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do understory or overstory traits drive tree encroachment on a drained raised bog?one of the most important threats to peatland ecosystems is drainage, resulting in encroachment of woody species. the main aim of this study was to check which features -ndash- overstory or understory vegetation -ndash- are more important for shaping the seedling bank of pioneer trees colonizing peatlands (pinus sylvestris and betula pubescens). we hypothesized that tree stand parameters will be more important predictors of natural regeneration density than understory vegetation parameters, and ...201728376255
influence of nitrogen availability on growth of two transgenic birch species carrying the pine gs1a gene.an alternative way to increase plant productivity through the use of nitrogen fertilizers is to improve the efficiency of nitrogen utilization via genetic engineering. the effects of overexpression of pine glutamine synthetase (gs) gene and nitrogen availability on growth and leaf pigment levels of two betula species were studied. untransformed and transgenic plants of downy birch (b. pubescens) and silver birch (b. pendula) were grown under open-air conditions at three nitrogen regimes (0, 1, o ...201728067821
phenological research of climate changes in the north part of lithuania by the phenological garden of šiauliai university.šiauliai university botanical garden is a member of the international phenological garden network since 2005. it is the only one botanical garden in the east europe that participated in the programme. in 2015, 18 species were observed. for research, data of 14 plants was used. the aim of this study is to estimate the responsiveness of the species of plants of the phenological garden to annual and monthly precipitation and temperature of the air. the main variables in this investigation were grow ...201727604576
ecosystem nitrogen fixation throughout the snow-free period in subarctic tundra: effects of willow and birch litter addition and warming.nitrogen (n) fixation in moss-associated cyanobacteria is one of the main sources of available n for n-limited ecosystems such as subarctic tundra. yet, n2 fixation in mosses is strongly influenced by soil moisture and temperature. thus, temporal scaling up of low-frequency in situ measurements to several weeks, months or even the entire growing season without taking into account changes in abiotic conditions cannot capture the variation in moss-associated n2 fixation. we therefore aimed to esti ...201727391280
photosynthesis, nutrient accumulation and growth of two betula species exposed to waterlogging in late dormancy and in the early growing season.increased risk of soil waterlogging in winter and spring at northern latitudes will potentially affect forest production in the future. we studied gas exchange, chlorophyll content index, chlorophyll fluorescence, nutrient concentration and biomass accumulation in 1-year-old silver (betula pendula roth) and pubescent birch (betula pubescens ehrh.) seedlings. we hypothesized that b. pubescens has different physiological mechanisms that make it tolerate waterlogging better than b. pendula. the tre ...201728338895
multispecies genetic structure and hybridization in the betula genus across eurasia.boreal and cool temperate forests are the major land cover of northern eurasia, and information about continental-scale genetic structure and past demographic history of forest species is important from an evolutionary perspective and has conservation implications. however, although many population genetic studies of forest tree species have been conducted in europe or eastern asia, continental-scale genetic structure and past demographic history remain poorly known. here, we focus on the birch ...201727763698
waterlogging in late dormancy and the early growth phase affected root and leaf morphology in betula pendula and betula pubescens seedlings.the warmer winters of the future will increase snow-melt frequency and rainfall, thereby increasing the risk of soil waterlogging and its effects on trees in winter and spring at northern latitudes. we studied the morphology of roots and leaves of 1-year-old silver birch (betula pendula roth) and pubescent birch (betula pubescens ehrh.) seedlings exposed to waterlogging during dormancy or at the beginning of the growing season in a growth-chamber experiment. the experiment included 4-week dorman ...201626420790
selective behaviour of honeybees in acquiring european propolis plant precursors.honey bees harvest resins from various plant species and use them in the hive as propolis. while there have been a number of studies concerning the chemical composition of this antimicrobial product, little is known about selective behavior and bee preference when different potential plant sources of resin are available. the main objective of this paper was to investigate some aspects of behavioral patterns of honeybees in the context of resin acquisition. samples of propolis originating from te ...201627294416
shelters of leaf-tying herbivores decompose faster than leaves damaged by free-living insects: implications for nutrient turnover in polluted habitats.leaf-eating insects can influence decomposition processes by modifying quality of leaf litter, and this impact can be especially pronounced in habitats where leaf-eating insects reach high densities, for example in heavily polluted areas. we hypothesized that the decomposition rate is faster for shelters of leaf-tying larvae than for leaves damaged by free-living insects, in particular due to the accumulation of larval frass within shelters. we exposed litter bags containing samples of three dif ...201627288287
unidirectional diploid-tetraploid introgression among british birch trees with shifting ranges shown by restriction site-associated markers.hybridization may lead to introgression of genes among species. introgression may be bidirectional or unidirectional, depending on factors such as the demography of the hybridizing species, or the nature of reproductive barriers between them. previous microsatellite studies suggested bidirectional introgression between diploid betula nana (dwarf birch) and tetraploid b. pubescens (downy birch) and also between b. pubescens and diploid b. pendula (silver birch) in britain. here, we analyse introg ...201627065091
nutrient fluxes from insect herbivory increase during ecosystem retrogression in boreal forest.ecological theory, developed largely from ungulates and grassland systems, predicts that herbivory accelerates nutrient cycling more in productive than unproductive systems. this prediction may be important for understanding patterns of ecosystem change over time and space, but its applicability to other ecosystems and types of herbivore remain uncertain. we estimated fluxes of nitrogen (n) and phosphorus (p) from herbivory of a common tree species (betula pubescens) by a common species of herbi ...201627008782
seventeen-year trends in spring and autumn phenophases of betula pubescens in a boreal environment.trends in the timing of spring and autumn phenophases of betula pubescens were investigated in the southern, middle, and northern boreal zones in finland. the field observations were carried out at 21 sites in the finnish national phenological network in 1997-2013. the effective temperature sum of the thermal growth period, i.e. the sum of the positive differences between diurnal mean temperatures and 5 °c (ets1), increased annually on average by 6-7 degree day units. timing of bud burst remaine ...201626686678
transfer of elements relevant to nuclear fuel cycle from soil to boreal plants and animals in experimental meso- and microcosms.uranium (u), cobalt (co), molybdenum (mo), nickel (ni), lead (pb), thorium (th) and zinc (zn) occur naturally in soil but their radioactive isotopes can also be released into the environment during the nuclear fuel cycle. the transfer of these elements was studied in three different trophic levels in experimental mesocosms containing downy birch (betula pubescens), narrow buckler fern (dryopteris carthusiana) and scandinavian small-reed (calamagrostis purpurea ssp. phragmitoides) as producers, s ...201626363398
how reproducible are the measurements of leaf fluctuating asymmetry?fluctuating asymmetry (fa) represents small, non-directional deviations from perfect symmetry in morphological characters. fa is generally assumed to increase in response to stress; therefore, fa is frequently used in ecological studies as an index of environmental or genetic stress experienced by an organism. the values of fa are usually small, and therefore the reliable detection of fa requires precise measurements. the reproducibility of fluctuating asymmetry (fa) was explored by comparing th ...201526157612
comparative analyses of plastid and aflp data suggest different colonization history and asymmetric hybridization between betula pubescens and b. nana.birches (betula spp.) hybridize readily, confounding genetic signatures of refugial isolation and postglacial migration. we aimed to distinguish hybridization from range-shift processes in the two widespread and cold-adapted species b. nana and b. pubescens, previously shown to share a similarly east-west-structured variation in plastid dna (pdna). we sampled the two species throughout their ranges and included reference samples of five other betula species and putative hybrids. we analysed 901 ...201526113148
sámi reindeer herders' perspective on herbivory of subarctic mountain birch forests by geometrid moths and reindeer: a case study from northernmost finland.geometrid moths and semi-domesticated reindeer are both herbivores which feed on birch leaves in the subarctic mountain birch forests in northern fennoscandia. the caterpillars of autumnal and winter moths have episodic outbreaks, which can occasionally lead to extensive defoliation of birch forests. earlier studies have shown that reindeer have a negative effect on the regeneration of defoliated birches by grazing and browsing their seedlings and sprouts.201525825690
decomposition of birch leaves in heavily polluted industrial barrens: relative importance of leaf quality and site of exposure.the decrease in litter decomposition rate in polluted habitats is well documented, but the factors that explain the observed variation in the magnitude of this pollution effect on litter decomposition remain poorly understood. we explored effects of environmental conditions and leaf quality on decomposition rate of mountain birch (betula pubescens ssp. czerepanovii) leaves in a heavily polluted industrial barren near the nickel-copper smelter at monchegorsk. litter bags filled with leaves collec ...201525663340
carbon sequestration is related to mycorrhizal fungal community shifts during long-term succession in boreal forests.boreal forest soils store a major proportion of the global terrestrial carbon (c) and below-ground inputs contribute as much as above-ground plant litter to the total c stored in the soil. a better understanding of the dynamics and drivers of root-associated fungal communities is essential to predict long-term soil c storage and climate feedbacks in northern ecosystems. we used 454-pyrosequencing to identify fungal communities across fine-scaled soil profiles in a 5000 yr fire-driven boreal fore ...201525494880
rapid carbon turnover beneath shrub and tree vegetation is associated with low soil carbon stocks at a subarctic treeline.climate warming at high northern latitudes has caused substantial increases in plant productivity of tundra vegetation and an expansion of the range of deciduous shrub species. however significant the increase in carbon (c) contained within above-ground shrub biomass, it is modest in comparison with the amount of c stored in the soil in tundra ecosystems. here, we use a 'space-for-time' approach to test the hypothesis that a shift from lower-productivity tundra heath to higher-productivity decid ...201525367088
essential and non-essential elements in natural vegetation in southern norway: contribution from different sources.concentrations of essential and non-essential elements in five widespread species of natural boreal vegetation were studied with respect to seasonal variation and contribution from different sources. the plant species included in the study were betula pubescens, sorbus aucuparia, vaccinium myrtillus, vaccinium uliginosum, calluna vulgaris and deschampsia flexuosa. concentrations of elements essential to plants remained essentially constant or decreased slightly throughout the growing season. con ...201525268568
the contribution of trees to ecosystem methane emissions in a temperate forested wetland.wetland-adapted trees are known to transport soil-produced methane (ch4 ), an important greenhouse gas to the atmosphere, yet seasonal variations and controls on the magnitude of tree-mediated ch4 emissions remain unknown for mature forests. we examined the spatial and temporal variability in stem ch4 emissions in situ and their controls in two wetland-adapted tree species (alnus glutinosa and betula pubescens) located in a temperate forested wetland. soil and herbaceous plant-mediated ch4 emiss ...201525665153
sap-feeding insects on forest trees along latitudinal gradients in northern europe: a climate-driven patterns.knowledge of the latitudinal patterns in biotic interactions, and especially in herbivory, is crucial for understanding the mechanisms that govern ecosystem functioning and for predicting their responses to climate change. we used sap-feeding insects as a model group to test the hypotheses that the strength of plant-herbivore interactions in boreal forests decreases with latitude and that this latitudinal pattern is driven primarily by midsummer temperatures. we used a replicated sampling design ...201525044643
mitochondrial toxin betulinic acid induces in vitro eryptosis in human red blood cells through membrane permeabilization.betulinic acid (ba), a compound isolated from the bark of white birch (betula pubescens), was reported to induce apoptosis in many types of cancer through mitochondrial dysfunction with low side effects in normal cells. because of these features, ba is regarded as a potential anti-cancer agent. however, the effect of ba on the induction of cell death in human erythrocytes remains unknown. given that ba is a mitochondrial toxin and mitochondria are the central cell death regulator, we hypothesize ...201424241250
effect of heat treatment of wood on the morphology, surface roughness and penetration of simulated and human blood.wood has been used as a model material for the development of novel fiber-reinforced composite bone substitute biomaterials. in previous studies heat treatment of wood was perceived to significantly increase the osteoconductivity of implanted wood material.201424840198
molecular footprints of the holocene retreat of dwarf birch in britain.past reproductive interactions among incompletely isolated species may leave behind a trail of introgressed alleles, shedding light on historical range movements. betula pubescens is a widespread native tetraploid tree species in britain, occupying habitats intermediate to those of its native diploid relatives, b. pendula and b. nana. genotyping 1134 trees from the three species at 12 microsatellite loci, we found evidence of introgression from both diploid species into b. pubescens, despite the ...201424762172
treeline advances along the urals mountain range - driven by improved winter conditions?high-altitude treelines are temperature-limited vegetation boundaries, but little quantitative evidence exists about the impact of climate change on treelines in untouched areas of russia. here, we estimated how forest-tundra ecotones have changed during the last century along the ural mountains. in the south, north, sub-polar, and polar urals, we compared 450 historical and recent photographs and determined the ages of 11,100 trees along 16 altitudinal gradients. in these four regions, boundari ...201424756980
spatial heterogeneity in the timing of birch budburst in response to future climate warming in ireland.in order to predict the impact of future climate warming on trees it is important to quantify the effect climate has on their development. our understanding of the phenological response to environmental drivers has given rise to various mathematical models of the annual growth cycle of plants. these models simulate the timing of phenophases by quantifying the relationship between development and its triggers, typically temperature. in addition, other environmental variables have an important rol ...201424037345
gas chromatographic and mass spectrometric characterization of trimethylsilyl derivatives of some terpene alcohol phenylpropenoids.this paper reports mass spectra and linear temperature programmed retention indices (i(t)) for 31 esters of mono- and sesquiterpene alcohols with hydroxycinnamic acids. in this study, 14 phenylpropenoids were synthesized by esterification of terpenols with p-coumaric, ferulic, caffeic and sinapinic acids. other phenylpropenoids were semi-quantitatively isolated by column chromatography from exudates covering the buds of two birch species (betula pubescens and b. litwinowii). main diagnostic ions ...201323749131
simulated browsing affects leaf shedding phenology and litter quality of oak and birch saplings.herbivore effects on leaf litter can have a strong impact on ecosystem nutrient cycling. although such effects are well described for insect herbivory, research on the impacts of browsing by mammalian herbivores on leaf litter dynamics and nutrient cycling has been more limited, particularly at the level of the individual plant. clipping treatments (66% shoot removal twice, plus unclipped) were applied to analyse the effect of browsing on the phenology (start date and pattern of leaf shedding) a ...201323574752
effect of different steam explosion conditions on methane potential and enzymatic saccharification of birch.birch (betula pubescens) was steam exploded at 13 different conditions with temperatures ranging from 170 to 230 °c and residence times ranging from 5 to 15 min. increasing severity in the pretreatment led to degradation of xylan and formation of pseudo-lignin. the effect of the pretreatments was evaluated by running enzymatic saccharification and anaerobic digestion followed by analysis of sugar and methane yields, respectively. enzymatically released glucose increased with pretreatment severit ...201323131658
effects of species-specific leaf characteristics and reduced water availability on fine particle capture efficiency of trees.trees can improve air quality by capturing particles in their foliage. we determined the particle capture efficiencies of coniferous pinus sylvestris and three broadleaved species: betula pendula, betula pubescens and tilia vulgaris in a wind tunnel using nacl particles. the importance of leaf surface structure, physiology and moderate soil drought on the particle capture efficiencies of the trees were determined. the results confirm earlier findings of more efficient particle capture by conifer ...201323735814
defining an adequate sample of earlywood vessels for retrospective injury detection in diffuse-porous species.vessels of broad-leaved trees have been analyzed to study how trees deal with various environmental factors. cambial injury, in particular, has been reported to induce the formation of narrower conduits. yet, little or no effort has been devoted to the elaboration of vessel sampling strategies for retrospective injury detection based on vessel lumen size reduction. to fill this methodological gap, four wounded individuals each of grey alder (alnus incana (l.) moench) and downy birch (betula pube ...201222761707
species-specific effect of uv-b radiation on the temporal pattern of leaf growth.recent molecular and physiological studies have demonstrated that ultraviolet-b radiation (uv-b) can affect some of the processes involved in leaf growth, but the phases of leaf growth affected have not been clearly delimited. we used functional growth analysis to assess the effects of uv-b radiation on the time course of leaf growth in seedlings of two birch species (betula pendula and betula pubescens). our aim was to identify the phase(s) of leaf development affected by uv-b radiation. in a g ...201222224454
changes in crown architecture as a strategy of mountain birch for survival in habitats disturbed by pollution.although trees in polluted areas often exhibit modified growth habits, the immediate causes of changes in crown architecture and their consequences for persistence of plant populations in disturbed habitats are not well understood. we compared individuals of mountain birch, betula pubescens ssp. czerepanovii, growing in severely disturbed habitats (industrial barrens) surrounding a nickel-copper smelter in north-western russia, with birches growing in unpolluted habitats. they were found to have ...201223274240
genetic and environmental factors behind foliar chemistry of the mature mountain birch.previous studies of mountain birch (betula pubescens spp. czerepanovii) repeatedly have found differences between individual trees in herbivory-related traits, but rarely have yielded estimates of the additive genetic variation of these traits or of their relationship to habitat. we used thirty-year-old birch half-sibs in a northern common garden to estimate the effect of genetics and local microhabitat on resistance-related traits. genetic estimates of foliar chemistry have been studied only ra ...201222684775
nonvolatile chemical cues affect host-plant ranking by gravid polygonia c-album females.in a multiple-choice test, the preference of egg-laying polygonia c-album (comma butterfly) females was studied for oviposition on plants bearing surrogate leaves treated with crude methanol extracts obtained from leaves of seven host-plant species: humulus lupulus, urtica dioica, ulmus glabra, salix caprea, ribes nigrum, corylus avellana, and betula pubescens. the ranking order of surrogate leaves treated with host-plant extracts corresponded well to that reported on natural foliage, except r. ...201222486046
the minimum temperature for budburst in betula depends on the state of dormancy.vegis has put forward the theory that the range of growth-promoting temperatures changes during the induction and the release of dormancy. we have tested the response of buds of betula pubescens ehrh. and b. pendula roth. on temperature during the induction and release of dormancy. betula seedlings were exposed to dormancy-inducing high-temperature and short-day conditions and subsequently to dormancy-releasing chilling conditions in darkness. to monitor the dormancy status of the seedlings, sub ...201222391009
ethanol extract from birch bark (betula pubescens) suppresses human dendritic cell mediated th1 responses and directs it towards a th17 regulatory response in vitro.extracts and fractions from birch bark have been used to treat various diseases, such as skin disorders and rheumatism, and for analgesic effects. results from studies in vitro and in vivo have shown that birch bark extracts can have immunoregulatory effects. these effects have mainly been attributed to the various triterpenes found in birch bark. the effects of birch bark from betula pubescens on immune responses have not been reported. ethanol extract was prepared from dry birch bark (dbbee) a ...201121237202
browsing affects intra-ring carbon allocation in species with contrasting wood anatomy.current knowledge on tree carbon (c) allocation to wood is particularly scarce in plants subjected to disturbance factors, such as browsing, which affects forest regeneration worldwide and has an impact on the c balance of trees. furthermore, quantifying the degree to which tree rings are formed from freshly assimilated vs. stored carbohydrates is highly relevant for our understanding of tree c allocation. we used (13)c labelling to quantify seasonal allocation of stored c to wood formation in t ...201121388994
potential macro-detritivore range expansion into the subarctic stimulates litter decomposition: a new positive feedback mechanism to climate change?as a result of low decomposition rates, high-latitude ecosystems store large amounts of carbon. litter decomposition in these ecosystems is constrained by harsh abiotic conditions, but also by the absence of macro-detritivores. we have studied the potential effects of their climate change-driven northward range expansion on the decomposition of two contrasting subarctic litter types. litter of alnus incana and betula pubescens was incubated in microcosms together with monocultures and all possib ...201121735203
Assessment of biological and environmental phenology at a landscape level from 30 years of fixed-date repeat photography in northern Sweden.A 30-year series (1978-2007) of photographic records were analysed to determine changes in lake ice cover, local (low elevation) and montane (high elevation) snow cover and phenological stages of mountain birch (Betula pubescens ssp. czerepanovii) at the Abisko Scientific Research Station, Sweden. In most cases, the photographic-derived data showed no significant difference in phenophase score from manually observed field records from the same period, demonstrating the accuracy and potential of ...201121954723
tree and shrub expansion over the past 34 years at the tree-line near abisko, sweden.shrubs and trees are expected to expand in the sub-arctic due to global warming. our study was conducted in abisko, sub-arctic sweden. we recorded the change in coverage of shrub and tree species over a 32- to 34-year period, in three 50 x 50 m plots; in the alpine-tree-line ecotone. the cover of shrubs and trees (<3.5 cm diameter at breast height) were estimated during 2009-2010 and compared with historical documentation from 1976 to 1977. similarly, all tree stems (> or =3.5 cm) were noted and ...201121954730
Decreased frost hardiness of Vaccinium vitis-idaea in reponse to UV-A radiation.The aim was to investigate plant frost hardiness responses to UV radiation, since the few results reported are largely contradictory. It was hypothesized that functional adaptation of life forms could explain these contradictions. Dwarf shrubs and tree seedlings, representing both evergreen and deciduous forms, were tested (Vaccinium vitis-idaea, V. myrtillus, Pinus sylvestris, Betula pubescens, and its red form f. rubra). The research was performed in Sodankylä, Northern Finland (67ºN), with en ...201122182287
interspecific variation in resistance of asian, european, and north american birches (betula spp.) to bronze birch borer (coleoptera: buprestidae).bronze birch borer (agrilus anxius gory) is the key pest of birches (betula spp.) in north america, several of which have been recommended for ornamental landscapes based on anecdotal reports of borer resistance that had not been confirmed experimentally. in a 20-yr common garden experiment initiated in 1979 in ohio, north american birch species, including paper birch (betula papyrifera marshall), 'whitespire' gray birch (betula populifolia marshall), and river birch (betula nigra l.), were muc ...201122251643
[comparative evaluation of 238u and 226ra absorption by herbaceous and woody species under man-made pollution].the results of studies on uranium and radium distribution in soil and vegetation at the territory contaminated by wastes of radium plant in 1930-1950 are presented. specific activities of 226ra and 238u in soil varied as 0.01-200 and 0.004-7.58 bq/g per ash respectively. the radionuclides are mainly concentrated in the upper layer of soil profile. in the vegetation concentrations of 226ra and 238u varied as 0.64-132 0.001-0.02 bq/g per ash respectively. among the woody species studied, betula pu ...201021434390
the rhizosphere and pah amendment mediate impacts on functional and structural bacterial diversity in sandy peat soil.to reveal the degradation capacity of bacteria in pah polluted soil and rhizosphere we combined bacterial extradiol ring-cleavage dioxygenase and 16s rrna analysis in betula pubescens rhizoremediation. characterisation of the functional bacterial community by rflp revealed novel environmental dioxygenases, and their putative hosts were studied by 16s rrna amplification. plant rhizosphere and pah amendment effects were detected by the rflp/t-rflp analysis. functional species richness increased in ...201020022155
forage quantity, quality and depletion as scale-dependent mechanisms driving habitat selection of a large browsing herbivore.1. mechanisms that affect the spatial distribution of animals are typically scale-dependent and may involve forage distribution. forage quality and quantity are often inversely correlated and a much discussed trade-off is whether or not to select for high-quality forage at the expense of forage abundance. this discussion has rarely involved scale-dependence or been applied to northern browsing herbivores. at small spatial scales, browsers are assumed to select for the best quality forage. but, a ...201020443990
doubled volatile organic compound emissions from subarctic tundra under simulated climate warming.*biogenic volatile organic compound (bvoc) emissions from arctic ecosystems are important in view of their role in global atmospheric chemistry and unknown feedbacks to global warming. these cold ecosystems are hotspots of climate warming, which will be more severe here than averaged over the globe. we assess the effects of climatic warming on non-methane bvoc emissions from a subarctic heath. *we performed ecosystem-based chamber measurements and gas chromatography-mass spectrometry (gc-ms) ana ...201020456056
effects of elevated ultraviolet-b radiation on a plant-herbivore interaction.enhanced ultraviolet-b (uv-b) radiation may have multiple effects on both plants and animals and affect plant-herbivore interactions directly and indirectly by inducing changes in host plant quality. in this study, we examined combined effects of uv-b and herbivory on the defence of the mountain birch (betula pubescens ssp. czerepanovii) and also the effects of enhanced uv-b radiation on a geometrid with an outbreak cycle: the autumnal moth (epirrita autumnata). we established an experiment mimi ...201020473770
seasonal fluctuations in leaf phenolic composition under uv manipulations reflect contrasting strategies of alder and birch trees.seasonal variation in leaf phenolic composition may be important for acclimation of plants to seasonal changes in their biotic and abiotic environment. for a realistic assessment of how plants respond to solar uv-b (280-315 nm) and uv-a (315-400 nm) radiation, seasonal variation in both environment and plant responses needs to be taken into account. this also has implications for studies concerning stratospheric ozone depletion and resulting increased uv-b radiation, as other environmental varia ...201020626643
the ecological significance of phenology in four different tree species: effects of light and temperature on bud burst.the process of adaptation is the result of stabilising selection caused by two opposite forces: protection against an unfavourable season (survival adaptation), and effective use of growing resources (capacity adaptation). as plant species have evolved different life strategies based on different trade offs between survival and capacity adaptations, different phenological responses are also expected among species. the aim of this study was to compare budburst responses of two opportunistic speci ...201021113629
experimental evidence for herbivore limitation of the treeline.the treeline ecotone divides forest from open alpine or arctic vegetation states. treelines are generally perceived to be temperature limited. the role of herbivores in limiting the treeline is more controversial, as experimental evidence from relevant large scales is lacking. here we quantify the impact of different experimentally controlled herbivore densities on the recruitment and survival of birch betula pubescens tortuosa along an altitudinal gradient in the mountains of southern norway. a ...201021141202
ectomycorrhizal roots select distinctive bacterial and ascomycete communities in swedish subarctic forests.ectomycorrhizal (ecm) roots represent important niches for interactions with bacteria and ascomycete fungi, since they have a large surface area and receive a direct supply of plant assimilates from their tree hosts. we tested the hypothesis that the roots colonized by specific ecm fungi harbour distinct bacteria/ascomycete communities. roots were collected from two different locations in a subarctic shrub forest dominated by betula pubescens. bacterial and ascomycete communities were analysed b ...201021176055
mycorrhizal colonisation of mountain birch (betula pubescens ssp. czerepanovii) along three environmental gradients: does life in harsh environments alter plant-fungal relationships?environmental stress affects ectomycorrhizal communities (ecm), but it is not known how general the detected ecm responses are. we investigated ecm fungi on roots of mountain birch, betula pubescens subsp. czerepanovii (orlova) hämet-ahti, along three environmental gradients, two natural (altitude, seashore) and one human-induced (pollution), within the kola peninsula, nw russia. chlorophyll fluorescence of birch leaves indicated no environmental stress even in the conditions that were presumed ...200918327653
effect of birch (betula spp.) and associated rhizoidal bacteria on the degradation of soil polyaromatic hydrocarbons, pah-induced changes in birch proteome and bacterial community.two birch clones originating from metal-contaminated sites were exposed for 3 months to soils (sand-peat ratio 1:1 or 4:1) spiked with a mixture of polyaromatic hydrocarbons (pahs; anthracene, fluoranthene, phenanthrene, pyrene). pah degradation differed between the two birch clones and also by the soil type. the statistically most significant elimination (p < or = 0.01), i.e. 88% of total pahs, was observed in the more sandy soil planted with birch, the clearest positive effect being found with ...200918675498
larval parasitism of the autumnal moth reduces feeding intensity on the mountain birch.plants respond to grazing by herbivorous insects by emitting a range of volatile organic compounds, which attract parasitoids to their insect hosts. however, a positive outcome for the host plant is a necessary precondition for making the attraction beneficial or even adaptive. parasitoids benefit plants by killing herbivorous insects, thus reducing future herbivore pressure, but also by curtailing the feeding intensity of the still living, parasitised host. in this study, the effect of parasiti ...200919066967
mountain birch under multiple stressors--heavy metal-resistant populations co-resistant to biotic stress but maladapted to abiotic stress.stress adaptations often include a trade-off of weakened performance in nonlocal conditions, resulting in divergent selection, and potentially, genetic differentiation and evolutionary adaptation. results of a two-phase (greenhouse and field) common garden experiment demonstrated adaptation of mountain birch (betula pubescens subsp. czerepanovii) populations from industrially polluted areas of the kola peninsula, north-western russia, to heavy metals (hm), whereas no adaptations to wind or droug ...200919226419
the effect of heat treatment of wood on osteoconductivity.wood is a natural porous fibre composite, which has some structural similarities to bone. recently, it has been used as a modelling material in developing synthetic fibre-reinforced composite to be used as load-bearing non-metallic artificial bone material. in this study, the behaviour of wood implanted into bone was studied in vivo in the femur bone of the rabbit. wood was pre-treated by heat, which altered its chemical composition and structure, as well as the biomechanical properties. in the ...200919231305
effects of a warmer climate on seed germination in the subarctic.in a future warmer subarctic climate, the soil temperatures experienced by dispersed seeds are likely to increase during summer but may decrease during winter due to expected changes in snow depth, duration and quality. because little is known about the dormancy-breaking and germination requirements of subarctic species, how warming may influence the timing and level of germination in these species was examined.200919443459
effect of ecosystem retrogression on stable nitrogen and carbon isotopes of plants, soils and consumer organisms in boreal forest islands.in the prolonged absence of catastrophic disturbance, ecosystem retrogression occurs, and this involves increased nutrient limitation, and reduced aboveground and belowground ecosystem processes rates. little is known about how the nitrogen and carbon stable isotope ratios (delta(15)n and delta(13)c) of plants, soils and consumer organisms respond to retrogression in boreal forests. we investigated a 5000 year chronosequence of forested islands in the boreal zone of northern sweden, for which th ...200919462406
solar ultraviolet radiation alters alder and birch litter chemistry that in turn affects decomposers and soil respiration.solar ultraviolet (uv)-a and uv-b radiation were excluded from branches of grey alder (alnus incana) and white birch (betula pubescens) trees in a field experiment. leaf litter collected from these trees was used in microcosm experiments under laboratory conditions. the aim was to evaluate the effects of the different uv treatments on litter chemical quality (phenolic compounds, c, n and lignin) and the subsequent effects of these changes on soil fauna and decomposition processes. we measured th ...200919597848
climatic warming increases isoprene emission from a subarctic heath.emissions of isoprene, a reactive hydrocarbon, from subarctic vegetation are not well documented. however, the arctic is likely to experience the most pronounced effects of climatic warming, which may increase temperature-dependent isoprene emission. here, we assessed isoprene emission from a subarctic heath subjected to a 3-4 degrees c increase in air temperature and mountain birch (betula pubescens ssp. czerepanovii) litter addition for 7-8 yr, simulating climatic warming and the subsequent ex ...200818680543
concentrations of foliar quercetin in natural populations of white birch (betula pubescens) increase with latitude.we investigated latitudinal and regional variations in the composition and concentrations of foliar flavonoids and condensed tannins in wild populations of white birch (betula pubescens ehrh) in a large climatic transect in finland. concentrations of quercetin derivatives were correlated positively with latitude. by contrast, the concentrations of apigenin and naringenin derivatives were correlated negatively with latitude. these compound-specific latitudinal gradients compensated each other, re ...200818946705
comparative measurements of transpiration and canopy conductance in two mixed deciduous woodlands differing in structure and species composition.transpiration of two heterogeneous broad-leaved woodlands in southern england was monitored by the sap flux technique throughout the 2006 growing season. grimsbury wood, which had a leaf area index (lai) of 3.9, was dominated by oak (quercus robur l.) and birch (betula pubescens l.) and had a continuous hazel (corylus avellana l.) understory. wytham woods, which had an lai of 3.6, was dominated by ash (fraxinus excelsior l.) and sycamore (acer pseudoplatanus l.) and had only a sparse understory. ...200818381276
from plants to birds: higher avian predation rates in trees responding to insect herbivory.background: an understanding of the evolution of potential signals from plants to the predators of their herbivores may provide exciting examples of co-evolution among multiple trophic levels. understanding the mechanism behind the attraction of predators to plants is crucial to conclusions about co-evolution. for example, insectivorous birds are attracted to herbivore-damaged trees without seeing the herbivores or the defoliated parts, but it is not known whether birds use cues from herbivore-d ...200818665271
trends in phenology of betula pubescens across the boreal zone in finland.timing of plant phenophases is a useful biological indicator which shows how nature responds to the variation in climate. thus, long phenological observation series help to estimate the impact of changing climate on forest plants. we investigated whether phenological patterns of downy birch betula pubescens respond to warming climate and whether the intensity of the responses varies among phytogeographical zones. we studied data collected by the finnish national phenological network from 30 obse ...200817957389
rapid evolution towards heavy metal resistance by mountain birch around two subarctic copper-nickel smelters.adaptations to pollution among long-lived trees have rarely been documented, possibly because of their long reproductive cycles and the evolutionarily short timescales of anthropogenic pollution. here, i present the results of a greenhouse experiment that suggest rapid evolutionary adaptation of mountain birch [betula pubescens subsp. czerepanovii (orlova) hämet-ahti] to heavy metal (hm) stress around two copper-nickel smelters in nw russia. the adaptation incurs a cost with reduced performance ...200818194230
fecundity of the autumnal moth depends on pooled geometrid abundance without a time lag: implications for cyclic population dynamics.1. the abundance and fecundity-related body size variation of the cyclic autumnal moth epirrita autumnata were monitored from the early increase phase and throughout the outbreak to the end of the density decline in northernmost norway during 1999-2006. another geometrid, the winter moth operophtera brumata, did not increase in density until the autumnal moth had its post-peak in 2004, and was at its own peak concurrent with the steeply declining autumnal moth abundance in 2005-06. 2. the body s ...200818284477
ecological role of reindeer summer browsing in the mountain birch (betula pubescens ssp. czerepanovii) forests: effects on plant defense, litter decomposition, and soil nutrient cycling.mammalian herbivores commonly alter the concentrations of secondary compounds in plants and, by this mechanism, have indirect effects on litter decomposition and soil carbon and nutrient cycling. in northernmost fennoscandia, the subarctic mountain birch (betula pubescens ssp. czerepanovii) forests are important pasture for the semidomestic reindeer (rangifer tarandus). in the summer ranges, mountain birches are intensively browsed, whereas in the winter ranges, reindeer feed on ground lichens, ...200717123112
connection of gnomonia intermedia to discula betulina and its relationship to other taxa in gnomoniaceae.discula betulina is a foliar pathogen on birch (betula) and gnomonia intermedia is found on overwintered birch leaves. perithecia of g. intermedia developed in vitro on colonies of d. betulina isolated from birch tissues in late summer, and single ascospores of g. intermedia consistently developed into colonies similar to d. betulina, producing typical d. betulina conidia. isolates of d. betulina could be grouped into two mating types, which produced fertile perithecia of g. intermedia when mate ...200717164084
budburst phenology of white birch in industrially polluted areas.effects of environmental contamination on plant seasonal development have only rarely been properly documented. monitoring of leaf growth in mountain birch, betula pubescens subsp. czerepanovii, around a nickel-copper smelter at monchegorsk hinted advanced budburst phenology in most polluted sites. however, under laboratory conditions budburst of birch twigs cut in late winter from trees naturally growing around three point polluters (nickel-copper smelter at monchegorsk, aluminium factory at ka ...200717175079
recent invasion of the mountain birch betula pubescens ssp. tortuosa above the treeline due to climate change: genetic and ecological study in northern sweden.mountain birch, betula pubescens ssp. tortuosa, forms the treeline in northern sweden. a recent shift in the range of the species associated with an elevation of the treeline is commonly attributed to climate warming. using microsatellite markers, we explored the genetic structure of populations along an altitudinal gradient close to the treeline. low genetic differentiation was found between populations, whereas high genetic diversity was maintained within populations. high level of gene flow c ...200717210030
element contents in leaves of four plant species (birch, mountain ash, fern and spruce) along anthropogenic and geogenic concentration gradients.forty samples each of leaves of birch (betula pubescens ehrh.), european mountain ash (sorbus aucuparia (l.)) and bracken fern (pteridium aquilinum (l.) kuhn) as well as spruce needles (picea abies (l.) karsten) were collected along a 120 km south-north transect running through norway's largest city, oslo. concentrations of 25 chemical elements (ag, au, b, ba, ca, cd, co, cr, cu, fe, hg, k, la, mg, mn, mo, na, ni, p, pb, s, sb, sr, ti, and zn) as well as loss on ignition for the 4 sample materia ...200717379275
foliar phenolics are differently associated with epirrita autumnata growth and immunocompetence.the quality of available food may affect insect herbivores directly (via growth and survivorship) and/or indirectly (by modifying insect vulnerability to parasitoids and pathogens). we examined the relationship between different phenolic compounds, belonging to various phenolic groups, in betula pubescens spp. czerepanovii (mountain birch) foliage and the larval performance of the geometrid epirrita autumnata (autumnal moth). direct effects on insect performance were described by pupal weight, d ...200717415626
morphological variation among betula nana (diploid), b. pubescens (tetraploid) and their triploid hybrids in iceland.introgressive hybridization between two co-existing betula species in iceland, diploid dwarf birch b. nana and tetraploid downy birch b. pubescens, has been well documented. the two species are highly variable morphologically, making taxonomic delineation difficult despite stable ploidy levels. here an analysis is made of morphological variation within each ploidy group with an aim to establishing a reliable means to distinguish the species.200717495985
remediation of heavy metal-contaminated forest soil using recycled organic matter and native woody plants.the main aim of this study was to determine how the application of a mulch cover (a mixture of household biocompost and woodchips) onto heavy metal-polluted forest soil affects (i) long-term survival and growth of planted dwarf shrubs and tree seedlings and (ii) natural revegetation. native woody plants (pinus sylvestris, betula pubescens, empetrum nigrum, and arctostaphylos uva-ursi) were planted in mulch pockets on mulch-covered and uncovered plots in summer 1996 in a highly polluted scots pin ...200717596623
[an orientational examination of the effects of extracts from mixtures of herbal drugs on selected renal functions].the paper aimed to determine the effects of mixtures of selected medicinal plants on some physiological renal functions, i.e. excretion of urine and electrolytes and changes in the quantity of prostaglandins e2 (pge2) and kallikrein-kinins in rat blood plasma after water and salt load. the following medicinal plants were selected for the examination: downy birch (betula pubescens ehrh.), everlasting flower (helichrysum arenarium l. moench.), hawthorn (crataegus oxyacantha l.), woodland strawberr ...200717619305
fragmented environment affects birch leaf endophytes.the effect of environmental fragmentation on the species distribution and frequency of horizontally transmitted endophytic fungi in betula pubescens and betula pendula leaves was studied in an archipelago in southwestern finland. the study system consisted of 14 islands, ranging in size and distance to the mainland, and five mainland sites. endophytic fungi were grown out from surface-sterilized leaves. the frequency of endophytic fungi mainly depended on the size of the island, explaining 32-35 ...200717635229
wound-induced oxidative responses in mountain birch leaves.the aim of the study was to examine oxidative responses in subarctic mountain birch, betula pubescens subsp. czerepanovii, induced by herbivory and manual wounding.200616254021
newly hatched neonate larvae can glycosylate: the fate of betula pubescens bud flavonoids in first instar epirrita autumnata.betula pubescens bud flavonoid aglycones reportedly have negative effects on the performance of first instar epirrita autumnata and, thus, may defend birch leaves from larval defoliation. we hypothesized that the detrimental effects of these lipophilic flavonoids on larvae are due to their high levels in birch buds and/or the inability of naïve neonates to glycosylate them, which we have shown to occur in fifth instars. to test the latter hypothesis, we investigated the biochemical transformatio ...200616572299
growing seasons of nordic mountain birch in northernmost europe as indicated by long-term field studies and analyses of satellite images.the phenophases first greening (bud burst) and yellowing of nordic mountain birch (betula pubescens ssp.tortuosa, also called b. p. ssp. czerepanovii) were observed at three sites on the kola peninsula in northernmost europe during the period 1964-2003, and at two sites in the trans-boundary pasvik-enare region during 1994-2003. the field observations were compared with satellite images based on the gimms-ndvi dataset covering 1982-2002 at the start and end of the growing season. a trend for a d ...200616832653
sexual reproduction advances autumn leaf colours in mountain birch (betula pubescens ssp. czerepanovii).autumnal change in leaf colour of deciduous trees is one of the most fascinating displays in nature. current theories suggest that autumn leaf colours are adaptations to environmental stress. here i report that the number of ripening female catkins altered timing of yellow autumn leaf colours in mountain birch. the tree's autumnal colour change was brought forward if the tree matured plenty of female catkins. since yellow colour pigments in leaves are unmasked as leaf nitrogen is re-translocated ...200616911002
sources of variation in concentrations of nickel and copper in mountain birch foliage near a nickel-copper smelter at monchegorsk, north-western russia: results of long-term monitoring.concentrations of nickel and copper, two principal metal pollutants of the 'severonikel' smelter at monchegorsk, nw russia, were measured in unwashed leaves of mountain birch, betula pubescens subsp. czerepanovii, collected in eight study sites along the pollution gradient during 1991-2003. in spite of significant decline in metal emissions, concentrations of foliar metals in most of the study sites did not decrease, indicating that soil contamination remains extremely high. multiyear mean value ...200515701396
phenology and abundance in relation to climatic variation in a sub-arctic insect herbivore-mountain birch system.the two forest-defoliating geometrid moth species operophtera brumata and epirrita autumnata are known to exhibit different altitudinal distribution patterns in northern birch forests. one possible explanation for this is that altitudinal climatic variation differentially affects the performance of two species through mismatching larval and host plant phenology. we explored this hypothesis by investigating the relationship between larval phenology and leaf phenology of betula pubescens, which is ...200516003503
do competition and herbivory alter the internal nitrogen dynamics of birch saplings?deciduous trees recycle nitrogen within their tissues. the aim of this study was to test the hypothesis that reductions in plant growth, caused by competition and herbivory, reduce the sink strength for n during autumn nutrient withdrawal, and reduce the storage capacity and hence the amount of n remobilized in the following spring. we used (15)n-labelled fertilizer to quantify n uptake, leaf n withdrawal and remobilization. betula pubescens saplings were grown with either molinia caerulea or ca ...200516219080
pollution resistance of mountain birch, betula pubescens subsp. czerepanovii, near the copper-nickel smelter: natural selection or phenotypic acclimation?mountain birch, betula pubescens subsp. czerepanovii (orlova) hamet-ahti, is one of the very few woody plants surviving in the heavily polluted industrial barrens of the kola peninsula, north-western russia. the present study was designed to find out whether long-lasting pollution impact caused selection of resistant birch genotypes, and to investigate possible trade-offs between pollution resistance and performance by exploring growth of birch seedlings in the different environments. in the rec ...200415722090
rapid herbivore-induced changes in mountain birch phenolics and nutritive compounds and their effects on performance of the major defoliator, epirrita autumnata.insect damage changes plant physiology and chemistry, and such changes may influence the performance of herbivores. we introduced larvae of the autumnal moth (epirrita autumnata borkh.) on individual branches of its main host plant. mountain birch (betula pubescens ssp. czerepanovii (orlova) hämet-ahti) to examine rapid-induced plant responses, which may affect subsequent larval development. we measured systemic responses to herbivory by analyzing chemistry, photosynthesis, and leaf growth, as w ...200415112726
defoliation increases carbon limitation in ectomycorrhizal symbiosis of betula pubescens.boreal forest trees are highly dependent on root-colonizing mycorrhizal fungi. since the maintenance of mycorrhizal symbiosis implies a significant carbon cost for the host plant, the loss of photosynthetic leaf area due to herbivory is expected to reduce the host investment in mycorrhizae. we tested this hypothesis in a common garden experiment by exposing ectomycorrhizal white birch (betula pubescens ehrh.) seedlings to simulated insect defoliation of 50 or 100% intensity during either the pre ...200415148601
autumn coloration as a signal of tree condition.hamilton and brown suggested that bright autumn coloration in trees is an energetically expensive and therefore honest (handicap) signal of defensive commitment against insects. if this is so, one should expect that the intensity of the proposed signal should depend strongly on tree health. however, to the best of our knowledge, the link between vigour and autumn colour has never been tested. we explored the relationship between autumn coloration and tree condition (i.e. leaf fluctuating asymmet ...200415252978
reproduction of mountain birch along a strong pollution gradient near monchegorsk, northwestern russia.we explored effects of severe pollution on sexual reproduction of mountain birch, betula pubescens subsp. czerepanovii, by counting catkins on sample branches and weighing both somatic and generative structures of both short and long shoots from birches growing at 21 sites around large nickel-copper smelter at monchegorsk, northwestern russia. proportion of reproducing trees, production of catkins, shoot and catkin weight, as well as the relative difference in weight of somatic structures of gen ...200415325460
reduction in size and fecundity of the autumnal moth, epirrita autumnata, in the increase phase of a population cycle.increasing fecundity with increasing density has been observed for many cyclic herbivore populations, including some forest lepidoptera. we monitored population density, body size and reproductive capacity of the cyclic lepidopteran, the autumnal moth (epirrita autumnata, geometridae), from the early increase phase to the devastating outbreak density in northernmost norway. larval density of the species increased exponentially from 1998 to 2002 and remained at the outbreak level also in 2003. wi ...200415338264
stature of sub-arctic birch in relation to growth rate, lifespan and tree form.sub-arctic mountain birch betula pubescens var. pumila communities in the north atlantic region are of variable stature, ranging from prostrate scrubs to forests with trees up to 12 m high. four hypotheses were tested, relating growth and population characteristics of sub-arctic birch woodland and scrub to tree stature; i.e. the variable stature of birch woods is due to differences in (1) the mean growth rate; (2) the age-related patterns of growth rate; (3) the life expectancy of stems; or (4) ...200415374837
defensive effect of surface flavonoid aglycones of betula pubescens leaves against first instar epirrita autumnata larvae.the surface of birch leaves contains glandular trichomes that secrete exudates containing flavonoid aglycones. we investigated the biological activities of white birch (betula pubescens) leaf surface exudates against larvae of the autumnal moth, epirrita autumnata, a common insect pest of birch. we found that tree-specific mortality (up to 100%) of first instar larvae correlated strongly with the tree-specific contents of surface flavonoid aglycones (r(s) = 0.905) in emerging leaves. we also fou ...200415672669
metabolic modifications of birch leaf phenolics by an herbivorous insect: detoxification of flavonoid aglycones via glycosylation.the metabolic modifications of birch (betula pubescens ehrh.) leaf phenolics in the digestive tract of its major defoliator, larvae of the autumnal moth epirrita autumnata, were studied. the main phenolic acids of birch, i.e. chlorogenic and p-coumaroylquinic acids, were isomerised in the alkaline digestive tract. moreover, only 16 to 92% of the ingested amounts of chlorogenic acid were found in the faeces of individual larvae; the missing portion is possibly being used in the formation of react ...200418998416
extensive sharing of chloroplast haplotypes among european birches indicates hybridization among betula pendula, b. pubescens and b. nana.extensive sharing of chloroplast haplotypes among the silver birch, betula pendula roth., the downy birch, b. pubescens ehrh., and the dwarf birch, b. nana l., was discovered using polymerase chain reaction-restriction fragment length polymporphism markers. the geographical component of the genetic variation was stronger than the species component: the species were not significantly different while 11% of the variation could be attributed to differentiation between the two main regions studied, ...200414653797
photoperiod and temperature differentially regulate the expression of two dehydrin genes during overwintering of birch (betula pubescens ehrh.).the overwintering of trees in northern areas depends on processes regulated by photoperiod and temperature. to identify the physiological and genetic factors involved in this environmental control, three latitudinal ecotypes of pubescent birch (betula pubescens ehrh.) growing in a common garden experiment were used. each ecotype responded to the shortening of the photoperiod according to its specific critical daylength, resulting in the induction of freezing tolerance and dehydration of buds fir ...200414739271
xylem ray parenchyma cells in boreal hardwood species respond to subfreezing temperatures by deep supercooling that is accompanied by incomplete desiccation.it has been accepted that xylem ray parenchyma cells (xrpcs) in hardwood species respond to subfreezing temperatures either by deep supercooling or by extracellular freezing. present study by cryo-scanning electron microscopy examined the freezing responses of xrpcs in five boreal hardwoods: salix sachalinensis fr. schmit, populus sieboldii miq., betula platyphylla sukat. var japonica hara, betula pubescens ehrh., and red osier dogwood (cornus sericea), in which xrpcs have been reported to respo ...200312586897
spatial responses of two herbivore groups to a geometrid larva on mountain birch.direct or plant-mediated interactions between herbivores may modify their spatial distribution among and within plants. in this study, we examined the effect of a leaf-chewing geometrid, the autumnal moth (epirrita autumnata), on two different herbivore groups, leaf rolling deporaus betulae weevils and eriocrania spp. leafminers, both feeding on mountain birch (betula pubescens ssp. czerepanovii). the exact locations of herbivores within tree canopies were mapped during three successive summers. ...200312647161
putting the insect into the birch-insect interaction.leaf maturation in mountain birch (betula pubescens ssp. czerepanovii) is characterized by rapid shifts in the types of dominant phenolics: from carbon-economic flavonoids aglycons in flushing leaves, via hydrolysable tannins and flavonoid glycosides, to carbon-rich proanthocyanidins (condensed tannins) in mature foliage. this shift accords with the suggested trade-offs between carbon allocation to plant defense and growth, but may also relate to the simultaneous decline in nutritive leaf traits ...200312684856
resource allocation in different parts of juvenile mountain birch plants: effect of nitrogen supply on seedling phenolics and growth.the composition and concentrations of phenolic compounds were studied in the first true leaves, cotyledons, stems and roots of 2.5-week-old seedlings of mountain birch (betula pubescens ssp. czerepanovii). the differences in secondary compounds among these plant parts were both qualitative and quantitative. in all parts, condensed tannins accounted for more than 50% of the phenolics. in the first true leaves and cotyledons, chlorogenic acid was the most abundant of the hplc phenolics. the main c ...200312702020
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