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The parameters of the birch pollen seasons in Cracow in 1991-2008 were analysed in relation to some meteorological elements and synoptic situations (circulation types, air masses and atmospheric fronts). Two types of the pollen seasons were distinguished – highly dense and less dense. The first type of the season started on the 15th of April (on average), lasted 11-20 days and the maximum daily concentration exceeded 500 pgm-3. The less dense type started generally earlier (the first decade of April), lasted more than 20 days and the peak days were unstable. In this type of the pollen season, two peak days were often observed. The relationship between the type of the season and the meteorological conditions before the season was pointed out. Additionally, the influence of circulation types, types of air masses and atmospheric fronts over south-eastern Poland on a given day on the number of days with a daily concentration > 80 pgm-3 was analysed. The relationship between the pollen season type and meteorological conditions before the season was found, among others, the influence of types of synoptic situations and air masses on the number of days with a concentration of over 80 pgm-3 was established.
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Birch pollen grains are one of the most important groups of atmospheric biological particles that induce allergic processes. The fluctuation pattern of birch pollen seasons in selected cities of Poland is presented. Measurements were performed by the volumetric method (Burkard and Lanzoni 2000 pollen samplers). The distributions of the data were not normal (Shapiro–Wilk test) and statistical error risk was estimated at a significance level of α = 0.05. Pollen season was defined as the period in which 95% of the annual total catch occurred. The linear trend for the selected features of the pollen season, skewness, kurtosis and coefficient of variation (V%) were also analyzed. During the 12–14 years of study, the beginnings of birch pollen seasons were observed 7–14 days earlier, the ends were noted 5–10 days earlier, and the days with maximum values occurred 7–14 days earlier compared to the long-term data. The left-skewed distribution of the pollen season starts in most sampling sites confirms the short-lasting occurrence of pollen in the air. The threat of birch pollen allergens was high during the pollen seasons. If vegetation is highly diverse, flowering and pollen release are extended in time, spread over different weeks and occur at different times of the day. Flowering time and pollen release are affected by insolation, convection currents, wind, and turbulence. Therefore, pollen seasons are characterized by great inter-annual variability.
Plant breeders have focused much attention on polyploid trees because of their resistance for forestry. To evaluate the impact of intraspecies genome duplication on NaHCO3 stress, a series of Betula platyphylla autotetraploids and diploids were generated from the same family. The growth, proline content and proline-associated gene expression of these autotetraploid individuals were compared with those diploid trees. Autotetraploids were superior in injury index and relative growth of height and base diameter compared to diploids. The proline content was higher in autotetraploid individuals compared to diploids. Gene expression data revealed autotetraploids were generally higher expression in BpP5CS1, BpP5CS2, Bp- P5CR1, BpP5CR2, BpP5CR3 and BpOAT and were lower expression in BpProDH and BpP5CDH compared to diploid trees. These results shed light on resistance variation in birch autotetraploidization and polyploidy breeding as a new approach for genetic improvement of birch trees.
Shrub birch (Betula humilis Schrk.) is endangered glacial relict growing in natural and drained fens and transitional mires. At present study we examined karyotypes of 103 individuals of B. humilis, collected in six populations from eastern and northeastern Poland. We found 60% of diploid individuals with 2n = 28. The rest of studied plants were aneuploids with 26, 27, 29, 30 and 31 chromosomes in their karyotypes. High frequencies of aneuploids in Polish populations of B. humilis could be a consequence of: (i) hybridization with congeneric species, (ii) stress resulting from range fragmentation, (iii) karyotype instability of individuals with 2n ≠ 28, or (iv) vegetative reproduction.
Research on soil microorganisms associated with plant roots (endophytes) and their outside habitats (rhizosphere, soil) under exposure to high concentrations of heavy metals in the environment may contribute to an increased knowledge about the effects of unfavorable pollutants in the natural ecosystem and improve the efficiency of remediation processes of degraded soils. The main goal of our study was to evaluate properties of microbial populations inhabiting different but spatially closed habitats: interior of the tree roots – endophytes (Betula pendula L. and Alnus glutinosa L.), rhizosphere and soil not influenced by plant roots at two heavy metal polluted areas in southern Poland where the content of cadmium, lead and zinc ranged 9.2–14.9, 26.2–75.1 and 1080–1559 mg∙kg–1 of dried soil, respectively. In our experiment, we analyzed their density as well as determined the total metabolic activity and ability for utilization of different carbon sources. The density of endophytes (5.76–7.16 log10 c.f.u. × g dw–1) was higher than the density of bacteria inhabiting outside habitats – the rhizosphere and soil (5.43–5.91 and 5.08–5.57 log10 c.f.u. × g dw–1, respectively) and was not affected by heavy metal content. However, the total metabolic activity of endophytic populations was strongly influenced by the physicochemical properties of the soil and was significantly lower at more contaminated site. In general, the metabolic activity of endophytes was ~15 times lower than the activity of rhizobacteria and at the same level or lower than the activity of soil microorganisms. Discriminant analysis revealed a higher utilization of α-Cyclodextrin and D-Xylose by microorganisms isolated from more polluted test site. The use of an artificial neural network (ANN) followed by principal component analysis (PCA) allowed the distinguishing of preferences in the utilization of carbon sources by microorganisms due to tree species but not the zone of isolation – endophytes, rhizosphere, soil. Our study revealed no significant impact of the metal concentrations present in the soil on the density of microorganisms (bacteria and fungi) inhabiting three analyzed zones (interior of the roots, rhziosphere, soil); however, their total metabolic activity was decreased in more contaminated site. Since the density of endophytes was higher compared to the number of bacteria present in the outside habitats (rhizosphere and soil), and their total metabolic activity was in general lower, we suggest a high specialization of microorganisms associated with the cellular spaces of plant roots compared to other microbial populations.
A study was carried out on the leaf abscission zone from birch trees growing on polluted sites (two) and a non-polluted site (one). Samples for anatomical investigation were collected from six trees on each site, during three succeeding vegetation seasons. It was observed that in trees growing at the polluted sites: 1) maturation of the abscission zone was faster, 2) the protective layer was thinner and 3) the formation of leaf scar periderm was delayed in comparison with trees from the non-polluted site. The results obtained suggest that environmental pollution influences the formation of the abscission zone and the protection of the leaf scar.
Protective role of mycorrhizal fungus for plants against contamination with heavy metals makes a possibility to use fungi inocula for recultivation areas devastated by industry. Use of mycorrhizal symbiont for improving the living conditions of trees requires unambiguous identification of fungi that are able to form successful mycorrhizae in contaminated areas. We took up studies on identification of fungal species, which create mycorrhizal symbiosis with roots of birch growing on metallurgic heap. The identification of fungi collected directly from roots was performed by comparing patterns of restriction fragments of the fungal ITS products with DNA pattern obtained from fruiting bodies of Basidiomycetes fungi growing in the study area.
The aim of the present study was to establish the value of desorption stresses and the rate of their increase in the samples of juvenile and mature birch wood as well as in aspen samples of different physiological age. The stress value was calculated on the basis of the measurement of the force necessary to restrain shrinkage in the sample being dried. Additionally, moisture strain and mechanical-moisture strain (both real and apparent) were measured during the experiments. The samples were dried at temperatures of 30, 50 and 70°C. It was concluded that both the rate of increase and the absolute values of stress and strain are different in juvenile and mature birch wood. Also in aspen they depend on the physiological age of the wood tissue. Juvenile birch wood and the physiologically younger aspen proved more susceptible to strain caused by desorption stresses.
Nitrogen flow through birch stand canopies was studied in the Kampinos National Park (large forested area with inland dunes and wetlands close to Warsaw) during the growing seasons (April-October) of 2005–2006. The amount of nitrogen deposition including main forms like NO₃, NH₄, organic N and the aerosolgaseous fraction of deposition were estimated as well as the influence of birch canopies on this process. Because a method of “artificial foliage” allows to measure an aerosol-gaseous fraction of deposition a gradient of rain collectors equipped with artificial foliage of known surfaces were used. The results were compared with amounts of nitrogen measured in the throughfall of three birch forests. All stands (age 20–50 years) were rather similar, but stand II has smaller LAI (Leaf Area Index = 2.5 m² m⁻²) than stands II and III (3.8 and 3.9 m² m⁻²). It was found that nitrogen deposition in the Kampinos National Park is rather high – 1.6 kg ha⁻¹ month⁻¹. Ammoniumnitrogen made almost half of this value, organic nitrogen – over one third, and nitrate-nitrogen constituted the rest. Aerosol-gaseous input significantly made the deposition increased only in the case of nitrate-nitrogen, but deposition of ammonium- and organic nitrogen were similar and independent of catching leaf area. All fractions of nitrogen were effectively taken up during their passing through birch canopies (57% of nitrogen deposition was retained). Generally two thirds of deposited ammonium-nitrogen, more than half of organic N, and one third of nitratenitrogen were taken up by birch canopies. However, uptake efficiency of all N forms was lower for stand with smallest leaf area with no statistically significant retention of organic N.
Breeding scientists have given extensive attention to triploids in trees because of their importance to forestry. Consequently, creating and breeding triploids of good quality has become one of purposes of tree breeding. We chose two autotetraploids (Betula platyphylla, named Q10 and Q65) as female parents and eight hybrid diploids (B. platyphylla × B. pendula, named F1 – F8) as male parents to obtain progenies through controllable pollination, resulting in triploid progenies. Germination rate and germination energy of triploid seeds of Q65 were significantly higher (P < 0.01) than in triploid seed s of Q10. Triploid families with Q65 as female parent had a large quantity of saplings, whereas triploid families with Q10 as female parent had a small quantity of saplings. Triploid families with Q65 as female parent were generally superior in base diameter and height to base diameter ratio when compared to a diploid family. Q65×F3 was preliminarily recognized as the superior family. These results demonstrate that the female parent has a major influence on triploid progenies, although the male parent also has a small influence. The results provided a reference to build seed orchards of triploid birch trees, choose tetraploids as female parents and forecast triploid families of good quality.
Adventitious bud cultures were established by using buds of a selected birch clone (Betula pendula Roth.) resistant to industrial pollution. The Murashige and Skoog medium (1/2 and 1/4 MS) was used for multiplication and rooting of shoots. Aluminium was added to the medium, in the form of aluminium sulphate (50–100 mg Al dm–3), and birch culture was continued in vitro for over 12 months. The shoots developed on media with aluminium (Al+) proved to be more tolerant to aluminium and copper (added to the medium as nitrates or sulphates, at a concentration of 0.05–2.0 mM) during multiplication and rooting than those developed on media without aluminium (Al–). Rooted birch microcuttings obtained from cultures on media with aluminium (Al+) grew better in the soil from an unpolluted area (Zwierzyniec, Z) and from an area polluted by a phosphate fertilise factory (Luboń, L) than those from media without aluminium (Al–).
This paper aims to verify the hypothesis that magpies in urban environments favour poplars as nesting trees, as suggested by previous authors. The fieldwork was conducted in a 180 ha area in a district of Gdańsk (North Poland). The study area held 5294 trees and high shrubs, where 124 magpie nests were found in 10 species of trees. Results of log-linear analysis showed that the magpies chose particular tree species rather than types of spatial tree organization. The lombardy poplar (Populus nigra “Italica”) is the species most frequently chosen as a nest tree, however – the magpies showed a significant preference for trees growing separately or in pairs. The choice index (the ratio of expected to observed frequency) confirmed the magpies’ strong preference for black poplar cultivars and for birches, regardless of the trees’ grouping. The magpies preferred lombardy poplar when they had the choice of two poplar cultivars. This cultivar has a crown suitable for the magpie’s nest construction because of the small angle between the trunk and the branches. The thin, almost vertical branches probably also limit predators from penetrating the crown because these branches do not provide much support for tree climbers. The large-scale planting of lombardy poplars in Polish towns in the 1960s and 1970s has probably contributed to the significant increase of the magpie population in the urban environment.
Natural regeneration of forest depends on the light regimes of floor. Point-based methods such as fisheye photo and radiometer can not provide a full panorama of light regime of heterogeneous forest stand. Eastern Tibetan Plateau is a major forest belt characteristic of diverse forest type and topographic differentiation. Understanding the trend of changes of light regime along succession series of forest may be helpful for the management of ecosystems. Fragmented forest patches due to tectonic activity and human intervention have made this prediction difficult. We use a spatially explicit forest stand light model (tRAYci) to simulate light distribution within forest in typical subalpine forest succession series of eastern Tibetan Plateau. Due to the spatial heterogeneity of tree distribution in the subalpine area, the forest stand can be approximated with a spatially explicit model of trees. Three typical subalpine forest stands (Sabina forest (SF), Fir forest (FF) and Birch forest (BF)) are selected in the eastern Tibetan Plateau. The dominant species are sabina (Sabina saltuaria (Rehd. et Wils.) Cheng), fir (Abies faxoniana Rehd. et Wils.) and birch (Betula platyphylla Suk.) for each stand and they are spatially clumped in distribution. They represent old growth coniferous forest (SF, 330 years old), coniferous-broadleaved forest (FF, 180 ys) and pioneer broadleaved forest (BF, 40 ys). The parameters of the three-dimensional model of trees are calibrated with field measurements. The simulated values are generally consistent with observed values of radiation measured by radiometers installed in these stands and values derived from fisheye photos. Test failures may be caused by the incomplete submodel of crown as a gap free one. Light regimes in old growth and pioneer forest are much more heterogeneous than intermediate stages of forest. Light regimes of these forests are also reflected by the composition of understory herb layers.
The paper presents the results of long-term phenological observations of silver birch (Betula pendula) during the years 1991–2015 across the phenological network of the Czech Hydrometeorological Institute (CHMI – Český hydrometeorologický ústav). The data assembled over this period were used for identification of timing of generative phenophases associated with pollen release into the air: inflorescence emergence 10%, beginning of flowering 10%, beginning of flowering 50%, beginning of flowering 100%, and end of flowering. The stations are situated at altitudes from 155 m (Doksany) to 1102 m (Modrava). The average timing of beginning of flowering 10% was 8th April (Lednice = lowland station) and 14th May (Modrava = mountain station); the average timing of beginning of flowering 50% was 12th April (Lednice) and 20th May (Modrava); the average timing of beginning of flowering 100% was 18th April (Lednice) and 22nd May (Modrava), and the average timing of end of flowering was 26th April (Lednice) and 28th May (Modrava). The totals of effective temperatures above 5°C (TS5) and sums of daily precipitation were used as a bio-climatological criterion for assessment of the dependence of phenological phases on meteorological variables. The average sums of TS5 and the average sums of daily precipitation total were as follows: 61.0–80.8°C, 82.8–327.4 mm (inflorescence emergence); 105.2–106.4°C, 85.9–365.2 mm (beginning of flowering 10%); 124.8–130.8°C, 89.8–385.9 mm (beginning of flowering 50%); 144.7–158.6°C, 95.2–390.7 mm (beginning of flowering 100%); and 181.6–223.8°C, 104.7–427.4 mm (end of flowering). Synoptic situations occurring during interphase intervals were obtained – the most often found synoptic situations were B (stationary trough over Central Europe), Bp (east travelling trough), NEa (northeast anticyclonic situation), Sa (south anticyclonic situation) and SWc2 (southwest cyclonic situation moving northeast to eastwards). The period of occurrence of birch pollen in the air lasts 52 days on average and the highest concentration was recorded on 23rd April, 2003 – 2606 pollen grains/m3.
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