollen morphology. The new genus, Maxia Ö. Nilss., is described. One new species, Montia clara Ö. Nilss., is described and some new combinations are made.

Pollen morphological diagnoses are given for 46 different taxa. The aperture conditions for 96 different species are presented.     

Comparative study of seasonal and intradiurnal variation of airborne herbaceous pollen in urban and rural areas

The content of herbaceous pollen in the atmosphere depends on the vegetal cover, climate and the weather and geographical conditions. The aim of the study reported here was to compare aerobiological data obtained from pollen monitoring stations located at sites differing with respect to their flora and microclimate – i.e. a town and a rural area. A volumetric method was used for sampling. In each microscopic preparation 12 vertical strips corresponding with 2-h intervals were analysed. A 90% method was used to determine the pollen season. The results were statistically verified using the u test and the Kolmogorov-Smirnov, Spearman and Wilcoxon tests. Higher values of the Seasonal Pollen Index (SPI), higher daily average concentrations and higher peak values were recorded in the rural area. An analysis of intradiurnal variations of airborne pollen showed that apart from the Poaceae the number of pollen grains in the air began to increase earlier in the day in the rural area; in the case of Rumex and Ambrosia, the maximum values also appeared a few hours earlier. For all the taxa investigated, the analysis of correlation showed a significant association between the daily average concentrations at both sites. The weakest association occurred for Plantago lanceolata; for all other taxa, the determination coefficients (R ²) were high. The results of the Wilcoxon test showed that, despite the strong positive association between daily concentrations of the pollen types investigated, there were differences in mean pollen concentrations in the overlapping pollen season. Mean concentrations of Poaceae and Rumex airborne pollen were significantly higher in the rural area in both years, and those of Urtica and P. lanceolata were significantly higher only in 2002.     

Threat of allergenic airborne grass pollen in Szczecin,NW Poland: the dynamics of pollen seasons,effect of meteorological variables and air pollution

The dynamics of Poaceae pollen season, in particularly that of the Secale genus, in Szczecin (western Poland) 2004–2008 was analysed to establish a relationship between the meteorological variables, air pollution and the pollen count of the taxa studied. Consecutive 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 season was determined using the 98% method. On the basis of this analysis, the temporary differences in the dynamics of the seasons were most evident for Secale in 2005 and 2006 with the longest main pollen season (90% total pollen). The pollen season of Poaceae started the earliest in 2007, when thermal conditions were the most favourable. Correlation analysis with meteorological factors demonstrated that the relative humidity, mean and maximum air temperature, and rainfall were the factors influencing the average daily pollen concentrations in the atmosphere; also, the presence of air pollutants such as ozone, PM₁₀ and SO₂ was statistically related to the pollen count in the air. However, multiple regression models explained little part of the total variance. Atmospheric pollution induces aggravation of symptoms of grass pollen allergy.     

Automated pollen recognition using 3D volume images from fluorescence microscopy

Identifying and counting of pollen grains in ambient air samples is still a demanding and time-consuming task even for an experienced microscopist. This article describes a technique which may be employed to establish a fully automated system for this task. Based on a 3D volume fluorescence image of a pollen grain taken with a confocal laser scanning microscope, the described system is able to recognize the pollen taxa. The system autonomously extracts all required information for the recognition from a data base with reference objects (self-learning system) and only needs to calculate very general purpose features of the volumetric data sets (so-called gray scale invariants). This allows for easy adaptation of the system to other conditions (e.g., pollen of a special area) or even other objects than pollen (e.g., spores, bacteria etc.) just by exchanging the reference data base. When using a reference data base with the 26 most important German pollen taxa, the recognition rate is 92%. With a special database for allergic purposes recognizing only Corylus, Alnus, Betula, Poaceae, Secale, Artemisia and ``allergically non-relevant' the recognition rate is 97.4%.     

Aerobiological behaviour of Platanus L. pollen in Catalonia (North-East Spain)

The aim of this paper is to characterise theairborne behaviour of an allergenic andabundant pollen type, Platanus, in sevensites of the Aerobiological Network ofCatalonia (Xarxa Aerobiològica deCatalunya, XAC). In Catalonia, the mostextended Platanus species is Platanus × hybrida Brot., widely planted inforestry and as ornamental tree in streets andgardens. Naturalised specimens can also befound along river banks.The pollen records analysed are from differentperiods comprised between 1994 and 2000 inBarcelona, Bellaterra, Cambrils, Girona,Lleida, Manresa and Tarragona. All data wereobtained using seven-day volumetric spore Hirsttraps.Platanus pollination is concentrated in afew weeks, between March and April. Platanus pollen is present in all theatmospheric pollen spectra for the sitesmentioned above. In Barcelona, Platanuspollen attained the highest concentrations,with an extreme annual index (sum of the meandaily concentrations) of 25790 in 1997, and amaximum daily concentration of 2567 P/m³on 15th March 2000. The lowest annual index(647) corresponds to Cambrils, 2000, and thelowest maximum daily concentration (74P/m³) was registered on 7th April1996, in Manresa.The interannual variation of Platanuspollen values can be explained not only bymeteorological parameters and the endogenousfactors of the tree, but also by human activitysuch as elimination, pruning and watering.     

Pollen spectrum in Northern Tunis,Tunisia

This study has been focused on airborne pollen concentration in Northern Tunis. Pollen has been detected by a volumetric Hirst-type spore trap. This suction sampler was placed for two hydrologic years in the area of Mornag, northeastof Tunisia (36°40N; 10°17E). Fifty-two taxa were identified with heterogeneous daily pollen concentrations and a dominance of anemophilous plants. The main pollen types detected in the atmosphere were Olea europaea (38.7 and 20.75%), Cupressus (33.57 and 55.4%), Urticaceae (9.22 and 12.24%), Poaceae (3.55 and 3.32%), Mercurialis annua (2.96 and 1.6%) and Amaranthaceae (2.49 and 1.55%). The monthly pollen spectrum indicated a seasonal periodicity of airborne pollen with the main pollen season during spring. Two pollen seasons have been observed during these hydrologic years, due to both Cupressus and Amaranthaceae airborne pollen is represented during winter or spring, and also during autumn and late summer, respectively. Other pollen types represent a long pollen season, i.e., Urticaceae, starting in autumn and following until late spring. Daily pollen concentration showed a different behavior during the flowering season between both years, observing differences related to pollen index. Correlation between daily pollen concentrations of the dominant taxa showed a positive and significant correlation between airborne pollen concentrations of spring-pollinated taxa and mean temperature, but negative with maximum temperature, humidity and rainfall. In the case of minimum temperature, a different response, positive for trees and negative for herbaceous plants, has been observed.     

The pollen season dynamics and the relationship among some season parameters (start,end, annual total,season phases) in Kraków,Poland, 1991–2008

The dynamics of 15 taxa pollen seasons in Kraków, in 1991–2008 was monitored using a Burkard volumetric spore trap of the Hirst design. The highest daily pollen concentrations were achieved in the first half of May, and they were caused mainly by Betula and Pinus pollen. The second period of the high concentrations took place from the middle of July to the end of August (mainly Urtica pollen). Tree pollen seasons were shorter (18–24 days) in comparison with the most herbaceous pollen seasons (73–89 days), except at Artemisia and Ambrosia seasons (30 and 24 days, respectively). The season phases (percentyles) of the spring and late-summer taxa were the most variable in the consecutive years. The highest annual sums were noted for Urtica, Poaceae (herbaceous pollen seasons) and for Betula, Pinus, Alnus (tree pollen seasons), and the highest variability of annual totals was stated for Urtica, Populus, Fraxinus and the lowest for Ambrosia, Corylus, Poaceae. For the plants that pollinate in the middle of the pollen season (Quercus, Pinus and Rumex), the date of the season start seems not to be related to the season end, while for late pollen seasons, especially for Ambrosia and Artemisia, the statistically negative correlation between the start and the end season dates was found. Additionally, for the most studied taxa, the increase in annual pollen totals was observed. The presented results could be useful for the allergological practice and general botanical knowledge.     

An aeropalynological study of metropolitan Toronto

This study uses 6 years of atmospheric pollen data to examine temporal variability of airborne pollen concentrations at various scales. Airborne pollen was collected from 1985 to 1990 with a Burkard trap, located 18 m above ground at Scarborough College, Toronto, Canada. Pollen season parameters are defined and summarized for all taxa in preparation for developing forecasting models. Annual totals of pollen concentration show great interannual variability. The highest coefficient of variation occurs inTsuga, Fraxinus, Betula andFagus, while the lowest inQuercus andAmbrosia. Some taxa show periodic cycles consistent with mast reproductive behaviour. In many studies, the start of the pollen season is defined as an arbitrary percentage of the annual sum. As a result, the start of the season cannot be identified until the season has passed. As well, due to large fluctuations in annual sum, start dates are more variable. This is not practical for the purposes of forecasting. In this study, the start of the pollen season is defined by a critical concentration threshold which signals the onset of the main pollen season in all years. These critical levels ranged from 2 to 60 grains/m³ for the abundant taxa. Interannual variation in the start of the season is approximately 20 days for tree taxa, 5 days for Poaceae, and 2 days forAmbrosia. For many plants, dehiscence is triggered at a critical level of accumulated degree-days. Since annual rates of temperature increase show great variation, there is also interannual variability in the onset of pollen release. Multi-year average pollen curves incorporate these differences in onset and may give an inaccurate representation of the pollen season in a typical year. This paper presents a method of aligning yearly pollen curves to reduce seasonal variation and more accurately represent both the average timing and magnitude of the pollen season. For some types, such asBetula and Poaceae, the resulting curves are positively skewed. Tree taxa, in general, exhibit a more symmetric pollen concentration curve. Aligned average pollen concentration curves are presented for Toronto in the form of a pollen calendar. In addition, phenological data for all common taxa are summarized.     

Relative rates of nucleotide substitution at the rbcl locus of monocotyledonous plants

Summary We subjected 35 rbcL nucleotide sequences from monocotyledonous taxa to maximum likelihood relative rate tests and estimated relative differences in rates of nucleotide substitution between groups of sequences without relying on knowledge of divergence times between taxa. Rate tests revealed that there is a hierarchy of substitution rate at the rbcL locus within the monocots. Among the taxa analyzed the grasses have the most rapid substitution rate; they are followed in rate by the Orchidales, the Liliales, the Bromeliales, and the Arecales. The overall substitution rate for the rbcL locus of grasses is over 5 times the substitution rate in the rbcL of the palms. The substitution rate at the third codon positions in the rbcL of the grasses is over 8 times the third position rate in the palms. The pattern of rate variation is consistent with the generation-time-effect hypothesis. Heterogenous rates of substitution have important implications for phylogenetic reconstruction.Offprint requests to: M.T. Clegg     

Aerobiology of Fagaceae pollen in Trieste (NE Italy)

The aerobiological behaviour of Fagaceae in Trieste and the correlations with the meteorological parameters were examined. Airborne pollen grains of Castanea, Fagus and Quercus were collected from 1990 to 2003 using a Hirst type spore trap. The main pollen season (MPS) takes place in April and May for Quercus and Fagus, in June and July for Castanea. The highest values occur in year 1993 for Quercus, in 1998 for Castanea and in 1992 for Fagus. The Fagaceae content of the air is mainly due to Quercus and Castanea pollen, Fagus usually having a scarce pollen shedding in Trieste. The highest counts of Fagaceae pollen grains are found from late April to mid May and are mainly due to the pollen shedding of oaks. The cumulative counts vary over the years, with a mean value of 2.719 pollen grains, a lowest total of 1.341 in 2002 and a highest total of 4.704 in 1993. No positive nor negative long-term trends in pollen shedding are found. No cyclic variations were observed. Spearman’s correlation was used to establish the relationship between the daily pollen counts and the daily meteorological data. Daily pollen concentrations present sometimes positive correlation with temperature, negative with rainfall and wind speed, and no correlation with humidity. Fagus and Quercus start dates result positively correlated between themselves. Significant correlations are found between the start of MPS and the mean and maximum temperature in March for Fagus and Quercus, and May for Castanea.     

Changes in the pollen seasons of the early flowering trees <Emphasis Type="Italic">Alnus</Emphasis> spp. and <Emphasis Type="Italic">Corylus</Emphasis> spp. in Worcester,United Kingdom, 1996–2005

Previous work on Betula spp. (birch) in the UK and at five sites in Europe has shown that pollen seasons for this taxon have tended to become earlier by about 5–10 days per decade in most regions investigated over the last 30 years. This pattern has been linked to the trend to warmer winters and springs in recent years. However, little work has been done to investigate the changes in the pollen seasons for the early flowering trees. Several of these, such as Alnus spp. and Corylus spp., have allergens, which cross-react with those of Betula spp., and so have a priming effect on allergic people. This paper investigates pollen seasons for Alnus spp. and Corylus spp. for the years 1996–2005 at Worcester, in the West Midlands, United Kingdom. Pollen data for daily average counts were collected using a Burkard volumetric trap sited on the exposed roof of a three-storey building. The climate is western maritime. Meteorological data for daily temperatures (maximum and minimum) and rainfall were obtained from the local monitoring sites. The local area up to approximately 10 km surrounding the site is mostly level terrain with some undulating hills and valleys. The local vegetation is mixed farmland and deciduous woodland. The pollen seasons for the two taxa investigated are typically late December or early January to late March. Various ways of defining the start and end of the pollen seasons were considered for these taxa, but the most useful was the 1% method whereby the season is deemed to have started when 1% of the total catch is achieved and to have ended when 99% is reached. The cumulative catches (in grains/m³) for Alnus spp. varied from 698 (2001) to 3,467 (2004). For Corylus spp., they varied from 65 (2001) to 4,933 (2004). The start dates for Alnus spp. showed 39 days difference in the 10 years (earliest 2000 day 21, latest 1996 day 60). The end dates differed by 26 days and the length of season differed by 15 days. The last 4 years in the set had notably higher cumulative counts than the first 2, but there was no trend towards earlier starts. For Corylus spp. start days also differed by 39 days (earliest 1999 day 5, latest 1996 day 44). The end date differed by 35 days and length of season by 26 days. Cumulative counts and lengths of season showed a distinct pattern of alternative high (long) and low (short) years. There is some evidence of a synchronous pattern for Alnus spp.. These patterns show some significant correlations with temperature and rainfall through the autumn, winter and early spring, and some relationships with growth degree 4s and chill units, but the series is too short to discern trends. The analysis has provided insight to the variation in the seasons for these early flowering trees and will form a basis for future work on building predictive models for these taxa.     

Pollen representation of vegetational patterns along an elevational gradient

Abstract. Modern pollen assemblages from 16 small lakes (< 2.5 ha) and 11 moderate-sized lakes (4.5–19.3 ha) arrayed along an elevational gradient (300 to 1320 m) in the east-central Adirondack Mountains were studied to determine how well the pollen assemblages recorded patterns of forest composition along the gradient. Forest composition ranges from Pinus strobus/Tsuga/ hardwoods forests at low elevations through Tsuga/ hardwoods, hardwoods, and Picea/Abies forests to Abies-dominated forests at high elevations. Modern pollen percentages for 10 tree taxa were compared with lake elevation using scatter plots and correlation and regression analysis. Differential smoothing of vegetational patterns along the elevational gradient occurred among the 10 taxa owing to differences in pollen dispersibility, pollen production, and spatial pattern of taxon abundance in forests of the region. No differences were observed in pollen-elevation patterns between small and moderate-sized lakes. Pollen-elevation patterns were obscured for most taxa when the gradient was shortened (e.g. to 600–1320 m) owing to increased spatial smoothing by pollen dispersal. Design and interpretation of paleoecological studies of spatial gradients can be improved by careful attention to site spacing, gradient length, and gradient steepness in the context of pollen dispersal and representation models.     

Pollenemission und pollenflug von kräuterpollen

Die anemogamen Sommerkräuter Artemisia, Rumex und Plantago sind die Kräuter mit der höchsten allergologischen Bedeutung. Der Pollenflug dieser Pflanzen wurde in zwei verschiedenen Höhen über.Grund (Essen, 1,8 m und 18 m) an demselben Standort durch stündliche Pollenmessungen in den Saisons von 1988 und 1989 untersucht. Die Pollenfreisetzung von Artemisia vulgaris und des Rumex conglomeratus-Typs (R. acetosella, R. conglomeratus, R. longifolius, R. sanguineus) wird durch deutliche Tagesgänge charakterisiert, bei denen ein morgendlicher Freisetzungsgipfel typisch ist. Die zeitliche Verschiebung und die quantitativen Unterschiede des Tagesganges der Artemisia-Pollen bei bodenfernen und bodennahen Pollenfallen wird durch den Tagesgang der Luftkonvektion beeinflußt, die der wichtigste Faktor für den Vertikaltransport von Pollen ist. Mit dem Sonnenaufgang beginnt ganz allmäblich die Erwärmung des Bodens und es entsteht Thermik (Luftkonvektion) — erst bodennah und dann von Stunde zu Stunde in höhere Schichten hinaufreichend. Daraus folgt, daß eine bodennahe Falle früher die Artemisia-Pollenemission dokumentiert als eine bodenferne Falle und auch quantitativ die bodennahe Falle höhere Beifußkonzentrationen wiedergibt. Dieses gilt auch für den Rumex conglomeratus-Typ, dessen hohes Gewicht zusätzlich einen schlechten Vertikaltransport bedingt.

Die Pollenemission von Plantago lanceolata und Rumex acetosa ist durch keinen typischen Tagesgang ausgezeichnet. Beide Pollentypen können leichter in höhere Luftschichten transportiert werden, weil ihre Pollenkörner nicht in den thermisch ungünstigen Morgenstunden freigesetzt werden. Daher sind in einer bodennahen und einer bodenfernen Falle nahezu identische Pollenkonzentrationen dieser Typen feststellbar.

The wind pollinated summer weeds Artemisia, Rumex and Plantago are the most important weed pollen of allergologie relevance. The pollen flight of these weeds at two different levels (Essen 1,8 m and 18 m above ground) was investigated by hourly pollen analysis during the seasons 1988 and 1989.

The emission of Artemisia vulgaris and Rumex conglomeratus-type pollen (R. acetosella, R. conglomeratus, R. longifolius, R. sanguineus) is characterized by a distinct diurnal pattern with a prominent mid-morning peak.

The phase shift and the quantitative differences for Artemisia pollen registration in a pollen trap at high level is influenced by the daily variation of air convection, which is the most important vertical transport factor for pollen. After sunrise, the ground warms up gradually and the result is the so called thermal current, at first at ground level and in time to higher layers. As a result the ground-level traps register Artemisia pollen earlier and also in greater quantities than those at roof level. This holds also true for the pollen of the Rumex conglomeratus-type.

The pollen emission of Plantago lanceolata and Rumex acetosa can be observed during the whole day. Pollen of these two species can be lifted up easier to higher atmospheric levels than those of Artemisia vulgaris and R. conglomeratus-type because they show a lower gravity and do not emit pollen under unfavorable convection conditions in the morning. Thus, in the same daily variation, a high- and a low-level trap register the same amount of emitted pollen of R. acetosa and P. lanceolata.     

Pollen from tree and shrub taxa in the atmosphere of Caxias do Sul (Rio Grande do Sul, Brazil)

An aerobiological study has been carried out in the region of Caxias do Sul in southern Brazil. Pollen monitoring was performed from January 1, 2001 through to December 31, 2002. A total of 30,469 pollen grains were collected during this period, and 40 pollen types were identified; of these, 23,389 pollen grains, representing 29 pollen types, originated from tree and shrub taxa. The maximum pollen concentration was registered in August 2001 and October 2002. In the study area, the pollen type Mimosa scabrella (18.8%) was much more abundant than all of the pollen types from tree and shrub taxa, such as: Urticaceae (18.4%), Myrtaceae (10.2%), Cupressaceae (7.7%), Myrsine (4.8%), Sorocea (3.9%), Pinaceae (2.9%), Asteraceae (2.2%) and Ricinus (2.1%). These nine pollen types accounted for the largest pollen concentrations of all the tree and shrub taxa. The pollen types Carya, Melastomataceae, Mimosa scabrella, Myrsine and Sorocea are reported for the first time in an aerobiological study in Brazil.