Elena Severova

A numerical model of birch pollen emission and dispersion in the atmosphere. Description of the emission module

A birch pollen emission model is described and its main features are discussed. The development of the model is based on a double-threshold temperature sum model that describes the propagation of the flowering season and naturally links to the thermal time models to predict the onset and duration of flowering. For the flowering season, the emission model considers ambient humidity and precipitation rate, both of which suppress the pollen release, as well as wind speed and turbulence intensity, which promote it. These dependencies are qualitatively evaluated using the aerobiological observations. Reflecting the probabilistic character of the flowering of an individual tree in a population, the model introduces relaxation functions at the start and end of the season. The physical basis of the suggested birch pollen emission model is compared with another comprehensive emission module reported in literature. The emission model has been implemented in the SILAM dispersion modelling system, the results of which are evaluated in a companion paper.

The European Modern Pollen Database (EMPD) project

Modern pollen samples provide an invaluable research tool for helping to interpret the quaternary fossil pollen record, allowing investigation of the relationship between pollen as the proxy and the environmental parameters such as vegetation, land-use, and climate that the pollen proxy represents. The European Modern Pollen Database (EMPD) is a new initiative within the European Pollen Database (EPD) to establish a publicly accessible repository of modern (surface sample) pollen data. This new database will complement the EPD, which at present holds only fossil sedimentary pollen data. The EMPD is freely available online to the scientific community and currently has information on almost 5,000 pollen samples from throughout the Euro-Siberian and Mediterranean regions, contributed by over 40 individuals and research groups. Here we describe how the EMPD was constructed, the various tables and their fields, problems and errors, quality controls, and continuing efforts to improve the available data.

Structural basis of harmomegathy: evidence from Boraginaceae pollen

Upon release from the anther, pollen grains can be exposed to dry environment and dehydrate. To survive in dry conditions, the pollen wall possesses the ability to fold itself due to water loss-harmomegathic mechanism. Apertures seem to function as the primary elements of harmomegathy as they are more elastic than the remainder of the pollen wall. Contribution of other sporoderm structures, surface features, and pseudocolpi in harmomegathy are usually not considered in palynological studies. The nature of pseudocolpi has not been properly understood until now, partly because of common use of acetolysis method as a standard procedure. Different structures involved in the harmomegathy mechanism were studied in Cryptantha celosioides, Cryptantha coryi, Heliotropium europaeum, Myosotis palustris, Rindera bungei, and Rindera tetraspis. Scanning electron microscopy was used to study harmomegathy in hydrated and dehydrated pollen grains. In addition, transmission electron microscopy was used to elucidate the ultrastructural basis of pseudocolpi and other harmomegathic structures with special attention to intine structure. Our data reveal that additional flexibility of the pollen wall in Boraginaceae is provided by pseudocolpi, rugulate surface, tectate–columellate ultrastructure, and a transverse groove. Curious triangular polar poroid areas are described in M. palustris.

A 6500-year pollen record from the Polistovo-Lovatskaya Mire System (northwest European Russia). Vegetation dynamics and signs of human impact

Abstract New pollen and plant macrofossil evidence from the Polistovo-Lovatskaya Mire System is presented. The results show that local vegetation of the mire system was affected by various factors such as climate, hydrogeology and autochthonous processes in the peat bog. An important palaeoecological event took place around 6500 cal bp and led to a dramatic increase of paludification processes and lateral expansion of the mire. Forests of spruce and broad-leaved species in various combinations represented primary vegetation of uplands; they began to degrade around 1500 years ago and disappeared in historical times (400–500 cal bp). First signs of arable farming in the area occurred around 4200 cal bp, regular and mild human pressure established about 1000 years cal bp, and a significant impact at the regional level became evident around 400 years ago.

Variations and trends of Betula pollen seasons in Moscow (Russia) in relation to meteorological parameters

This study investigates possible links of meteorological data and the start date, end date, duration, date of peak, peak value and Seasonal Pollen Index (SPI) of birch pollen seasons recorded in Moscow, Russia, during 1993–2015. Pollen data were collected by a volumetric spore trap. Correlation analysis was used to study relationships between various parameters of pollen seasons. Simple linear regression analysis was conducted to investigate trends over time; multiple stepwise regression analysis was used to describe SPI fluctuations as a function of seasonal or monthly climatic parameters. Air temperatures increased significantly during the study period, but no effect on the timing of the birch pollen season was found. Only the severity of the season showed significant changes that can be considered as a consequence of global warming. Rainfall in May and June of the year preceding flowering, total rainfall in the 40-day pre-season period and average temperature during the pollination were shown to be the most important parameters affecting birch pollen concentrations.

Pollen morphology and taxonomy of Atraphaxis (Polygoneae, Polygonaceae)

Pollen grains of 32 species of Atraphaxis L. including six species previously attributed to Polygonum L. s.str. were investigated with LM (acetolysed pollen) and SEM (dry pollen). Pollen grains of all studied species are spheroidal to oblong-spheroidal, mostly tricolporate, rarely 4-6-loxocolporate, ellipsoidal in equatorial view, rounded-trilobed or trilobed in polar view, with striate or striato-perforate, reticulato-foveolate, or reticulato-perforate sporoderm ornamentation. Exine sculpture is the most variable feature, differing in width, distinctness, and spacing of the striae, which are divided by grooves with small pits or perforations in rows. The most distinct variants of sporoderm ornamentation are connected by a full range of transitions. Striato-perforate ornamentation is common in species with the perianth typical for Atraphaxis, whereas reticulato-foveolate or reticulato-perforate sporoderm ornamentation was found in species with the perianth of Polygonum-type.

Chapter 7.4 On influence of long-range transport of pollen grains onto pollinating seasons

Abstract Pollen grains can be transported over hundreds and even thousands of kilometres and significantly affect pollen concentration in many regions making it less dependent upon the local conditions. In this study we have used the Finnish operational dispersion model SILAM to delineate birch pollen source areas as well as to forward simulations for pollen long-range transport. We have considered an episode of very high birch pollen concentration in Finland in April 1999 both in forward and inverse point of view. As a representative of easterly located areas, we considered also Moscow region. Source delineation for early pollen peaks is done for years 1999, 2002 and 2004.

Six years of observation of airborne and deposited pollen in central European Russia: first results

Abstract The aim of the study was to compare the pollen spectra recorded in rural and urban environments in order to examine whether pollen data obtained in the urban environment could also represent the situation in surrounding rural areas and how urban planting affects the regional pollen spectrum. Daily airborne pollen observations were performed with a volumetric Hirst type trap in Moscow (Russia). Modified Tauber traps were located in the Moscow region. The Tauber traps were installed and treated according to Pollen Monitoring Programme (PMP) guidelines. Spearman correlation coefficients were determined between the percentage of total pollen recorded in the Tauber and Hirst type samplers. The data showed that the Tauber spectra are characterised by higher taxonomic variability, mainly due to the greater occurrence of local herbaceous plants. Pollen types registered by Hirst type samplers were predominantly represented by anemophilous arboreal species, used in urban planting. A significant correlation for annual sums was only observed for Betula pollen, the most abundant component in both sampler types. Data obtained in big cities for dominant taxa can be extrapolated to the surrounding rural territories. The simultaneous use of volumetric and gravimetric samplers can be very useful for palaeo-ecological studies to evaluate the presence of local and transported pollen.

Erratum to: The European Modern Pollen Database (EMPD) project

Unfortunately, the list of authors contains a number of duplications, omissions and other errors in the original publication of the article. The correct list appears in this erratum.

A statistical model for predicting the inter-annual variability of birch pollen abundance in Northern and North-Eastern Europe

The paper suggests a methodology for predicting next-year seasonal pollen index (SPI, a sum of daily-mean pollen concentrations) over large regions and demonstrates its performance for birch in Northern and North-Eastern Europe. A statistical model is constructed using meteorological, geophysical and biological characteristics of the previous year). A cluster analysis of multi-annual data of European Aeroallergen Network (EAN) revealed several large regions in Europe, where the observed SPI exhibits similar patterns of the multi-annual variability. We built the model for the northern cluster of stations, which covers Finland, Sweden, Baltic States, part of Belarus, and, probably, Russia and Norway, where the lack of data did not allow for conclusive analysis. The constructed model was capable of predicting the SPI with correlation coefficient reaching up to 0.9 for some stations, odds ratio is infinitely high for 50% of sites inside the region and the fraction of prediction falling within factor of 2 from observations, stays within 40-70%. In particular, model successfully reproduced both the bi-annual cycle of the SPI and years when this cycle breaks down.