Publications
| Title | Abstract | Year Filter | PMID(sorted descending) Filter |
|---|
| spruce budworm growth, development and food utilization on young and old balsam fir trees. | laboratory rearing of spruce budworm, choristoneura fumiferana, in conjunction with field rearing, gravimetric analyses, a transfer experiment, and foliage chemical analyses at six dates during the period of budworm feeding activity indicated that the age of balsam fir, abies balsamea, trees (70-year-old mature trees or 30-year-old juvenile trees) affected tree suitability for the spruce budworm via the chemical profile of the foliage. insects reared on old trees had greater survival and pupal w ... | 1994 | 28313739 |
| factors influencing choice of balsam fir twigs from thinned and unthinned stands by moose. | moose were observed to browse preferentially on balsam fir (abies balsamea) trees in stands where the stem density had been mechanically reduced to about 2000 stems/ha from over 30,000 stems/ha. twigs from trees in thinned and unthinned stands were analyzed to test the hypotheses that moose were choosing thinned stands to maximize intake of a nutrient, or avoiding plant secondary compounds deliterious to digestion. analyses included: twig length, weight, diameter, acid detergent fiber, neutral d ... | 1989 | 28312645 |
| effects of canopy components on throughfall chemistry: an experimental analysis. | five canopy components of subalpine balsam fir forests (branches with young needles, branches with old needles, non-foliated twigs, lichen-covered twigs, and boles) were treated with simulated rain to test the influence of these components on throughfall and stemflow chemistry. effects on the fluxes of potassium, sodium, hydrogen, sulfate, nitrate and ammonium ions by the canopy components were tested in relation to rain application rate, duration of rain, and time since the last rain. interacti ... | 1984 | 28311206 |
| does climate affect host-plant quality? annual variation in the quality of balsam fir as food for spruce budworm. | the hypothesis that annual climatic variation can affect the nutritive value of host-plant tissue for a herbivore was tested. larvae of a single generation of western spruce budworm, choristoneura occidentalis free., were fed foliages that had been collected on five consecutive springs from a stand of balsam fir abies balsamea (l.) mill. budworm of both sexes were about 20 percent heavier at pupation when fed folages that had been produced in early rather than later spring seasons. this could re ... | 1989 | 28311186 |
| canopy processing of acidic precipitation by coniferous and hardwood forests in new england. | there are several important factors that may influence how forest canopies interact with acidic deposition, including forest community species composition, phenological status, and differences in atmospheric loading of strong acids. results from comparative throughfall chemistry studies in new hampshire, where precipitation ph is 4.1, indicate that northern hardwood canopies produce a throughfall solution chemistry that is less acid and higher in basic cations than either direct precipitation or ... | 1983 | 28310235 |
| comparison of energy budgets for spruce budworm choristoneura fumiferana (clemens) on balsam fir and white spruce. | a determination was made of the differences in the utilization of energy by laboratory reared larval choristoneura fumiferana fed either balsam fir or white spruce foliage. this enabled us to quantitatively measure the quality of these foliages vis a vis the spruce budworm.the larval strategy was to feed rapidly and develop quickly. development time was longer on spruce than on fir. total consumption was virtually identical on both foliage types though production was ca 20% greater on a white sp ... | 1981 | 28309443 |
| potential alteration of precipitation chemistry by epiphytic lichens. | epiphytic lichen growth is abundant on the boles and branches of balsam fir trees at high elevations in new hampshire. these lichens absorb elements needed for growth from solutions flowing over their surfaces and from direct impaction of water droplets. this study describes how epiphytic lichens and fir needles altered the chemistry of simulated rain water solutions under laboratory conditions. experiments showed: 1) lichens absorbed ammonium and nitrate from solution; the rate of uptake increa ... | 1976 | 28308868 |
| testing the ecophysiological basis for the control of monoterpene concentrations along canopy profiles in thinned and unthinned balsam fir stands. | to determine which ecophysiological factors appear to control monoterpene concentrations in balsam fir foliage [abies balsamea (l.) p. mill.], the percentage of photosynthetically active radiation (%par), specific leaf area (sla), light-saturated photosynthesis (a max), and concentrations per unit leaf area of foliar nitrogen (n), total soluble sugars (tss), starch and monoterpenes were measured on current-year needles from three canopy levels (upper, middle and lower) the year following a pre-c ... | 2000 | 28308769 |
| spruce budworm impact, abundance and parasitism rate in a patchy landscape. | the hypothesis that vegetational diversity may lessen the impact of forest insect pests by favoring natural enemies is appealing to those who seek ecologically sound solutions to pest problems. we investigated the effect of forest diversity on the impact of the spruce budworm choristoneurafumiferana following the last outbreak, as well as the budworm's current abundance and parasitism rate, in the boreal forest of northwestern québec. mortality of balsam fir caused by the budworm was greater in ... | 1998 | 28307937 |
| larval feeding behaviour affects the impact of staminate flower production on the suitability of balsam fir trees for spruce budworm. | laboratory rearing of spruce budworm, choristoneura fumiferana, in conjunction with field rearing indicated that the feeding behaviour of the larvae, which is affected by the insect population density, significantly influenced the impact of balsam fir, abies balsamea, staminate flowering on spruce budworm biology. at low budworm density, the production of pollen in the midcrown of host trees reduced the insect development time by 5 days without affecting pupal weight, fecundity and survival. how ... | 1996 | 28307131 |
| 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 |
| 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 |
| a reassessment of areal variability of throughfall deposition measurements. | throughfall deposition in a low-elevation red spruce-balsam fir stand in east-central maine was measured for 10 chemical constituents over four sampling seasons to evaluate areal variability of throughfall deposition measurements. forty collectors within one stand were sampled weekly and combined to provide 40 monthly samples. areal variation in measurements of throughfall deposition differed greatly among chemical constituents and from month to month. sulfate showed the least areal variability ... | 1993 | 27759237 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| transmission of a gammabaculovirus within cohorts of balsam fir sawfly (neodiprion abietis) larvae. | nucleopolyhedroviruses (npv: gammabaculovirus: baculoviridae) of diprionid sawflies (diprionidae: hymenoptera) are highly host specific and only infect the midgut epithelium. while still alive, infected sawfly larvae excrete npv-laden diarrhea that contaminates food sources. the diarrhea can then be consumed by conspecific larvae, resulting in rapid horizontal transmission of the virus. to better understand the efficacy of gammabaculovirus-based biological control products, the horizontal spread ... | 2012 | 26466722 |
| spread of a gammabaculovirus within larval populations of its natural balsam fir sawfly (neodiprion abietis) host following its aerial application. | field trials and assessments of the balsam fir sawfly (neodiprion abietis) nucleopolyhedrovirus (neabnpv: baculoviridae, gammabaculovirus) against its natural host were conducted in july and august 2002 near corner brook, newfoundland and labrador, canada, in naturally regenerated, precommercially thinned stands dominated by balsam fir (abies balsamea). two experimental blocks, each with its own untreated control, were established. the purpose of the island pond block was to examine the spread o ... | 2012 | 26466719 |
| 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 |
| orientation behavior of second-instar larvae of eastern spruce budwormchoristoneura fumiferana (clem.) (lepidoptera: tortricidae) in a y-type olfactometer. | a two-choice, wind-tunnel olfactometer was designed and contructed to determine whether second-instar eastern spruce budworm larvae,christoneura fumiferana (clem.), could detect and discriminate among host-plant volatiles. volatiles of current year's growth ofpicea glauca were preferred over those ofp. rubens, p. mariana, or air.abies balsamea was preferred overp. mariana or air.p. rubens andp. mariana were both preferred over air. two-year-old growth ofp. glauca, a. balsamea, p. rubens, andp. m ... | 1985 | 24310270 |
| tests for induction of feeding preferences in larvae of eastern spruce budworm using extracts from three host plants. | feeding preferences to extracts from three host plants were determined for sixth-instar eastern spruce budworm larvae reared on one of three hosts or on artificial diet. preferences of foliage-reared larvae were compared to those of diet-reared, or naive, larvae. no effect of plant induction was found using amino acids and bases and chloroform extracts on test disks in three-choice experiments. possible effects of habituation for sugars and glycosides from white spruce were shown. organic acids ... | 1985 | 24310225 |
| 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 |
| 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 |
| enniatins fromfusarium avenaceum isolated from balsam fir foliage and their toxicity to spruce budworm larvae,choristoneura fumiferana (clem.) (lepidoptera: tortricidae). | material extracted from hyphae offusarium avenaceum, isolated from foliage of balsam fir,abies balsamea, was toxic to spruce budworm larvae when incorporated into insect diet. the major insecticidal component of the toxic fraction was identified by chemical and spectroscopic methods as enniatin complex, rich in enniatin a/a1. possible ecological implications of these observations are considered. | 1988 | 24276128 |
| trichothecene mycotoxins produced byfusarium sporotrichioides daom 197255 and their effects on spruce budworm,choristoneura fumiferana. | trichothecene mycotoxins were produced byfusarium sporotrichioides daom 197255 isolated from a spruce budworm cadaver. an extract from the culture filtrate containing these metabolites was toxic to budworm when ingested at concentrations as low as 10 ppm in diet, and survivors were predisposed to infection with a fungal entomopathogen. the possible role of these metabolites in the balsam fir-spruce budworm habitat is discussed. | 1990 | 24263830 |
| 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 |
| effects of insecticide use on breeding birds in christmas tree plantations in quebec. | : this research, which was carried out in the spring of 1989 and 1990 in seven balsam fir (abies balsamea) plantations in southeastern quebec, examines potential deleterious effects of three insecticides (i.e. dimethoate, diazinon and insecticidal soap) on breeding american robins (turdus migratorius) (n=87 nests) and song sparrows (melospizsa melodia) (n=41 nests). through analyses of blood serum cholinesterases (ache and bche) activity both prior to and the second day following applications of ... | 1995 | 24197796 |
| 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 |
| 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 |
| 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 |
| 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 |
| abibalsamins a and b, two new tetraterpenoids from abies balsamea oleoresin. | abibalsamins a (1) and b (2), two unprecedented tetraterpenoids featuring a 3,4-seco-rearranged lanostane system fused with a β-myrcene lateral chain via a [4 + 2] diels-alder cycloaddition, were isolated from the oleoresin of abies balsamea. their structures were elucidated by means of extensive 2d nmr, ir, and ms spectroscopy analyses. the absolute configuration of 1 was determined by single-crystal x-ray diffraction. both compounds exhibited significant cytotoxic activity against cancer cell ... | 2012 | 22394397 |
| bifunctional cis-abienol synthase from abies balsamea discovered by transcriptome sequencing and its implications for diterpenoid fragrance production. | the labdanoid diterpene alcohol cis-abienol is a major component of the aromatic oleoresin of balsam fir (abies balsamea) and serves as a valuable bioproduct material for the fragrance industry. using high-throughput 454 transcriptome sequencing and metabolite profiling of balsam fir bark tissue, we identified candidate diterpene synthase sequences for full-length cdna cloning and functional characterization. we discovered a bifunctional class i/ii cis-abienol synthase (abcas), along with the pa ... | 2012 | 22337889 |
| mode of coniferous wood decay by the white rot fungus phanerochaete carnosa as elucidated by ftir and tof-sims. | the softwood degrading white-rot fungus, phanerochaete carnosa, was investigated for its ability to degrade two coniferous woods: balsam fir and lodgepole pine. p. carnosa grew similarly on these wood species, and like the hardwood-degrading white-rot fungus ceriporiopsis subvermispora, p. carnosa demonstrated selective degradation of lignin, as observed by fourier transform infrared spectroscopy and time-of-flight secondary ion mass spectrometry (tof-sims). lignin degradation across cell walls ... | 2012 | 22290642 |
| 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 |
| carry-over effect of host nutritional quality on performance of spruce budworm progeny. | the effect of host nutritional quality on spruce budworm (choristoneura fumiferana (clemens)) parental and offspring performance was studied using field and laboratory rearing experiments, and foliar chemical analyses. foliage of balsam fir (abies balsamea (l.) mill.), white spruce (picea glauca (moench) voss) and black spruce (p. mariana (mill.) bsp) was used to rear the parental generation in the field, whereas an artificial diet was used to rear the progeny under laboratory conditions. import ... | 2012 | 22077965 |
| two-dimensional wavelet analysis of spruce budworm host basal area in the border lakes landscape. | increases in the extent and severity of spruce budworm (choristoneura fumiferana clem.) outbreaks over the last century are thought to be the result of changes in forest structure due to forest management. a corollary of this hypothesis is that manipulations of forest structure and composition can be used to reduce future forest vulnerability. however, to what extent historical forest management has influenced current spatial patterns of spruce budworm host species is unknown. to identify landsc ... | 2011 | 21939054 |
| 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 |
| genetic variation and population structure in central and isolated populations of balsam fir, abies balsamea (pinaceae). | genetic variation and spatial genetic structure in balsam fir (abies balsamea) were examined in two isolated populations in iowa and minnesota thought to be paleorefugia and in two ecologically central populations in old-growth forests of upper michigan. overall levels of genetic variability at 22 allozyme loci were lower than that found in most conifer species (h(o) values ranged from 0.005 in the isolated populations to 0.025 in the central populations). the mean f(is) value (0.154) was larger ... | 2002 | 21665678 |
| reproductive potential of balsam fir (abies balsamea), white spruce (picea glauca), and black spruce (p. mariana) at the ecotone between mixedwood and coniferous forests in the boreal zone of western quebec. | the reproductive potentials of balsam fir and white spruce (co-dominants in mixedwood forests) and black spruce (dominant in coniferous forests) were studied to explain the location of the ecotone between the two forest types in the boreal zone of quebec. four sites were selected along a latitudinal gradient crossing the ecotone. cone crop, number of seeds per cone, percentage filled seeds, and percentage germination were measured for each species. balsam fir and white spruce cone crops were sig ... | 2007 | 21636443 |
| effects of soil moisture manipulations on fine root dynamics in a mature balsam fir (abies balsamea l. mill.) forest. | we tested the hypothesis that moisture stress affects fine root dynamics during and after the stress. to this end, we investigated the effects of soil moisture on annual and seasonal fine root production and mortality over 4 years in a mature balsam fir (abies balsamea l. mill.) stand using a minirhizotron and soil coring. droughting and irrigating treatments were imposed for 17 weeks during the third year of the study, and post-treatment recovery was measured during the fourth year. monthly fin ... | 2011 | 21489968 |
| 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 |
| transcriptomic responses of the softwood-degrading white-rot fungus phanerochaete carnosa during growth on coniferous and deciduous wood. | to identify enzymes that could be developed to reduce the recalcitrance of softwood resources, the transcriptomes of the softwood-degrading white-rot fungus phanerochaete carnosa were evaluated after growth on lodgepole pine, white spruce, balsam fir, and sugar maple and compared to the transcriptome of p. carnosa after growth on liquid nutrient medium. one hundred fifty-two million paired-end reads were obtained, and 63% of these reads were mapped to 10,257 gene models from p. carnosa. five-hun ... | 2011 | 21441342 |
| species composition of saproxylic fungal communities on decaying logs in the boreal forest. | coarse woody debris supports large numbers of saproxylic fungal species. however, most of the current knowledge comes from scandinavia and studies relating the effect of stand or log characteristics on the diversity and composition of decomposer fungi have not been conducted in northeastern canada. logs from five tree species were sampled along a decomposition gradient in nine stands representing three successional stages of the boreal mixed forest of northwestern quebec, canada. using a molecul ... | 2011 | 21246195 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| wood formation in abies balsamea seedlings subjected to artificial defoliation. | we determined the cambial sensitivity and quantified the anatomical differences in xylem of abies balsamea (l.) mill. seedlings subjected to artificial defoliation to simulate spruce budworm feeding. defoliation was performed by removing two-thirds of needles of all current-year shoots for up to four consecutive growth cycles to account for inter- and intra-annual xylem formation. in experiment 1, xylem development was studied from may to october 2005 in seedlings defoliated at the end of june. ... | 2009 | 19203970 |
| 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 |
| 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 |
| impact of nutrient removal through harvesting on the sustainability of the boreal forest. | the cycling of base cations (k, ca, mg, and na) was investigated in a boreal balsam fir forest (the lake laflamme watershed) between 1999 and 2005. base cation budgets were calculated for the soil rooting zone that included atmospheric deposition and soil leaching losses, two scenarios of tree uptake (whole-tree and stem-only harvesting), and three scenarios of mineral weathering, leading to six different scenarios. in every scenario there was a net accumulation of mg within the soil exchangeabl ... | 2008 | 18839760 |
| cambial activity and intra-annual xylem formation in roots and stems of abies balsamea and picea mariana. | studies on xylogenesis focus essentially on the stem, whereas there is basically no information about the intra-annual growth of other parts of the tree. as roots strongly influence carbon allocation and tree development, knowledge of the dynamics of xylem production and maturation in roots at a short time scale is required for a better understanding of the phenomenon of tree growth. this study compared cambial activity and xylem formation in stem and roots in two conifers of the boreal forest i ... | 2008 | 18708643 |
| 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 |
| springtime resumption of photosynthesis in balsam fir (abies balsamea). | photosynthesis in balsam fir (abies balsamea (l.) mill.) was measured in the field at two locations in new brunswick, canada from late winter to late spring in 2004 and 2005. no photosynthesis was detectable while the soil remained below 0 degrees c throughout the rooting zone. in both years, photosynthesis began once soil temperature rose to 0 degrees c. in potted seedlings in growth chambers, there was no photosynthesis at an air temperature of 10 degrees c if the pots were frozen. these findi ... | 2008 | 18450571 |
| modeling spruce budworm population revisited: impact of physiological structure on outbreak control. | understanding the dynamics of spruce budworm population is very important for the protection of spruce and balsam fir trees of north american forests, and a full understanding of the dynamics requires careful consideration of the individual physiological structures that is essential for outbreak control. a model as a delay differential equation is derived from structured population system, and is validated by comparing simulation results with real data from the green river area of new brunswick ... | 2008 | 18306004 |
| spectral analysis of coniferous foliage and possible links to soil chemistry: are spectral chlorophyll indices related to forest floor dissolved organic c and n? | dissolved organic matter in soils can be predicted from forest floor c:n ratio, which in turn is related to foliar chemistry. little is known about the linkages between foliar constituents such as chlorophylls, lignin, and cellulose and the concentrations of water-extractable forest floor dissolved organic carbon and dissolved organic nitrogen. lignin and cellulose are not mobile in foliage and thus may be indicative of growing conditions during prior years, while chlorophylls respond more rapid ... | 2008 | 18191443 |
| 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 |
| kinetic characterization for dilute sulfuric acid hydrolysis of timber varieties and switchgrass. | hydrolysis of four timber species (aspen, balsam fir, basswood, and red maple) and switchgrass was studied using dilute sulfuric acid at 50 g dry biomass/l under similar conditions previously described as acid pretreatment. the primary goal was to obtain detailed kinetic data of xylose formation and degradation from a match between a first order reaction model and the experimental data at various final reactor temperatures (160-190 degrees c), sulfuric acid concentrations (0.25-1.0% w/v), and pa ... | 2008 | 17904838 |