Rafael Tormo Molina

Pollen production in anemophilous trees

Abstract A study was made of the total pollen production per individual tree in ten anemophilous arboreal species (including wild, cultivated and ornamental species) of considerable aerobiological importance: Pinus pinaster, Ulmus minor, Juglans regia, Platanus hispanica, Quercus rotundifolia, Salix atrocinerea, Populus nigra, Acer negundo, Olea europaea and Fraxinus angustifolia. For each species three isolated well-shaped specimens of medium height were chosen, and the number of flowers per individual tree and the number of pollen grains per anther was estimated. The values of total pollen production varied between a little over 1000 million grains in Juglans regia and more than 500,000 million in one single tree in Quercus rotundifolia. For the production of pollen grains per anther, the values oscillated between 3000 grains in Juglans regia and 100,000 in Olea europaea. There is an exponential correlation between the size of the anthers and the number of pollen grains they contain. A linear correlatio...

The importance of interactions between meteorological conditions when interpreting their effect on the dispersal of pollen from homogeneously distributed sources

The interaction between different meteorological conditions recorded in Badajoz (SW Spain) over a 13-year period has been studied. The results were used for analysis of the effect of these conditions on atmospheric concentrations of Plantago and Brassicaceae pollen grain. For both types of pollen there was a positive effect of NE winds and a negative effect of SW winds which could not be explained by the location of the sources, because these species are very abundant all around the sampling station. The two effects were interpreted on the basis of the action of these winds on temperatures and relative humidity, because these conditions physically and biologically directly determine the concentrations of these types of pollen. Wind from the west is associated with an increase of wind speed and a decline in calm periods; wind from the south is associated with increased rainfall and humidity; wind from the opposite directions is associated with a decrease in these meteorological conditions. These main associations can explain the variation in pollen concentration, although there are also variations in seasons and years. These types of pollen also behave differently, so wind speed reduces the concentration of pollen from Plantago but increases it from Brassicaceae. Beyond the immediate application of the analysis to this specific case, there is a clear interest in observing the interaction between meteorological factors to gain a broader perspective for interpretation of the results of aerobiological studies aimed at determining the effect of these factors on the release and transport of particles into the air.

Sampling in aerobiology. Differences between traverses along the length of the slide in Hirst sporetraps

Two years of data from four longitudinal traverses along each days slide prepared from a continuously running Burkard sporetrap have been analyzed statistically. Using the Friedman test, a statistically significant difference was found between the four traverses, with a greater than 7% loss of pollen grains in the two outer traverses in relation to the inner. Four slides were then selected for more detailed analysis, using 18 longitudinal traverses with a 1-mm separation from the upper to the lower edge of the Melinex tape. There was found to be a progressive decline from the centre to the outside, and more than 4% of pollen grains were found outside the typical 14 mm width of the impaction orifice. There was no correlation between pollen grain size and the decline in counts from the centre to the outside. For the complete data set, there was a general rise in the diversity of bollen types with increasing sample counts, but above about 1000 pollen grains per sample there were no more than 27 pollen types found, often even fewer. A discussion is presented of whether four traverses really should be a fixing sample size, or whether it might be better to fix the total pollen count beginning with a traverse in the middle of the slide and ending with a variable number of traverses when that count is reached.

Dispersal of Amaranthaceae and Chenopodiaceae pollen in the atmosphere of Extremadura (SW Spain)

A study over six consecutive years of the pollination dynamics of the Amaranthaceae and Chenopodiaceae in Badajoz, and a comparative study over three years with stations in Mérida and Cáceres showed that there were different factors affecting this process. Thus, the proximity of croplands was found to be important in determining the magnitude of the concentrations, and this was also confirmed with a study of the concentrations measured directly in the croplands. Autumn and summer rainfall was found to affect, and also to have a certain influence on the length of the flowering period. The daily variations in pollen levels were studied in relation to meteorological parameters, finding a correlation that was positive with respect to temperature and negative with respect to atmospheric humidity and the distance travelled by the wind, i.e. airflow measured in hm with a revolving-cup anemometer. These correlations were the same in all three of the localities studied. The direction of the wind, however, was found to have different effects according to the locality studied. This is explained by their positions relative to the irrigation zones in the region. The pattern of diurnal pollen release from these taxa shows the greatest levels to be reached between 10:00 and 12:00 hours in Mérida as well as in Badajoz. In Cáceres, however, the distribution throughout the day was very even, with few hourly variations. This may be due to the sparse representation of these species in the neighbourhood of the Cáceres trap, with the pollen having been transported from sources that were farther away.

Two sampling methods for the Petri dish detection of airborne fungi

Abstract Burkard personal samplers for Petri dishes use two air throughput devices, either with a sieve or with a funnel, for monitoring of airborne fungi concentration. These two different methods have been compared in a comparative study. The two personal traps used for comparison were run simultaneously, one equipped with a sieve and one with a funnel only. Possible correlations with rainfall, temperature, wind speed, and relative humidity were studied. The average concentrations were 74 and 339 colony forming units/m3 (a factor of 4.6 difference) for the funnel and sieve devices, respectively. More than 70 taxa of airborne fungi were identified. The four most important genera in decreasing order of concentration were Cladosporium, Alternaria, Penicillium, and Aspergillus, the last two present in similar concentration. A significant negative correlation with wind speed was detected. Statistical analysis (ANOVA) revealed significant differences between the two sampler types except for Alternaria. In conclusion, the sampler with a sieve provides more colonies than the same sampler with a funnel. Both kinds of samplers are affected by wind speed, with the capture of airborne fungi propagules being reduced as the speed increases.Abstract Burkard personal samplers for Petri dishes use two air throughput devices, either with a sieve or with a funnel, for monitoring of airborne fungi concentration. These two different methods have been compared in a comparative study. The two personal traps used for comparison were run simultaneously, one equipped with a sieve and one with a funnel only. Possible correlations with rainfall, temperature, wind speed, and relative humidity were studied. The average concentrations were 74 and 339 colony forming units/m3 (a factor of 4.6 difference) for the funnel and sieve devices, respectively. More than 70 taxa of airborne fungi were identified. The four most important genera in decreasing order of concentration were Cladosporium, Alternaria, Penicillium, and Aspergillus, the last two present in similar concentration. A significant negative correlation with wind speed was detected. Statistical analysis (ANOVA) revealed significant differences between the two sampler types except for Alternaria. In con...

Use of personal sporetraps to complement continuous aerobiological monitoring

Abstract We analysed pollen and spore data obtained from one continuous and two personal Burkard sporetraps during the spring months of three years (2007–2009). For the statistical analysis, the data was normalised with a log transformation, and then subjected to an ANOVA and a Pearson correlation analysis. The best time to use the personal samplers was determined from 15 years of continuous aerobiological monitoring pollen data to be between 11:00–16:00, when highest concentration was found and in a steady way. Height of sampling was compared at floor level and at 1.1 m with personal samplers; both of them were on a terrace at 6 m above the ground, but no statistically significant differences were found. The results revealed that there were apparently no differences between continuous and personal Burkard samplers for total pollen and spores. Nevertheless, distinguishing the main pollen types (i.e., Poaceae, Quercus, Olea, Cupressaceae, Plantago, and Platanus) revealed that there are some differences for Poaceae pollen only. In conclusion, personal samplers could be used to anticipate continuous monitoring data because their sampling is shorter and the results may be obtained quicker than with a continuous sampler, although they must never be considered as a replacement.

Comparison between two adhesives (silicone and petroleum jelly) in Hirst pollen traps in a controlled environment

Abstract Aerobiological sampling through volumetric pollen traps requires the use of an appropriate adhesive, whose selection is a critical factor in these studies. This study compares the differences between two adhesives that have been widely used in aerobiological studies with the aim of providing a persuasive argument for using petroleum jelly as a viable alternative to silicone diluted with the banned substance carbon tetrachloride. The study was performed using Hirst-type pollen traps in an indoor controlled environment to avoid interference attributed to outdoor meteorological parameters. Furthermore, a gravimetric study was conducted simultaneously as a control. Four different pollen types with different pollen sizes and similar flowering seasons were studied (Acer, Platanus, Quercus and Rumex). Differences between pollen traps were minimised by interchanging the drums in each pollen trap every 24 hours. Gravimetric results showed homogeneous airborne pollen distribution in the study. No statistically significant differences were found between the results for the sample adhesives for Quercus and Platanus, whereas significant differences were observed for Rumex and Acer. In the case of Acer, more pollen grains were recorded using the petroleum jelly, while for Rumex, more pollen grains were recorded with silicone. After this experiment we consider that petroleum jelly can be used as a viable alternative adhesive to the banned silicone diluted with carbon tetrachloride.

Variations in airborne pollen in central and south-western Spain in relation to the distribution of potential sources

Abstract The present study seeks to compare daily and hourly airborne pollen concentrations at eight different stations in Castilla-La Mancha (central Spain) and Extremadura (south-western Spain) and assess pollen distribution sources. Sampling stations were located 69–440 km apart in a straight line in Albacete, Toledo, Talavera de la Reina and Ciudad Real in Castilla-La Mancha, and in Badajoz, Plasencia, Santa Amalia and Zafra in Extremadura. Airborne pollen was collected using Hirst-type volumetric spore traps. Quercus was the most abundant pollen type at all stations except for Ciudad Real, where Olea pollen predominated. Comparisons of daily data between pairs of stations revealed statistically significant positive correlations in all cases for Poaceae and Olea. Comparisons of hourly data between stations indicated greater differences than daily data. Analysis of correlation coefficients and straight-line distances between stations revealed a strong negative correlation. Analysis of total airborne pollen data for the eight sampling stations suggests that airborne pollen concentrations decrease from west to east and from south to north, partly reflecting dominant wind patterns. A clear correlation was observed between airborne pollen concentrations and the surface area covered by olive crops in a 50 km radius around the sampling stations.

Airborne propagules of Phytophthora and related taxa in SW Spain including a predictive model

The airborne sporangia of Oomycota, including Phytophthora species and other species, are usually recorded by volumetric spore traps. The aim of this work was to create a predictive model for the seasonality and weather parameters that may affect sporangia distribution by analysing their presence over the course of a year. Three Hirst spore traps were located in the SW of Spain (Plasencia, Don Benito and Zafra), and the presence of sporangia was recorded throughout 2012–2013. Phytophthora sporangia were recorded on 76–110 days per year. Autumn and spring were the seasons when the highest concentration peaks of airborne sporangia were recorded; these peaks were recorded on the same day in each of the three locations. When analysing weekly sums of the daily concentration of sporangia, there was a statistically significant correlation between the sporangia concentration and amount of rain in the three locations studied; however, this correlation was not observed when comparing the individual daily concentrations. When comparing the daily concentration to the daily rain levels, the highest correlation coefficient and statistically significant correlation was reached on the second day after rain. The proposed predictive model considered the previous rain to be the main environmental factor. Holm oak and cork oak woods in Plasencia may be responsible for a higher concentration of airborne Phytophthora-type sporangia. Rain seems to have a direct influence on the concentration of airborne sporangia, but the highest concentrations appear on the second day after rain.