Pollen Trap Research Articles

Airborne grass pollen in Leiden, The Netherlands: annual variations and trends in quantities and season starts over 26 years

The long-term, 26 years’ data set of observations on daily concentrations of airborne grass pollen in Leiden is analyzed to present the variations and trends in quantities, and season starting dates. Monitoring of airborne pollen has been done continuously at one location, with a volumetric pollen trap. Annual totals of daily average grass-pollen concentrations are within a normal range of an urban site between 3690 and 9277, averagely 5510. The annual totals are irregularly fluctuating from year to year, and show no increasing or decreasing trend. Each year’s seasonal fluctuation is different, probably under the influence of changing weather conditions. The typical grass-pollen month is June. Using the Σ 75 criterium, the average starting date is on 16 May, whereas with the 1% threshold criterium the start of the grass-pollen season averagely is on 3 June. The mean air temperature in the preceding period is taken as the main factor for the timing of the season start. Analyzing the relationships of the two different criteria for the season starts with a number of temperature observation periods, the best relations were found between the mean air temperature in the period 11 April to 20 May and the Σ 75 criterium season start on 16 May (r=−0.78); and between the mean air temperature in May and the 1% threshold criterium season start on 3 June (r=−0.76). Forecasts of the season start which are significantly better than the average starting date are only possible with the mean air temperature up to a few days before the actual start. This limits the practical usefulness of the forecasting system.

Bark as a natural pollen trap

Samples, a few millimetres in diameter, taken from bark of beech, birch, hophornbeam, oak, pine, sycamore and willow contained enough pollen grains for reliable counts (between 200 and 600 pollen grains per slide), not only from the said species, but also from the local vegetation. Pollen deposition at various levels in the vegetation and at different times of the year provide useful information on vegetation composition, and the possible effect of wind direction. No systematical study has been carried out so far concerning the potential and bias of this kind of pollen trap. This paper is merely meant to draw attention to the possibilities to use bark as an easily available pollen trap in the reconstruction of the vegetation. Analysis of archaeological bark samples forms another promising application besides pollen data from soil samples.

Pollen dispersal and representation in a neotropical rain forest

Results of 3 years of pollen trapping on Barro Colorado Island, Panama, are presented. Minimum pollen dispersal distances are estimated for the most abundant pollen taxa. Dispersal distances for some taxa appear to be as low as 5 m, while for other taxa at least 50% of the trapped pollen had travelled more than 40 m. No consistent pattern of spatial variation was reflected in the pollen rain, however, samples close to large canopy gaps had exceptional abundances of ‘disturbance’ taxa. A preliminary analysis of the representation of canopy components indicates that as much as 19% of pollen caught in the traps was derived from large tree species.

Aerobiologic particle sampling by a new personal collector (Partrap FA52) in comparison to the Hirst (Burkard) sampler

A new personal portable sampler of biologic particles (Partrap FA52, Coppa, Biella, Italy) was used for pollen sampling in comparison with Hirst's (Burkard) fixed device. The aerobiologic samplings were carried out simultaneously outdoors with the two devices coupled on the same axis, during the daytime of 10 dry, nonconsecutive spring days. The total amount and the percentages of the pollens most often trapped by the two collectors were compared by Student's t-test for paired samples. The Partrap FA52 showed a highly significant efficacy, quite comparable to that of the Burkard device, in pollen trapping for both the total number (P < 0.0001) and the percentages of Parietaria (P < 0.0001), pine (P < 0.002), and grass (P < 0.0001) pollens. Therefore, Partrap FA52 proved to be highly effective in obtaining quantitative and qualitative aerobiologic samples in comparison with the commonly used fixed samplers.

Pollen dispersal and long distance transport: the case of thermophilic pollen in subarctic Canada

At Kuujjuarapik, on the eastern coast of Hudson Bay (Canada), thermophilic tree pollens, all of long distance origin, are found in low concentrations, but throughout the pollen season. A Cour impaction pollen trap has allowed us to obtain statistically significant concentrations. The analysis of the origins of synchronous air masses by back-trajectories shows that the weekly variations of thermophilic pollens can be linked to air masses coming either from northern regions (Alaska or Beaufort Sea) for minima, and southern regions (Gulf of Mexico) for maxima.

Annual variation of airborne pollen in the city of Palencia, Spain, 1990–1992

The aim of this work is to present the atmospheric pollen concentrations of Palencia, Spain. Data were collected for three consecutive years (1990–92). An active volumetric pollen trap, type CAP2, was used. During this time, 88 different pollen types were identified, of which 27 occured at more than 0.15% of the total pollen recorded annually. These types formed the main pollen spectrum of this sampling station. Pollen coming from herbs (Poaceae, Chenopodiaceae, Plantago Urticaceae, etc.) was predominant (53.79%); arboreal pollen (Quercus, Populus Cupressaceae, etc.) represented 42.11%, and pollen from shrubs (Ericaceae, Sambucus etc.) only 4.10%. May and June was the time of the year with maximum pollen emission to the air. This was due to the quantities of pollen coming from Poaceae and Quercus which together represent 47.25% of the pollen recorded over the three‐year sampling period. Herbaceous pollen appeared throughout the year with maximum concentrations recorded in the spring, coinciding with the maximum levels of arboreal pollen in the atmosphere. An analysis of multiple regression and one‐way anova test between pollen concentrations and selected meteorological parameters show that relative humidity and average temperature are the meteorological factors most correlated with the concentrations of specific pollen types (Plantago, Ligustrum, Sambucus, Carex). In the same way, when the winds are predominantly from the northeast (second quadrant), there are higher pollen concentrations of Sambucus Ericaceae and Mercurialis.

The results of 2-year pollen monitoring of an urban network in Perugia, Central Italy

Continuous pollen monitoring of an urban network consisting of three stations has been undertaken for a period of 2 years in Perugia, central Italy. The aim has been to establish whether the Perugia pollen trap, active since 1983, is still representative of the area following recent urbanisation. Quantitative differences were found between the stations, reflecting different vegetational areas, but only slight differences were detected in relation to the timing of the principal period of pollination. Therefore, although individual pollen traps are necessary to characterize fully the different areas, one trap is sufficient to determine the key allergenic thresholds in the studied area.

Monitoring of pollen rain in moss polsters and mats in view of their suitability as controls for determining the air-borne component of pollen spectra in herbivore faeces

Pollen has been extracted from six bryophyte and two lichen taxa, sampled from three habitats: upland heath, lowland bog and mixed woodland, in both west and east Scotland. The highest number of pollen taxa was recorded in bothSphagnum andThuidium; the lowest numbers of pollen taxa were recorded in two of the mosses and both lichens. For pollen rain control purposes in herbivore faecal studies, woodland species of bryophytes are not suitable due to the sheltering effects from rain provided by the overhead canopy. Open habitats such as moorland heath and bog provide polsters/mats which normally trap pollen rain more effectively for control purposes. The aim of this study was twofold: to observe the effectiveness of selected polsters and lichens as traps for pollen rain and to establish eventually, whether or not such vegetative traps could be used as controls in pollen spectra analyses of herbivore faeces for the determination of nutritional regime and habitat. From a comparison with recent studies in north west Spain of three taxa in common with Scottish samples,Polytrichum demonstrated a consistently higher number of pollen taxa trapped.Thuidium andCladonia all yielded between one and a half and three times the number of pollen taxa as in the same three bryophyte/lichen taxa sampled in Scotland. Investigation relating the pollen rain trapped in polsters to that in faecal material are continuing, and will be reported in due course.

Holocene tree‐line fluctuations and climate in central troms, Northern Norway

Based mainly on pollen influx data, an attempt is made at reconstructing Holocene tree‐line fluctuations and palaeotemperatures in central Troms, North Norway. Both past and present‐day (Tauber trap) pollen influx data suggest that influx rates exceeding 250–300 pollen/cm2/year for each of the major arboreal taxa (Betula pubescens and Pinus sylvestris) are only found at sites with corresponding forest types in the immediate surroundings. High influx rates, raised tree‐lines and favourable climatic periods are recorded at 7500–4500 and 3000–2600 B.P. Betula and Pinus woodlands may have reached more than 200 m above their present altitude limits, suggesting a July mean temperature 2°C higher than at present during the Holocene optimum.

Time linkages between pollination onsets of different taxa over an 11-year period in Perugia, Central Italy

Times of pollination of different taxa in the atmosphere of Perugia (Central Italy) over an 11-year period (1982–1992) were recorded and analysed by means of a 7-day volumetric Hirst-type pollen trap. For some taxa, the pollination period varied from year to year from a chronological and/or quantitative point of view. Several taxa showed a linkage in their starting dates of pollination. Knowledge of this kind of linkage allows us to build a forecasting model.

Seasonal appearance of grass pollen allergen in natural, pauci-micronic aerosol of various size fractions. Relationship with airborne grass pollen concentration.

In a study during the 1993 grass pollen season at Leiden, the relationship between atmospheric pollen allergen carried by five size fractions of pauci-micronic (few microns) particles and the grass pollen count was investigated. Sampling was carried out on dry days, and atmospheric pollen allergen in the particle fractions was assessed by a RAST-inhibition assay while grass pollen quantities were measured with a volumetric pollen trap. It appears that the atmospheric presence of grass pollen allergen in all size fractions is restricted mainly to the period of presence of grass pollen grains. Before and after the grass pollen season atmospheric grass pollen allergen quantities are generally very low. It is concluded that a routinely performed grass pollen count is a reliable measurement for the estimation of the amount of atmospheric grass pollen allergen, also in the pauci-micronic particle fraction.

Modern pollen spectra and vegetation in southern Ontario, Canada

A weekly census of air borne pollen grains was conducted for three years (1983–1985) at four sampling stations (from north to south: Sudbury, Peterborough, Toronto and London) in the Great Lakes region, southern Ontario, Canada.A Cour volumetric vane sampler was used at each site, located at the respective meteorological station, providing pollen spectra from an area of surrounding vegetation with an estimated radius of 40 km. Filter samples were processed by a standard, established procedure.The study area forms part of the Upper Canada Peninsula vegetation region. Two sites, Sudbury and Peterborough, occur in one of the two major vegetation zones, the Mixed-Hardwood; the others, Toronto and London, are located in the second zone, the Deciduous Forest.Previous studies of pollen-vegetation relations in this region were based on analysis of moss polsters. The pollen trap method used here provides a more sensitive registration of regional pollen and while the seven most important taxa quantitatively are found in the both data sets, such important taxa as Cupressaceae and Populus are under-represented or absent in polster data because of poor preservation, but well represented in the trap analyses (Cupressaceae at 9% and Populus at nearly 3%). Similarly, some spore taxa that are absent from previously published results occur in the present data in significant frequencies (Lycopodium at 4% from Sudbury and Sphagnaceae from all stations).The results of statistical analyses show the predictable major change in the regional pollen spectra between Sudbury and Peterborough.

Do Barren Zones and Pollen Traps Reduce Gene Escape From Transgenic Crops?

As genetically engineered crop varieties near widespread cultivation, both agronomic and environmental concerns mandate the development of effective strategies for isolating transgenic varieties from related non—transgenic varieties or cross—fertile weeds. We present the results of the first field experiment designed to test the effectiveness of two containment strategies that are commonly used in field trials of transgenic crops: (1) an isolation zone devoid of vegetation to discourage emigration of insect pollinators from transgenic plots; and (2) trap crops (non—transgenic varieties of the same crop planted adjacent to the transgenic plot that can "cleanse" emigrating pollinators of transgenic pollen). In conjunction with field trials of genetically engineered canola (Brassica napus) conducted by Calgene, Inc., in California and Georgia, we varied both the width of the barren zone and the presence or absence of a trap crop, and measured the effects on gene escape. Escape was easily detected since the genetic construct inserted into the transgenic canola contained a gene that rendered seedlings resistant to the normally lethal antibiotic kanamycin. Our results suggest that barren zones 4—8 m in width may actually increase seed contamination over what would be expected if the intervening ground were instead planted entirely with a trap crop. When trap crops occupied a limited portion of the isolation zone separating transgenic and non—transgenic varieties, the effectiveness of the trap depended on the width of the isolation zone: they reduced gene escape when the two varieties were separated by 8 m, but increased escape across a 4—m isolation zone. We conclude that, for the relatively short isolation distances we examined, the most effective strategy for reducing the escape of transgenic pollen is to devote the entire region between transgenic and non—transgenic varieties to a trap crop.

Airborne birch pollen antigens in different particle sizes

Two particle samplers for ambient air, situated together: a static size-selective bio-aerosol sampler (SSBAS) and a Burkard pollen and spore trap were compared in sampling intact birch pollen grains through one flowering period of Betula (a total of 44 days). The SSBAS trapped pollen grains three times more efficiently than the Burkard trap, but the variations in pollen counts were significantly correlated. In contrast, birch pollen antigenic activity and the pollen count in the Burkard samples were not closely correlated. The antigenic concentration was occasionally high both before and after the pollination period. There was a high birch pollen antigenic activity in particle size classes where intact pollen grains were absent, even on days when the pollen count was very low. Correspondingly, on days with high birch pollen counts in the air, pollen antigenic activity was on several occasions low, indicating that pollen grains were empty of antigenic material. The small particle size classes are especially important to allergic patients because they are able to penetrate immediately into the alveoli and provoke asthmatic reactions. Therefore, aerobiological information systems based on pollen and spore counts should be supplemented with information concerning antigenic activities in the air.

Meristic and Organogenetic Variation in Ruppia occidentalis and R. maritima

Floral meristic and organogenetic variation was sampled in Ruppia occidentalis from an alkaline lake of the Nebraska Sandhills and in Ruppia maritima var. rostrata from a saline, non-Sandhills lake nearby. The androecium is meristically stable, always having two stamens, but the gynoecium is not. Seventy-two percent of the flowers of R. maritima had four carpels and the others had three, and in 80% of inflorescences the two flowers had the same number. In about one-third of inflorescences having dissimilar carpel numbers, the four-carpellate flower was uppermost. The number of carpels in each flower of R. occidentalis ranged from four to nine, averaging six, and in 57% of inflorescences both flowers had the same number; of those that did not, most had more in the lower than upper flower. Twenty-five percent of the flowers had four carpels, 8% had five, 35% had six, 15% had seven, 14% had eight, and 3% had nine. Ordered, dimerous, decussate organogenesis through the first four carpels followed the same pattern in both species, but carpels beyond four were alternate with the first four and the decussate pattern was broken. The stomatiferous dorsal lobe of each carpel produced persistent gas bubbles that probably aid flotation of the inflorescence and might function in trapping pollen as well. Only ephydrophilous pollination was observed in both species.

Modern pollen deposition in cave sites: experimental results from New York State

SUMMARYResults from two years of pollen trapping experiments in New York State show that pollen spectra inside the three caves studied are highly similar to the pollen rain outside the caves. Statistical comparisons of modern pollen spectra derived from Tauber traps, speleothems, moss polsters, and nearby pond sediments suggest that pollen deposition inside caves can provide a reliable index of the regional and local vegetation, directly comparable to the more conventional spectra derived from lake sediments and moss polsters. Because of the relatively low pollen influx inside caves, however, stochastic and episodic forms of particle transport may influence pollen deposition inside caves in proportions that are unique to each site. With careful attention to site parameters such as entrance size, pollen preservation, and modes of sedimentation, investigators could make greater use of caves in palynological studies.

Airborne pollen and spores of Le�n (Spain)

A qualitative and quantitative analysis of airborne pollen and spores was carried out over 2 years (from September 1987 to August 1989) in the city of Leon. Slides were prepared daily using a volumetric pollen trap, which was placed on the Faculty of Veterinary Science building (University of Leon) 12m above ground-level. Fifty-one pollen types were observed; the most important of these were: Cupressaceae during the winter,Pinus andQuercus in spring, and Poaceae, Leguminosae and Chenopodiaceae in the summer. The results also showed the existence of a rich mould spore assemblage in the atmosphere. The group of Amerospores (Penicillium, Aspergillus andCladosporium) as well as Dictyospores (Alternaria) were the most abundant;Puccinia was common in the air in August. Fluctuations in the total pollen and spores m3 of air were compared with meteorological parameters (temperature, relative humidity and rainfall). From the daily sampling of the atmosphere of Leon, considering the maximum and minimum temperature and duration of rainfall, the start of the pollen grain season was observed generally to coincide with a rise in temperature in the absence of rain.

Aerobiology and palaeoecology

Aerobiology involves the study of particles present in the air. Of these, palaeoecologists are most interested in pollen and spores, specially those which come to rest on the surface of the ground. Pollen sampling in palaeoecological studies, therefore, uses a pollen trap which is placed at ground level and the sampling period is a whole season or year. Using examples from northern Finland, for each vegetation type sampled, a pollen analogue is obtained which comprises percentage presence and deposition values cm−2 year−1 for the pollen types recorded. This analogue is used to interpret pollen assemblages from the past. In general, the tree pollen provides information of the regional situation and the herbaceous pollen of specific local conditions. Both natural and man-made environments are considered. The absolute deposition values are often crucial in distinguishing between two plant communities with otherwise similar percentage pollen values. They can also be used to follow the location of the boundaries between different vegetation types through time. Seasonal records of pollen deposition are sometimes useful in distinguishing the different source of the pollen reaching a specific site. In certain instances, annual pollen deposition values can be employed to estimate the rate of accumulation of a peat deposit. In addition, long series of annual pollen deposition values can be compared with meteorological data for the same period to test for trends and correlations. This, potentially, allows both a more detailed interpretation of past climatic changes and provides a basis for models predicting futures ones.

Results of three years of aerobiological sampling in the atmosphere of Busto Arsizio

The Compositae rarely cause respiratory allergy, but in our area located North-West of Milan, symptoms of sensitization appear with ever increasing frequency and are wide-spread. The importance of the pollination of Ragweed has been documented thanks to aerobiological sampling carried over a period of three years, using a pollen trap (Lanzoni VPPS 2000) and collecting weekly data. The results show that the Ragweed pollen is present as from mid July and that the highest pollen concentration is found at the end of August (1988: 125 grains/m3 of air; 1989: 289 grains/m3 of air; 1990: 378 grains/m3 of air). It is possible to find a significant quantity of pollen until the first days of October. Because of the allergological importance of Ragweed, it is advisable that the stations of aerobiological sampling consider Ragweed pollen much more carefully and carry out the pollen count of Ragweed separately from that of the other Compositae. We would also advise that Ragweed be included in the standard Skin-Prick-Test panel for patients with late-summer allergy symptoms.

A simple yet efficient pollen trap for use in vegetation studies

A simple yet efficient pollen trap for use in vegetation studies