Relative Pollen Research Articles

Relative pollen productivity estimates for major plant taxa of cultural landscapes in central eastern China

In this study we estimate relative pollen productivity (RPP) for plant taxa characteristic of human-induced vegetation in ancient cultural landscapes of the low mountain ranges of Shandong province in eastern temperate China. RPP estimates are required to achieve pollen-based reconstructions of Holocene plant cover using modelling approaches based on Prentice’s and Sugita’s theoretical background and models (REVEALS and LOVE). Pollen counts in moss samples and vegetation data from 36 sites were used in the Extended R-Value (ERV) model to estimate the relevant source area of pollen (RSAP) of moss polsters and RPP of major plant taxa. The best results were obtained with the ERV sub-model 3 and Prentice’s taxon-specific method (using a Gaussian Plume dispersal model) to distance weight vegetation data. RSAP was estimated to 145 m using the maximum likelihood method. RPP was obtained for 18 taxa of which two taxa had unreliable RPP (Amaranthaceae/Chenopodiaceae and Vitex negundo). RPPs for Castanea, Cupressaceae, Robinia/Sophora, Aster/Anthemis-type, Cannabis/Humulus, Caryophyllaceae, Brassicaceae and Galium-type are the first ones for China. Trees, except Robinia/Sophora (RPP = 0.78 ± 0.03) have larger RPPs than herbs other than Artemisia (RPP = 24.7 ± 0.36). The RPPs for Quercus, Pinus and Artemisia are comparable with other RPPs obtained in China, the RPPs for Pinus, Quercus, Ulmus, Cyperaceae and Galium-type with the mean RPPs obtained in Europe, and RPP for Cupressaceae with that for Juniperus in Europe. The values for Aster/Anthemis-type, Caryophyllaceae, Asteraceae SF Cichorioideae and Juglans differ from the few RPPs available in China and/or Europe.

Ultrastructural changes of pistachio (Pistacia vera L.) mature seeds and pollen in relation to desiccation

Pistachio seeds and pollen have desiccation tolerance and desiccation sensitivity ultrastructural characters at maturation, respectively. Seed cells filled with storage matter remain integrated, whereas some pollen show cell rupture. Maturation drying is a common trait of seeds and pollen. Orthodox seeds and pollen become tolerant to desiccation at maturation and remain their germinability in an inactive dry state for a period of time, whereas recalcitrant ones remain sensitive and must germinate immediately after maturation. This study investigated the moisture content, germinability and ultrastructure of pistachio (Pistacia vera L.) mature seeds and pollen in fresh and 24 h-desiccated states using microscopy methods. Seeds lost 90.5% water and remained 100% germinable demonstrating their orthodoxy. Fresh and desiccated cells of both cotyledon and ground meristem of root tip, mostly contained lipid and protein reserves. Large autophagic vacuoles in fresh cells contained autophagic bodies digesting organelles related to active metabolism and became converted to protein storage vacuoles at desiccated state. In ground meristem of root tip, most lipid bodies were tiered adjacent to plasma membrane probably with a secretory function and the cell walls were waved at desiccated state. Pollen lost 46.7% water along with 93% germinability by desiccation demonstrating its recalcitrance. After desiccation, 1.8% of pollen grains displayed intine degeneration, vegetative cell plasmolysis and detachment from intine, lobed vegetative cell nucleus, great vacuolation along with organelles destruction in both vegetative and generative cells and finally cell rupture. However, most pollen displayed normal structure indicating the recalcitrance behavior of pistachio pollen is not mainly related to cell structural damages but, lack of germinability through molecular damages that should be studied in details.

Relative pollen productivities and relevant source area of pollen in the forest–steppe ecotone of northern China

Modeling efforts to quantitatively reconstruct vegetation from pollen have never been attempted along the forest–steppe border of China, however such studies are important in interpreting fossil pollen assemblages of vegetation change along this ecotone. In this paper, relative pollen productivity (RPP) and relevant source area of pollen (RSAP) as two important parameters in quantitative vegetation reconstruction using the LRA (Landscape Reconstruction Algorithm approach) model, are estimated from the forest–steppe ecotone north of Shanxi, China, where pollen sampling and vegetation survey were performed at 18 random sample sites. The pollen analysis results show that Artemisia, Asteraceae, Poaceae, Pinus, Picea, Quercus, Betula and Hippophae dominate the pollen assemblages with more than 80% proportion. ERV (Extended R-value) analysis showed that the RSAP is about 600m and that around 50% of the pollen in each sample comes from beyond this distance. RPPPoaceae (pollen productivity relative to Poaceae) is estimated as more than 10 for Pinus and Hippophae and around 5 for Picea and Betula. Estimates for Artemisia (3–4) are substantially lower than those reported from other studies in the steppe biome, and for Quercus (0.5) are substantially lower than those from the forest biome in north-east China or Europe. Four additional samples were then used to test the effectiveness of two different methods for reconstruction of vegetation proportion from pollen assemblages, the Landscape Reconstruction Algorithm (LRA) and the Modern Analogue Technique (MAT) showed that both methods can give generally reasonable results with similarity index more than 0.6, but there is still some discrepancy between the two methods.

Relation between modern pollen rain, vegetation and climate in northern China: Implications for quantitative vegetation reconstruction in a steppe environment

Vegetation reconstructions from palaeoecological records depend on adequate understanding of relationships between modern pollen, vegetation and climate. A key parameter for quantitative vegetation reconstructions is the Relative Pollen Productivity (RPP). Differences in both environmental and methodological factors are known to alter the RPP estimated significantly, making it difficult to determine whether the underlying pollen productivity does actually vary, and if so, why. In this paper, we present the results of a replication study for the Bashang steppe region, a typical steppe area in northern China, carried out in 2013 and 2014. In each year, 30 surface samples were collected for pollen analysis, with accompanying vegetation survey using the “Crackles Bequest Project” methodology. Sampling designs differed slightly between the two years: in 2013, sites were located completely randomly, whilst in 2014 sampling locations were constrained to be within a few km of roads. There is a strong inter-annual variability in both the pollen and the vegetation spectra therefore in RPPs, and annual precipitation may be a key influence on these variations. The pollen assemblages in both years are dominated by herbaceous taxa such as Artemisia, Amaranthaceae, Poaceae, Asteraceae, Cyperaceae, Fabaceae and Allium. Artemisia and Amaranthaceae pollen are significantly over-represented for their vegetation abundance. Poaceae, Cyperaceae and Fabaceae seem to have under-represented pollen for vegetation with correspondingly lower RPPs. Asteraceae seems to be well-represented, with moderate RPPs and less annual variation. Estimated Relevant Source Area of Pollen (RSAP) ranges from 2000 to 3000m. Different sampling designs have an effect both on RSAP and RPPs and random sample selection may be the best strategy for obtaining robust estimates. Our results have implications for further pollen-vegetation relationship and quantitative vegetation reconstruction research in typical steppe areas and in other open habitats with strong inter-annual variation.

A comparison of relative pollen productivity from forest steppe, typical steppe and desert steppe in Inner Mongolia

Relative pollen productivity (RPP) is the ratio of the absolute pollen productivity of a certain pollen taxon to the pollen reference taxon. It is an important parameter that can be used for quantitative reconstruction of paleovegetation at a landscape scale. Here we report a study on the estimation of the RPPs of five common pollen types of grassland vegetation from forest steppe, typical steppe and desert steppe in Hulunbuir, Xilinhot and Sonid Left Banner of Inner Mongolia. We used a 1 m×1 m quadrat to record plant species, rooted frequency and percentage cover at upwind to downwind direction at 0, 1, 2, 3.5, 5.5, 7.5, 9.5, 14.5 and 19.5 m distance from the trap. For the sites of 20–100 m distance from the trap, we investigated vegetation composition of the 1 m × 1 m quadrat with a 10-m interval. In the three study areas, Artemisia , Compositae, Gramineae, Chenopodiaceae and Cyperaceae were dominant plants. In the Hulunbuir forest steppe, Artemisia and Gramineae had the highest percentage. In the Xilinhot with typical steppe and the Sonid Left Banner with desert steppe, the percentage of Gramineae was the highest. We collected the pollen samples using modified Tauber traps from 2007 to 2013. The percentage of Chenopodiaceae in the Hulunbuir forest steppe was the lowest, but reached the highest in the Sonid Left Banner desert steppe, in contrast to those of Compositae, Gramineae and Cyperaceae. Our results show that the fall speed ( v g) varies among the five pollen types with 0.032 m/s for Gramineae, 0.027 m/s for Cyperaceae and Chenopodiaceae, 0.021 m/s for Artemisia and 0.019 m/s for Compositae. The RPPChe. was found the highest and RPPGra. the lowest in the three areas. When we used Artemisia as a reference taxon, the RPPs of the same pollen type are different in the three areas. For example, in the Hulunbuir forest steppe, the RPP Art . was 1.00, RPPCom. was 0.33, RPPGra. was 0.44, RPPChe. was 4.78 and RPPCyp. was 1.21. However, in the Xilinhot typical steppe, RPP Art. became 1.00, RPPCom. 4.72, RPPGra. 0.01, RPPChe. 2.05 and RPPCyp. 1.31×10 - 4; in the Sonid Left Banner desert steppe, RPP Art . was 1.00, RPPCom. 6.72, RPPGra. 2.15, RPPChe. 36.25 and RPPCyp. 0.41 respectively. The main reasons for the RPP differences might be the species dissimilarity in diverse vegetation types and the number of the sampling sites used in the models. The estimated relevant source areas of pollens (RSAPs) in all the three areas were less than 20 m. The coverage of different plants was reconstructed by the REVEALS model and presented a large difference among the three areas. In the Hulunbuir forest steppe, the Artemisia ’s coverage was 29.16%, Compositae18.66%, Gramineae 39.40%, Chenopodiaceae 3.53% and Cyperaceae 9.25%. In the Xilinhot typical steppe, the coverage of Artemisia reached 13.42%, Compositae 0.12%, Gramineae 61.69%, Chenopodiaceae 17.59% and Cyperaceae 7.17%. And in the Sonid Left Banner desert steppe, Artemisia reached a coverarge of 93.81%, Compositae 0.59%, Gramineae 1.22%, Chenopodiaceae 3.13% and Cyperaceae 1.25%. Compared with the actual vegetation coverage, the reconstructed coverage of Artemisia and Chenopodiaceae are higher, while that of Gramineae is far lower, which might be caused by the high background value of Artemisia .

The beginnings of rye (Secale cereale) cultivation in the East Baltics

In this paper we review the earliest Secale (rye) records, both pollen and macroremains, from the eastern Baltic region (northeast Poland, Lithuania, Latvia, Estonia and Finland) in order to understand the processes evident in the beginnings of rye cultivation. By taking note of the abundance of recovered Secale grains and pollen in relation to other cereals found in published archaeobotanical data, we try to understand when rye began to be used regionally as a staple food. The clarification of the timing of Secale in the East Baltic, that had social and economic implications, is of particular importance. In this publication we also present a radiocarbon date directly derived from dating a Secale grain from a Roman period hillfort in Lithuania. The date obtained constitutes the earliest record of Secale in the eastern Baltic region, showing that rye cultivation traditions and concomitant innovations in agricultural technology started there much earlier than previously suggested.

Replicability of data collected for empirical estimation of relative pollen productivity

The effects of repeated survey and fieldwork timing on data derived from a recently proposed standard field methodology for empirical estimation of relative pollen productivity (RPP) have been tested. Seasonal variations in vegetation and associated pollen assemblages were studied in three contrasting cultural habitat types; semi-natural ancient woodlands, lowland heaths, and unimproved, traditionally managed hay meadows. Results show that in woodlands and heathlands the standard method generates vegetation data with a reasonable degree of similarity throughout the field season, though in some instances additional recording of woodland canopy cover should be undertaken, and differences were greater for woodland understorey taxa than for arboreal taxa. Large differences in vegetation cover were observed over the field season in the grassland community, and matching the phenological timing of surveys within and between studies is clearly important if RPP estimates from these sites are to be comparable. Pollen assemblages from closely co-located moss polsters collected on different visits are shown to be variable in all communities, to a greater degree than can be explained by the sampling error associated with pollen counting, and further study of moss polsters as pollen traps is recommended.

Airborne Weed Pollen in Relation to Allergic Rhinitis in Riyadh, Saudi Arabia

Airborne Weed Pollen in Relation to Allergic Rhinitis in Riyadh, Saudi Arabia

Approaches to quantitative reconstruction of woody vegetation in managed woodlands from pollen records

There has been increasing interest in developing quantitative methods for reconstructing the dynamics of cultural landscapes over the last 15years. This paper adds to this literature by using various approaches to reconstruct the vegetation of two woodlands subject to rotational coppicing (the periodic cutting of broadleaved trees and shrubs for wood products). Pollen deposition at ground level was determined at both sites using ‘Tauber’ traps placed near to the centre of 14 compartments of differing age in the coppice rotation. For the main woody taxa, Relative Pollen Productivity (RPP) estimates were derived using linear regression for pollen influx data and Extended R-value analysis for percentage data. The vegetation around three ponds was reconstructed by applying four methods (inverting the two RPP estimate approaches, the modern analogue technique and correction for pollen productivity using the linear regression estimated RPP values) to pollen data obtained from the uppermost sample of sediment from the ponds. To determine whether these methods gave better estimates of the vegetation composition than the original pollen proportions, the results were compared with the surveyed vegetation around each pond using the Bray–Curtis Index. Linear regression of pollen influx produced RPP values which are comparable with previous European studies, whilst for some taxa the Extended R-value analysis produced estimates which are orders of magnitude different both from values derived from the linear regression and previous work. No single approach performed equally well at reconstructing the vegetation around the ponds, and at two of the three locations the uncorrected pollen proportions were most similar to the surveyed vegetation. We conclude that applying quantitative reconstruction methods to individual small sites is, currently, not likely to be useful in complex cultural landscapes. In the context of coppiced woodland, deficiencies in our understanding of pollen taphonomy and the impact of the practice on pollen production first need to be rectified, and we identify strategies to address this situation.

A novel approach for honey pollen profile assessment using an electronic tongue and chemometric tools

Nowadays the main honey producing countries require accurate labeling of honey before commercialization, including floral classification. Traditionally, this classification is made by melissopalynology analysis, an accurate but time-consuming task requiring laborious sample pre-treatment and high-skilled technicians. In this work the potential use of a potentiometric electronic tongue for pollinic assessment is evaluated, using monofloral and polyfloral honeys. The results showed that after splitting honeys according to color (white, amber and dark), the novel methodology enabled quantifying the relative percentage of the main pollens (Castanea sp., Echium sp., Erica sp., Eucaliptus sp., Lavandula sp., Prunus sp., Rubus sp. and Trifolium sp.). Multiple linear regression models were established for each type of pollen, based on the best sensors' sub-sets selected using the simulated annealing algorithm. To minimize the overfitting risk, a repeated K-fold cross-validation procedure was implemented, ensuring that at least 10–20% of the honeys were used for internal validation. With this approach, a minimum average determination coefficient of 0.91 ± 0.15 was obtained. Also, the proposed technique enabled the correct classification of 92% and 100% of monofloral and polyfloral honeys, respectively. The quite satisfactory performance of the novel procedure for quantifying the relative pollen frequency may envisage its applicability for honey labeling and geographical origin identification. Nevertheless, this approach is not a full alternative to the traditional melissopalynologic analysis; it may be seen as a practical complementary tool for preliminary honey floral classification, leaving only problematic cases for pollinic evaluation.

Differential selection on pollen and pistil traits in relation to pollen competition in the context of a sexual conflict over timing of stigma receptivity.

Sexual conflict and its evolutionary consequences are understudied in plants, but the theory of sexual conflict may help explain how selection generates and maintains variability. Here, we investigated selection on pollen and pistil traits when pollen arrives sequentially to partially receptive pistils in relation to pollen competition and a sexual conflict over timing of stigma receptivity in the mixed-mating annual Collinsia heterophylla (Plantaginaceae). In this species the conflict is generated by early fertilizing pollen that reduces seed production, which is counteracted by delaying receptivity in the recipient. We performed sequential two-donor pollinations at early floral developmental stages involving two pollen deposition schedules (with or without a time lag of 1 day), using only outcross or self and outcross pollen. We investigated pollen and pistil traits in relation to siring success (male fitness) and seed production (female fitness). In contrast to previous findings in receptive pistils in C. heterophylla and in other species, last arriving pollen donors showed highest siring success in partially receptive pistils. The last male advantage was weaker when self pollen was the first arriving donor. Two measures of germination rate (early and late) and pollen tube growth rate of first arriving donors were important for siring success in crosses with a time lag, while only late germination rate had an effect in contemporary crosses. Curiously, late stigma receptivity was negatively related to seed production in our contemporary crosses, which was opposite to expectation. Our results in combination with previous studies suggest that pollen and pistil traits in C. heterophylla are differentially advantageous depending on stage of floral development and varying pollen deposition schedules. Variation in success of these traits over floral development time may result from sexually antagonistic selection.

Degradation of habitat disrupts plant–pollinator interactions for a rare self-compatible plant

Habitat destruction has immediate consequences on biodiversity, whereas the effects of habitat degradation are slower and more subtle. Habitat quality and structure influence reproduction in rare plant species because changes in the local environment can disrupt sensitive plant–pollinator interactions. We used the self-compatible rare species Synthyris bullii to examine pollination and reproduction in response to woody encroachment, a type of degradation that occurs in prairies and savannas in the absence of fire. Additionally, we determined if autonomous selfing occurred more frequently than pollinator-mediated fertilization in degraded habitats. Infructescences from populations in open, semi-shaded, shaded habitats (i.e., different levels of encroachment) were collected to assess reproductive output (e.g., fruit/seed set) and fitness (i.e., germination). In addition, a pollinator exclusion treatment was conducted in these habitats to estimate pollen quantity (i.e., stigma pollen load). Pollinators contributed 32–57 % of pollen loads on average. We observed a significant increase in reproductive output associated with the pollinator treatment, even when the relative pollen contribution was small. Further, fruit and seed set were negatively affected by pollinator exclusion regardless of habitat type. We found evidence that pollen quantity/quality was lower in shaded habitats, which also played a role in lower fruit/seed set and germination compared to other habitats. Autonomous selfing does not occur at a sufficiently high rate, even in shaded habitats, to compensate for pollinator absence. As habitats degrade, reduced pollen quantity/quality and low autonomous selfing rates may contribute to the loss of rare species.

Pollen productivity estimates from old-growth forest strongly differ from those obtained in cultural landscapes: Evidence from the Białowieża National Park, Poland

Pollen productivity estimates of individual plant taxa are necessary when determining changes of vegetation cover during the Holocene. To date, studies describing this parameter in lowland temperate Europe have been carried out in cultural landscapes showing low forest cover and dominated by human activities. However, these may be of limited use when applied to reconstruct past land cover, for instance, from pre-agricultural landscapes. The aim of this paper is to ascertain whether pollen productivity from the closed-canopy old-growth forest in the Białowieża National Park, Poland, where human impact has been minimal for nearly a century, is different from that calculated in much more open landscapes. We ask: how much does forest antiquity and structure influence the amount of pollen released from particular taxa? We implemented maximum likelihood estimation of relative pollen productivity for seven tree species and for Poaceae using 18 modern pollen assemblages and distance-weighted plant abundances. Our results demonstrate that the ratio of pollen productivity between high producers ( Pinus sylvestris and Quercus robur) and low producers ( Poaceae, Corylus avellana) is on an average six times greater in Białowieża than across other European cultural landscapes. Pollen from forest Poaceae and C. avellana is six times more under-represented in old-growth forest than hitherto estimated from cultural landscapes. This finding reinforces the idea that pollen productivity can vary in response to changes in the prevailing environmental settings and we present for the first time a quantification of this variability, likely induced by differences in light availability.

Relative pollen productivity estimates for common taxa of the northern Siberian Arctic

Pollen productivity estimates (PPE) are used to quantitatively reconstruct variations in vegetation within a specific distance of the sampled pollen archive. Here, for the first time, PPEs from Siberia are presented. The study area (Khatanga region, Krasnoyarsk territory, Russia) is located in the Siberian Sub-arctic where Larix is the sole forest-line forming tree taxon. Pollen spectra from two different sedimentary environments, namely terrestrial mosses (n=16) and lakes (n=15, median radius~100m) and their surrounding vegetation were investigated to extract PPEs. Our results indicate some differences in pollen spectra between moss and lake pollen. Larix and Cyperaceae for example obtained higher representation in the lacustrine than in terrestrial moss samples. This highlights that in calibration studies, modern and fossil datasets should use archives of similar sedimentary origin. Results of an Extended R-Value model were applied to assess the relevant source area of pollen (RSAP) and to calculate the PPEs for both datasets. As expected, the RSAP of the moss samples was very small (about 10m) compared to the lacustrine samples (about 25km). Calculation of PPEs for the six most common taxa yielded generally similar results for both datasets. Relative to Poaceae (reference taxon, PPE=1) Betula nana-type (PPEmoss: 1.8, PPElake: 1.8) and Alnus fruticosa-type (PPEmoss:6.4, PPElake:2.9) were overrepresented while Cyperaceae (PPEmoss:0.5, PPElake:0.1), Ericaceae (PPEmoss: 0.3, PPElake<0.01), Salix (PPEmoss:0.03, PPElake<00.1) and Larix (PPEmoss: <0.01, PPElake:0.2) were under-represented in the pollen spectra compared to the vegetation in the RSAP. The estimation for the dominant tree in the region, Larix gmelinii, is the first published result for this species, but needs to be considered very preliminary. The inferred sequence from over- to under-representation is mostly consistent with results from Europe; however, the absolute values show some differences. Gathering vegetation data was limited by the remoteness of our study area and a lack of high-resolute satellite imagery and vegetation maps. Our estimate may serve as a first reference to strengthen future vegetation reconstructions in this climate-sensitive region.

Chemical Composition and Amounts of Mineral Elements in Honeybee-Collected Pollen in Relation to Botanical Origin

Abstract This study was conducted at the apiary of the Agricultural and Veterinary Training and Research Station, King Faisal University, Al-Ahsa, Saudi Arabia. The purpose was to study the relationship between the botanical origin and chemical composition of bee-collected pollen. The amount of mineral elements present in bee-collected pollen was also studied. The composition of pollen loads showed the maximum contents of dry matter, ash, glucose, fructose, magnesium (Mg), phosphorus (P), and manganese (Mn) for the date palm; the maximum contents of protein, calcium (Ca), and zinc (Zn) for alfalfa; the maximum contents of fiber, and copper (Cu) for the sunflower; the maximum contents of the lipids and iron (Fe) for summer squash; and the maximum contents of sodium (Na), and potassium (K) for rape. Calcium was found to be correlated in a significantly (p&lt;0.01) positive way with K, Na, Mg, P, Mn, and Zn. Copper, though, was correlated in a significantly (p&lt;0.01) negative way with Ca, Mg, P, Mn, and Zn. The high levels of protein, ash, glucose, and fructose, and low lipid content found in bee-pollen from the date palm and from alfalfa, mean that pollen from the date palm and from alfalfa make an excellent food supplement. It was concluded, that the chemical composition of beecollected pollen can be correlated with the plant species from which pollen was collected.

Disentangling the effects of feedback structure and climate on Poaceae annual airborne pollen fluctuations and the possible consequences of climate change

Pollen allergies are the most common form of respiratory allergic disease in Europe. Most studies have emphasized the role of environmental processes, as the drivers of airborne pollen fluctuations, implicitly considering pollen production as a random walk. This work shows that internal self-regulating processes of the plants (negative feedback) should be included in pollen dynamic systems in order to give a better explanation of the observed pollen temporal patterns. This article proposes a novel methodological approach based on dynamic systems to investigate the interaction between feedback structure of plant populations and climate in shaping long-term airborne Poaceae pollen fluctuations and to quantify the effects of climate change on future airborne pollen concentrations. Long-term historical airborne Poaceae pollen data (30years) from Cordoba city (Southern Spain) were analyzed. A set of models, combining feedback structure, temperature and actual evapotranspiration effects on airborne Poaceae pollen were built and compared, using a model selection approach. Our results highlight the importance of first-order negative feedback and mean annual maximum temperature in driving airborne Poaceae pollen dynamics. The best model was used to predict the effects of climate change under two standardized scenarios representing contrasting temporal patterns of economic development and CO2 emissions. Our results predict an increase in pollen levels in southern Spain by 2070 ranging from 28.5% to 44.3%. The findings from this study provide a greater understanding of airborne pollen dynamics and how climate change might impact the future evolution of airborne Poaceae pollen concentrations and thus the future evolution of related pollen allergies.

Variation of the group 5 grass pollen allergen content of airborne pollen in relation to geographic location and time in season

Allergies to grass pollen are the number one cause of outdoor hay fever. The human immune system reacts with symptoms to allergen from pollen. We investigated the natural variability in release of the major group 5 allergen from grass pollen across Europe. Airborne pollen and allergens were simultaneously collected daily with a volumetric spore trap and a high-volume cascade impactor at 10 sites across Europe for 3 consecutive years. Group 5 allergen levels were determined with a Phl p 5-specific ELISA in 2 fractions of ambient air: particulate matter of greater than 10 μm in diameter and particulate matter greater than 2.5 μm and less than 10 μm in diameter. Mediator release by ambient air was determined in FcεRI-humanized basophils. The origin of pollen was modeled and condensed to pollen potency maps. On average, grass pollen released 2.3 pg of Phl p 5 per pollen. Allergen release per pollen (potency) varied substantially, ranging from less than 1 to 9 pg of Phl p 5 per pollen (5% to 95% percentile). The main variation was locally day to day. Average potency maps across Europe varied between years. Mediator release from basophilic granulocytes correlated better with allergen levels per cubic meter (r(2) = 0.80, P < .001) than with pollen grains per cubic meter (r(2) = 0.61, P < .001). In addition, pollen released different amounts of allergen in the non-pollen-bearing fraction of ambient air, depending on humidity. Across Europe, the same amount of pollen released substantially different amounts of group 5 grass pollen allergen. This variation in allergen release is in addition to variations in pollen counts. Molecular aerobiology (ie, determining allergen in ambient air) might be a valuable addition to pollen counting.

Forest dynamics in relation to multi-decadal late-Holocene climatic variability, eastern Ontario, Canada

Pollen profiles from two lakes, Tawny Pond (44°48′59″N, 77°10′54″W, 276m) and Stoll Lake (44°58′16″N, 77°17′22″W,303m) in Addington Highlands, eastern Ontario, Canada were analyzed to determine the effects of late-Holocene climate change and European settlement on eastern Ontario's forests. Both lakes were analyzed at high temporal resolution and record vegetation dynamics over the last 1000years. Throughout the past 1000years, Pinus, Tsuga, Betula, Quercus, Acer and Fagus were the dominant taxa in the pollen record. From 950–1550AD the forest was dominated by Tsuga, Fagus and Acer. Between 1550 and 1730AD Pinus and boreal tree species became more abundant and/or had increased relative pollen production. Low pollen influx to the sediment, high values of Pinus and relatively low values of Tsuga and hardwoods between 1730 and 1870AD suggest colder temperatures. Since 1870AD, herbaceous plants (weeds) increased in abundance, whereas softwoods decreased and hardwoods increased, due to landscape changes associated with European settlement. A comparison of the temperature reconstruction based on the pollen assemblages and the Toronto and Ottawa climate records shows a close correspondence, suggesting pollen records can record decadal-scale climate fluctuations.

Investigating the present vegetation to understand the past one: “modern analogues” in the Sultanate of Oman

The study of the present-day pollen rain in modern sites reveals the relationship between vegetation and relative pollen spectra, and provides a useful key for the interpretation of the past pollen records resulting from palaeoenvironmental researches. The modern sites, or “modern analogues”, are accurately selected and considered paradigmatic models. In this paper the first results of two archaeobotanical studies carried out in two different areas of the Sultanate of Oman are presented: Salut (northern Oman) and the ancient town of Sumhuram (southern Oman, Dhofar).

Separating morphologically similar pollen types using basic shape features from digital images: A preliminary study(1.).

• Premise of the study: One of the many advantages offered by automated palynology systems is the ability to vastly increase the number of observations made on a particular sample or samples. This is of particular benefit when attempting to fully quantify the degree of variation within or between closely related pollen types.• Methods: An automated palynology system (Classifynder) has been used to further investigate the variation in pollen morphology between two New Zealand species of Myrtaceae (Leptospermum scoparium and Kunzea ericoides) that are of significance in the New Zealand honey industry. Seven geometric features extracted from automatically gathered digital images were used to characterize the range of shape and size of the two taxa, and to examine the extent of previously reported overlap in these variables.• Results: Our results indicate a degree of overlap in all cases. The narrowest overlap was in measurements of maximum Feret diameter (MFD) in grains oriented in polar view. Multivariate statistical analysis using all seven factors provided the most robust discrimination between the two types.• Discussion: Further work is required before this approach could be routinely applied to separating the two pollen types used in this study, most notably the development of comprehensive reference distributions for the types in question.