Publications

TitleAbstractYear
Filter
PMID(sorted ascending)
Filter
change in atp-binding cassette b1/19, glutamine synthetase and alcohol dehydrogenase gene expression during root elongation in betula pendula roth and alnus glutinosa l. gaertn in response to leachate and leonardite humic substances.humic substances (hs) are complex and heterogeneous compounds of humified organic matter resulting from the chemical and microbiological decomposition of organic residues. hs have a positive effect on plant growth and development by improving soil structure and fertility. they have long been recognized as plant growth-promoting substances, particularly with regard to influencing nutrient uptake, root growth and architecture. the biochemical and molecular mechanisms through which hs influence pla ...201626595095
[genotoxic and mutagenic properties of synthetic betulinic and betulonic acids].synthesis of betulinic acid was performed from the birch bark extract (betula pendula). betulonic acid was intermediate of the synthesis. both acids were isolated with purity 95%. genotoxicity and mutagenicity of obtained compounds were analyzed by ames test and sos chromotest, none of these properties have been detected.201526615642
hierarchical self-assembly of a renewable nanosized pentacyclic dihydroxy-triterpenoid betulin yielding flower-like architectures.betulin, a naturally occurring 6-6-6-6-5 pentacyclic dihydroxy-triterpenoid, is extractable from the bark of white birch (betula papyrifera). we report the first self-assembly properties of betulin in different liquids. the molecule spontaneously self-assembled in different media, yielding flower-like architectures of nano- to micrometers diameters via the formation of fibrillar networks. the self-assemblies have been characterized by optical microscopy, scanning electron microscopy, transmissio ...201526671722
hormesis and paradoxical effects of drooping birch (betula pendula roth) parameters under motor traffic pollution.various plant indexes are used or recommended for bioindication. however, the nonmonotonic dose-response dependences (hormesis and paradoxical effects) of these indexes are insufficiently explored upon exposure to pollution. we studied the dependences of these betula pendula indexes on the intensity of motor traffic pollution. regression analysis did not reveal any dependence of chlorophyll and carotenoid content on traffic intensity (in 2008 and 2010-2013). lipid peroxidation rate had different ...201726676071
dependence of guaiacol peroxidase activity and lipid peroxidation rate in drooping birch (betula pendula roth) and tillet (tilia cordata mill) leaf on motor traffic pollution intensity.hormesis and paradoxical effects are frequently found for different plant parameters. these phenomena were also observed for lipid peroxidation (lp) rate at environmental pollution. however, the role of antioxidant enzymes, particularly guaiacol peroxidases (gpx), in a nonmonotonic variation in the lp rate remains insufficiently explored. therefore, dependence of gpx activity and lp rate in betula pendula and tilia cordata leaf on motor traffic pollution intensity was studied. regression analysi ...201726676174
in vivo protective effect of betulinic acid on dexamethasone induced thymocyte apoptosis by reducing oxidative stress.dexamethasone (dex), a synthetic glucocorticoid, is strictly controlled for use due to its serious side effects, including immune suppression. betulinic acid (ba), an antioxidant prepared from the white birch, exhibits immunomodulation properties. to assess the implications and investigate the mechanisms of ba-elicited immunomodulation, we hypothesized that dex induced thymocyte apoptosis via oxidative stress could be lessened by ba.201626721359
replacing monocultures with mixed-species stands: ecosystem service implications of two production forest alternatives in sweden.whereas there is evidence that mixed-species approaches to production forestry in general can provide positive outcomes relative to monocultures, it is less clear to what extent multiple benefits can be derived from specific mixed-species alternatives. to provide such insights requires evaluations of an encompassing suite of ecosystem services, biodiversity, and forest management considerations provided by specific mixtures and monocultures within a region. here, we conduct such an assessment in ...201626744048
evaluation of urban environment pollution based on the accumulation of macro- and trace elements in epiphytic lichens.nitrogen, phosphorus, potassium, magnesium, zinc, nickel, copper, manganese, iron and lead accumulation properties of three epiphytic lichen species (hypogymnia physodes (l.) nyl., parmelia sulcata taylor and xanthoria parietina (l.) th. fr.) were compared. an assessment of pollution of the municipal environment in słupsk (poland) according to macro- and trace elements was also done. lichen samples were taken in autumn 2013 from betula pendula, fraxinus excelsior, acer platanoides, a. pseudoplat ...201626745547
chemometrics in biomonitoring: distribution and correlation of trace elements in tree leaves.the concentrations of 15 elements were measured in the leaf samples of aesculus hippocastanum, tilia spp., betula pendula and acer platanoides collected in may and september of 2014 from four different locations in belgrade, serbia. the objective was to assess the chemical characterization of leaf surface and in-wax fractions, as well as the leaf tissue element content, by analyzing untreated, washed with water and washed with chloroform leaf samples, respectively. the combined approach of self- ...201626748000
bvoc responses to realistic nitrogen fertilization and ozone exposure in silver birch.emission of bvoc (biogenic volatile organic compounds) from plant leaves in response to ozone exposure (o3) and nitrogen (n) fertilization is poorly understood. for the first time, bvoc emissions were explored in a forest tree species (silver birch, betula pendula) exposed for two years to realistic levels of o3 (35, 48 and 69 ppb as daylight average) and n (10, 30 and 70 kg ha(-1) yr(-1), applied weekly to the soil as ammonium nitrate). the main bvocs emitted were: α-pinene, β-pinene, limonene, ...201626809503
photosynthetic limitation of several representative subalpine species in the catalan pyrenees in summer.information on the photosynthetic process and its limitations is essential in order to predict both the capacity of species to adapt to conditions associated with climate change and the likely changes in plant communities. considering that high-mountain species are especially sensitive, three species representative of subalpine forests of the central catalan pyrenees: mountain pine (pinus uncinata mill.), birch (betula pendula roth) and rhododendron (rhododendron ferrugineum l.) were studied und ...201626833754
rhododenol and raspberry ketone impair the normal proliferation of melanocytes through reactive oxygen species-dependent activation of gadd45.rhododenol or rhododendrol (rd, 4-(4-hydroxyphenyl)-2-butanol) occurs naturally in many plants along with raspberry ketone (rk, 4-(4-hydroxyphenyl)-2-butanone), a ketone derivative, which include nikko maple tree (acer nikoense) and white birch (betula platyphylla). de-pigmenting activity of rd was discovered and it was used as a brightening ingredient for the skin whitening cosmetics. recently, cosmetics containing rd were withdrawn from the market because a number of consumers developed leukod ...201626867644
the efficacy of six elite isolates of the fungus chondrostereum purpureum against the sprouting of european aspen.the sprouting of broad-leaved trees after cutting is problematic in forest regeneration areas, along roads and railways, under electric power and above gas pipe lines. in finland, one of the most difficult species to control in these areas is the european aspen (populus tremula), which produces both stump sprouts and root suckers after saplings have been cut. in this study, we investigated whether a decay fungus of broad-leaved trees, chondrostereum purpureum, could be used as a biological contr ...201626899306
simultaneous determination of inorganic and organic ions in plant parts of betula pendula from two different types of ecosystems (wielkopolski national park and chemical plant in luboń, poland).the results of inorganic and organic anion concentrations in samples of soils and plant parts of betula pendula (tap roots, lateral roots, stem, twigs, leaves), in the bioavailable fraction, are presented in this study. an ion chromatography method was applied for the first time in the simultaneous determination of inorganic and organic anions, as an effective tool for qualitative and quantitative analysis of samples with different matrix. a linear gradient elution with potassium hydroxide allow ...201626903135
pollen-associated microbiome correlates with pollution parameters and the allergenicity of pollen.pollen allergies have been rapidly increasing over the last decades. many allergenic proteins and non-allergenic adjuvant compounds of pollen are involved in the plant defense against environmental or microbial stress. the first aim of this study was to analyze and compare the colonizing microbes on allergenic pollen. the second aim was to investigate detectable correlations between pollen microbiota and parameters of air pollution or pollen allergenicity. to reach these aims, bacterial and fung ...201626910418
quantification of overnight movement of birch (betula pendula) branches and foliage with short interval terrestrial laser scanning.the goal of the study was to determine circadian movements of silver birch (petula bendula) branches and foliage detected with terrestrial laser scanning (tls). the study consisted of two geographically separate experiments conducted in finland and in austria. both experiments were carried out at the same time of the year and under similar outdoor conditions. experiments consisted of 14 (finland) and 77 (austria) individual laser scans taken between sunset and sunrise. the resulting point clouds ...201626973668
effect of different pretreatment methods on birch outer bark: new biorefinery routes.a comparative study among different pretreatment methods used for the fractionation of the birch outer bark components, including steam explosion, hydrothermal and organosolv treatments based on the use of ethanol/water media, is reported. the residual solid fractions have been characterized by atr-ftir, (13)c-solid-state nmr and morphological alterations after pretreatment were detected by scanning electron microscopy. the general chemical composition of the untreated and treated bark including ...201627043513
comprehensive transcriptome analysis of response to nickel stress in white birch (betula papyrifera).white birch (betula papyrifera) is a dominant tree species of the boreal forest. recent studies have shown that it is fairly resistant to heavy metal contamination, specifically to nickel. knowledge of regulation of genes associated with metal resistance in higher plants is very sketchy. availability and annotation of the dwarf birch (b. nana) enables the use of high throughout sequencing approaches to understanding responses to environmental challenges in other betula species such as b. papyrif ...201627082755
antitumor drug effect of betulinic acid mediated by polyethylene glycol modified liposomes.betulinic acid (ba), as a natural pentacyclic lupine-type triterpene, principally derives from bark of white birch, due to its potent pharmacological properties and low side-effect, which has been demonstrated a prominent efficiency on cancer therapy. however, the poor solubility and low bioavailability limit its pharmaceutical effect. herein, we reported the rapid efficient synthesis of the polyethylene glycol modified (pegylated) ba liposomes using ethanol injection technique for the first tim ...201627127036
determining the composition of lignins in different tissues of silver birch.quantitative and qualitative lignin analyses were carried out on material from the trunks of silver birch (betula pendula roth) trees. two types of material were analyzed. first, whole birch trunk pieces were cryosectioned into cork cambium, non-conductive phloem, the cambial zone (conductive phloem, cambium and differentiating xylem), lignified xylem and the previous year's xylem; material that would show differences in lignin amount and quality. second, clonal material from one natural birch p ...201527135322
analyzing tree cores to detect petroleum hydrocarbon-contaminated groundwater at a former landfill site in the community of happy valley-goose bay, eastern canadian subarctic.this research examines the feasibility of analyzing tree cores to detect benzene, toluene, ethylbenzene, and m, p, o-xylene (btex) compounds and methyl tertiary-butyl ether (mtbe) in groundwater in eastern canada subarctic environments, using a former landfill site in the remote community of happy valley-goose bay, labrador. petroleum hydrocarbon contamination at the landfill site is the result of environmentally unsound pre-1990s disposal of households and industrial solid wastes. tree cores we ...201627151238
long-term changes of metal contents in two metallophyte species (olkusz area of zn-pb ores, poland).the authors present the changes of the as, cd, fe, mn, pb and zn contents in two plant-considered metallophytes: common bent agrostis capillaris (blades) and birch betula pendula (leaves and seeds), recorded in a zn-pb industrial region of olkusz (poland) in 1994 and 2014. the highest amounts of cd (12 ppm) and zn (2524 ppm) in the common bent occur in the vicinity of the mining and metallurgical works 'bolesław' in bukowno. however, these values are significantly lower than those in 1994: cd by ...201627165603
synthesis of siderophores by plant-associated metallotolerant bacteria under exposure to cd(2.).rhizosphere and endophytic bacteria are well known producers of siderophores, organic compounds that chelate ferric iron (fe(3+)), and therefore play an important role in plant growth promotion in metalliferous areas, thereby improving bioremediation processes. however, in addition to their primary function in iron mobilization, siderophores also have the capacity to chelate other heavy metals, such as al(3+), zn(2+), cu(2+), pb(2+) and cd(2+), that can affect homeostasis and the heavy metal tol ...201627183333
nickel and copper toxicity and plant response mechanisms in white birch (betula papyrifera).nickel (ni) and copper (cu) are the most prevalent metals found in the soils in the greater sudbury region (canada) because of smelting emissions. the main objectives of the present study were to (1) determine the toxicity of nickel (ni) and copper (cu) at different doses in betula papyrifera (white birch), (2) characterize nickel resistance mechanism, and (3) assess segregating patterns for ni and cu resistance in b. papyrifera populations. this study revealed that b. papyrifera is resistant to ...201627230027
artificially decreased vapour pressure deficit in field conditions modifies foliar metabolite profiles in birch and aspen.relative air humidity (rh) is expected to increase in northern europe due to climate change. increasing rh reduces the difference of water vapour pressure deficit (vpd) between the leaf and the atmosphere, and affects the gas exchange of plants. little is known about the effects of decreased vpd on plant metabolism, especially under field conditions. this study was conducted to determine the effects of artificially decreased vpd on silver birch (betula pendula roth.) and hybrid aspen (populus tr ...201627255929
low vapour pressure deficit affects nitrogen nutrition and foliar metabolites in silver birch.air humidity indicated as vapour pressure deficit (vpd) is directly related to transpiration and stomatal function of plants. we studied the effects of vpd and nitrogen (n) supply on leaf metabolites, plant growth, and mineral nutrition with young micropropagated silver birches (betula pendula roth.) in a growth chamber experiment. plants that were grown under low vpd for 26 d had higher biomass, larger stem diameter, more leaves, fewer fallen leaves, and larger total leaf area than plants that ...201627259554
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
osmolality and non-structural carbohydrate composition in the secondary phloem of trees across a latitudinal gradient in europe.phloem osmolality and its components are involved in basic cell metabolism, cell growth, and in various physiological processes including the ability of living cells to withstand drought and frost. osmolality and sugar composition responses to environmental stresses have been extensively studied for leaves, but less for the secondary phloem of plant stems and branches. leaf osmotic concentration and the share of pinitol and raffinose among soluble sugars increase with increasing drought or cold ...201627313582
the role of selected tree species in industrial sewage sludge/flotation tailing management.the aim of the study was to estimate the ability of ten tree and bush species to tolerate and accumulate cd, cu, pb, zn, and as species [as(iii), as(v), and total organic arsenic] in industrial sewage sludge extremely contaminated with arsenic (almost 27.5 g kg(-1)) in a pot experiment. the premise being that it will then be possible to select the most promising tree/bush species, able to grow in the vicinity of dams where sewage sludge/flotation tailings are used as landfill. six of the ten tes ...201627348264
betulinic acid ameliorates experimental diabetic-induced renal inflammation and fibrosis via inhibiting the activation of nf-κb signaling pathway.diabetic nephropathy (dn) is the leading cause of end-stage renal failure and is characterized by excessive deposition of extracellular matrix (ecm) proteins such as fibronectin (fn), in the glomerular mesangium and tubulointerstitium. betulinic acid (ba), a pentacyclic triterpene derived from the bark of the white birch tree, has been demonstrated to have many pharmacological activities. however, the effect of ba on dn has not been fully elucidated. to explore the possible anti-inflammatory eff ...201627364889
betulin attenuates atherosclerosis in apoe(-/-) mice by up-regulating abca1 and abcg1.betulin is a pentacyclic triterpenoid isolated from the bark of yellow and white birch trees with anti-cancer and anti-malaria activities. in this study we examined the effects of betulin on atherosclerosis in apoe(-/-) mice and the underlying mechanisms.201627374487
development of betulinic acid as an agonist of tgr5 receptor using a new in vitro assay.g-protein-coupled bile acid receptor 1, also known as tgr5 is known to be involved in glucose homeostasis. in animal models, treatment with a tgr5 agonist induces incretin secretion to reduce hyperglycemia. betulinic acid, a triterpenoid present in the leaves of white birch, has been introduced as a selective tgr5 agonist. however, direct activation of tgr5 by betulinic acid has not yet been reported.201627578964
unravelling the distinct crystallinity and thermal properties of suberin compounds from quercus suber and betula pendula outer barks.the main purpose of this study was to investigate the potential of suberin (a naturally occurring aromatic-aliphatic polyester ubiquitous to the vegetable realm) as a renewable source of chemicals and, in particular, to assess their physical properties. a comparison between cork and birch suberin fragments obtained by conventional depolymerisation processes (hydrolysis or methanolysis) is provided, focusing essentially on their thermal and crystallinity properties. it was found that suberin frag ...201627632951
effect of betula pendula leaf extract on α-glucosidase and glutathione level in glucose-induced oxidative stress.b. pendula leaf is a common ingredient in traditional herbal combinations for treatment of diabetes in southeastern europe. present study investigated b. pendula ethanolic and aqueous extract as inhibitors of carbohydrate hydrolyzing enzymes, as well as their ability to restore glutathione concentration in hep g2 cells subjected to glucose-induced oxidative stress. phytochemical analysis revealed presence of rutin and other quercetin derivatives, as well as chlorogenic acid. in general, ethanoli ...201627668005
levels of selected trace elements in scots pine (pinus sylvestris l.), silver birch (betula pendula l.), and norway maple (acer platanoides l.) in an urbanized environment.the aim of the study was to determine the concentrations of selected trace elements in needles and bark of scots pine (pinus sylvestris l.), leaves and bark of silver birch (betula pendula l.), and norway maple (acer platanoides l.), as well as in the soil in which the trees grew, depending on their localization and hence the distribution of local pollution sources. the content of trace elements in needles of scots pine, leaves of silver birch, and norway maple and in bark of these trees depende ...201627696092
design and application of sporopollenin microcapsule supported palladium catalyst: remarkably high turnover frequency and reusability in catalysis of biaryls.bio-based catalyst support materials with high thermal and structural stability are desired for catalysts systems requiring harsh conditions. in this study, a thermally stable palladium catalyst (up to 440°c) was designed from sporopollenin, which occurs naturally in the outer exine layer of pollens and is widely acknowledged as chemically very stable and inert biological material. catalyst design procedure included (1) extraction of sporopollenin microcapsules from betula pendula pollens (∼25μm ...201727701017
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
clinical validation of controlled exposure to birch pollen in the environmental exposure unit (eeu).the environmental exposure unit (eeu) in kingston, ontario, canada is a controlled allergen challenge facility (cacf) that has been previously clinically validated for the use of ragweed and grass pollen in clinical studies. in this study we aim to validate the use of birch pollen to challenge allergic participants.201627777594
the competitive status of trees determines their responsiveness to increasing atmospheric humidity - a climate trend predicted for northern latitudes.the interactive effects of climate variables and tree-tree competition are still insufficiently understood drivers of forest response to global climate change. precipitation and air humidity are predicted to rise concurrently at high latitudes of the northern hemisphere. we investigated whether the growth response of deciduous trees to elevated air humidity varies with their competitive status. the study was conducted in seed-originated silver birch and monoclonal hybrid aspen stands grown at th ...201727779805
ecophysiological responses of betula pendula, pinus uncinata and rhododendron ferrugineum in the catalan pyrenees to low summer rainfall.climate change is producing modifications in the intensity and frequency of rainfall in some regions of the planet. according to predictions, annual rainfall distribution in western europe will result in an increase in episodes of drought, thereby negatively affecting nutrient availability. since high mountain systems will be particularly vulnerable, the physiological and nutritional responses to changes in summer rainfall were monitored over the course of two consecutive summers on three specie ...201627784825
evidence of prokaryote like protein associated with nickel resistance in higher plants: horizontal transfer of tonb-dependent receptor/protein in betula genus or de novo mechanisms?mechanisms of metal resistance have been reported in many plants but knowledge in woody species is scarce. the tonb-dependent receptors family (tbdts) is a large group of proteins that facilitate the transport of molecules across the membrane of gram-negative bacteria. some evidence exists that tbdts are involved in metal stress. the existence of a tonb-like mechanism in non-prokaryotes has not been established. the recent development of the betula papyrifera (white birch) transcriptome has allo ...201727804963
two birch species demonstrate opposite latitudinal patterns in infestation by gall-making mites in northern europe.latitudinal patterns in herbivory, i.e. variations in plant losses to animals with latitude, are generally explained by temperature gradients. however, earlier studies suggest that geographical variation in abundance and diversity of gall-makers may be driven by precipitation rather than by temperature. to test the above hypothesis, we examined communities of eriophyoid mites (acari: eriophyoidea) on leaves of betula pendula and b. pubescens in boreal forests in northern europe. we sampled ten s ...201627835702
accumulative response of scots pine (pinus sylvestris l.) and silver birch (betula pendula roth) to heavy metals enhanced by pb-zn ore mining and processing plants: explicitly spatial considerations of ordinary kriging based on a gis approach.plants have an accumulative response to heavy metals present in soils or deposited from airborne sources of emissions. therefore, their tissues are very often used in studies of heavy metal contamination originating from different sources as a bioindicator of environmental pollution. this research was undertaken to examine accumulation capacities of pb, zn, cd, cu and cr in washed and unwashed needles of scots pine (pinus sylvestris l.) and leaves of silver birch (betula pendula roth) growing in ...201727836278
reaction of leaf weevil phyllobius arborator (coleoptera: curculionidae) to manganese content in diet.reaction of leaf weevil (phyllobius arborator (herbst)) to increased concentration of manganese in diet was investigated in laboratory rearing with controlled temperature, humidity, and light conditions. food for leaf weevils in rearing (leaves of birch betula pendula roth) was contaminated by soaking the leaves in solutions of mncl2.4h2o with graded concentration of manganese. direct influence of food was characterized by the consumed amount of leaves, period of feeding, and weight of p. arbora ...201728031428
tree diversity affects chlorophyll a fluorescence and other leaf traits of tree species in a boreal forest.an assemblage of tree species with different crown properties creates heterogeneous environments at the canopy level. changes of functional leaf traits are expected, especially those related to light interception and photosynthesis. chlorophyll a fluorescence (chlf) properties in dark-adapted leaves, specific leaf area, leaf nitrogen content (n) and carbon isotope composition (δ13c) were measured on picea abies (l.) h.karst., pinus sylvestris l. and betula pendula roth. in monospecific and mixed ...201728100710
foliar fungi of betula pendula: impact of tree species mixtures and assessment methods.foliar fungi of silver birch (betula pendula) in an experimental finnish forest were investigated across a gradient of tree species richness using molecular high-throughput sequencing and visual macroscopic assessment. we hypothesized that the molecular approach detects more fungal taxa than visual assessment, and that there is a relationship among the most common fungal taxa detected by both techniques. furthermore, we hypothesized that the fungal community composition, diversity, and distribut ...201728150710
leaf traits and photosynthetic responses of betula pendula saplings to a range of ground-level ozone concentrations at a range of nitrogen loads.ground-level ozone (o3) concentrations and atmospheric nitrogen (n) deposition rates have increased strongly since the 1950s. rising ground-level o3 concentrations and atmospheric n deposition both affect plant physiology and growth, however, impacts have often been studied in isolation rather than in combination. in addition, studies are often limited to a control treatment and one or two elevated levels of ozone and/or nitrogen supply. in the current study, three-year old betula pendula saplin ...201728152417
evaluation of the antioxidant activity of betula pendula leaves extract and its effects on model foods.betula pendula roth (betulaceae) exhibits many pharmacological activities in humans including anticancer, antibacterial, and antiviral effects. however, the antioxidant activity of bp towards lipid degradation has not been fully determined.201728152668
incorporating interspecific competition into species-distribution mapping by upward scaling of small-scale model projections to the landscape.there are a number of overarching questions and debate in the scientific community concerning the importance of biotic interactions in species distribution models at large spatial scales. in this paper, we present a framework for revising the potential distribution of tree species native to the western ecoregion of nova scotia, canada, by integrating the long-term effects of interspecific competition into an existing abiotic-factor-based definition of potential species distribution (psd). the ps ...201728207782
formic acid aided hot water extraction of hemicellulose from european silver birch (betula pendula) sawdust.hemicellulose has been extracted from birch (betula pendula) sawdust by formic acid aided hot water extraction. the maximum amount of hemicellulose extracted was about 70mol% of the total hemicellulose content at 170°c, measured as the combined yield of xylose and furfural. lower temperatures (130 and 140°c) favored hemicellulose hydrolysis rather than cellulose hydrolysis, even though the total hemicellulose yield was less than at 170°c. it was found that formic acid greatly increased the hydro ...201728231535
the shifting phenological landscape: within- and between-species variation in leaf emergence in a mixed-deciduous woodland.many organisms rely on synchronizing the timing of their life-history events with those of other trophic levels-known as phenological matching-for survival or successful reproduction. in temperate deciduous forests, the extent of matching with the budburst date of key tree species is of particular relevance for many herbivorous insects and, in turn, insectivorous birds. in order to understand the ecological and evolutionary forces operating in these systems, we require knowledge of the factors i ...201728303184
the influence of ozone and nutrition on δ(13)c in betula pendula.in the cellulose of stems and leaves, δ(13)c was investigated in a birch clone (betula pendula), which was exposed throughout the growing season to either <3 (control) or 90/40 nl o3 1(-1) (day/night). each regime was split into plants under high or low nutrient supply. δ(13)c was increased (becoming less negative), in stems rather than leaves, by both high nutrition (+2‰) and o3 stress (+1‰). whereas high nutrition raised the wateruse efficiency (wue) while lowering the co2 concentration in the ...199528306987
xylem dysfunction during winter and recovery of hydraulic conductivity in diffuse-porous and ring-porous trees.xylem embolism in winter and spring as well as the occurrence of positive xylem pressure were monitored in several diffuse-porous and one ring-porous tree species (fraxinus excelsior). in acer pseudoplatanus and betula pendula embolism reversal was associated with positive (above-atmospheric) xylem pressures that frequently occurred during a 2-month period prior to leaf expansion. in acer high stem pressures were occasionally triggered on sunny days after a night frost. the other species investi ...199628307135
regenerating temperate forest mesocosms in elevated co2: belowground growth and nitrogen cycling.the response of temperate forest ecosystems to elevated atmospheric co2 concentrations is important because these ecosystems represent a significant component of the global carbon cycle. two important but not well understood processes which elevated co2 may substantially alter in these systems are regeneration and nitrogen cycling. if elevated co2 leads to changes in species composition in regenerating forest communities then the structure and function of these ecosystems may be affected. in mos ...199728307286
elevated co2 reduces field decomposition rates of betula pendula (roth.) leaf litter.the effect of elevated atmospheric co2 and nutrient supply on elemental composition and decomposition rates of tree leaf litter was studied using litters derived from birch (betula pendula roth.) plants grown under two levels of atmospheric co2 (ambient and ambient +250 ppm) and two nutrient regimes in solar domes. co2 and nutrient treatments affected the chemical composition of leaves, both independently and interactively. the elevated co2 and unfertilized soil regime significantly enhanced lig ...199628307453
herbivore-induced resistance in betula pendula: the role of plant vascular architecture.we studied the role of plant vascular architecture in the determination of the spatial extent of herbivore induced responses within betula pendula roth saplings. the induced responses were measured in bioassays in terms of the relative growth rate of larvae of a geometrid moth, epirrita autumnata. we hypothesised that the level of induced resistance of a certain leaf would be determined by the degree of vascular connectivity between the leaf in question and a damaged leaf, as suggested by recent ...199628307807
population- and ecosystem-level effects of predation on microbial-feeding nematodes.we studied the role of nematode predation in the functioning of detrital food webs assembled in microcosms. the microcosms contained defaunated humus and litter materials, a diverse microbial community with bacteria, fungi and protozoa, and a birch (betula pendula) seedling infected with mycorrhizal fungi. different levels of top-down control upon microbivorous nematodes were set up by assembling food webs either without predators, or in combinations with a specialist and a non-specialist predat ...199928308090
the charcoal effect in boreal forests: mechanisms and ecological consequences.wildfire is the principal disturbance regime in northern boreal forests, where it has important rejuvenating effects on soil properties and encourages tree seedling regeneration and growth. one possible agent of this rejuvenation is fire-produced charcoal, which adsorbs secondary metabolites such as humus phenolics produced by ericaceous vegetation in the absence of fire, which retard nutrient cycling and tree seedling growth. we investigated short-term ecological effects of charcoal on the bore ...199828308435
the decomposition of branch-wood in the canopy and floor of a mixed deciduous woodland.the pattern of decomposition of branch-wood greater than 2 cm diameter is described for a one hectare site at meathop wood, cumbria, based on studies carried out as part of the ibp between 1967 and 1972. three phases of decomposition are recognised. following the death of branches in the canopy and their colonisation by fungi, decomposition proceeded at an average annual loss rate of about 8.4%. wood at branch-fall had on average lost about 40% of its original dry weight. on the forest floor the ...197628309258
root growth and water relations of oak and birch seedlings.first year seedlings of english oak (quercus cobur) and silver birch (betula pendula) were subjected to pressure-volume analysis to investigate the water potential components and cell wall properties of single leaves. it was hoped that this rapid-drying technique would differentiate between reductions in plant solute potential resulting from dehydration and the effects of solute accumulation.comparison of results from these experiments with those of slow drying treatments (over a number of days) ...198128310018
seasonal variation of phenols, crude protein and cell wall content of birch (betula pendula roth.) in relation to ruminant in vitro digestibility.birch twigs of diameter ≦1.5 mm exhibit seasonal trends in ruminant in vitro organic matter digestibility (ivomd), and in the contents of crude protein, cell walls (neutral detergent fibre, ndf), and phenolic compounds. the ivomd is low in winter twigs, increases in spring, and reaches a maximum in early summer. crude protein behaves similarly. on the other hand, the proportion of hydrophilic phenols and cell walls (cellulose, hemicellulose, and lignin) to dry weight decreases dramatically in sp ...198528310434
the influence of plant water stress on stomatal control of gas exchange at different levels of atmospheric humidity.leaves of well-watered and mildly water-stressed seedlings of betula pendula roth. and gmelina aroborea l. were subjected to a range of vapour pressure deficits (vpd) between 10 and 24 kpa. the stomatal conductance of birch seedlings decreased as vpd was increased and at least in mildly-stressed seedlings this response seemed to be closely linked to the water status of the air rather than to the bulk water status of the plant. mild water stressing enhanced the degree of the stomatal humidity-res ...198028310617
rapid wound-induced resistance in white birch (betula pubescens) foliage to the geometrid epirrita autumnata: a comparison of trees and moths within and outside the outbreak range of the moth.two strains of a geometrid defoliator, epirrita autumnata, were used in bioassays to test existence and relative efficacy of rapid, wound-induced foliage resistance in two provenances of the white birch. one birch and one moth strain originated in the outbreak range of the moth and another outside it. both birch provenances responded to manual leaf damage by changes in foliage quality which significantly retarded growth of the insects, reducing their pupal weights and protracting larval periods. ...198528310669
chemical defense in birch: inhibition of digestibility in ruminants by phenolic extracts.the biological activity of phenolic extracts originating from winter twigs of birch (betula pendula roth.) was measured using the ruminant in vitro method and the nylon bag technique. different extracts were prepared by extraction with organic solvents, removing phenols of corresponding solubility. the extract of birch twigs (diameter <1.5 mm) contained about 19% phenol equivalents, corresponding to 6% of twig dry matter (dm). coarse birch twigs (diameter 1.5-5 mm) contained about 3% in the dm p ...198528310902
the influence of water stress on the photosynthetic performance and stomatal behaviour of tree seedlings subjected to variation in temperature and irradiance.seedlings of betula pendula roth. and gmelina arborea l. were subjected to variation in temperature and irradiance. the influence of a mild water-stressing treatment on the photosynthetic performance and stomatal behaviour of these plants was assessed. for both species, the shape of the relationships between irradiance and photosynthesis and temperature and photosynthesis resembled those reported for other species. the effect of water stress was to reduce the rate of photosynthesis, particularly ...198028310929
leaf growth of betula and acer in simulated shadelight.leaves of birch (betula pendula roth) and sycamore (acer pseudoplatanus l.) were initiated and grown either in a simulated shadelight (80 μmol m(-2) s(-1), r/fr ratio 0.28)/dark photoenvironment or a white light (250 μmol m(-2) s(-1), r/fr>1)/dark photoenvironment. until the leaves were more than 50% expanded, growth rates (measured every 24 h) were the same for both species in both environments. after this time, growth rate slowed and this correlated well with a decrease in wall extensibility ( ...198628311620
the role of coprophagy in the feeding strategies of terrestrial isopods.the hypothesis that faeces recycling in isopods evolved as an adaption to facilitate maintenance of an adequate copper balance in terrestrial environments is examined. experimental observations on the consumption, absorption and growth rates of porcellio scaber fed betula pendula leaf litter varying in copper content and extent of microbial decay are reported. preventing the isopods from reingesting their faeces caused a reduction in the growth rates of experimental animals fed their natural low ...198228311744
the inhibition of phenolic biosynthesis in damaged and undamaged birch foliage and its effect on insect herbivores.1. the leaves of betula pendula roth trees were damaged artificially, or by insect-grazing. both induced an increase in phenolic levels in damaged leaves, larger in the case of insect attack.-2. some of the damaged trees were sprayed with an inhibitor of phenolic biosynthesis, (aminoxy) acetic acid, which led to a reduction in phenolic levels in both undamaged and damaged leaves. hence both the effects of damage per se and damage-induced changes in foliage phenolic levels on insect feeding prefe ...198828312381
effects of different types of damage on the chemistry of birch foliage, and the responses of birch feeding insects.1. we collected insect-grazed, mined, and holepunched leaves of betula pendula roth, and assessed their palatability to four species of birch-feeding lepidopteran caterpillars (apocheima pilosaria d. & s., erranis defolaria clerck, epirrita dilutata d. & s., and euproctis similis fuessly) in laboratory preference tests. the palatability of hole-punched leaves of different ages was also determined, using apocheima pilosaria only. 2. the total phenolic content and protein-precipitating ability of ...198728312484
effects of terrestrial isopods on the decomposition of woodland leaf litter.the indirect contribution terrestrial isopods make to decomposition processes by stimulating microbial activites has been quantified in laboratory experiments. the extent to which microbial metabolism is enhanced as a result of the passage of betula pendula leaf litter through the alimentary system of isopods was measured for both freshly fallen and decayed leaves. faeces derived from 1 g freshly fallen litter lost 75 mg g(-1) d.w. more than did intact leaves, as a result of enhanced microbial m ...198728312524
do birch-feeding caterpillars make the right feeding choices?the effects of leaf quality on caterpillar performance are frequently investigated, as are the feeding preferences of caterpillars, but rarely are the two considered together to see how preferences match performance. i looked at the preferences and performance of the specialist feeder achlya flavicornis and the generalist spilosoma luteum on betula pendula leaves which were artificially damaged, mined or left undamaged, and on leaves of different ages. often feeding preferences were not for the ...199128313843
the effect of elevated carbon dioxide and fertilization on primary and secondary metabolites in birch,betula pendula (roth).seedlings of european white birch (betula pendula roth) were grown in growth chambers for one growth season under four carbon dioxide regimes (350, 700, 1050 and 1400 ppm) and at three fertilization levels (0, 100 and 500 kg ha(-1) monthly). the soluble carbohydrates and secondary phenolics in the leaves and stems were analysed. it was found that fertilizer addition reduced the amounts of glucose and fructose while sucrose remained almost unaffected. the sugar content of leaves increased at 700 ...199428313886
an efficient protocol for isolation of inhibitor-free nucleic acids even from recalcitrant plants.for fast and easy isolation of inhibitor-free genomic dna even from the toughest plant leaf samples, including those high in polyphenols and polysaccharides, a protocol has been developed. to prevent the solubility of polysaccharides in the dna extract, high salt concentration (1.4 m) was used in the extraction buffer. polyvinylpyrrolidone (pvp) was used for the removal of polyphenols as polymerase chain reaction (pcr) inhibitors. proteins like various enzymes were degraded by proteinase k and r ...201628330131
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
Refresh
firstprev
123456
nextlast
Displaying items 501 - 574 of 574