Publications
| Title | Abstract | Year Filter | PMID(sorted ascending) Filter |
|---|
| genetic mosaics of ecosystem functioning across aspen-dominated landscapes. | genetic diversity is the foundation of all biodiversity, and the genetic variation within species is increasingly recognized as being important to ecosystem level processes. recent research demonstrates that plant genotype influences above- and belowground communities as well as basic ecosystem functions. however, the extent to which plant genotypes create spatial mosaics of genetically mediated ecosystem processes in natural forests is uncertain. we use populus tremuloides as a model system to ... | 2009 | 19214586 |
| nonstomatal versus stomatal uptake of atmospheric mercury. | atmospheric constituents may be deposited to and incorporated into plant leaves, with gases entering via stomata, and gas and particles being sorbed at the surface and in some cases traversing the cuticle, possibly reaching the epidermis. plants are known to be a sink for atmospheric mercury (hg), and the current paradigm is that uptake of gaseous elemental hg occurs by way of the stomata. four plant species, rudbeckia hirta, sorghastrum nutans, andropogon gerardii, and populus tremuloides, were ... | 2009 | 19350905 |
| transcriptomic comparison in the leaves of two aspen genotypes having similar carbon assimilation rates but different partitioning patterns under elevated [co2]. | this study compared the leaf transcription profiles, physiological characteristics and primary metabolites of two populus tremuloides genotypes (clones 216 and 271) known to differ in their responses to long-term elevated [co2] (e[co2]) at the aspen free-air co2 enrichment site near rhinelander, wi, usa. the physiological responses of these clones were similar in terms of photosynthesis, stomatal conductance and leaf area index under e[co2], yet very different in terms of growth enhancement (0-1 ... | 2009 | 19383098 |
| development of a combined sex pheromone-based monitoring system for malacosoma disstria (lepidoptera: lasoicampidae) and choristoneura conflictana (lepidoptera: tortricidae). | sympatric insect species that do not share sex pheromone components but have a common host and overlapping adult flight periods are potential targets for the development of a combined sex pheromone-based monitoring tool. a system using a single synthetic pheromone blend in a single lure to bait a single trap to monitor two pests simultaneously represents a novel approach. in this study, a combined pheromone-based monitoring system was developed for two lepidopterous defoliators of trembling aspe ... | 2009 | 19389296 |
| behavioral archives link the chemistry and clonal structure of trembling aspen to the food choice of north american porcupine. | understanding the links among plant genotype, plant chemistry, and food selection by vertebrate herbivores is critical to assess the role of herbivores in the evolution of plant secondary chemistry. some specialized vertebrate herbivores have been shown to select plants differentially according to plant genotype, but examples from generalists, which constitute the vast majority of vertebrate herbivores, are few, especially in natural conditions. we examined the relationship between the north ame ... | 2009 | 19390868 |
| design to monitor trend in abundance and presence of american beaver (castor canadensis) at the national forest scale. | wildlife conservationists design monitoring programs to assess population dynamics, project future population states, and evaluate the impacts of management actions on populations. because agency mandates and conservation laws call for monitoring data to elicit management responses, it is imperative to design programs that match the administrative scale for which management decisions are made. we describe a program to monitor population trends in american beaver (castor canadensis) on the us dep ... | 2010 | 19396556 |
| endomembrane system of aspen root cells plays a key role in defense against a common fungal root endophyte, cryptosporiopsis radicicola. | the host-endophyte interaction between roots of aspen (populus tremuloides) and cryptosporiopsis radicicola was examined primarily by transmission electron microscopy. hyphae growing on the exterior of the inoculated roots had a thick, electron-dense, adhesive sheath. at hyphal contact and penetration, host epidermal cells exhibited a series of defense responses (viz. formation of papillae and partition walls, general wall thickening and walling-off of internal hyphae). in papilla formation, loo ... | 2009 | 19397190 |
| the ectomycorrhizal morphotype pinirhiza sclerotia is formed by acephala macrosclerotiorum sp. nov., a close relative of phialocephala fortinii. | relatively few ectomycorrhizal fungal species are known to form sclerotia. usually, sclerotia are initiated at the extraradical mycelium. in this study, we present anatomical and ultrastructural evidence for the formation of sclerotia directly in the hyphal mantle of the mycorrhizal morphotype pinirhiza sclerotia. a dark-pigmented fungal strain was isolated from pinirhiza sclerotia and identified by molecular tools as acephala macrosclerotiorum sp. nov., a close relative of phialocephala fortini ... | 2009 | 19415343 |
| performance and secondary chemistry of two hybrid aspen (populus tremula l. x populus tremuloides michx.) clones in long-term elevated ozone exposure. | the effects of moderately elevated ozone (ca. 35 ppb) on the growth and secondary chemistry of the leaves of two soil-grown finnish hybrid aspen (populus tremula l. x populus tremuloides michx.) clones with different ozone sensitivities were studied at an open-air exposure field in kuopio, finland. stomatal conductance, photosynthetic rate, and chlorophyll fluorescence were measured during the third growing season. foliar phenolic concentrations, ergosterol concentration of fine roots, and final ... | 2009 | 19462207 |
| larval nutrition affects life history traits in a capital breeding moth. | fitness depends not only on resource uptake but also on the allocation of these resources to various life history functions. this study explores the life-history consequences of larval diet in terms not only of larval performance but also of adult body composition and reproductive traits in the forest tent caterpillar (malacosoma disstria hübner). caterpillars were reared on their preferred tree host, trembling aspen (populus tremuloides), or on one of three artificial foods: high protein:low ca ... | 2009 | 19482996 |
| impact of simulated herbivory on water relations of aspen (populus tremuloides) seedlings: the role of new tissue in the hydraulic conductivity recovery cycle. | physiological mechanisms behind plant-herbivore interactions are commonly approached as input-output systems where the role of plant physiology is viewed as a black box. studies evaluating impacts of defoliation on plant physiology have mostly focused on changes in photosynthesis while the overall impact on plant water relations is largely unknown. stem hydraulic conductivity (k(h)), stem specific conductivity (k(s)), percent loss of hydraulic conductivity (plc), co(2) assimilation (a) and stoma ... | 2009 | 19603186 |
| spring leaf flush in aspen (populus tremuloides) clones is altered by long-term growth at elevated carbon dioxide and elevated ozone concentration. | early spring leaf out is important to the success of deciduous trees competing for light and space in dense forest plantation canopies. in this study, we investigated spring leaf flush and how long-term growth at elevated carbon dioxide concentration ([co(2)]) and elevated ozone concentration ([o(3)]) altered leaf area index development in a closed populus tremuloides (aspen) canopy. this work was done at the aspen face experiment where aspen clones have been grown since 1997 in conditions simul ... | 2010 | 19625117 |
| altered leaf morphology, leaf resource dilution and defense chemistry induction in frost-defoliated aspen (populus tremuloides). | in may 2007, a widespread frost event defoliated much of utah's high elevation aspen. about 5 weeks later, the frost-defoliated aspen produced a second leaf flush. the objective of this study was to characterize changes in leaf morphology and function in re-flush leaves following frost defoliation. leaf size and thickness, photosynthesis, carbohydrate and nutrient status, and defense chemistry (phenolic glycosides and condensed tannins) were measured in first and second flush leaves. the second ... | 2009 | 19671568 |
| the influence of weather and fuel type on the fuel composition of the area burned by forest fires in ontario, 1996-2006. | forest fires are influenced by weather, fuels, and topography, but the relative influence of these factors may vary in different forest types. compositional analysis can be used to assess the relative importance of fuels and weather in the boreal forest. do forest or wild land fires burn more flammable fuels preferentially or, because most large fires burn in extreme weather conditions, do fires burn fuels in the proportions they are available despite differences in flammability? in the canadian ... | 2009 | 19688931 |
| take me to your leader: does early successional nonhost vegetation spatially inhibit pissodes strobi (coleoptera: curculionidae)? | the spatial influences of host and nonhost trees and shrubs on the colonization patterns of white pine weevil pissodes strobi (peck) were studied within a stand of planted interior hybrid spruce [picea glauca (moench) voss x picea engelmannii (parry) ex engelm.]. planted spruce accounted for one third of all trees within the stand, whereas the remaining two thirds were comprised of early-successional nonhost vegetation, such as alder (alnus spp.), paper birch (betula papyrifera marsh.), black co ... | 2009 | 19689899 |
| species-specific responses to atmospheric carbon dioxide and tropospheric ozone mediate changes in soil carbon. | we repeatedly sampled the surface mineral soil (0-20 cm depth) in three northern temperate forest communities over an 11-year experimental fumigation to understand the effects of elevated carbon dioxide (co(2)) and/or elevated phyto-toxic ozone (o(3)) on soil carbon (c). after 11 years, there was no significant main effect of co(2) or o(3) on soil c. however, within the community containing only aspen (populus tremuloides michx.), elevated co(2) caused a significant decrease in soil c content. t ... | 2009 | 19754884 |
| analysis of a farquhar-von caemmerer-berry leaf-level photosynthetic rate model for populus tremuloides in the context of modeling and measurement limitations. | the balance of mechanistic detail with mathematical simplicity contributes to the broad use of the farquhar, von caemmerer and berry (fvcb) photosynthetic rate model. here the fvcb model was coupled with a stomatal conductance model to form an [a,g(s)] model, and parameterized for mature populus tremuloides leaves under varying co(2) and temperature levels. data were selected to be within typical forest light, co(2) and temperature ranges, reducing artifacts associated with data collected at ext ... | 2010 | 19766365 |
| leaf and canopy conductance in aspen and aspen-birch forests under free-air enrichment of carbon dioxide and ozone. | increasing concentrations of atmospheric carbon dioxide (co2) and tropospheric ozone (o3) have the potential to affect tree physiology and structure, and hence forest feedbacks on climate. here, we investigated how elevated concentrations of co2 (+45%) and o3 (+35%), alone and in combination, affected conductance for mass transfer at the leaf and canopy levels in pure aspen (populus tremuloides michx.) and in mixed aspen and birch (betula papyrifera marsh.) forests in the free-air co2-o3 enrichm ... | 2009 | 19773339 |
| phenolic compounds in ectomycorrhizal interaction of lignin modified silver birch. | the monolignol biosynthetic pathway interconnects with the biosynthesis of other secondary phenolic metabolites, such as cinnamic acid derivatives, flavonoids and condensed tannins. the objective of this study is to evaluate whether genetic modification of the monolignol pathway in silver birch (betula pendula roth.) would alter the metabolism of these phenolic compounds and how such alterations, if exist, would affect the ectomycorrhizal symbiosis. | 2009 | 19788757 |
| diurnal changes in photosynthetic parameters of populus tremuloides, modulated by elevated concentrations of co2 and/or o3 and daily climatic variation. | the diurnal changes in light-saturated photosynthesis (pn) under elevated co(2) and/or o(3) in relation to stomatal conductance (g(s)), water potential, intercellular [co(2)], leaf temperature and vapour-pressure difference between leaf and air (vpd(l)) were studied at the aspen face site. two aspen (populus tremuloides michx.) clones differing in their sensitivity to ozone were measured. the depression in pn was found after 10:00 h. the midday decline in pn corresponded with both decreased g(s) ... | 2010 | 19796856 |
| elevated co2 response of photosynthesis depends on ozone concentration in aspen. | the effect of elevated co(2) and o(3) on apparent quantum yield (varphi), maximum photosynthesis (p(max)), carboxylation efficiency (v(cmax)) and electron transport capacity (j(max)) at different canopy locations was studied in two aspen (populus tremuloides) clones of contrasting o(3) tolerance. local light climate at every leaf was characterized as fraction of above-canopy photosynthetic photon flux density (%ppfd). elevated co(2) alone did not affect varphi or p(max), and increased j(max) in ... | 2010 | 19854548 |
| dna damage in populus tremuloides clones exposed to elevated o3. | the effects of elevated concentrations of atmospheric tropospheric ozone (o(3)) on dna damage in five trembling aspen (populus tremuloides michx.) clones growing in a free-air enrichment experiment in the presence and absence of elevated concentrations of carbon dioxide (co(2)) were examined. growing season mean hourly o(3) concentrations were 36.3 and 47.3 ppb for ambient and elevated o(3) plots, respectively. the 4th highest daily maximum 8-h ambient and elevated o(3) concentrations were 79 an ... | 2010 | 19879681 |
| direct amplification of dna from fresh and preserved ectomycorrhizal root tips. | methods are described by which dna can be amplified directly from ectomycorrhizal root tip homogenates of a variety of plant species (picea mariana (black spruce), betula papyrifera (paper birch), populus tremuloides (trembling aspen) and alnus sp.(alder)), including root tips that have been preserved in rna later (ambion, austin, tx). in most cases for extracts and homogenates diluted 10-fold prior to pcr, and in all cases for 100-fold dilutions, direct amplification of dna from fresh root tip ... | 2010 | 19963016 |
| inhibitor studies of leaf lamina hydraulic conductance in trembling aspen (populus tremuloides michx.) leaves. | the present study investigated leaf water transport properties in trembling aspen (populus tremuloides) leaves. leaf lamina hydraulic conductance (k(lam)) and stomatal conductance (g(s)) were drastically suppressed by naf (a general metabolic inhibitor). in leaves treated with 0.2 mm hgcl(2) (an aquaporin blocker), k(lam) declined by 22% when the leaves were sampled in june but the decline was not significant when the leaves were sampled in august. the leaves sampled in june that transpired 30 m ... | 2010 | 20022867 |
| glycosylation-mediated phenylpropanoid partitioning in populus tremuloides cell cultures. | phenylpropanoid-derived phenolic glycosides (pgs) and condensed tannins (cts) comprise large, multi-purpose non-structural carbon sinks in populus. a negative correlation between pg and ct concentrations has been observed in several studies. however, the molecular mechanism underlying the relationship is not known. | 2009 | 20040108 |
| thermal acclimation of photosynthesis: a comparison of boreal and temperate tree species along a latitudinal transect. | common gardens were established along a approximately 900 km latitudinal transect to examine factors limiting geographical distributions of boreal and temperate tree species in eastern north america. boreal representatives were trembling aspen (populus tremuloides michx.) and paper birch (betula papyrifera marsh.), while temperate species were eastern cottonwood (populus deltoides bartr ex. marsh var. deltoides) and sweetgum (liquidambar styraciflua l.). the species were compared with respect to ... | 2010 | 20082671 |
| solution-state 2d nmr of ball-milled plant cell wall gels in dmso-d(6)/pyridine-d(5). | nmr fingerprinting of the components of finely divided plant cell walls swelled in dmso has been recently described. cell wall gels, produced directly in the nmr tube with perdeutero-dimethylsulfoxide, allowed the acquisition of well resolved/dispersed 2d (13)c-(1)h correlated solution-state nmr spectra of the entire array of wall polymers, without the need for component fractionation. that is, without actual solubilization, and without apparent structural modification beyond that inflicted by t ... | 2010 | 20090974 |
| the impact of vessel size on vulnerability curves: data and models for within-species variability in saplings of aspen, populus tremuloides michx. | the objective of this study was to quantify the relationship between vulnerability to cavitation and vessel diameter within a species. we measured vulnerability curves (vcs: percentage loss hydraulic conductivity versus tension) in aspen stems and measured vessel-size distributions. measurements were done on seed-grown, 4-month-old aspen (populus tremuloides michx) grown in a greenhouse. vcs of stem segments were measured using a centrifuge technique and by a staining technique that allowed a vc ... | 2010 | 20199629 |
| changes in diurnal patterns within the populus transcriptome and metabolome in response to photoperiod variation. | changes in seasonal photoperiod provides an important environmental signal that affects the timing of winter dormancy in perennial, deciduous, temperate tree species, such as hybrid aspen (populus tremula x populus tremuloides). in this species, growth cessation, cold acclimation and dormancy are induced in the autumn by the detection of day-length shortening that occurs at a given critical day length. important components in the detection of such day-length changes are photoreceptors and the ci ... | 2010 | 20302601 |
| induction of phenolic glycosides by quaking aspen (populus tremuloides) leaves in relation to extrafloral nectaries and epidermal leaf mining. | we studied the effect of epidermal leaf mining on the leaf chemistry of quaking aspen, populus tremuloides, during an outbreak of the aspen leaf miner, phyllocnistis populiella, in the boreal forest of interior alaska. phyllocnistis populiella feeds on the epidermal cells of p. tremuloides leaves. eleven days after the onset of leaf mining, concentrations of the phenolic glycosides tremulacin and salicortin were significantly higher in aspen leaves that had received natural levels of leaf mining ... | 2010 | 20354896 |
| the speciation of water-soluble al and zn in the rhizosphere of forest soils. | this study focuses on the relationships of dissolved al and zn speciation with microbial and chemical soil properties in the bulk and rhizosphere of forest soils. the soil components were sampled under populus tremuloides michx. at six sites located close to industrial facilities. total water-soluble (al(ws), zn(ws)) and reactive (al(r), zn(r)) al and zn concentrations measured in soil water extracts, speciation data modeled by wham 6, chemical properties (ph, doc, major cations and anions) and ... | 2010 | 20383395 |
| impact of host tree on forest tent caterpillar performance and offspring overwintering mortality. | one of the most damaging insect pests in deciduous forests of north america is the forest tent caterpillar, malacosoma disstria hübner. it can feed on a variety of plants, but trembling aspen (populus tremuloides michaux) is its preferred host and sugar maple (acer saccharum marshall) serves as a secondary one in the northern part of its distribution. because host plant characteristics influence insect performance and survival, we evaluated the impact of trembling aspen and sugar maple foliage o ... | 2010 | 20388280 |
| targeted integration and removal of transgenes in hybrid aspen (populus tremula l. x p. tremuloides michx.) using site-specific recombination systems. | two site-specific recombination systems, cre/lox and flp/frt, were tested for marker gene removal and targeted gene transfer in a model tree system. a hybrid aspen clone (populus tremula x populus tremuloides) was co-transformed with plasmids containing either the flp or the cre recombinase, both under control of a heat-inducible promoter (hsp, gmhsp17.5-e from soybean) flanked by the two recognition sites (frt or lox). molecular investigations of heat-shock treated cre or flp transgenic lines i ... | 2010 | 20398239 |
| circadian clock components regulate entry and affect exit of seasonal dormancy as well as winter hardiness in populus trees. | this study addresses the role of the circadian clock in the seasonal growth cycle of trees: growth cessation, bud set, freezing tolerance, and bud burst. populus tremula x populus tremuloides (ptt) late elongated hypocotyl1 (pttlhy1), pttlhy2, and timing of cab expression1 constitute regulatory clock components because down-regulation by rna interference of these genes leads to altered phase and period of clock-controlled gene expression as compared to the wild type. also, both rna interference ... | 2010 | 20530613 |
| alteration of microbial communities colonizing leaf litter in a temperate woodland stream by growth of trees under conditions of elevated atmospheric co2. | elevated atmospheric co(2) can cause increased carbon fixation and altered foliar chemical composition in a variety of plants, which has the potential to impact forested headwater streams because they are detritus-based ecosystems that rely on leaf litter as their primary source of organic carbon. fungi and bacteria play key roles in the entry of terrestrial carbon into aquatic food webs, as they decompose leaf litter and serve as a source of nutrition for invertebrate consumers. this study test ... | 2010 | 20543045 |
| mass spectrometry-based sequencing of lignin oligomers. | although the primary structure of proteins, nucleic acids, and carbohydrates can be readily determined, no sequencing method has been described yet for the second most abundant biopolymer on earth (i.e. lignin). within secondary-thickened plant cell walls, lignin forms an aromatic mesh arising from the combinatorial radical-radical coupling of monolignols and many other less abundant monomers. this polymerization process leads to a plethora of units and linkage types that affect the physicochemi ... | 2010 | 20554692 |
| recovery of populus tremuloides seedlings following severe drought causing total leaf mortality and extreme stem embolism. | in contrast with other native populus species in north america, populus tremuloides (aspen) can successfully establish itself in drought-prone areas, yet no comprehensive analysis has been performed on the ability of seedlings to withstand and recover from a severe drought resulting in complete leaf mortality. here, we subjected 4-month-old aspen seedlings grown in two contrasting soil media to a progressive drought until total leaf mortality, followed by a rewatering cycle. stomatal conductance ... | 2010 | 20618763 |
| aging in a long-lived clonal tree. | from bacteria to multicellular animals, most organisms exhibit declines in survivorship or reproductive performance with increasing age ("senescence"). evidence for senescence in clonal plants, however, is scant. during asexual growth, we expect that somatic mutations, which negatively impact sexual fitness, should accumulate and contribute to senescence, especially among long-lived clonal plants. we tested whether older clones of populus tremuloides (trembling aspen) from natural stands in brit ... | 2010 | 20808953 |
| temperature response of isoprene emission in vivo reflects a combined effect of substrate limitations and isoprene synthase activity: a kinetic analysis. | the responses of isoprene emission rate to temperature are characterized by complex time-dependent behaviors that are currently not entirely understood. to gain insight into the temperature dependencies of isoprene emission, we studied steady-state and transient responses of isoprene emission from hybrid aspen (populus tremula × populus tremuloides) leaves using a fast-response gas-exchange system coupled to a proton-transfer reaction mass spectrometer. a method based on postillumination isopren ... | 2010 | 20837700 |
| defensive effects of extrafloral nectaries in quaking aspen differ with scale. | the effects of plant defenses on herbivory can differ among spatial scales. this may be particularly common with indirect defenses, such as extrafloral nectaries (efns), that attract predatory arthropods and are dependent on predator distribution, abundance, and behavior. we tested the defensive effects of efns in quaking aspen (populus tremuloides michx.) against damage by a specialist herbivore, the aspen leaf miner (phyllocnistis populiella cham.), at the scale of individual leaves and entire ... | 2010 | 20931234 |
| changes in composition and sugar release across the annual rings of populus wood and implications on recalcitrance. | understanding structural characteristics that are responsible for biomass recalcitrance by identifying why it is more difficult for some plants, or portions of plants, to release their sugars would be extremely valuable in overcoming this barrier. with this in mind, this study investigated the recalcitrance of wood by considering the effects of aging in two populus tremuloides cross sections. by applying our novel small scale systems, including a multi-well pretreatment and enzymatic hydrolysis ... | 2010 | 20943384 |
| are wolves saving yellowstone's aspen? a landscape-level test of a behaviorally mediated trophic cascade. | behaviorally mediated trophic cascades (bmtcs) occur when the fear of predation among herbivores enhances plant productivity. based primarily on systems involving small-bodied predators, bmtcs have been proposed as both strong and ubiquitous in natural ecosystems. recently, however, synthetic work has suggested that the existence of bmtcs may be mediated by predator hunting mode, whereby passive (sit-and-wait) predators have much stronger effects than active (coursing) predators. one bmtc that h ... | 2010 | 20957967 |
| morphology and phylogenetic placement of endoconidioma, a new endoconidial genus from trembling aspen. | endoconidioma populi gen. et sp. nov. is described from black subicula on twigs of trembling aspen, populus tremuloides, in alberta, canada. pycnidium-like conidiomata are produced on twigs and in culture, but, unlike pycnidia, conidiomata of e. populi have a closed peridium and a locule filled with conidiogenous cells that form conidia endogenously. these endoconidia are hyaline, unicellular and released by the dissolution of the peridial cell wall. in addition to endoconidia, mostly two-celled ... | 2004 | 21148931 |
| contrasting the morphology, anatomy and fungal colonization of new pioneer and fibrous roots. | • not all roots born as first-order branches are the same and this has important consequences for overall function. we hypothesized that, compared with fibrous roots, pioneer roots are built to live longer at the expense of absorptive capacity. • we tested this hypothesis by investigating pioneer and fibrous roots in their first 14 d of life in the arbuscular mycorrhizal tree species: acer negundo, acer saccharum, juglans nigra, liriodendron tulipifera and populus tremuloides. root observations ... | 2011 | 21210817 |
| comparisons of sporl and dilute acid pretreatments for sugar and ethanol productions from aspen. | this study reports comparative evaluations of sugar and ethanol production from a native aspen (populus tremuloides) between sulfite pretreatment to overcome recalcitrance of lignocellulose (sporl) and dilute acid (da) pretreatments. all aqueous pretreatments were carried out in a laboratory wood pulping digester using wood chips at 170°c with a liquid to oven dry (od) wood ratio (l/w) of 3:1 at two levels of acid charge on wood of 0.56 and 1.11%. sodium bisulfite charge on od wood was 0 for da ... | 2010 | 21240938 |
| perturbation of wood cellulose synthesis causes pleiotropic effects in transgenic aspen. | genetic manipulation of cellulose biosynthesis in trees may provide novel insights into the growth and development of trees. to explore this possibility, the overexpression of an aspen secondary wall-associated cellulose synthase (ptdcesa8) gene was attempted in transgenic aspen (populus tremuloides l.) and unexpectedly resulted in silencing of the transgene as well as its endogenous counterparts. the main axis of the transgenic aspen plants quickly stopped growing, and weak branches adopted a w ... | 2011 | 21300756 |
| effects of canopy-deposition interaction on h+ supply to soils in pinus banksiana and populus tremuloides ecosystems in the athabasca oil sands region in alberta, canada. | soil acidification has been of concern in the oil sands region in alberta due to increased acid deposition. using the canopy budget model, and accounting for h(+) canopy leaching by organic acids, we determined sources and sinks of h+ in throughfall in jack pine (pinus banksiana) and trembling aspen (populus tremuloides) stands in two watersheds from 2006 to 2009. in pine stands, h+ deposition was greater in throughfall than in bulk precipitation while the opposite was true in aspen stands. the ... | 2011 | 21310518 |
| ultra-structural organisation of cell wall polymers in normal and tension wood of aspen revealed by polarisation ftir microspectroscopy. | polarisation fourier transform infra-red (ftir) microspectroscopy was used to characterize the organisation and orientation of wood polymers in normal wood and tension wood from hybrid aspen (populus tremula × populus tremuloides). it is shown that both xylan and lignin in normal wood are highly oriented in the fibre wall. their orientation is parallel with the cellulose microfibrils and hence in the direction of the fibre axis. in tension wood a similar orientation of lignin was found. however, ... | 2011 | 21340698 |
| the influence of recent climate change on tree height growth differs with species and spatial environment. | tree growth has been reported to increase in response to recent global climate change in controlled and semi-controlled experiments, but few studies have reported response of tree growth to increased temperature and atmospheric carbon dioxide (co2) concentration in natural environments. this study addresses how recent global climate change has affected height growth of trembling aspen (populus tremuloides michx) and black spruce (picea mariana mill b.s.) in their natural environments. we sampled ... | 2011 | 21358817 |
| developmental contributions to phenotypic variation in functional leaf traits within quaking aspen clones. | phenotypic variation in plant traits is strongly influenced by genetic and environmental factors. over the life span of trees, developmental factors may also strongly influence leaf phenotypes. the objective of this study was to fill gaps in our understanding of developmental influences on patterns of phenotypic trait variation among different-aged ramets within quaking aspen (populus tremuloides michx.) clones. we hypothesized that phenotypic variation in leaf functional traits is strongly infl ... | 2011 | 21389003 |
| root-associated ectomycorrhizal fungi shared by various boreal forest seedlings naturally regenerating after a fire in interior alaska and correlation of different fungi with host growth responses. | the role of common mycorrhizal networks (cmns) in postfire boreal forest successional trajectories is unknown. we investigated this issue by sampling a 50-m by 40-m area of naturally regenerating black spruce (picea mariana), trembling aspen (populus tremuloides), and paper birch (betula papyrifera) seedlings at various distances from alder (alnus viridis subsp. crispa), a nitrogen-fixing shrub, 5 years after wildfire in an alaskan interior boreal forest. shoot biomasses and stem diameters of 4- ... | 2011 | 21441343 |
| root carbon reserve dynamics in aspen seedlings: does simulated drought induce reserve limitation? | in a greenhouse study we quantified the gradual change of gas exchange, water relations and root reserves of aspen (populus tremuloides michx.) seedlings growing over a 3-month period of severe water stress. the aim of the study was to quantify the complex interrelationship between growth, water and gas exchange, and root carbon (c) dynamics. various growth, gas exchange and water relations variables in combination with root reserves were measured periodically on seedlings that had been exposed ... | 2011 | 21444372 |
| surface tension phenomena in the xylem sap of three diffuse porous temperate tree species. | in plant physiology models involving bubble nucleation, expansion or elimination, it is typically assumed that the surface tension of xylem sap is equal to that of pure water, though this has never been tested. in this study we collected xylem sap from branches of the tree species populus tremuloides, betula papyrifera and sorbus aucuparia over 3 months. we measured the instantaneous surface tension and followed changes over a period of 0.5-5 h using the pendant drop technique. in all thr ... | 2011 | 21470981 |
| comparisons of sporl and dilute acid pretreatments for sugar and ethanol productions from aspen. | this study reports comparative evaluations of sugar and ethanol production from a native aspen (populus tremuloides) between sulfite pretreatment to overcome recalcitrance of lignocellulose (sporl) and dilute acid (da) pretreatments. all aqueous pretreatments were carried out in a laboratory wood pulping digester using wood chips at 170°c with a liquid to oven dry (od) wood ratio (l/w) of 3:1 at two levels of acid charge on wood of 0.56 and 1.11%. sodium bisulfite charge on od wood was 0 for da ... | 2011 | 21485032 |
| induction of a longer term component of isoprene release in darkened aspen leaves: origin and regulation under different environmental conditions. | after darkening, isoprene emission continues for 20 to 30 min following biphasic kinetics. the initial dark release of isoprene (postillumination emission), for 200 to 300 s, occurs mainly at the expense of its immediate substrate, dimethylallyldiphosphate (dmadp), but the origin and controls of the secondary burst of isoprene release (dark-induced emission) between approximately 300 and 1,500 s, are not entirely understood. we used a fast-response gas-exchange system to characterize the control ... | 2011 | 21502186 |
| using next generation transcriptome sequencing to predict an ectomycorrhizal metabolome. | abstract: background: mycorrhizae, symbiotic interactions between soil fungi and tree roots, are ubiquitous in terrestrial ecosystems. the fungi contribute phosphorous, nitrogen and mobilized nutrients from organic matter in the soil and in return the fungus receives photosynthetically-derived carbohydrates. this union of plant and fungal metabolisms is the mycorrhizal metabolome. understanding this symbiotic relationship at a molecular level provides important contributions to the understanding ... | 2011 | 21569493 |
| conifer expansion reduces the competitive ability and herbivore defense of aspen by modifying light environment and soil chemistry. | disturbance patterns strongly influence plant community structure. what remains less clear, particularly at a mechanistic level, is how changes in disturbance cycles alter successional outcomes in plant communities. there is evidence that fire suppression is resulting in longer fire return intervals in subalpine forests and that these lengthened intervals increase competitive interactions between aspen and conifer species. we conducted a field and greenhouse study to compare photosynthesis, grow ... | 2011 | 21602559 |
| within-plant distribution of phenolic glycosides and extrafloral nectaries in trembling aspen (populus tremuloides; salicaceae). | expression of foliar secondary compounds and extrafloral nectaries (efns) within the same leaves may be incompatible if secondary compounds repel beneficial insects that might otherwise be attracted to efns. this study examined the within-plant distributions of phenolic glycosides and efns in trembling aspen, populus tremuloides, and their relationships to herbivore damage. populus tremuloides expresses extrafloral nectaries (efns) on a subset of its leaves. we studied short and tall naturally o ... | 2010 | 21622422 |
| molecular and dendrochronological analysis of natural root grafting in populus tremuloides (salicaceae). | trembling aspen (populus tremuloides) is a clonal tree species, which regenerates mostly through root suckering. in spite of vegetative propagation, aspen maintains high levels of clonal diversity. we hypothesized that the maintenance of clonal diversity in this species can be facilitated by integrating different clones through natural root grafts into aspen's communal root system. to verify this hypothesis, we analyzed root systems of three pure aspen stands where clones had been delineated wit ... | 2009 | 21628295 |
| does clonal integration improve competitive ability? a test using aspen (populus tremuloides [salicaceae]) invasion into prairie. | many clonal plants consist of many connected individual ramets, allowing them to share water and nutrients via physiological integration. integration among ramets may also improve the ability of clonal plants to tolerate abiotic stress or improve the competitive ability of individual ramets. here i use a field experiment to determine whether clonal integration improves ramet performance for a widespread clonal tree species invading into native prairie. aspen (populus tremuloides) dominates the s ... | 2002 | 21665647 |
| acute o(3) damage on first year coppice sprouts of aspen and maple sprouts in an open-air experiment. | we studied the effect of high ozone (o(3)) concentration (110-490 nmol mol(-1)) on regenerating aspen (populus tremuloides) and maple (acer saccharum) trees at an open-air o(3) pollution experiment near rhinelander wi usa. this study is the first of its kind to examine the effects of acute o(3) exposure on aspen and maple sprouts after the parent trees, which were grown under elevated o(3) and/or co(2) for 12 years, were harvested. acute o(3) damage was not uniform within the crowns of aspen suc ... | 2011 | 21750809 |
| functional and expressional analyses of pmdam genes associated with endodormancy in japanese apricot (prunus mume). | bud endodormancy in woody plants plays an important role in their perennial growth cycles. we previously identified a mads-box gene, prunus mume dormancy associated mads6 (pmdam6), expressed in the endodormant lateral buds of japanese apricot (p. mume) as a candidate for the dormancy-controlling gene. in this study, we demonstrated the growth inhibitory functions of pmdam6 by overexpressing it in transgenic poplar (populus tremula x tremuloides). transgenic poplar plants constitutively expressin ... | 2011 | 21795580 |
| high titer ethanol production from simultaneous enzymatic saccharification and fermentation of aspen at high solids: a comparison between sporl and dilute acid pretreatments. | native aspen (populus tremuloides) was pretreated using sulfuric acid and sodium bisulfite (sporl) and dilute sulfuric acid alone (da). simultaneous enzymatic saccharification and fermentation (ssf) was conducted at 18% solids using commercial enzymes with cellulase loadings ranging from 6 to 15fpu/g glucan and saccharomyces cerevisiae y5. compared with da pretreatment, the sporl pretreatment reduced the energy required for wood chip size-reduction, and reduced mixing energy of the resultant sub ... | 2011 | 21824766 |
| assisted migration to address climate change: recommendations for aspen reforestation in western canada. | human-aided movement of species populations in large-scale reforestation programs could be a potent and cost-effective climate change adaptation strategy. such large-scale management interventions, however, tend to entail the risks of unintended consequences, and we propose that three conditions should be met before implementing assisted migration in reforestation programs: (1) evidence of a climate-related adaptational lag, (2) observed biological impacts, and (3) robust model projections to ta ... | 2011 | 21830704 |
| atmospheric change alters foliar quality of host trees and performance of two outbreak insect species. | this study examined the independent and interactive effects of elevated carbon dioxide (co(2)) and ozone (o(3)) on the foliar quality of two deciduous trees species and the performance of two outbreak herbivore species. trembling aspen (populus tremuloides) and paper birch (betula papyrifera) were grown at the aspen face research site in northern wisconsin, usa, under four combinations of ambient and elevated co(2) and o(3). we measured the effects of elevated co(2) and o(3) on aspen and birch p ... | 2011 | 21971584 |
| climate change intensification of herbivore impacts on tree recruitment. | altered species interactions are difficult to predict and yet may drive the response of ecological communities to climate change. we show that declining snowpack strengthens the impacts of a generalist herbivore, elk (cervus elaphus), on a common tree species. thick snowpack substantially reduces elk visitation to sites; aspen (populus tremuloides) shoots in these areas experience lower browsing rates, higher survival and enhanced recruitment. aspen inside herbivore exclosures have greatly incre ... | 2011 | 21976686 |
| leaf respiratory acclimation to climate: comparisons among boreal and temperate tree species along a latitudinal transect. | in common gardens along an ∼900 km latitudinal transect through wisconsin and illinois, u.s.a., tree species typical of boreal and temperate forests were compared with respect to the nature and magnitude of leaf respiratory acclimation to contrasting climates. the boreal representatives were trembling aspen (populus tremuloides michx.) and paper birch (betula papyrifera marsh.), while the temperate species were eastern cottonwood (populus deltoides bartr ex. marsh var. deltoides) and sweetgum (l ... | 2011 | 21990024 |
| hebeloma crustuliniforme facilitates ammonium and nitrate assimilation in trembling aspen (populus tremuloides) seedlings. | this study examined the role of ectomycorrhizal associations in nitrogen assimilation of populus tremuloides seedlings. seedlings were inoculated with hebeloma crustuliniforme and compared with non-inoculated plants. nitrogen-metabolizing enzymatic properties were also determined in h. crustuliniforme grown in sterile culture. the seedlings and fungal cultures were subjected to nitrogen treatments (including no₃⁻, nh₄⁺ and a combination of no₃⁻ + nh₄⁺) for 2 months to examine the effects on grow ... | 2011 | 22011965 |
| will changes in root-zone temperature in boreal spring affect recovery of photosynthesis in picea mariana and populus tremuloides in a future climate? | future climate will alter the soil cover of mosses and snow depths in the boreal forests of eastern canada. in field manipulation experiments, we assessed the effects of varying moss and snow depths on the physiology of black spruce (picea -mariana (mill.) b.s.p.) and trembling aspen (populus tremuloides michx.) in the boreal black spruce forest of western québec. for 1 year, naturally regenerated 10-year-old spruce and aspen were grown with one of the following treatments: additional n fertiliz ... | 2011 | 22021010 |
| fungal planet description sheets: 69-91. | novel species of microfungi described in the present study include the following from australia: bagadiella victoriae and bagadiella koalae on eucalyptus spp., catenulostroma eucalyptorum on eucalyptus laevopinea, cercospora eremochloae on eremochloa bimaculata, devriesia queenslandica on scaevola taccada, diaporthe musigena on musa sp., diaporthe acaciigena on acacia retinodes, leptoxyphium kurandae on eucalyptus sp., neofusicoccum grevilleae on grevillea aurea, phytophthora fluvialis from wate ... | 2011 | 22025808 |
| accounting for density reduction and structural loss in standing dead trees: implications for forest biomass and carbon stock estimates in the united states. | abstract: background: standing dead trees are one component of forest ecosystem dead wood carbon (c) pools, whose national stock is estimated by the u.s. as required by the united nations framework convention on climate change. historically, standing dead tree c has been estimated as a function of live tree growing stock volume in the u.s.'s national greenhouse gas inventory. initiated in 1998, the usda forest service's forest inventory and analysis program (responsible for compiling the nation ... | 2011 | 22115425 |
| The roles of hydraulic and carbon stress in a widespread climate-induced forest die-off. | Forest ecosystems store approximately 45% of the carbon found in terrestrial ecosystems, but they are sensitive to climate-induced dieback. Forest die-off constitutes a large uncertainty in projections of climate impacts on terrestrial ecosystems, climate-ecosystem interactions, and carbon-cycle feedbacks. Current understanding of the physiological mechanisms mediating climate-induced forest mortality limits the ability to model or project these threshold events. We report here a direct and in s ... | 2011 | 22167807 |
| evaluation of a new battery of toxicity tests for boreal forest soils: assessment of the impact of hydrocarbons and salts. | the ability to assess the toxic potential of soil contamination within boreal regions is currently limited to test species representative of arable lands. this study evaluated the use of six boreal plant (pinus banksiana, picea glauca, picea mariana, populus tremuloides, calamagrostis canadensis, and solidago canadensis) and four invertebrate (dendrodrilus rubidus, folsomia nivalis, proisotoma minuta, and oppia nitens) species, and compared their performance to a suite of standard agronomic soil ... | 2012 | 22228553 |