| effects of volatile substances released by foliage of abies balsamea. | | 1972 | 4621720 |
| insect-plant interactions: endocrine defences. | it is the inevitable consequence of evolution that competitive species living together in a restricted space must try to exclude each other. plants and insects are prime examples of this eternal competition, and although neither of these is in danger of extinction, their mutual defensive strategies are of compelling interest to the human race. plant defences based on the insecticidal activity of certain of their secondary chemicals are readily apparent. only through research into the fundamental ... | 1984 | 6559111 |
| electrophoretic analysis of coniferyl alcohol oxidase and related laccases. | gradient gel electrophoretic methods enabled a distinction to be made between coniferyl alcohol oxidase (cao) of lignifying cell walls and a pi approximately 9 pine "laccase" recently implicated in lignification (science 1993 260, 672). following treatment of a partially purified protein mixture from developing xylem of pinus strobus with 2-[n-morpholine]ethanesulfonic acid (mes) buffer, isoelectric focusing and sodium dodecyl sulphate-polyacrylamide gel electrophoresis indicated that cao had be ... | 1994 | 7859710 |
| comparison of ribosomal dna length and restriction site polymorphisms in gremmeniella and ascocalyx isolates. | the small subunit (ssu) and the internal transcribed spacer (its) of nuclear ribosomal dna genes from 27 specimens of the fungal genera gremmeniella and ascocalyx were amplified by pcr. length polymorphisms were observed in the ssu and allowed the differentiation of four groups among the isolates tested: (i) ascocalyx abietis; (ii) gremmeniella isolates from picea spp.; (iii) gremmeniella isolates from abies balsamea; and (iv) gremmeniella isolates from abies sacchalinensis, larix spp., and pinu ... | 1994 | 7912501 |
| modern pollen-representation of some boreal species on islands in a large lake in canada. | studies of pollen source areas of closed-canopy sites are contradictory. some authors found that closed-canopy sites mainly collect local pollen while others found more distant sources. this dichotomy might stem from the use of canopies of varying degrees of closure, and from variations in the pollen productivity of the local vegetation and the background pollen rain. here, 30 islands were used to evaluate the pollen sources of closed-canopy sites. we compared pollen with the forest inventory in ... | 2000 | 10704644 |
| developmental expression and stress induction of glutathione s-transferase in the spruce budworm, choristoneura fumiferana. | developmental and stress-induced expression of choristoneura fumiferana glutathione s-transferase (cfgst) mrna and protein were examined using northern blots and western blots. high levels of cfgst mrna and protein were detected in 1st instar larvae and diapausing 2nd instar larvae. expression of cfgst gradually decreased during larval development from 3rd to 5th instar, after which the expression increased once again, reaching peak levels in 6th instar larvae. cfgst mrna and protein were undete ... | 2001 | 11033162 |
| photosynthesis and carbon allocation of six boreal tree species grown in understory and open conditions. | one-year-old seedlings of abies balsamea (l.) mill, picea glauca (moench) voss, pinus contorta loudon, betula papyrifera marsh., populus tremuloides michx. and populus balsamifera l. were transplanted in the spring, in pots, to the understory of a mixed p. tremuloides-p. balsamifera stand or to an adjacent open site. growth and leaf characteristics were measured and photosynthetic light response curves determined in mid-august. overall, the coniferous seedlings showed less photosynthetic plastic ... | 2001 | 11276418 |
| chemical characterization of fine particle emissions from fireplace combustion of woods grown in the northeastern united states. | a series of source tests was conducted to determine the chemical composition of fine particle emissions from the fireplace combustion of six species of woods grown in the northeastern united states: red maple, northern red oak, paper birch, eastern white pine, eastern hemlock, and balsam fir. results include fine particle emission rates for total mass, organic and elemental carbon, ionic species, elemental species including potassium, and over 250 specific organic compounds. the data are intende ... | 2001 | 11452590 |
| fate of spinosad in litter and soils of a mixed conifer stand in the acadian forest region of new brunswick. | spinosad is a natural insecticide, produced via fermentation culture of the actinomycete saccharopolyspora spinosa, with potential use against a number of forest pests including spruce budworm (choristoneura fumiferana [clem]). persistence of spinosad was determined in terrestrial fate experiments conducted within a semimature stand of black spruce (picea mariana [mill.]) and balsam fir (abies balsamea [l]) in the acadian forest region of new brunswick, canada. results of experiments established ... | 2002 | 11829646 |
| changes in foliar spectral reflectance and chlorophyll fluorescence of four temperate species following branch cutting. | spectral reflectance and chlorophyll fluorescence are rapid non-invasive methods that can be used to quantify plant stress. because variation in ambient light (e.g., diurnal patterns of solar radiation) may have a confounding effect on these measurements, branches are often excised in the field and then measured under controlled conditions in the laboratory. we studied four temperate tree species (abies balsamea (l.) mill. (balsam fir), betula papyrifera var. cordifolia (regel) fern. (paper birc ... | 2002 | 11986053 |
| mercury levels in lichens from different host trees around a chlor-alkali plant in new brunswick, canada. | mercury concentrations were determined in the epiphytic lichen hypogymnia physodes along five transects starting from a chlor-alkali plant located at dalhousie, new brunswick, a landfill site and a nearby electricity generating station. lichen samples were collected from white birch (betula papyrifera) and spruce (picea sp.) or balsam fir (abies balsamea). average lichen background mercury values were 0.088+/-0.005 microg/g from white birch and 0.148+/-0.046 microg/g from spruce trees, with a de ... | 2002 | 12109479 |
| lethal and sublethal effects of a neem-based insecticide on balsam fir sawfly (hymenoptera: diprionidae). | lethal and sublethal effects of neemix 4.5 ec, a commercial neem preparation, on balsam fir sawfly, neodiprion abietis (harris), were determined in the laboratory. larval mortality of n. abietis increased in a concentration-dependent manner, and lethal time decreased with increasing neemix 4.5 ec concentration. fifty percent of the larvae died after 4.6 d at a concentration of 90 ppm azadirachtin (aza) and 12.3 d at a concentration of 0.08 ppm. neemix 4.5 ec showed some deterrent effects to feed ... | 2003 | 12650342 |
| advantages of a mixed diet: feeding on several foliar age classes increases the performance of a specialist insect herbivore. | two field studies were carried out to determine the influence of abies balsamea foliage age on the preference and performance of larvae of neodiprion abietis, a specialist diprionid sawfly. preference was determined by examining n. abietis defoliation on all age classes of foliage. performance was estimated using larval survival, cocoon weights and the percentage of adults that were females. neodiprion abietis preference for, and performance on, current-year foliage was very low, peaked on 2 or ... | 2003 | 12721829 |
| constituents within pulp mill effluent deplete retinoid stores in white sucker and bind to rainbow trout retinoic acid receptors and retinoid x receptors. | wild female and male white sucker (catostomus commersoni) inhabiting an area receiving pulp mill effluent had reduced hepatic levels of retinol, didehydroretinol, retinyl esters, and didehydroretinyl esters, while vitamin e levels were unaffected. this disruption of the retinoid system led us to test methanol and dichloromethane extracts from the effluent of 11 pulp mills from across canada for their ability to bind to rainbow trout (oncorhynchus mykiss) retinoic acid receptors (rars) from the g ... | 2003 | 14713038 |
| neutralization and buffering capacity of leaves of sugar maple, largetooth aspen, paper birch and balsam fir. | we compared the acidity, the external acid neutralizing capacity and the buffering capacity of leaves of four commercially important tree species, largetooth aspen (populus grandidentata michx.), sugar maple (acer saccharum marsh.), paper birch (betula papyrifera marsh.) and balsam fir (abies balsamea (l.) mill), at two sites of contrasting soil fertility in southern quebec. external acid neutralizing capacity (enc) of leaves was determined by measuring the change in ph induced by soaking fresh ... | 1993 | 14969931 |
| auxin and ethylene regulation of diameter growth in trees. | recent studies on the phytohormonal regulation of seasonal cell-division activity in the cambium, primary-wall radial expansion of cambial derivatives, differentiation of xylem cells, and growth of the cortex in forest trees of the north temperate zone are reviewed. indol-3-ylacetic acid (iaa, auxin) has been characterized by combined gas chromatography-mass spectrometry (gc-ms) in the cambial region of abies balsamea, pinus densiflora, pinus sylvestris and quercus robur. all of the evidence sup ... | 1988 | 14972810 |
| 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 |
| design and evaluation of an aerial spray trial with true replicates to test the efficacy of bacillus thuringiensis insecticide in a boreal forest. | a field trial using true replicates was conducted successfully in a boreal forest in 1996 to evaluate the efficacy of two aerially applied bacillus thuringiensis formulations, abg 6429 and abg 6430. a complete randomized design with four replicates per treatment was chosen. twelve to 15 balsam fir (abies balsamea [l.] mill.) per plot were randomly selected as sample trees. interplot buffer zones, > or = 200 m wide, adequately prevented cross contamination from sprays that were atomized with four ... | 2003 | 14994805 |
| bacillus thuringiensis subsp. kurstaki aerial spray prescriptions for balsam fir stand protection against spruce budworm (lepidoptera: tortricidae). | although commercial formulations of bacillus thuringiensis subsp. kurstaki (btk) are being widely used in forest protection against lepidopteran defoliators, optimal application prescriptions have often yet to be worked out in detail. we conducted field experiments over a 6-yr period (1996-2001) in southwestern québec to determine application prescriptions for optimal protection of balsam fir, abies balsamea (l.), healthy stands against the spruce budworm, choristoneura fumiferana (clemens) (lep ... | 2004 | 15568352 |
| interacting influence of light and size on aboveground biomass distribution in sub-boreal conifer saplings with contrasting shade tolerance. | plant size often influences shade tolerance but relatively few studies have considered the functional response of taller plants to contrasting light environments. several boreal and sub-boreal abies, picea and pinus species were studied along a light (0-90% full sunlight) and size (30-400-cm high) gradient to examine the interactive influence of tree size and light availability on aboveground biomass distribution. sampling was conducted in two regions of canada: (a) british columbia, for abies l ... | 2005 | 15631985 |
| virulence of a nucleopolyhedrovirus to neodiprion abietis (hymenoptera: diprionidae). | different larval stages of balsam fir sawfly, neodiprion abietis (harris) (hymenoptera: diprionidae), were challenged by different concentrations of a nucleopolyhedrovirus in the laboratory to determine larval susceptibility to the virus and to test treatment effects of the virus on the sawfly survivors. the results indicated that younger larvae were more susceptible to the virus than older instars. the speed of larval death depended on the larval age and the virus concentration. generally, the ... | 2005 | 16539106 |
| influence of larval stage and virus inoculum on virus yield in insect host neodiprion abietis (hymenoptera: diprionidae). | virus yield produced by dead larvae of balsam fir sawfly, neodiprion abietis (harris) (hymenoptera: diprionidae), that had been infected at four different larval stages (second, third, fourth, or fifth instar) with two virus concentrations (10(5) polyhedral inclusion bodies (pib) /ml or 10(7) pib/ml), were analyzed and compared to determine the effects of instar and amount of virus inoculum on virus production. the results indicate that both larval stage and inoculation dosage significantly affe ... | 2005 | 16539107 |
| dark respiration rate increases with plant size in saplings of three temperate tree species despite decreasing tissue nitrogen and nonstructural carbohydrates. | in shaded environments, minimizing dark respiration during growth could be an important aspect of maintaining a positive whole-plant net carbon balance. changes with plant size in both biomass distribution to different tissue types and mass-specific respiration rates (r(d)) of those tissues would have an impact on whole-plant respiration. in this paper, we evaluated size-related variation in r(d), biomass distribution, and nitrogen (n) and total nonstructural carbohydrate (tnc) concentrations of ... | 2006 | 16585037 |
| composition and antibacterial activity of abies balsamea essential oil. | the antibacterial activity of the essential oil of abies balsamea (balsam fir) was evaluated against escherichia coli and staphylococcus aureus. the essential oil of a. balsamea was found to be inactive against e. coli (>100 microg/ml) and active against s. aureus, with an mic of 56 microg/ml. the oil composition was analysed by gc-ms and the antibacterial activity of each oil constituent was determined. the essential oil of a. balsamea is essentially constituted of monoterpenes (>96%) and some ... | 2006 | 16619365 |
| relationships between stand composition and ectomycorrhizal community structure in boreal mixed-wood forests. | we investigated the community structure of ectomycorrhizal fungi under varying overstory tree compositions in the southern mixed-wood boreal forest of quebec. sampling took place at two locations of differing postfire ages and nine 100-m2 plots were sampled per location. the dominant overstory tree species in the plots were trembling aspen (populus tremuloides michx.), white birch (betula papyrifera marsh.) or white spruce [picea glauca (moench) voss], and balsam fir [abies balsamea (l.) mill.]. ... | 2006 | 16699911 |
| sequence analysis and organization of the neodiprion abietis nucleopolyhedrovirus genome. | of 30 baculovirus genomes that have been sequenced to date, the only nonlepidopteran baculoviruses include the dipteran culex nigripalpus nucleopolyhedrovirus and two hymenopteran nucleopolyhedroviruses that infect the sawflies neodiprion lecontei (nelenpv) and neodiprion sertifer (nesenpv). this study provides a complete sequence and genome analysis of the nucleopolyhedrovirus that infects the balsam fir sawfly neodiprion abietis (hymenoptera, symphyta, diprionidae). the n. abietis nucleopolyhe ... | 2006 | 16809301 |
| forest dynamics after successive spruce budworm outbreaks in mixedwood forests. | in order to assess the long-term spatiotemporal influence of the spruce budworm in sub-boreal mixedwood forests, we studied the effect of three successive outbreaks in a region of western quebec, canada. we used dendrochronology to detect past outbreaks in three areas (111-185 ha), based on the recruitment age of balsam fir (abies balsamea) and on growth patterns of white spruce (picea glauca), the two main host species of this defoliating insect. we also used a series of aerial photographs take ... | 2006 | 16995632 |
| diversity of the small subunit ribosomal rna gene of the arbuscular mycorrhizal fungi colonizing clintonia borealis from a mixed-wood boreal forest. | arbuscular mycorrhizal fungi (amf) communities in clintonia borealis roots from a boreal mixed forests in northwestern québec were investigated. roots were sampled from 100 m2 plots whose overstory was dominated by either trembling aspen (populus tremuloides michx.), white birch (betula papyrifera marsh.), or mixed white spruce (picea glauca (moench) voss) and balsam fir (abies balsamea (l.) mill.). part of the 18s ribosomal gene of the amf was amplified and the resulting pcr products were clone ... | 2006 | 17064264 |
| interannual consistency in canopy stomatal conductance control of leaf water potential across seven tree species. | we investigated interannual variability of canopy transpiration per unit ground area (e (c)) and per unit leaf area (e (l)) across seven tree species in northern wisconsin over two years. these species have previously been shown to be sufficient to upscale stand-level transpiration to the landscape level during one growing season. our objective was to test whether a simple plant hydraulic model could capture interannual variation in transpiration. three species, wetland balsam fir (abies balsame ... | 2007 | 17169902 |
| comparative use of mindarus abietinus (homoptera: aphididae) by two coccinellids (coleoptera: coccinellidae), the native anatis mali and the exotic harmonia axyridis, in a christmas tree plantation. | the exotic coccinellid harmonia axyridis (pallas) recently expanded its range into eastern canada and elsewhere in north america. we hypothesized that this coccinellid should be less well adapted to the prey mindarus abietinus koch. on balsam fir trees than the native coccinellid anatis mali (say), which evolved in close association with aphids on conifers in north america. we compared, under field conditions, prey use by both species by collecting data on their synchrony with m. abietinus, thei ... | 2007 | 17445366 |
| in vivo replication kinetics and transcription patterns of the nucleopolyhedrovirus (neabnpv) of the balsam fir sawfly, neodiprion abietis. | dna replication and transcription of neabnpv, the nucleopolyhedrovirus (npv) of the balsam fir sawfly, neodiprion abietis (hymenoptera: diprionidae), in host larvae were investigated. npv dna replication kinetics and gene-expression patterns have been resolved only in lepidopteran cell-culture systems and in limited in vivo experiments with lepidopteran larvae. furthermore, there are significant differences in pathologies caused by lepidopteran npvs, which replicate in many tissues, and hymenopt ... | 2007 | 17554027 |
| distribution and hosts of callidiellum rufipenne (coleoptera: cerambycidae), an asian cedar borer established in the eastern united states. | the distribution and hosts of the exotic cedar-boring beetle, callidiellum rufipenne (motschulsky) (coleoptera: cerambycidae), were determined in five northeastern u.s. states by capturing adults on cedar trap logs and by rearing adults from various conifers. this beetle was detected in the coastal states of massachusetts, rhode island, connecticut, new york, and new jersey. in these states, adults emerged from the live or dead wood of four genera and eight species of cupressaceae; species of pi ... | 2007 | 17849882 |
| plant community influences on soil microfungal assemblages in boreal mixed-wood forests. | we studied the relationships between assemblages of soil microfungi and plant communities in the southern boreal mixed-wood forests of quebec. sampling took place in 18,100 m2 plots from an existing research site. plots were separated into three categories based on dominant overstory tree species: (i) trembling aspen, (ii) white birch and (iii) a mixture of white spruce and balsam fir. within each plot a 1 m2 subplot was established in which the understory herbaceous layer was surveyed and soil ... | 2007 | 17883027 |
| element mobility and partitioning along a soil acidity gradient in central ontario forests, canada. | the potential environmental risk posed by metals in forest soils is typically evaluated by modeling metal mobility using soil-solution partitioning coefficients (k(d)), although such information is generally restricted to a few well-studied metals. soil-solution partitioning coefficients were determined for 17 mineral elements (al, as, be, ba, ca, cr, cu, fe, ga, k, li, mg, rb, sr, tl, u and v) in a-horizon (0-5 cm) soil at 46 forested sites that border the precambrian shield in central ontario, ... | 2008 | 18058024 |
| ecophysiology and growth of advance red spruce and balsam fir regeneration after partial cutting in yellow birch-conifer stands. | we investigated ecophysiological and growth responses of short (0.4 to 1.3 m in height) advance regeneration of red spruce (picea rubens sarg.) and balsam fir (abies balsamea l.) six years after removal of 0, 40, 50, 60 and 100% of the overstory basal area (ba) in two yellow birch-conifer stands. partial cuts significantly increased stomatal conductance of red spruce only. light-saturated photosynthesis (leaf-area basis) of both species increased with ba removal, but unlike red spruce, specific ... | 2008 | 18519253 |
| genetic variability of canadian populations of the sapstain fungus ophiostoma piceae. | abstract genetic diversity was studied in seven canadian populations of ophiostoma piceae, the most prevalent sapstain fungus in canadian softwoods. a total of 239 single-spore isolates were recovered following a systematic survey of sapstain fungi in logs and lumber at seven selected sawmills in six canadian provinces (british columbia, alberta, saskatchewan, ontario, québec, and new brunswick). sampling was carried out on five commercially important softwood species: balsam fir (abies balsamea ... | 2001 | 18943849 |
| seasonal changes in abundance and phosphorylation status of photosynthetic proteins in eastern white pine and balsam fir. | during winter, the light-harvesting complexes of evergreen plants change function from energy-harvesting to energy-dissipating centers. the goal of our study was to monitor changes in the composition of the photosynthetic apparatus that accompany these functional changes. seasonal changes in chlorophyll fluorescence, pigment concentration, and abundance and phosphorylation status of photosynthetic proteins in pinus strobus l. (sun-exposed trees) and abies balsamea (l.) p. mill. (sun-exposed and ... | 2009 | 19203960 |
| host tree age as a selective pressure leading to local adaptation of a population of a polyphagous lepidoptera in virgin boreal forest. | we tested the hypothesis that host tree age may act as a selective factor and lead to local adaptation of the hemlock looper (lambdina fiscellaria), a geometrid lepidoptera that has a wide geographical distribution and has evolved in different eco-zones characterized by different levels of floristic composition, age structure and fragmentation level. considering that hemlock looper outbreaks mainly occurred in old forests, we compared the biological performances of two populations. the first pop ... | 2009 | 19224661 |
| genomic differences among pathotypes of bursaphelenchus xylophilus. | total genomic dna from bursaphelenchus xylophilus pathotypes mpsy-1 and vpst-1 and from b. mucronatus was digested with restriction endonucleases. dna fragments were electrophoretically separated, southern blotted to nitrocellulose, and hybridized to genomic dna from one of the isolates. the resulting hybridization patterns indicate genomic differences in repetitive dna sequences among these populations. greatest differences were seen between b. xylophilus and b. mucronatus, but genomic differen ... | 1988 | 19290214 |
| wood losses and economical threshold of btk aerial spray operation against spruce budworm. | spruce budworm, choristoneura fumiferana (clem.), causes cumulative defoliation and hence annual growth loss of the balsam fir, abies balsamea (l.) mill, host tree. annual growth increments of mixed balsam fir stands were measured by stem analysis over a 9 year period (1994-2002), when bacillus thuringiensis ssp. kurstaki (btk) was applied to control spruce budworm defoliation. with this approach, it was possible to quantify the change in stand volume growth after aerial spray applications of bt ... | 2010 | 19938000 |
| anti-insect secondary metabolites from fungal endophytes of conifer trees. | choristoneura fumiferana is the most economically-important insect pest in eastern north america. historically, strategies to control epidemics have relied on chemical pesticides that are no longer approved for use. the presence of fungal endophytes in cool area grass species and their role in reducing the impact of herbivorous insects is well understood. recent work has demonstrated that foliar endophytes of conifers also produce anti-insect toxins. field and nursery studies testing trees infec ... | 2009 | 19967982 |
| boring in response to bark and phloem extracts from north american trees does not explain host acceptance behavior of orthotomicus erosus (coleoptera: scolytidae). | when invasive herbivorous insects encounter novel plant species, they must determine whether the novel plants are hosts. the mediterranean pine engraver, orthotomicus erosus (wollaston), an exotic bark beetle poised to expand its range in north america, accepts hosts after contacting the bark. to test the hypothesis that o. erosus accepts hosts on the basis of gustatory cues, we prepared bark and phloem extracts from logs of four north american tree species that we had used in previous host acce ... | 2010 | 20388300 |
| forest restoration in a mixed-ownership landscape under climate change. | the extent to which current landscapes deviate from the historical range of natural variability (rnv) is a common means of defining and ranking regional conservation targets. however, climate-induced shifts in forest composition may render obsolete restoration strategies and conservation targets based on historic climate conditions and disturbance regimes. we used a spatially explicit forest ecosystem model, landis-ii, to simulate the interaction of climate change and forest management in northe ... | 2010 | 20405791 |
| optimization of spray drying process for bacillus thuringiensis fermented wastewater and wastewater sludge. | response surface methodology was used to optimize spray drying process for producing biopesticide powders of bacillus thuringiensis by using fermented broth of starch industry wastewater and wastewater sludge. analysis of variance was carried out using number of viable spores in the powder as dependent variable. the determination coefficients of models were 92 and 94% for fermented broth of starch industry wastewater and wastewater sludge, respectively. under the optimal conditions of the operat ... | 2011 | 20835715 |
| cree antidiabetic plant extracts display mechanism-based inactivation of cyp3a4. | seventeen cree antidiabetic medicinal plants were studied to determine their potential to inhibit cytochrome p450 3a4 (cyp3a4) through mechanism-based inactivation (mbi). the ethanolic extracts of the medicinal plants were studied for their inhibition of cyp3a4 using the substrates testosterone and dibenzylfluorescein (dbf) in high pressure liquid chromatography (hplc) and microtiter fluorometric assays, respectively. using testosterone as a substrate, extracts of alnus incana, sarracenia purpur ... | 2011 | 21186373 |
| host associations between fungal root endophytes and boreal trees. | fungal root endophytes colonize root tissue concomitantly with mycorrhizal fungi, but their identities and host preferences are largely unknown. we cultured fungal endophytes from surface-sterilized cenococcum geophilum ectomycorrhizae of betula papyrifera, abies balsamea, and picea glauca from two boreal sites in eastern canada. isolates were initially grouped on the basis of cultural morphology and then identified by internal transcribed spacer ribosomal dna sequencing or by pcr restriction fr ... | 2011 | 21475991 |
| site factors and management influence short-term host resistance to spruce budworm, choristoneura fumiferana (clem.), in a species-specific manner. | background: this study examined the interactions between thinning and soil drainage classes on the resistance of balsam fir, abies balsamea (l.) mill, white spruce, picea glauca (moench) voss, and black spruce, p. mariana (mill.) bsp, to spruce budworm, choristoneura fumiferana (clem.), defoliation 1 year after treatment. to estimate host tree resistance, foliage production and larval foliage consumption were determined to generate an index of resistance quantifying the amount of residual foliag ... | 2011 | 21796758 |
| spectral reflectance and photosynthetic properties of betula papyrifera (betulaceae) leaves along an elevational gradient on mt. mansfield, vermont, usa. | we studied relationships between spectral reflectance and photosynthesis of mountain paper birch, betula papyrifera var. cordifolia (regel) fern., leaves from three different elevations on mt. mansfield (summit elevation 1339 m above sea level) in the green mountains of vermont, usa. the different reflectance indices we used all suggested progressively increasing stress with increasing elevation. the photochemical reflectance index (pri) indicated lower photosynthetic radiation use efficiency at ... | 2002 | 21669715 |
| selected beetle assemblages captured in pitfall traps baited with deer dung or meat in balsam fir and sugar maple forests of central quebec. | vertebrate dung and carrion are rich and strongly attractive resources for numerous beetles that are often closely linked to them. the presence and abundance of beetles exploiting such resources are influenced by various ecological factors including climate and forest cover vegetation. we studied selected assemblages of coprophilous and necrophagous beetles in quebec along a 115-km north-south transect in three balsam fir (abies balsamea (l.) miller) forest sites and in a fourth forest site dom ... | 2010 | 22127165 |
| fenitrothion and aminocarb residues in water and balsam fir foliage following spruce budworm spraying programs in quebec, 1979 to 1982. | | 2013 | 3697537 |
| the persistence and fate of fenitrothion insecticide in a forest environment. ii. accumulation of residues in balsam fir foliage. | | 2014 | 4433873 |
| composition of the spruce budworm (choristoneura fumiferana) midgut microbiota as affected by rearing conditions. | the eastern spruce budworm (choristoneura fumiferana) is one of the most destructive forest insect pests in canada. little is known about its intestinal microbiota, which could play a role in digestion, immune protection, communication and/or development. the present study was designed to provide a first characterization of the effects of rearing conditions on the taxonomic diversity and structure of the c. fumiferana midgut microbiota, using a culture-independent approach. three diets and insec ... | 2015 | 26636571 |
| molecular and microscopic analysis of the gut contents of abundant rove beetle species (coleoptera, staphylinidae) in the boreal balsam fir forest of quebec, canada. | experimental research on beetle responses to removal of logging residues following clearcut harvesting in the boreal balsam fir forest of quebec revealed several abundant rove beetle (staphylinidae) species potentially important for long-term monitoring. to understand the trophic affiliations of these species in forest ecosystems, it was necessary to analyze their gut contents. we used microscopic and molecular (dna) methods to identify the gut contents of the following rove beetles: atheta caps ... | 2013 | 24294095 |
| new antibacterial hydrophobic assay reveals abies balsamea oleoresin activity against staphylococcus aureus and mrsa. | oleoresin of abies balsamea (l.) mill. was used by native americans of the boreal forest of canada and french canadians to treat various infections, suggesting that oleoresin has antibacterial properties. | 2016 | 27769946 |
| lanostane- and cycloartane-type triterpenoids from abies balsamea oleoresin. | phytochemical analysis of a. balsamea oleoresin led to the isolation of three new 3,4-seco-lanostane triterpenoids 1-3, one new cycloartane triterpenoid 4 along with fourteen known terpenoids. structure determinations were based on extensive 1d/2d nmr, ir and ms spectroscopic analyses, and comparison with literature data. the isolated compounds were evaluated in vitro for their cytotoxicity against human cell lines (a549, dld-1, ws1) and their antibacterial activity against e. coli and s. aureus ... | 2013 | 23946828 |
| cellulose digestion inmonochamus marmorator kby. (coleoptera: cerambycidae): role of acquired fungal enzymes. | larvae of the balsam fir sawyer,monochamus marmorator kby. (coleoptera, cerambycidae), contain midgut digestive enzymes active against hemicellulose and cellulose. cellulases from larvae fed on balsam fir wood infected with the fungus,trichoderma harzianum rifai (deuteromycetes, moniliales, moniliaceae), were found to be identical to those of the cellulase complex produced by this fungus when compared using chromatography, electrophoresis, and isofocusing. when larvae are maintained on a fungus- ... | 1986 | 24307047 |
| modelling moose-forest interactions under different predation scenarios at isle royale national park, usa. | loss of top predators may contribute to high ungulate population densities and chronic over-browsing of forest ecosystems. however, spatial and temporal variability in the strength of interactions between predators and ungulates occurs over scales that are much shorter than the scales over which forest communities change, making it difficult to characterize trophic cascades in forest ecosystems. we applied the landis-ii forest succession model and a recently developed ungulate browsing extension ... | 2017 | 28263421 |
| incorporating interspecific competition into species-distribution mapping by upward scaling of small-scale model projections to the landscape. | there are a number of overarching questions and debate in the scientific community concerning the importance of biotic interactions in species distribution models at large spatial scales. in this paper, we present a framework for revising the potential distribution of tree species native to the western ecoregion of nova scotia, canada, by integrating the long-term effects of interspecific competition into an existing abiotic-factor-based definition of potential species distribution (psd). the ps ... | 2017 | 28207782 |
| tree demography suggests multiple directions and drivers for species range shifts in mountains of northeastern united states. | climate change is expected to lead to upslope shifts in tree species distributions, but the evidence is mixed partly due to land-use effects and individualistic species responses to climate. we examined how individual tree species demography varies along elevational climatic gradients across four states in the northeastern united states to determine whether species elevational distributions and their potential upslope (or downslope) shifts were controlled by climate, land-use legacies (past logg ... | 2016 | 27935175 |
| ectomycorrhizal fungal response to warming is linked to poor host performance at the boreal-temperate ecotone. | rising temperatures associated with climate change have been shown to negatively affect the photosynthetic rates of boreal forest tree saplings at their southern range limits. to quantify the responses of ectomycorrhizal (em) fungal communities associated with poorly performing hosts, we sampled the roots of betula papyrifera and abies balsamea saplings growing in the b4warmed (boreal forest warming at an ecotone in danger) experiment. em fungi on the root systems of both hosts were compared fro ... | 2017 | 27658686 |
| tree phyllosphere bacterial communities: exploring the magnitude of intra- and inter-individual variation among host species. | the diversity and composition of the microbial community of tree leaves (the phyllosphere) varies among trees and host species and along spatial, temporal, and environmental gradients. phyllosphere community variation within the canopy of an individual tree exists but the importance of this variation relative to among-tree and among-species variation is poorly understood. sampling techniques employed for phyllosphere studies include picking leaves from one canopy location to mixing randomly sele ... | 2016 | 27635335 |
| host species identity, site and time drive temperate tree phyllosphere bacterial community structure. | the increasing awareness of the role of phyllosphere microbial communities in plant health calls for a greater understanding of their structure and dynamics in natural ecosystems. since most knowledge of tree phyllosphere bacterial communities has been gathered in tropical forests, our goal was to characterize the community structure and assembly dynamics of phyllosphere epiphytic bacterial communities in temperate forests in quebec, canada. we targeted five dominant tree species: acer saccharum ... | 2016 | 27316353 |
| allometric exponents as a tool to study the influence of climate on the trade-off between primary and secondary growth in major north-eastern american tree species. | trees invest in both primary (e.g. height) and secondary (e.g. diameter) growth. the trade-off between these investments varies between species and changes with the tree growing environment. to better establish this trade-off, readily available allometric exponents relating height to diameter at breast height (γ(h,dbh)) and stem volume to diameter at breast height (α(v,dbh)) were simultaneously studied. | 2016 | 26975315 |
| cyanobacterial gardens: the liverwort frullania asagrayana acts as a reservoir of lichen photobionts. | cyanobacteria are important mediators of unrelated lichen species, which form epiphytic communities that share the same cyanobiont. no study to date, however, has considered the role of cyanobacteria as mediator between lichens and bryophytes. in the present study, dna barcoding (16s rdna, rbclx) was used to identify filamentous cyanobacteria living in close association with members of an epiphytic liverwort-lichen community on balsam fir in newfoundland. this study is the first to confirm the p ... | 2016 | 26929112 |
| labeling feral spruce budworm (lepidoptera: tortricidae) populations with rubidium. | rubidium (rb) is a trace element that occurs naturally in low concentrations and is easily absorbed by plants, making it a useful tool for labeling insect defoliators, such as spruce budworm (choristoneura fumiferana clemens). balsam fir trees (abies balsamea (l.) miller) injected with either 8 or 16 g per tree of rubidium chloride (rbcl) showed quick uptake and distribution throughout the crown, with no negative effects on tree shoot growth or spruce budworm survival and development. adult spru ... | 2016 | 26920559 |
| demographic controls of aboveground forest biomass across north america. | ecologists have limited understanding of how geographic variation in forest biomass arises from differences in growth and mortality at continental to global scales. using forest inventories from across north america, we partitioned continental-scale variation in biomass growth and mortality rates of 49 tree species groups into (1) species-independent spatial effects and (2) inherent differences in demographic performance among species. spatial factors that were separable from species composition ... | 2016 | 26913575 |
| pheromone-based monitoring of spruce budworm (lepidoptera: tortricidae) larvae in relation to trap position. | the local abundance of male spruce budworm, choristoneura fumiferana (clemens) (lepidoptera: tortricidae), was evaluated in the province of quebec at 112 locations between 2002–2012 using pheromone-baited traps deployed on lower branches near the ground level (gl) or in the tree canopy (tc; three traps at gl and tc for each location); in addition, the presence of second instars (l2) was assessed at each location on three balsam fir branches. numbers of moths captured at gl and tc were highly cor ... | 2016 | 26721289 |
| understanding the physiology of postharvest needle abscission in balsam fir. | balsam fir (abies balsamea) trees are commonly used as a specialty horticultural species for christmas trees and associated greenery in eastern canada and united states. postharvest needle abscission has always been a problem, but is becoming an even bigger challenge in recent years presumably due to increased autumn temperatures and earlier harvesting practices. an increased understanding of postharvest abscission physiology in balsam fir may benefit the christmas tree industry while simultaneo ... | 2015 | 26635863 |
| dft calculations and roesy nmr data for the diastereochemical characterization of cytotoxic tetraterpenoids from the oleoresin of abies balsamea. | eight non-carotenoid tetraterpenoids, abibalsamins c-j (3-10), were isolated from the oleoresin of abies balsamea. their chemical structures were determined based on analysis of 1d/2d nmr and ms data. the assignment of their relative configurations was accomplished using homonuclear coupling constants in tandem with roesy data. however, the presence of two stereogenic centers on a flexible side chain complicated the characterization. in silico models and roesy data were analyzed in order to assi ... | 2015 | 26592897 |
| combining near infrared spectra of feces and geostatistics to generate forage nutritional quality maps across landscapes. | an important asset for the management of wild ungulates is recognizing the spatial distribution of forage quality across heterogeneous landscapes. to do so typically requires knowledge of which plant species are eaten, in what abundance they are eaten, and what their nutritional quality might be. acquiring such data, however, may be difficult and time consuming. here, we are proposing a rapid and cost-effective forage quality monitoring tool that combines near infrared (nir) spectra of fecal sam ... | 2015 | 26552270 |
| spruce budworm (lepidoptera: tortricidae) oral secretions ii: chemistry. | as sessile organisms, plants have evolved different methods to defend against attacks and have adapted their defense measures to discriminate between mechanical damage and herbivory by insects. one of the ways that plant defenses are triggered is via elicitors from insect oral secretions (os). in this study, we investigated the ability of second-instar (l2) spruce budworm [sbw; choristoneura fumiferana (clemens)] to alter the volatile organic compounds (vocs) of four conifer species [abies balsa ... | 2015 | 26454474 |
| synchronisms and correlations of spring phenology between apical and lateral meristems in two boreal conifers. | phenological synchronisms between apical and lateral meristems could clarify some aspects related to the physiological relationships among the different organs of trees. this study correlated the phenological phases of bud development and xylem differentiation during spring 2010-14 in balsam fir (abies balsamea mill.) and black spruce [(picea mariana mill. (bsp)] of the monts-valin national park (quebec, canada) by testing the hypothesis that bud development occurs after the reactivation of xyle ... | 2015 | 26377874 |
| regulation of liver cell glucose homeostasis by dehydroabietic acid, abietic acid and squalene isolated from balsam fir (abies balsamea (l.) mill.) a plant of the eastern james bay cree traditional pharmacopeia. | in our previous study, abies balsamea (l.) mill., a plant used in cree traditional medicine, had a strong effect on the regulation of glucose homeostasis in liver cells. this study aimed to isolate and identify its active constituents using a bioassay-guided fractionation approach as well as to elucidate their mechanism(s) of action. the effect of the crude extract and its constituents was evaluated on the activity of glucose-6-phosphatase (g6pase) and glycogen synthase (gs) and phosphorylation ... | 2015 | 26164238 |
| carbon allocation during defoliation: testing a defense-growth trade-off in balsam fir. | during repetitive defoliation events, carbon can become limiting for trees. to maintain growth and survival, the resources have to be shared more efficiently, which could result in a trade-off between the different physiological processes of a plant. the objective of this study was to assess the effect of defoliation in carbon allocation of balsam fir [abies balsamea (l.) mill.] to test the presence of a trade-off between allocation to growth, carbon storage, and defense. three defoliation inten ... | 2015 | 26029235 |
| integrating phylogeography and paleoecology to investigate the origin and dynamics of hybrid zones: insights from two widespread north american firs. | secondary contact between closely related taxa routinely occurs during postglacial migrations. after initial contact, the location of hybrid zones may shift geographically or remain spatially stable over time in response to various selective pressures or neutral processes. studying the extent and direction of introgression using markers having contrasted levels of gene flow can help unravel the historical dynamics of hybrid zones. thanks to their contrasted maternal and paternal inheritance, res ... | 2015 | 25865063 |
| less pollen-mediated gene flow for more signatures of glacial lineages: congruent evidence from balsam fir cpdna and mtdna for multiple refugia in eastern and central north america. | the phylogeographic structure and postglacial history of balsam fir (abies balsamea), a transcontinental north american boreal conifer, was inferred using mitochondrial dna (mtdna) and chloroplast dna (cpdna) markers. genetic structure among 107 populations (mtdna data) and 75 populations (cpdna data) was analyzed using bayesian and genetic distance approaches. population differentiation was high for mtdna (dispersed by seeds only), but also for cpdna (dispersed by seeds and pollen), indicating ... | 2015 | 25849816 |
| composition, antimicrobial and antioxidant activities of seven essential oils from the north american boreal forest. | essential oils (eos) were steam-extracted from the needles and twigs of balsam fir, black spruce, white spruce, tamarack, jack pine and eastern white cedar that remained after logging in eastern canada. these eos, similarly to that from labrador tea and other commercial eos from chinese cinnamon, clove and lemon eucalyptus, exhibited many common constituent compounds (mainly α-pinene, β-pinene, limonene and bornyl acetate) making up 91% of each oil based on gas chromatography-mass spectrometry a ... | 2015 | 25801172 |
| a molecular identification protocol for roots of boreal forest tree species. | | 2014 | 25383267 |
| inhibition of insect glutathione s-transferase (gst) by conifer extracts. | insecticide synergists biochemically inhibit insect metabolic enzyme activity and are used both to increase the effectiveness of insecticides and as a diagnostic tool for resistance mechanisms. considerable attention has been focused on identifying new synergists from phytochemicals with recognized biological activities, specifically enzyme inhibition. jack pine (pinus banksiana lamb.), black spruce (picea mariana (mill.) bsp.), balsam fir (abies balsamea (l.) mill.), and tamarack larch (larix l ... | 2014 | 25270601 |
| biogeographic variation in evergreen conifer needle longevity and impacts on boreal forest carbon cycle projections. | leaf life span is an important plant trait associated with interspecific variation in leaf, organismal, and ecosystem processes. we hypothesized that intraspecific variation in gymnosperm needle traits with latitude reflects both selection and acclimation for traits adaptive to the associated temperature and moisture gradient. this hypothesis was supported, because across 127 sites along a 2,160-km gradient in north america individuals of picea glauca, picea mariana, pinus banksiana, and abies b ... | 2014 | 25225397 |
| soil response to a 3-year increase in temperature and nitrogen deposition measured in a mature boreal forest using ion-exchange membranes. | the projected increase in atmospheric n deposition and air/soil temperature will likely affect soil nutrient dynamics in boreal ecosystems. the potential effects of these changes on soil ion fluxes were studied in a mature balsam fir stand (abies balsamea [l.] mill) in quebec, canada that was subjected to 3 years of experimentally increased soil temperature (+4 °c) and increased inorganic n concentration in artificial precipitation (three times the current n concentrations using nh4no3). soil el ... | 2014 | 25139238 |
| genetic evidence for three discrete taxa of melampsora (pucciniales) affecting willows (salix spp.) in new york state. | rust fungi in the genus melampsora (pucciniales) are the most important pathogens of shrub willows (salix spp.) cultivated for biomass in new york state and temperate regions worldwide. the taxonomy and species identification of these fungi historically have been problematic as they are morphologically indistinguishable on willow and often have complex life histories. melampsora of salix in north america, therefore, have been circumscribed to the collective species melampsora epitea thüm. and fu ... | 2014 | 25110133 |
| biodiversity elements vulnerable to climate change in the catskill high peaks subecoregion (ulster, delaware, sullivan, and greene counties, new york state). | climate change is expected to affect biodiversity elements in the catskill high peaks subecoregion of new york state with effects that are difficult to predict. the present communication details the species and communities of greatest conservation concern in this portion of the state and makes recommendations for monitoring the most pressing climate change-biodiversity vulnerabilities. specifically, we present sites for monitoring representative old-growth and successional stands of red spruce/b ... | 2013 | 25098491 |
| history of the spruce-fir forest in the catskill mountains of new york. | red spruce (picea rubens sarg.) and balsam fir (abies balsamea (l.) mill.) were present by 13,700 years b.c.e. in the catskills mountains of southeastern new york state. these conifers were, and still are, largely confined to the eastern and far western portions of the region. a gap in the distribution exists between these populations. both species are absent from the intervening east branch delaware river watershed. no red spruce macrofossils were found in this watershed, suggesting that this c ... | 2013 | 25098490 |
| xylem formation can be modeled statistically as a function of primary growth and cambium activity. | primary (budburst, foliage and shoot) growth and secondary (cambium and xylem) growth of plants play a vital role in sequestering atmospheric carbon. however, their potential relationships have never been mathematically quantified and the underlying physiological mechanisms are unclear. we monitored primary and secondary growth in picea mariana and abies balsamea on a weekly basis from 2010 to 2013 at four sites over an altitudinal gradient (25-900 m) in the eastern canadian boreal forest. we de ... | 2014 | 24861414 |
| influence of partial cutting on parasitism of endemic spruce budworm (lepidoptera: tortricidae) populations. | silvicultural treatments such as thinning have been suggested as management tools against the spruce budworm, choristoneura fumiferana (clemens) (lepidoptera: tortricidae). among other things, parasitoids are also proposed to be influenced by silvicultural procedures, but the effect of thinning on spruce budworm's natural enemies has not been tested yet. in this study, the influence of partial cutting on parasitism of endemic spruce budworm populations has been investigated in mature balsam fir- ... | 2014 | 24780195 |
| a large herbivore triggers alternative successional trajectories in the boreal forest. | alternative successional trajectories (ast) may result in multiple climax states within an ecosystem when disturbances affect colonization history. in the boreal forest, ungulates have been proposed to drive ast because, under herbivore pressure, preferred species may go extinct and apparent competition may benefit browsing-resistant species. over a 15-year period following logging, we tested whether deer herbivory altered plant species composition and whether the competitive advantage of resist ... | 2013 | 24597230 |
| physiology and growth of advance picea rubens and abies balsamea regeneration following different canopy openings. | we examined the ecophysiology and growth of 0.3-1.3 m tall advance red spruce (picea rubens sarg.) and balsam fir (abies balsamea [l.] mill.) regeneration during a 5-year period following the application of different harvest types producing three sizes of canopy openings: (i) small gaps (<100 m(2) in area; sma) created by partial uniform single-tree harvest; (ii) irregular gaps of intermediate size (100-300 m(2); int) created by group-selection harvest (removal of groups of trees, mainly balsam ... | 2014 | 24443326 |
| repellent effectiveness of seven plant essential oils, sunflower oil and natural insecticides against horn flies on pastured dairy cows and heifers. | plant essential oils (basil, geranium, balsam fir, lavender, lemongrass, peppermint, pine and tea tree), mixed with either sunflower oil or ethyl alcohol, were applied at 5% concentrations to the sides of holstein cattle. pastured cattle treated with essential oils diluted in sunflower oil had less flies than the untreated control for a 24-h period. however, the essential oil treatments were not significantly different than the carrier oil alone. barn-held heifers treated with essential oils and ... | 2014 | 24382265 |
| seedling ontogeny and environmental plasticity in two co-occurring shade-tolerant conifers and implications for environment-population interactions. | seedling success is determined by evolved strategies of intrinsic genetic programming and plasticity that are regulated by extrinsic pathways. we tested the relative importance of these mechanisms in red spruce (picea rubens sarg.) and balsam fir (abies balsamea lin.), which share understory regeneration niches in northeastern north america. although its reproductive effort is adequate, spruce has decreased in abundance, in relation to fir, in seedling and sapling populations, even in forests th ... | 2014 | 24368754 |
| ontogeny and stand condition influence the dispersal behavior of a defoliating specialist caterpillar. | a 4-yr field study was carried out to study the dispersal behavior of young larvae of the eastern spruce budworm (choristoneura fumiferana clemens) (lepidoptera: tortricidae) within and between crowns of balsam fir (abies balsamea (l.) miller), through the peak to decline of an outbreak. newly hatched neonates, searching for overwintering sites in the fall, were frequently captured in sticky traps as they dispersed via "ballooning" (on silken threads) between and within tree crowns. a relatively ... | 2013 | 24216325 |
| canadian boreal pulp and paper feedstocks contain neuroactive substances that interact in vitro with gaba and dopaminergic systems in the brain. | pulp and paper wood feedstocks have been previously implicated as a source of chemicals with the ability to interact with or disrupt key neuroendocrine endpoints important in the control of reproduction. we tested nine canadian conifers commonly used in pulp and paper production as well as 16 phytochemicals that have been observed in various pulp and paper mill effluent streams for their ability to interact in vitro with the enzymes monoamine oxidase (mao), glutamic acid decarboxylase (gad), and ... | 2014 | 24041600 |
| interspecific coordination and intraspecific plasticity of fine root traits in north american temperate tree species. | fine roots play an important role in nutrient and water absorption and hence overall tree performance. however, current understanding of the ecological role of belowground traits lags considerably behind those of aboveground traits. in this study, we used data on specific root length (srl), fine root diameter (d) and branching intensity (bi) of two datasets to examine interspecific trait coordination as well as intraspecific trait variation across ontogenetic stage and soil conditions (i.e., pla ... | 2013 | 23874347 |
| the action of antidiabetic plants of the canadian james bay cree traditional pharmacopeia on key enzymes of hepatic glucose homeostasis. | we determined the capacity of putative antidiabetic plants used by the eastern james bay cree (canada) to modulate key enzymes of gluconeogenesis and glycogen synthesis and key regulating kinases. glucose-6-phosphatase (g6pase) and glycogen synthase (gs) activities were assessed in cultured hepatocytes treated with crude extracts of seventeen plant species. phosphorylation of amp-dependent protein kinase (ampk), akt, and glycogen synthase kinase-3 (gsk-3) were probed by western blot. seven of th ... | 2013 | 23864882 |
| initial responses of rove and ground beetles (coleoptera, staphylinidae, carabidae) to removal of logging residues following clearcut harvesting in the boreal forest of quebec, canada. | increased interest in biomass harvesting for bioenergetic applications has raised questions regarding the potential ecological consequences on forest biodiversity. here we evaluate the initial changes in the abundance, species richness and community composition of rove (staphylinidae) and ground beetles (carabidae), immediately following 1) stem-only harvesting (soh), in which logging debris (i.e., tree tops and branches) are retained on site, and 2) whole-tree harvesting (wth), in which stems, ... | 2013 | 23653498 |
| the effects of throughfall exclusion on xylogenesis of balsam fir. | a 20-40% reduction in soil moisture is projected for the boreal forest of eastern canada for the period 2070-99 relative to 1971-2000. in order to better predict the effects of a reduced water supply on the growth of balsam fir (abies balsamea (l.) mill.), a dominant tree species of the boreal forest, we simulated 2 consecutive years of summer droughts (starting in july) by means of throughfall exclusion. four 100-m(2) plots were established in 2010 with polyethylene sheets maintained 1.3-2 m ab ... | 2013 | 23604743 |
| antioxidant potential of bark extracts from boreal forest conifers. | the bark of boreal forest conifers has been traditionally used by native americans to treat various ailments and diseases. some of these diseases involve reactive oxygen species (ros) that can be prevented by the consumption of antioxidants such as phenolic compounds that can be found in medicinal plants. in this study, ultrasonic assisted extraction has been performed under various solvent conditions (water:ethanol mixtures) on the bark of seven boreal forest conifers used by native americans i ... | 2013 | 26784337 |
| episodic recruitment of the seedling banks in balsam fir and white spruce. | | 2012 | 23204491 |
| comparing modern and presettlement forest dynamics of a subboreal wilderness: does spruce budworm enhance fire risk? | insect disturbance is often thought to increase fire risk through enhanced fuel loadings, particularly in coniferous forest ecosystems. yet insect disturbances also affect successional pathways and landscape structure that interact with fire disturbances (and vice-versa) over longer time scales. we applied a landscape succession and disturbance model (landis-ii) to evaluate the relative strength of interactions between spruce budworm (choristoneura fumiferana) outbreaks and fire disturbances in ... | 2012 | 22827135 |
| recovery kinetics of photochemical efficiency in winter stressed conifers: the effects of growth light environment, extent of the season and species. | evergreens undergo reductions in maximal photochemical efficiency (f(v)/f(m)) during winter due to increases in sustained thermal energy dissipation. upon removing winter stressed leaves to room temperature and low light, f(v)/f(m) recovers and can include both a rapid and a slow phase. the goal of this study was to determine whether the rapid component to recovery exists in winter stressed conifers at any point during the season in a seasonally extreme environment. additional goals were to comp ... | 2013 | 22575048 |