Publications

characterization of pin m iii cdna in western white pine.	maximum accumulation of pin m iii protein in western white pine (pinus monticola dougl. ex d. don) needles occurred during the winter months. to characterize pin m iii, an expression cdna library from poly(a)+ mrna of needles was immunoscreened and the full length cdna was cloned. an open reading frame of 486 bases encodes a protein of 161 amino acid residues with a molecular mass of 18 kd and a predicted isoelectric point of 5.5. the deduced amino acid sequence had some similarities (37%) with ...	2000	12651516
statistical evaluation of bud development theories: application to bud burst of betula pendula leaves.	resampling methods were used to evaluate models based on alternative bud development theories applied to betula pendula roth data. statistical testing based on the bootstrap method showed that the mean square errors (mse) of the predicted bud-burst dates of two models, in which the start of ontogenetic development depended on dormancy development only, did not differ significantly. however, the mse of the model in which the start of ontogenesis depended on a signal from light climate, indicated ...	1999	12651536
biomass investment in leaf lamina versus lamina support in relation to growth irradiance and leaf size in temperate deciduous trees.	foliar biomass investment in support and assimilative compartments was studied in four temperate deciduous tree species along a natural light gradient across the canopy. the species ranked according to shade tolerance as betula pendula roth. < populus tremula l. < fraxinus excelsior l. < tilia cordata mill. long-term light conditions at sampling locations were characterized as seasonal mean integrated quantum flux density (q(int), mol m(-2) day(-1)) estimated by a method combining hemispherical ...	1999	12651556
growth and nutrition of betula pendula at different relative supply rates of zinc.	small birch plants (betula pendula roth) were cultivated in a hydroponic spray solution where the relative growth rate (r(g); day(-1)) was controlled by the relative supply rate of zinc (r(zn); day(-1)). after an adjustment phase to steady-state growth, r(g) equaled r(zn). the r(zn) treatments were 0.05, 0.125 and 0.20 day(-1) with free access to all other nutrients. in an additional treatment, there was free access to all nutrients, including zinc (fa treatment). the ph of the nutrient solution ...	1999	12651590
different responses of northern and southern ecotypes of betula pendula to exogenous aba application.	we investigated responses of northern and southern ecotypes of silver birch (betula pendula roth) to exogenous abscisic acid (aba) under controlled environmental conditions to determine the role of aba in cold acclimation and dormancy development. abscisic acid was sprayed on the leaves and changes in freezing tolerance, determined by the electrolyte leakage test, and bud dormancy were monitored. applied aba induced cold acclimation but had no effect on growth cessation in seedlings grown in lon ...	2003	12670802
137cs distribution among annual rings of different tree species contaminated after the chernobyl accident.	the distributions of 137cs among annual rings of pinus sylvestris and betula pendula at four experimental sites located in the most contaminated areas in the russian territory after the chernobyl accident in 1986 were studied. trees of different ages were sampled from four forest sites with different tree compositions and soil properties. the data analysis shows that 137cs is very mobile in wood and the 1986 rings do not show the highest contamination. the difference between pine and birch in th ...	2003	12683726
physiology-based phenology models for forest tree species in germany.	models of phenology are needed for the projection of effects of a changing climate on, for example, forest production, species competition, vegetation-atmosphere feedback and public health. a new phenology model for deciduous tree bud burst is developed and parameters are determined for a wide geographical range (germany) and several forest tree species. the new model is based on considerations of simple interactions between inhibitory and promotory agents that are assumed to control the develop ...	2003	12698325
comparative analysis of leaf trichome structure and composition of epicuticular flavonoids in finnish birch species.	the morphology, ultrastructure, density and distribution of trichomes on leaves of betula pendula, b. pubescens ssp. pubescens, b. pubescens ssp. czerepanovii and b. nana were examined by means of light, scanning and transmission electron microscopy. the composition of flavonoids in ethanolic leaf surface extracts was analysed by high pressure liquid chromatography. all taxa examined contained both glandular and non-glandular trichomes (short and/or long hairs) but differed from each other in tr ...	2003	12714363
ethylene insensitivity modulates ozone-induced cell death in birch.	we have used genotypic variation in birch (betula pendula roth) to investigate the roles of ozone (o(3))-induced ethylene (et), jasmonic acid, and salicylic acid in the regulation of tissue tolerance to o(3). of these hormones, et evolution correlated best with o(3)-induced cell death. disruption of et perception by transformation of birch with the dominant negative mutant allele etr1-1 of the arabidopsis et receptor gene etr1 or blocking of et perception with 1-methylcyclopropene reduced but di ...	2003	12746524
physiological responses of birch (betula pendula) to ozone: a comparison between open-soil-grown trees exposed for six growing seasons and potted seedlings exposed for one season.	physiological responses of 4-year-old potted saplings of an o3-tolerant clone of betula pendula roth to short-term ozone (o3) exposure (one growing season) were compared with those of 6-year-old open-soil-grown trees of the same clone fumigated with o3 for six growing seasons. in the 2001 growing season, both groups of plants were exposed to ambient (control) and 1.6x ambient (elevated) o3 concentration under similar microclimatic conditions in a free air o3 exposure facility. growth, net photos ...	2003	12750053
impact of ozone on the growth of birch (betula pendula) saplings.	saplings of one half-sib family of birch, betula pendula, were exposed to three levels of ozone in open-top chambers (otcs) during two growing seasons 1997-1998. the ozone treatments were non-filtered air (nf, accumulated daylight aot40 over the two growing seasons of 3.0 l l-1 h), non-filtered air with extra ozone (nf+, accumulated daylight aot40 of 27.3 l l-1 h) and non-filtered air with additional extra ozone (nf++, accumulated daylight aot40 of 120 l l-1 h). the birch saplings, including the ...	2003	12758028
development and recovery from winter embolism in silver birch: seasonal patterns and relationships with the phenological cycle in oceanic scotland.	silver birch (betula pendula roth) is increasingly used in the united kingdom for reforestation. however, recent evidence indicates that, under some circumstances, planted birch can suffer serious and repeated mortality of the apical leaders and branches, with consequent loss of apical dominance and the formation of a contorted stem. plants from 37 seed sources of silver birch from scotland and northern england planted at two sites were compared for several characteristics related to hydraulic a ...	2003	12777239
responses of selected birch (betula pendula roth) clones to ozone change over time.	a long-term free air ozone fumigation experiment was conducted to study changes in physiological ozone responses during tree ontogeny and exposure time in ozone sensitive and tolerant clones of european white birch (betula pendula roth), originated from south and central finland. the trees were grown in soil in natural microclimatic conditions under ambient ozone (control) and 1.4-1.7 x ambient (elevated) ozone from may 1996 to october 2001, and were measured for stem and foliage growth, net pho ...	2003	12803615
silver birch (betula pendula) plants with aux and rol genes show consistent changes in morphology, xylem structure and chemistry.	the effects of agrobacterium pria4 rol and aux genes, controlled by their endogenous promoters, on tree growth and wood anatomy and chemistry were studied in 5- and 7-year-old silver birch (betula pendula roth) plants. southern hybridization confirmed the following rol and aux gene combinations: control plants (no genes transferred); plants with rolc and rold genes; plants with rola, rolb, rolc and rold genes; and plants with rola, rolb, rolc, rold, aux1 and aux2 genes. transgene mrna was most a ...	2003	12839726
betulinic acid-induced programmed cell death in human melanoma cells involves mitogen-activated protein kinase activation.	betulinic acid, a naturally occurring triterpene found in the bark of the white birch tree, has been demonstrated to induce programmed cell death with melanoma and certain neuroectodermal tumor cells. we demonstrate currently that treatment of cultured uiso-mel-1 (human melanoma cells) with betulinic acid leads to the activation of p38 and stress activated protein kinase/c-jun nh(2)-terminal kinase [widely accepted proapoptotic mitogen-activated protein kinases (mapks)] with no change in the pho ...	2003	12855667
developmental lignification and seasonal variation in beta-glucosidase and peroxidase activities in xylem of scots pine, norway spruce and silver birch.	we examined the relationship between beta-glucosidase and peroxidase activities and xylem lignification in the stems of scots pine (pinus sylvestris l.), norway spruce (picea abies (l.) karst.) and silver birch (betula pendula roth) during the 1999 growing season. examination of stem cross sections stained with safranin and alcian blue for lignin and cellulose, respectively, indicated that radial growth of pine and spruce xylem began in late may, whereas the growth of birch xylem was initiated 2 ...	2003	12952784
betulinic acid suppresses carcinogen-induced nf-kappa b activation through inhibition of i kappa b alpha kinase and p65 phosphorylation: abrogation of cyclooxygenase-2 and matrix metalloprotease-9.	betulinic acid (ba), a pentacyclic triterpene isolated from the bark of the white birch tree, has been reported to be a selective inducer of apoptosis in tumor cells. it also exhibits anti-inflammatory and immunomodulatory properties. how ba mediates these effects is not known. because of the critical role of the transcription factor nf-kappab in growth modulatory, inflammatory, and immune responses, we postulated that ba modulates the activity of this factor. in this study we investigated the e ...	2003	12960358
the dibenzodioxocin lignin substructure is abundant in the inner part of the secondary wall in norway spruce and silver birch xylem.	a specific condensed lignin substructure, dibenzodioxocin, was immunolocalized in differentiating cell walls of norway spruce ( picea abies (l.) h. karsten) and silver birch ( betula pendula roth) xylem. a fluorescent probe, alexa 488 was used as a marker on the dibenzodioxocin-specific secondary antibody. for the detection of this lignin substructure, 25-microm cross-sections of xylem were viewed with a confocal laser-scanning microscope with fluorescein isothiocyanate fluorescence filters. in ...	2004	13680231
genotypic variation in growth and resistance to insect herbivory in silver birch (betula pendula) seedlings.	if herbivory is unevenly distributed among different types of plants, or if individual plants differ in their response to herbivory, herbivores may affect seedling growth and survival, and consequently plant population structure. in this study we examined variation in resistance to insect herbivory and in growth responses to feeding among 20 silver birch (betula pendula roth) genotypes representing variation within a natural population. birch seedlings were grown in dense stands in random arrang ...	2003	14513349
new oleanene and fernane-type triterpenes from the stem bark of betula pendula roth.	a new oleanene-type triterpene, named betuloleanolic acid acetate and fernane-type triterpenes, namely betufernanediol a and betufernanediol b (isomers) have been isolated from the stem bark of betula pendula. their structures have been established as olean-12-en-3beta-ylacetate-29-oic acid, fern-22(29)-en-3beta,12beta-diol and fem-22(29)-en-3alpha,12beta-diol, respectively, on the basis of spectral data analysis and chemical reactions.	2003	14531469
high autumn temperature delays spring bud burst in boreal trees, counterbalancing the effect of climatic warming.	the effect of temperature during short-day (sd) dormancy induction was examined in three boreal tree species in a controlled environment. saplings of betula pendula roth, b. pubescens ehrh. and alnus glutinosa (l.) moench. were exposed to 5 weeks of 10-h sd induction at 9, 15 and 21 degrees c followed by chilling at 5 degrees c for 40, 70, 100 and 130 days and subsequent forcing at 15 degrees c in a 24-h photoperiod for 60 days. in all species and with all chilling periods, high temperature duri ...	2003	14532017
white birch (betula papyrifera marshall) foliar litter decomposition in relation to trace metal atmospheric inputs at metal-contaminated and uncontaminated sites near sudbury, ontario and rouyn-noranda, quebec, canada.	decomposition of white birch (betula papyrifera marshall) foliar litter was examined at metal-contaminated and uncontaminated sites established along gradients of soil cu, ni, pb and zn concentrations near sudbury, ontario and rouyn-noranda, quebec. over an 18-month study period, a significantly lower rate of litter mass loss was observed at the sudbury contaminated site (s1) than at the uncontaminated site (s2). this result was not duplicated at corresponding sites (rn1, rn2) in rouyn-noranda, ...	2004	14553996
white birch.		2003	14582806
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, ...	2004	14653797
boron uptake by ectomycorrhizas of silver birch.	boron (b) is an essential micronutrient for plants but it is thought not to be essential for fungi. we studied whether the extraradical mycelia of paxillus involutus in symbiosis with silver birch (betula pendula) take up b and transport it to the host plant. we grew mycorrhizal plants in flat microcosms with a partitioning wall, below which there was only extraradical mycelium. a boric acid solution enriched in 10b was applied to these mycelia. increased 10b/11b isotope ratios were subsequently ...	2004	14745630
effects of light quality on growth and n accumulation in birch seedlings.	we studied the effects of light quality and nutrient supply on growth and nitrogen accumulation in silver birch (betula pendula roth) seedlings to test three hypotheses: (1) growth of birch seedlings is sensitive to changes in light quality; (2) the response of birch seedling growth to light quality depends on nutrient supply; and (3) assimilation and allocation of nitrogen by birch seedlings are affected by light quality. the two light regimes simulated the spectral quality of sunlight and shad ...	1997	14759882
growth responses and related biochemical and ultrastructural changes of the photosynthetic apparatus in birch (betula pendula) saplings exposed to low concentrations of ozone.	saplings of ozone-sensitive and ozone-tolerant birch (betula pendula roth.), clones b and c, respectively, were exposed to ozone concentrations that were 1.7-fold higher than ambient for one growing season under open-field conditions. ambient air was used as the control treatment. in the ozone-sensitive clone b, there was an initial stimulation of leaf area growth in response to the ozone treatment, but further ozone exposure caused reductions in leaf and stem biomass growth, rubisco and chlorop ...	1996	14871697
improving the reliability of a combined phenological time series by analyzing observation quality.	collecting phenological data is a slow process. although such data have been collected by a number of organizations, the reliability of these data is not known because the data-generating process cannot be repeated. no further observations to improve the reliability can be obtained. however, the data usually consist of several overlapping observation series and this overlap can be utilized to construct a combined phenological time series and to improve its reliability. we have developed two tech ...	1996	14871705
micropropagation of adult birch trees: production and field performance.	we compared the growth of trees produced by micropropagation from nodal stem sections or callus tissue of a 20-year-old silver birch (betula pendula roth) tree with that of seedlings; growth was monitored for 17 months in pots followed by six years in the field. micropropagated trees from both nodal stem sections and callus tissue grew at a similar rate to seedling trees and no obvious mutant types were observed. however, micropropagated trees were more uniform in height and trunk girth than see ...	1996	14871723
comparison of the photosynthetic capacity of siberian and japanese birch seedlings grown in elevated co(2) and temperature.	the effects of increased co(2) and temperature on the photosynthetic capacity of siberian white birch and japanese white birch (betula platyphylla sukatch. and b. platyphylla sukatch. var. japonica hara) were measured. birch seedlings were raised with a co(2) partial pressure of 36 +/- 0.3 pa (i.e., ambient) or 70 +/- 0.6 pa at day/night temperatures of either 30/16 degrees c or 26/12 degrees c. siberian birch leaves were smaller and thicker than japanese birch leaves. water use efficiency and n ...	1996	14871740
impacts of water and nitrogen supplies on the physiology, leaf demography and nitrogen dynamics of betula pendula.	we determined the response of betula pendula roth. trees to a restricted water supply, and quantified the interactions between tree n and water status on leaf demography and internal n cycling. in april 1993, 3-year-old trees were planted in sand culture and four treatments applied: high-n supply (56 mg tree(-1) week(-1)) with either 2 dm(3) water week(-1) (hn+) or 0.9 dm(3) water week(-1) (hn-), or low-n supply (14 mg tree(-1) week(-1)) with 2 dm(3) (ln+) or 0.9 dm(3) (ln-) water week(-1). unti ...	1996	14871759
[myotrophic and myotonic effects of a new preparation, betul, a combination of sodium glycerophosphate, vitamin b1 and white birch].		1952	14919353
[association of white birch, sodium glycerophosphate, and vitamin b1 in the treatment of sequels of hemiplegia, lumbar arthrosis, and neuritis; preliminary observations].		1952	14937254
transcriptional responses of paxillus involutus and betula pendula during formation of ectomycorrhizal root tissue.	in order to obtain information on genes specifically expressed in the ectomycorrhizal symbiosis, 3,555 expressed sequence tags (ests) were analyzed from a cdna library constructed from ectomycorrhiza formed between the basidiomycete paxillus involutus and birch (betula pendula). cdna libraries from saprophytically growing fungus (3,964 ests) and from axenic plants (2,532 ests) were analyzed in parallel. by clustering all the est obtained, a nonredundant set of 2,284 unique transcripts of either ...	2004	14964534
allocation of mass in trees subject to nitrogen and magnesium limitation.	it has previously been shown that lack of magnesium, potassium or manganese depresses allocation of new mass to roots in trees, and that these elements often occur in low amounts in declining forest stands. a model for tree growth and nutrient uptake was used to examine the effect of allocation pattern of new plant mass on growth and development in soils with low nutrient concentrations. growth parameters and empirical allocation functions from steady-state experiments with birch (betula pendula ...	1995	14965958
nighttime exposure to ozone reduces whole-plant production in betula pendula.	for 20 weeks during the growing season, cuttings of one birch clone (betula pendula roth.) were exposed in the birmensdorf fumigation chambers to o(3)-free air (control) or 75 nl o(3) l(-1). ozone was supplied either from 1900 until 0700 h (nighttime regime), from 0700 until 1900 h (daylight regime), or all day (24-h regime). by autumn, reductions in whole-plant biomass production, root/shoot biomass and stem weight/length ratios were evident in all three o(3) regimes. the reductions in cuttings ...	1995	14965971
growth and nutrition of birch seedlings at varied relative addition rates of magnesium.	growth and nutrition of hydroponically cultivated birch seedlings (betula pendula roth.) were investigated at various magnesium (mg) availabilities. suboptimum mg conditions were created by adding mg once per hour in exponentially increasing amounts at one of four relative addition rates (r(mg)): 0.05, 0.10, 0.15 or 0.20 day(-1). seedlings given free access to mg were used as controls. after an acclimation period, the relative growth rate of the seedlings attained the same value as the correspon ...	1995	14965980
dormancy release and chilling requirement of buds of latitudinal ecotypes of betula pendula and b. pubescens.	bud burst and dormancy release of latitudinal ecotypes of betula pendula roth and b. pubescens ehrh. from denmark ( approximately 56 degrees n), mid-norway ( approximately 64 degrees n) and northern norway ( approximately 69 degrees n) were studied in controlled environments. dormant seedlings were chilled at 0, 5 or 10 degrees c from october 4 onward and then, at monthly intervals from mid-november to february, batches of seedlings were held at 15 degrees c in an 8-h (sd) or 24-h (ld) photoperi ...	1995	14965987
methods for combining phenological time series: application to bud burst in birch (betula pendula) in central finland for the period 1896-1955.	we compared four methods for combining separate fragmentary phenological time series into a single long reliable series. the systematic linear effect of differences in observers, genotypes, geography and climate at the observation points produces disturbing variation in the observations and bias in the means of some time points. the three methods based on the adjustment of individual series eliminated the disturbing variation and bias. the methods were compared based on phenological observations ...	1995	14965990
photosynthesis and canopy characteristics in genetically defined families of silver birch (betula pendula).	net photosynthetic rates (a) of leaves in upper and lower crown layers (a(upper) and a(lower)), leaf area index (lai), mean tilt angle (mta), several leaf characteristics, and volume growth were observed in fast- and slow-growing families of a 14-year-old full-sib and half-sib family progeny test of betula pendula roth. each measure of net photosynthetic rate was calculated after correcting measured net photosynthesis for the effects of environmental variables. the differences in a(upper) and la ...	1995	14966000
growth and nutrition of small betula pendula plants at different relative addition rates of manganese.	in a series of experiments, growth of small birch plants (betula pendula roth) was controlled by the relative addition rate of manganese, r(mn) (day(-1)). the r(mn) treatments were 0.05, 0.10, 0.15 and 0.20 day(-1) with free access to all other nutrients. in an additional treatment, fa, there was free access to all nutrients including mn. the ph of the nutrient solution ranged between 3.9 and 4.1, and the conductivity was between 100 and 200 micro s cm(-1). after an adjustment phase to steady-st ...	1994	14967693
growth and branching habit of rooted cuttings collected from epicormic shoots of betula pendula roth.	patterns of shoot growth and branching were studied over two growing seasons in rooted cuttings collected from both epicormic shoots and seedlings of betula pendula roth. epicormic shoots were induced to sprout on stumps and small logs of 5-, 10- and 30-year-old trees. the use of epicormic shoots enhanced the rooting capacity of stem cuttings collected from these shoots but did not appear to reverse the process of maturation. in this study, maturation was based on characteristics typical of matu ...	1994	14967697
variations in leaf morphometry and nitrogen concentration in betula pendula roth., corylus avellana l. and lonicera xylosteum l.	relations between leaf dry weight to leaf area (lwa), leaf nitrogen concentration and irradiance inside a natural canopy were studied in betula pendula roth., corylus avellana l. and lonicera xylosteum l. in all species, lwa increased with increasing irradiance. relative variability in lwa was smaller in betula pendula than in the other two species. in corylus avellana, lwa also depended on total plant height. foliar nitrogen concentration (on a dry weight basis) increased with increasing irradi ...	1993	14969921
effects of copper and cadmium on uptake and leakage of k(+) in birch (betula pendula) roots.	uptake and leakage experiments were performed to study the effects of copper and cadmium on k(+) fluxes in birch (betula pendula roth) roots. labeled rubidium ((86)rb(+)) was used as a tracer for k(+). plants were pretreated with cu or cd (0, 2, 5 or 25 microm) for 0-300 min and then transferred to radiolabeled nutrient solution (150 microm k(+)) with or without 2,4-dinitrophenol (dnp) to separate the effects of heavy metal on active and passive k(+) influxes. passive k(+) influx was decreased b ...	1992	14969953
diameters and dry weights of tree shoots: effects of young's modulus, taper, deflection and angle.	the structural theory for cantilever beams was used to calculate the diameters and dry weights of wood that unbranched shoots must produce to support their own weights. the study was done on picea sitchensis (bong.) carr., pinus contorta dougl., larix decidua mill. and betula pendula roth. syn. verrucosa ehrh. the weights of wood increased in a non-linear fashion with increase in shoot length. a large investment in wood (as measured by diameter and dry weight) was required to maintain a small en ...	1988	14972812
micropropagation of a mature colchicine-polyploid and irradiation-mutant of betula pendula roth.	tetraploid plantlets were regenerated from cultured apical and axillary buds of a 23-year-old colchicine-polyploid and irradiation-mutant betula pendula roth tree. bud explants were grown on modified murashige and skoog medium supplemented with 2.0 mg l(-1) benzylaminopurine (bap) and 0.01 mg l(-1) 1-naphthaleneacetic acid (naa). the medium allowed both induction of adventitious buds and development of shoots. the cut ends of new shoots produced new buds and shoots during a 4-week culture period ...	1988	14972827
the utilization of old phenological time series of budburst to compare models describing annual cycles of plants.	a phenological time series of the date of budburst of birch (betula pendula) was constructed using data from the years 1907-1950. data for the years 1908, 1910-1915 and 1930 are missing. the phenological observations were made at saarijärvi (62 degrees 42' n, 25 degrees 44' e) in central finland. different models describing the rate of development in the spring were analyzed using temperature data from the city of jyväskylä about 60 km to the southeast of saarijärvi. the models based on temperat ...	1991	14972878
changes in the water relations of balsam fir and white birch saplings after thinning.	in the autumn of 1987, young balsam fir (abies balsamea (l.) mill.) and white birch (betula papyrifera marsh.) trees were thinned and their water relations followed during the next two growing seasons. at the beginning of the first summer following treatment, thinned trees of both species had lower osmotic potentials at full saturation (psi(pi,sat)) and at turgor loss point (psi(pi,tlp)) compared with controls. at this time, psi(pi,sat) was linearly related to the percentage of full sunlight rea ...	1990	14972929
autotetraploid plants from callus cultures of betula pendula roth.	autotetraploid plants with 2n = 56 chromosomes were found in a population of plants derived from callus cultures of stem internodes of silver birch (betula pendula roth) with 2n = 28 chromosomes. these plants were readily identified by their twisted, pubescent foliage and slow rate of growth, and by cytological examination. the frequency of autotetraploidy varied with the auxin used in the culture medium. when indole-3-butyric acid was used, autotetraploids accounted for 3.8% of the total study ...	1990	14972954
uptake of carbon and nitrogen at decreased nutrient availability in small birch (betula pendula roth.) plants.	uptake of carbon and nitrogen in relation to mineral nutrient supply was investigated in small birch (betula pendula roth.) plants grown in solution culture. a step-decrease in nutrient availability (from near-optimal to a low rate of supply) caused an immediate and temporary cessation in net uptake of nitrogen to leaves and a sharp reduction in rate of leaf expansion. both net uptake of nitrogen to leaves and leaf area expansion subsequently resumed but at a rate matching the decreased nutrient ...	1986	14975842
young's modulus of sections of living branches and tree trunks.	young's modulus along the grain (elasticity, e) was measured on 10 sections of branches and three tree trunks, with bark, of picea sitchensis (bong.) carr., pinus contorta dougl. ex loud., larix decidua mill. and betula pendula roth. syn. verrucosa ehrh. the sections were simply supported and corrections were made for taper and deflection due to shear. the e values for trunks were at the lower end of the range reported for green timber (2.4-7.5 gpa), and those for branches were still lower (0.7- ...	1987	14975919
genotypic variation in drought response of silver birch (betula pendula): leaf water status and carbon gain.	to assess genotypic variation in drought response of silver birch (betula pendula roth), we studied the plasticity of 16 physiological traits in response to a 12-14-week summer drought imposed on four clones in two consecutive years. in a common garden experiment, 1-year-old clonal trees from regions with low (550 mm year(-1)) to high rainfall (1270 mm year(-1)) were grown in 45-l pots, and leaf gas exchange parameters, leaf water potentials, leaf osmotic potentials and leaf carbon isotope signa ...	2004	14996656
[polyclonal antisera to birch pollen allergen for the air allergen screening].	the cross reactivity of the pollen allergens of birch (betula pendula), hazel (corylus avelana), alder (alnus glutinosa), wormwood (artemisia absinthium), oak (quercus robur) and ashtree (fraxinus excelsior) was studied by the methods of the enzyme immunoassay and gel diffusion with the use of rabbit polyclonal antisera (pas) prepared against birch pollen allergen. pas was shown to be greatly related to all above-mentioned allergens with the exception of oak pollen allergen. pas was found capabl ...	2004	15024987
a new sbp-box gene bpspl1 in silver birch (betula pendula).	the sbp-box gene family represents a group of plant-specific genes encoding putative transcription factors. thus far, sbp-domain protein binding sites have been found in the promoters of arabidopsis apetala1 and antirrhinum squamosa. a putative sbp-domain binding element has been observed in the promoter of bpmads5, a close homologue of arabidopsis fruitfull in silver birch (betula pendula). a novel sbp-box gene from birch named bpspl1 has been cloned and characterized. the nucleotide sequence o ...	2004	15032847
functional characterization of sepallata3 and agamous orthologues in silver birch.	the development of flowers is regulated by a complex network of transcriptional activators and repressors, many of which belong to the mads box gene family. in this study, we describe two mads box genes of silver birch (betula pendula roth), bpmads1 and bpmads6, which are similar to sepallata3 and agamous in arabidopsis thaliana, respectively. in situ hybridization showed that bpmads1 was expressed in the inflorescence meristem at a very early stage, but not later. both genes were expressed in d ...	2004	15086829
landfill site restoration: the inimical challenges of ethylene and methane.	vertically migrating landfill gases pose inimical challenges to site revegetation strategies. laboratory studies were made to examine the efficacy of ectomycorrhizae and soil cover to obviate the challenges of ethylene and methane. in the presence of ethylene concentrations </= 640 ppm the mean colony radial extension rates of the fungal isolates laccaria proxima, paxillus involutus and hebeloma crustuliniforme were comparable with the non-ethylene controls. h. crustuliniforme afforded no protec ...	1994	15091739
foliar injury in young betula pendula roth., salix purpurea l. and ilex aquifolium l. trees and in propagated taxus baccata l. shoots exposed to intermittent fog at a range of acidities.	the occurrence of various visible symptoms of foliar injury was assessed on a 5-point scale for each of the species. there was a distinct increase in the incidence of most types of injury in plant material which has been exposed to ph 2.5 acid fog. no clear ph-related trend in foliar injury occurred in plants exposed to acid fog at ph 3.5, ph 4.5 and ph 5.6, indicating that a threshold for a range of different types of visible injury may exist between ph 2.5 and ph 3.5 for all four species.	1993	15091854
effects of sulphur dioxide and nitrogen dioxide, singly and in mixture, on the macroscopic growth of three birch clones.	an investigation of some aspects of the effects of low concentrations of the gases, sulphur dioxide and nitrogen dioxide, singly and in mixture, was made on the growth of three birch clones, two of betula pendula roth. (silver birch) and one of betula pubescens ehr. (downy birch). comparative measurements of the growth form and dry mass increment were made over one year in glasshouses supplied with charcoal-filtered ambient air, and so(2) and no(2), singly or in mixture, at mean concentrations o ...	1987	15092731
container-grown tree seedling responses to sodium chloride applications in different substrates.	seedlings of norway maple (acer platanoides), silver birch (betula pendula), norway spruce (picea abies) and scots pine (pinus sylvestris) were grown in selected sodium chloride (nacl) concentrations, soil types and under different watering regimes. plants were raised from seeds, except for scots pine plants which were obtained from a commercial source. among the plant species tested, scots pine was the most tolerant to soil salinity, while norway spruce was the most susceptible. for both norway ...	2000	15092891
differences in growth, leaf senescence and injury, and stomatal density in birch (betula pendula roth.) in relation to ambient levels of ozone in finland.	the differences in growth, leaf senescence, visible ozone injuries and stomatal density between one coastal site (natural ozone) and two inland sites (natural and elevated ozone) in finland were determined for saplings of betula pendula clones grown under open-field conditions during two growing seasons. responses in growth, leaf senescence, visible injuries, and stomatal density were determined in relation to cumulative ozone exposure accumulated over the thresholds of 30, 40 and 50 ppb (10(9)) ...	1997	15093411
antioxidant responses to simulated acid rain and heavy metal deposition in birch seedlings.	this study measured the responses of different anti-oxidants in 2-year-old birch (betula pendula roth) seedlings subjected to simulated acid rain (ph 4.0) and heavy metals (cu/ni), applied alone or in combination for 2 months. the applied concentrations of pollutants did not significantly affect seedling biomass or total glutathione levels. acid rain alone increased superoxide dismutase (sod) activity both in leaves and roots, while heavy metals alone inhibited sod activity in roots. both acid r ...	1997	15093466
variation in ozone sensitivity among clones of betula pendula and betula pubescens.	forty clones of betula pendula and 6 clones of betula pubescens, originating from southern and central finland, were ranked in order of ozone sensitivity according to visible injuries, growth and leaf senescense under low ozone exposure. the plants were fumigated in natural climatic conditions using an open-air exposure system during two growing seasons. control plants were grown under ambient air, and the elevated-ozone exposures were 1.6x the ambient in 1994 and 1.7x the ambient in 1995. the d ...	1997	15093472
effect of natural and artificial defoliation on concentration and composition of extractive substances in leaves of birch (betula pendula roth.): methods of analysis and results.		2004	15116567
effects of elevated concentrations of ozone and carbon dioxide on the electrical impedance of leaves of silver birch (betula pendula) clones.	effects of elevated concentrations of tropospheric ozone ([o3]) and carbon dioxide ([co2]) on leaves of two silver birch (betula pendula roth) clones were monitored for three growing seasons (1998, 1999, 2000) by means of electrical impedance spectroscopy (eis). the field trial with open-top chambers (otcs) was conducted on two clones (clone 4 and clone 80) with five treatments and four independent replicates. treatments were: (1) outside control, (2) chamber control, (3) 2x ambient [o3], (4) 2x ...	2004	15123455
development of leaf photosynthetic parameters in betula pendula roth leaves: correlations with photosystem i density.	the global modelling of photosynthesis is based on exact knowledge of the leaf photosynthetic machinery. the capacities of partial reactions of leaf photosynthesis develop at different rates, but it is not clear how the development of photoreactions and the calvin cycle are co-ordinated. we investigated the development of foliar photosynthesis in the temperate deciduous tree betula pendula roth. using a unique integrated optical/gas exchange methodology that allows simultaneous estimation of pho ...	2004	15143439
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 ...	2004	15148601
comparison of throughfall and soil solution chemistry between a high-density corsican pine stand and a naturally regenerated silver birch stand.	in flanders, critical loads for acidification and eutrophication are exceeded in the majority of the forest stands, and many previously nitrogen limited forest ecosystems have become nitrogen saturated. the present study investigates whether a naturally regenerated stand of silver birch (betula pendula roth) contributes less to the acidification and eutrophication of the forest soil than a high-density plantation of corsican pine (pinus nigra ssp. laricio maire). throughfall deposition of inorga ...	2004	15210279
field performance of chitinase transgenic silver birches (betula pendula): resistance to fungal diseases.	a field trial of 15 transgenic birch lines expressing a sugar beet chitinase iv gene and the corresponding controls was established in southern finland to study the effects of the level of sugar beet chitinase iv expression on birch resistance to fungal diseases. the symptoms caused by natural infections of two fungal pathogens, pyrenopeziza betulicola (leaf spot disease) and melampsoridium betulinum (birch rust), were analysed in the field during a period of 3 years. the lines that had shown a ...	2004	15221141
seasonal and within-stem variations of neutral lipids in silver birch (betula pendula) wood.	neutral lipids were analyzed in stem wood of a 7-year-old clone and in five 35-70-year-old mature trees of silver birch (betula pendula roth). in young trees and in mature wood of old trees, the free fatty acid fraction comprised less than 5% of the concentration of triacylglycerols (tg). the concentration of free linoleic acid was lowest in march when the young trees were dormant and highest during midsummer and september. in mature trees, the tg concentration increased toward the pith, indicat ...	2004	15234896
changes in leaf trichomes and epicuticular flavonoids during leaf development in three birch taxa.	changes in number of trichomes and in composition and concentrations of their exudates throughout leaf development may have important consequences for plant adaptation to abiotic and biotic factors. in the present study, seasonal changes in leaf trichomes and epicuticular flavonoid aglycones in three finnish birch taxa (betula pendula, b. pubescens ssp. pubescens, and b. pubescens ssp. czerepanovii) were followed.	2004	15238348
evidence that fungal pathogens inhibit recruitment of a shade-intolerant tree, white birch ( betula papyrifera), in understory habitats.	evidence from tropical forests suggests understory habitats are associated with a high risk of disease, which may prevent the establishment of vulnerable tree species; in contrast, canopy gaps can act as refuges from these pathogens. however, few studies have investigated the impacts of pathogens on regeneration in temperate forests. to determine whether losses to fungi of seeds of betula papyrifera, a light-loving species, varied between habitats that differed in their degree of openness, we ap ...	2004	15243795
investigating the history of prehistoric glues by gas chromatography-mass spectrometry.	although organic materials are very sensitive to biochemical alteration processes, they may be preserved for millennia in various archaeological contexts. remains of adhesives made during prehistory were discovered at different sites, in the form of residues adhering to flint tools and ceramic vessels or as free lumps in sediment. to characterise the natural substances exploited for adhesive production during late prehistory, we undertook gc and gc/ms analysis of 90 samples from 8 sites dating f ...	2004	15334911
silver birch and climate change: variable growth and carbon allocation responses to elevated concentrations of carbon dioxide and ozone.	we studied the effects of elevated concentrations of carbon dioxide ([co2]) and ozone ([o3]) on growth, biomass allocation and leaf area of field-grown o3-tolerant (clone 4) and o3-sensitive clones (clone 80) of european silver birch (betula pendula roth) trees during 1999-2001. seven-year-old trees of clones 4 and 80 growing outside in open-top chambers were exposed for 3 years to the following treatments: outside control (oc); chamber control (cc); 2 x ambient [co2] (ec); 2 x ambient [o3] (eo) ...	2004	15339732
[investigation of daily mitotic activity of the birch, betula pendula roth].	a study was made of the daily mitotic activity in the seedling root meristem of birch trees growing in an ecologically clear area--the biological station of voronezh state university "venevitinovo". the peak of mitotic activity was exposed at 9 a. m. (according to winter time). the rise of mitotic index was noted at 9 and 12 p. m. due to an increase in the share of cells being in the prophase stage, and to a high number of dividing cells with persistent nucleoli. a possibility of prolongation of ...	2004	15341127
dendroremediation of trinitrotoluene (tnt). part 1: literature overview and research concept.	for decades, very large areas of former military sites have been contaminated diffusely with the persistent nitroaromatic explosive 2,4,6-trinitrotoluene (tnt). the recalcitrance of the environmental hazard tnt is to a great extent due to its particulate soil existence, which leads to slow but continuous leaching processes. although improper handling during the manufacture of tnt seems to be a problem of the past in developed countries, environmental deposition of tnt and other explosives is sti ...	2004	15341318
ecology and molecular characterization of dark septate fungi from roots, living stems, coarse and fine woody debris.	the aim of the present work was to determine the identity and molecular relationships between 127 strains of dark septate (ds) fungi isolated from healthy root tips, decayed coarse roots, live healthy-looking stems, coarse (stumps, snags and logs) and fine (tree branches and tops) woody debris in temperate-boreal forests in sweden and lithuania. sequence analysis of its rdna was used to identify the fungi. in a neighbour-joining similarity tree, all sequences were grouped into five distinct clus ...	2004	15449602
reductive titration of photosystem i and differential extinction coefficient of p700+ at 810-950 nm in leaves.	we describe a method of reductive titration of photosystem i (psi) density in leaves by generating a known amount of electrons (e-) in photosystem ii (psii) and measuring the resulting change in optical signal as these electrons arrive at pre-oxidized psi. the method complements a recently published method of oxidative titration of psi donor side e- carriers p700, plastocyanin (pc) and cytochrome f by illuminating a darkened leaf with far-red light (frl) [v. oja, h. eichelmann, r.b. peterson, b. ...	2004	15450960
[cytogenetic characteristics of seed offspring of leafy tree plants from one-kilometer zone of novovoronezh nuclear power station].	cytogenetic characteristics (mitotic activity, level and spectrum of pathological mitoses, nucleoly characteristics) of seed offspring of quercus robur l. and betula pendula roth from novovoronezh nuclear power station's 1-kilometer zone have been studied. it has been shown the change of time of passing though mitotic stages by cells, the increasing of bridges frequency occur in spectrum of mitotic aberrations (that shows activation of reparation systems), the change in nucleoly characteristics ...	2004	15455676
allergy vaccine engineering: epitope modulation of recombinant bet v 1 reduces ige binding but retains protein folding pattern for induction of protective blocking-antibody responses.	human type 1 immediate allergic response symptoms are caused by mediator release from basophils and mast cells. this event is triggered by allergens aggregating preformed ige abs bound to the high-affinity receptor (fcepsilonri) on these cells. thus, the allergen/ige interaction is crucial for the cascade leading to the allergic and anaphylactic response. two genetically engineered forms of the white birch pollen major allergen bet v 1 with point mutations directed at molecular surfaces have bee ...	2004	15470071
effects of light availability versus hydraulic constraints on stomatal responses within a crown of silver birch.	responses of leaf conductance (gl) to variation in photosynthetic photon flux density (qp), leaf-to-air vapour pressure difference (vpd), bulk leaf water potential (psi(x)), and total hydraulic conductance (gt) were examined in silver birch (betula pendula roth) with respect to leaf position in the crown. to reduce limitations caused by insufficient water supply or low light availability, experiments were also performed with branchlets cut from two different canopy layers. the intact upper-canop ...	2005	15517405
effects of seed origin and sowing time on timing of height growth cessation of betula pendula seedlings.	we studied the effects of seed origin and sowing time on height development and timing of height growth cessation of first-year silver birch (betula pendula roth) seedlings in a greenhouse experiment. seeds of seven origins ranging in latitudes from 58 degrees to 67 degrees n were sown at 1-2-week intervals eight times from may 21 to july 30, 2001. the day/night temperature in the greenhouse was set at 20/10 degrees c, but lighting was natural and day length varied accordingly. seedling height w ...	2005	15519991
role of nutrient level and defoliation on symbiotic function: experimental evidence by tracing 14c/15n exchange in mycorrhizal birch seedlings.	high nutrient availability and defoliation generally reduce ectomycorrhizal colonization levels in trees, but it is not known how this affects the functional aspects of mycorrhizal symbiosis. it was therefore investigated whether (1) defoliation or increasing substrate n availability reduce c allocation from the plant to the fungus and n allocation from the fungus to the plant (symbiotic resource exchange), (2) symbiotic resource exchange depends on relative n and p availability, and (3) fungal ...	2005	15558328
short-day potentiation of low temperature-induced gene expression of a c-repeat-binding factor-controlled gene during cold acclimation in silver birch.	development of winter hardiness in trees is a two-stage process involving sequential perception of distinct environmental cues, short-day (sd) photoperiod and low temperature (lt). we have shown that both sd and lt are recognized by leaves of silver birch (betula pendula cv roth) leading to increased freezing tolerance, and thus leaves can be used as an experimental model to study the physiological and molecular events taking place during cold acclimation. to obtain a molecular marker for the ac ...	2004	15563624
variations in phenology and growth of european white birch (betula pendula) clones.	phenology can have a profound effect on growth and climatic adaptability of northern tree species. although the large interannual variations in dates of bud burst and growth termination have been widely discussed, little is known about the genotypic and spatial variations in phenology and how these sources of variation are related to temporal variation. we measured bud burst of eight white birch (betula pendula roth) clones in two field experiments daily over 6 years, and determined the terminat ...	2005	15574401
fungi associated with shoots of silver birch (betula pendula) in scotland.	the fungi associated with diseased and healthy shoots of young, planted betula pendula were studied at five sites in scotland where crown die-back of birch is occurring. at each site, 30 diseased and 30 healthy shoots were sampled twice, with 1 yr-old shoots collected in may 2002, and 4-5-month-old shoots collected in september/october 2002. overall, 34 different fungal species were recorded, with 92 % and 60 % of all diseased and healthy shoot pieces, respectively, colonised by at least one fun ...	2004	15587066
3-hydroxypropionic acid as a nematicidal principle in endophytic fungi.	3- hydroxypropionic acid was isolated by bioactivity-guided fractionation of extracts obtained from submerged cultures of several endophytic fungi isolated from above-ground plant organs. this compound showed selective nematicidal activity against the plant-parasitic nematode meloidogyne incognita with ld50 values of 12.5-15 microg/ml. activity against the saprophytic caenorhabditis elegans was fivefold lower. no antimicrobial, cytotoxic or phytotoxic effects were observed. propionic acid and d- ...	2004	15587708
characterization and discrimination of pollen by raman microscopy.	the chemical characterization and discrimination of allergy-relevant pollen (common ragweed (ambrosia artemisiifolia), white birch (betula pendula), english oak (quercus robur), and european linden (tilia cordata)) has been studied by raman microscopy. spectra were obtained at different excitation wavelengths (514, 633, and 780 nm) and various methods were examined to minimize the strong fluorescence background. the use of a he-ne laser (633 nm) for excitation yields high-quality single pollen r ...	2004	15605236
identification of genes differentially expressed in extraradical mycelium and ectomycorrhizal roots during paxillus involutus-betula pendula ectomycorrhizal symbiosis.	the development of ectomycorrhizal symbiosis leads to drastic changes in gene expression in both partners. however, little is known about the spatial regulation of symbiosis-regulated genes. using cdna array profiling, we compared the levels of expression of fungal genes corresponding to approximately 1,200 expressed sequenced tags in the ectomycorrhizal root tips (ecm) and the connected extraradical mycelium (em) for the paxillus involutus-betula pendula ectomycorrhizal association grown on pea ...	2005	15640212
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 ...	2004	15672669
prevention of flower development in birch and other plants using a bpfull1::barnase construct.	the prevention of flower formation is important for avoiding the spread of transgenes from genetically modified plants into wild populations. moreover, the resources not expended for the generation of flowers and fruits might be allocated to increased vegetative growth. we have been developing methods for preventing flower formation in silver birch (betula pendula), a tree species of considerable economical importance in the boreal region. here we study the suitability of the promoter of bpfruit ...	2005	15690161
components of apoplastic ascorbate use in betula pendula leaves exposed to co2 and o3 enrichment.	here, the aim was to estimate loads imposed on the apoplastic ascorbate (asc) pool by enzymatic and nonenzymatic reactions in betula pendula exposed to doubled co2 and o3 concentrations in open-top chambers. leaf apoplastic extracts were analysed for peroxidase and oxidase activities in vitro, using different substrates. partial loads in vivo were deduced using measured kinetic constants and substituted-enzyme catalysis approaches. ascorbate use in o3 scavenging was calculated using measured sto ...	2005	15720628
leaf photosynthetic characteristics of silver birch during three years of exposure to elevated concentrations of co2 and o3 in the field.	effects of elevated concentrations of carbon dioxide ([co2]) and ozone ([o3]) on photosynthesis and related biochemistry of two european silver birch (betula pendula roth) clones were studied under field conditions during 1999-2001. seven-year-old trees of clones 4 and 80 were exposed for 3 years to the following treatments in an open-top chamber experiment: outside control (oc), chamber control (cc), 2x ambient [co2] (ec), 2x ambient [o3] (eo) and 2x ambient [co2] + 2x ambient [o3] (ec+eo). dur ...	2005	15741148
effects of soil temperature and elevated atmospheric co2 concentration on gas exchange, in vivo carboxylation and chlorophyll fluorescence in jack pine and white birch seedlings.	one-year-old jack pine (pinus banksiana lamb.) and current-year white birch (betula papyrifera marsh.) seedlings were grown in ambient (360 ppm) or twice ambient (720 ppm) atmospheric co2 concentration ([co2]) and at three soil temperatures (tsoil = 7, 17 and 27 degrees c initially, increased to 10, 20 and 30 degrees c two months later, respectively) in a greenhouse for 4 months. in situ foliar gas exchange, in vivo carboxylation characteristics and chlorophyll fluorescence were measured after 2 ...	2005	15741153
temperature dependence of leaf-level co2 fixation: revising biochemical coefficients through analysis of leaf three-dimensional structure.	co2 fixation in a leaf is determined by biochemical and physical processes within the boundaries set by leaf structure. traditionally determined temperature dependencies of biochemical processes include physical processes related to co2 exchange that result in inaccurate estimates of parameter values. a realistic three-dimensional model of a birch (betula pendula) leaf was used to distinguish between the physical and biochemical processes affecting the temperature dependence of co2 exchange, to ...	2005	15760364
isolation of wood-inhabiting fungi from canadian hardwood logs.	wood-inhabiting fungi include many molds, wood-staining fungi, and decay fungi. most of these fungal species can result in economic losses to wood users. studies on molds, staining fungi, and decay fungi are necessary to be able to control their growth on wood and wood products. in this study, wood-inhabiting fungi were isolated from logs of 3 major canadian hardwood species: sugar maple, white birch, and yellow birch. two media were used for isolation. from these 3 wood species, a total of 1198 ...	2005	15782228
[effects of natural and artificial defoliations on the content and composition of extractive substances in birch leaves].	qualitative and quantitative compositions of extracts of birch (betula pendula roth.) leaves after natural and artificial defoliations were studied. composition of the fraction of total lipids was determined. overall, 11 fatty acids were identified. differences between the fatty acid compositions of total lipids in the trees subjected to defoliation, consisting in the increase in quantities of short-chain saturated fatty acids and trienoic acids, were detected. nine individual compounds--six fla ...	2005	15810741
essential oil of betula pendula roth. buds.	the essential oil of betula pendula roth. buds was obtained using both hydrodistillation and microdistillation techniques and their chemical compositions were analyzed using both gas chromatography (gc) and gas chromatography-mass spectrometry (gc-ms). overall, more than 50 compounds were identified representing 80% and 92% for hydrodistillation and microdistillation, respectively. the main components (by hydrodistillation and microdistillation, respectively) found were alpha-copaene (12% and 10 ...	2004	15841263
does the commonly used estimator of nutrient resorption in tree foliage actually measure what it claims to?	a descriptive temporal model is considered to be the best available estimator for accretion, resorption and proportional nutrient resorption. however, ecological studies rarely collect sufficient data for applying such a model. a less-demanding and commonly used estimator for proportional resorption (pr) calculates pr as the percentage of the nutrient pool that is withdrawn from mature foliage before leaf abscission. data from an intensive sampling campaign of the aboveground nutrient pools and ...	2005	15891824
control of cytochrome b6f at low and high light intensity and cyclic electron transport in leaves.	the light-dependent control of photosynthetic electron transport from plastoquinol (pqh(2)) through the cytochrome b(6)f complex (cyt b(6)f) to plastocyanin (pc) and p700 (the donor pigment of photosystem i, psi) was investigated in laboratory-grown helianthus annuus l., nicotiana tabaccum l., and naturally-grown solidago virgaurea l., betula pendula roth, and tilia cordata p. mill. leaves. steady-state illumination was interrupted (light-dark transient) or a high-intensity 10 ms light pulse was ...	2005	15949986
in situ net mineralization rates in a heterogeneous mixed deciduous forest receiving elevated n deposition.	in situ net mineralization was studied at 6 locations (e, eb, ec, f1, f2, f3) of a heterogeneous mixed deciduous forest ("de gulkeputten") with oak (quercus robur l., quercus rubra) and birch (betula pendula) as dominant species. net nitrogen mineralization was determined by means of a sequential in situ incubation experiment using intact soil cores. for all incubations, the net mineralization rates of the organic (f+h) layer varied between -0.4 and 2.0 g n m(-2) month(-1), while the net nitrifi ...	2001	15952425