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Richard Spruce, botânico e desbravador da América do Sul

Seaward,Mark R. D.
Fonte: Casa de Oswaldo Cruz, Fundação Oswaldo Cruz Publicador: Casa de Oswaldo Cruz, Fundação Oswaldo Cruz
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/10/2000 PT
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37.27%
No período entre 1849 e 1864, o botânico e explorador inglês Richard Spruce promoveu minucioso estudo da flora amazônica e dos costumes dos povos que habitavam essa região. Ainda hoje, grande parte do conhecimento sobre várias famílias botânicas daquela região advém do esforço desenvolvido por esse cientista. A amplitude de seus interesses, a meticulosidade e a exatidão de suas descrições foram fenomenais: nada parece ter escapado à sua atenção e capacidade de documentação. Spruce era não apenas notável botânico, mas também admirável antropólogo, lingüista (sabia francês, espanhol e português), geólogo, e geógrafo, bem como arguto observador sociológico dos sistemas políticos e dos hábitos das tribos amazônicas e andinas entre as quais esteve, trazendo considerável contribuição para o entendimento das crenças e práticas nativas e para o conhecimento das propriedades e usos das plantas, no contexto amazônico. Sua participação na exploração econômica de espécies locais também foi importante, particularmente em relação aos gêneros Hevea e Cinchona.

Methyl Jasmonate Induces Traumatic Resin Ducts, Terpenoid Resin Biosynthesis, and Terpenoid Accumulation in Developing Xylem of Norway Spruce Stems1

Martin, Diane; Tholl, Dorothea; Gershenzon, Jonathan; Bohlmann, Jörg
Fonte: American Society of Plant Physiologists Publicador: American Society of Plant Physiologists
Tipo: Artigo de Revista Científica
Publicado em /07/2002 EN
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27.46%
Norway spruce (Picea abies L. Karst) produces an oleoresin characterized by a diverse array of terpenoids, monoterpenoids, sesquiterpenoids, and diterpene resin acids that can protect conifers against potential herbivores and pathogens. Oleoresin accumulates constitutively in resin ducts in the cortex and phloem (bark) of Norway spruce stems. De novo formation of traumatic resin ducts (TDs) is observed in the developing secondary xylem (wood) after insect attack, fungal elicitation, and mechanical wounding. Here, we characterize the methyl jasmonate-induced formation of TDs in Norway spruce by microscopy, chemical analyses of resin composition, and assays of terpenoid biosynthetic enzymes. The response involves tissue-specific differentiation of TDs, terpenoid accumulation, and induction of enzyme activities of both prenyltransferases and terpene synthases in the developing xylem, a tissue that constitutively lacks axial resin ducts in spruce. The induction of a complex defense response in Norway spruce by methyl jasmonate application provides new avenues to evaluate the role of resin defenses for protection of conifers against destructive pests such as white pine weevils (Pissodes strobi), bark beetles (Coleoptera, Scolytidae), and insect-associated tree pathogens.

Winter at the Alpine Timberline. Why Does Embolism Occur in Norway Spruce But Not in Stone Pine?1

Mayr, Stefan; Schwienbacher, Franziska; Bauer, Helmut
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
Publicado em /02/2003 EN
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Conifers growing at the alpine timberline are exposed to frost drought and freeze-thaw cycles during winter—stress factors known to induce embolism in tree xylem. The two dominant species of the European Central Alps timberline were studied: Norway spruce (Picea abies [L.] Karst) and stone pine (Pinus cembra), which usually reaches higher altitudes. We hypothesized to find embolism only at the timberline and to observe less embolism in stone pine than in Norway spruce due to avoidance mechanisms. Seasonal courses of embolism and water potential were studied at 1,700 and 2,100 m during two winter seasons and correlated to vulnerability (to drought-induced embolism), leaf conductance, and micrometeorological data. Embolism was observed only at the timberline and only in Norway spruce (up to 49.2% loss of conductivity). Conductivity losses corresponded to low water potentials (down to −3.5 MPa) but also to the number of freeze-thaw events indicating both stress factors to contribute to embolism induction. Decreasing embolism rates—probably due to refilling—were observed already in winter. Stone pine did not exhibit an adapted vulnerability (50% loss of conductivity at −3.5 MPa) but avoided critical potentials (minimum −2.3 MPa): Cuticulare conductance was 3.5-fold lower than in Norway spruce...

Aminocyclopropane Carboxylic Acid Synthase Is a Regulated Step in Ethylene-Dependent Induced Conifer Defense. Full-Length cDNA Cloning of a Multigene Family, Differential Constitutive, and Wound- and Insect-Induced Expression, and Cellular and Subcellular Localization in Spruce and Douglas Fir12[W][OA]

Ralph, Steven G.; Hudgins, J.W.; Jancsik, Sharon; Franceschi, Vincent R.; Bohlmann, Jörg
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
Publicado em /01/2007 EN
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27.46%
In conifer stems, formation of chemical defenses against insects or pathogens involves specialized anatomical structures of the phloem and xylem. Oleoresin terpenoids are formed in resin duct epithelial cells and phenolics accumulate in polyphenolic parenchyma cells. Ethylene signaling has been implicated in the induction of these chemical defenses. Recently, we reported the cloning of 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) from spruce (Picea spp.) and Douglas fir (Pseudotsuga menziesii). ACO protein was constitutively expressed in Douglas fir and only weakly induced upon wounding. We now cloned seven full-length and one near full-length cDNA representing four distinct 1-aminocyclopropane-1-carboxylic acid synthases (ACS; ACS1, ACS2, ACS3, and ACS4) from spruce and Douglas fir. Cloning of ACS has not previously been reported for any gymnosperm. Using gene-specific, quantitative real-time polymerase chain reaction, we measured constitutive expression for the four ACS genes and the single-copy ACO gene in various tissues of Sitka spruce (Picea sitchensis) and in white spruce (Picea glauca) somatic embryos. ACO and ACS4 were ubiquitously expressed at high levels; ACS1 was predominantly expressed in developing embryos and ACS2 and ACS3 were expressed only at very low levels. Insect attack or mechanical wounding caused strong induction of ACS2 and ACS3 in Sitka spruce bark...

A Norway Spruce FLOWERING LOCUS T Homolog Is Implicated in Control of Growth Rhythm in Conifers1[OA]

Gyllenstrand, Niclas; Clapham, David; Källman, Thomas; Lagercrantz, Ulf
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
Publicado em /05/2007 EN
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27.52%
Growth in perennial plants possesses an annual cycle of active growth and dormancy that is controlled by environmental factors, mainly photoperiod and temperature. In conifers and other nonangiosperm species, the molecular mechanisms behind these responses are currently unknown. In Norway spruce (Picea abies L. Karst.) seedlings, growth cessation and bud set are induced by short days and plants from southern latitudes require at least 7 to 10 h of darkness, whereas plants from northern latitudes need only 2 to 3 h of darkness. Bud burst, on the other hand, is almost exclusively controlled by temperature. To test the possible role of Norway spruce FLOWERING LOCUS T (FT)-like genes in growth rhythm, we have studied expression patterns of four Norway spruce FT family genes in two populations with a divergent bud set response under various photoperiodic conditions. Our data show a significant and tight correlation between growth rhythm (both bud set and bud burst), and expression pattern of one of the four Norway spruce phosphatidylethanolamine-binding protein gene family members (PaFT4) over a variety of experimental conditions. This study strongly suggests that one Norway spruce homolog to the FT gene, which controls flowering in angiosperms...

Impact of Endochitinase-Transformed White Spruce on Soil Fungal Biomass and Ectendomycorrhizal Symbiosis▿

Stefani, Franck O. P.; Tanguay, Philippe; Pelletier, Gervais; Piché, Yves; Hamelin, Richard C.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
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27.46%
The impact of transgenic white spruce [Picea glauca (Moench) Voss] containing the endochitinase gene (ech42) on soil fungal biomass and on the ectendomycorrhizal fungi Wilcoxina spp. was tested using a greenhouse trial. The measured level of endochitinase in roots of transgenic white spruce was up to 10 times higher than that in roots of nontransformed white spruce. The level of endochitinase in root exudates of three of four ech42-transformed lines was significantly greater than that in controls. Analysis soil ergosterol showed that the amount of fungal biomass in soil samples from control white spruce was slightly larger than that in soil samples from ech42-transformed white spruce. Nevertheless, the difference was not statistically significant. The rates of mycorrhizal colonization of transformed lines and controls were similar. Sequencing the internal transcribed spacer rRNA region revealed that the root tips were colonized by the ectendomycorrhizal fungi Wilcoxina spp. and the dark septate endophyte Phialocephala fortinii. Colonization of root tips by Wilcoxina spp. was monitored by real-time PCR to quantify the fungus present during the development of ectendomycorrhizal symbiosis in ech42-transformed and control lines. The numbers of Wilcoxina molecules in the transformed lines and the controls were not significantly different (P > 0.05...

Biosynthesis of the Major Tetrahydroxystilbenes in Spruce, Astringin and Isorhapontin, Proceeds via Resveratrol and Is Enhanced by Fungal Infection1[W][OA]

Hammerbacher, Almuth; Ralph, Steven G.; Bohlmann, Joerg; Fenning, Trevor M.; Gershenzon, Jonathan; Schmidt, Axel
Fonte: American Society of Plant Biologists Publicador: American Society of Plant Biologists
Tipo: Artigo de Revista Científica
EN
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Stilbenes are dibenzyl polyphenolic compounds produced in several unrelated plant families that appear to protect against various biotic and abiotic stresses. Stilbene biosynthesis has been well described in economically important plants, such as grape (Vitis vinifera), peanut (Arachis hypogaea), and pine (Pinus species). However, very little is known about the biosynthesis and ecological role of stilbenes in spruce (Picea), an important gymnosperm tree genus in temperate and boreal forests. To investigate the biosynthesis of stilbenes in spruce, we identified two similar stilbene synthase (STS) genes in Norway spruce (Picea abies), PaSTS1 and PaSTS2, which had orthologs with high sequence identity in sitka (Picea sitchensis) and white (Picea glauca) spruce. Despite the conservation of STS sequences in these three spruce species, they differed substantially from angiosperm STSs. Several types of in vitro and in vivo assays revealed that the P. abies STSs catalyze the condensation of p-coumaroyl-coenzyme A and three molecules of malonyl-coenzyme A to yield the trihydroxystilbene resveratrol but do not directly form the dominant spruce stilbenes, which are tetrahydroxylated. However, in transgenic Norway spruce overexpressing PaSTS1...

Genetical Genomics Identifies the Genetic Architecture for Growth and Weevil Resistance in Spruce

Porth, Ilga; White, Richard; Jaquish, Barry; Alfaro, René; Ritland, Carol; Ritland, Kermit
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 04/09/2012 EN
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In plants, relationships between resistance to herbivorous insect pests and growth are typically controlled by complex interactions between genetically correlated traits. These relationships often result in tradeoffs in phenotypic expression. In this study we used genetical genomics to elucidate genetic relationships between tree growth and resistance to white pine terminal weevil (Pissodes strobi Peck.) in a pedigree population of interior spruce (Picea glauca, P. engelmannii and their hybrids) that was growing at Vernon, B.C. and segregating for weevil resistance. Genetical genomics uses genetic perturbations caused by allelic segregation in pedigrees to co-locate quantitative trait loci (QTLs) for gene expression and quantitative traits. Bark tissue of apical leaders from 188 trees was assayed for gene expression using a 21.8K spruce EST-spotted microarray; the same individuals were genotyped for 384 SNP markers for the genetic map. Many of the expression QTLs (eQTL) co-localized with resistance trait QTLs. For a composite resistance phenotype of six attack and oviposition traits, 149 positional candidate genes were identified. Resistance and growth QTLs also overlapped with eQTL hotspots along the genome suggesting that: 1) genetic pleiotropy of resistance and growth traits in interior spruce was substantial...

Space sequestration below ground in old-growth spruce-beech forests—signs for facilitation?

Bolte, Andreas; Kampf, Friederike; Hilbrig, Lutz
Fonte: Frontiers Media S.A. Publicador: Frontiers Media S.A.
Tipo: Artigo de Revista Científica
Publicado em 20/08/2013 EN
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Scientists are currently debating the effects of mixing tree species for the complementary resource acquisition in forest ecosystems. In four unmanaged old-growth spruce-beech forests in strict nature reserves in southern Sweden and northern Germany we assessed forest structure and fine rooting profiles and traits (≤2 mm) by fine root sampling and the analysis of fine root morphology and biomass. These studies were conducted in selected tree groups with four different interspecific competition perspectives: (1) spruce as a central tree, (2) spruce as competitor, (3) beech as a central tree, and (4) beech as competitor. Mean values of life fine root attributes like biomass (FRB), length (FRL), and root area index (RAI) were significantly lower for spruce than for beech in mixed stands. Vertical profiles of fine root attributes adjusted to one unit of basal area (BA) exhibited partial root system stratification when central beech is growing with spruce competitors. In this constellation, beech was able to raise its specific root length (SRL) and therefore soil exploration efficiency in the subsoil, while increasing root biomass partitioning into deeper soil layers. According to relative values of fine root attributes (rFRA), asymmetric below-ground competition was observed favoring beech over spruce...

Origin and demographic history of the endemic Taiwan spruce (Picea morrisonicola)

Bodare, Sofia; Stocks, Michael; Yang, Jeng-Chuann; Lascoux, Martin
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
EN
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27.46%
Taiwan spruce (Picea morrisonicola) is a vulnerable conifer species endemic to the island of Taiwan. A warming climate and competition from subtropical tree species has limited the range of Taiwan spruce to the higher altitudes of the island. Using seeds sampled from an area in the central mountain range of Taiwan, 15 nuclear loci were sequenced in order to measure genetic variation and to assess the long-term genetic stability of the species. Genetic diversity is low and comparable to other spruce species with limited ranges such as Picea breweriana, Picea chihuahuana, and Picea schrenkiana. Importantly, analysis using approximate Bayesian computation (ABC) provides evidence for a drastic decline in the effective population size approximately 0.3–0.5 million years ago (mya). We used simulations to show that this is unlikely to be a false-positive result due to the limited sample used here. To investigate the phylogenetic origin of Taiwan spruce, additional sequencing was performed in the Chinese spruce Picea wilsonii and combined with previously published data for three other mainland China species, Picea purpurea, Picea likiangensis, and P. schrenkiana. Analysis of population structure revealed that P. morrisonicola clusters most closely with P. wilsonii...

Disturbance and climatic effects on red spruce community dynamics at its southern continuous range margin

Ribbons, Relena Rose
Fonte: PeerJ Inc. Publicador: PeerJ Inc.
Tipo: Artigo de Revista Científica
Publicado em 06/03/2014 EN
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27.68%
Red spruce (Picea rubens) populations experienced a synchronous rangewide decline in growth and vigor starting in the 1960s, likely caused by climate change and a combination of environmental disturbances. However, it is not yet known if populations continue to decline or have recovered. Red spruce growing near its southern range margin in Massachusetts is a species of concern, in light of the vulnerability to climate change. This study uses population data from 17 permanent plots coupled with tree-ring data to examine radial growth rates, determine the growth-climate relationship, and document disturbance events. Red spruce at these plots ranged from 90 to 184 years old, and comprised 15 to 29 m2/ha basal area. Red spruce seedlings and saplings were common at plots with previously high overstory spruce abundance, indicating it could return to a more dominant position under favorable growing conditions. However, permanent plot measures over a 50 year time span did not indicate any consistent trends for changes in basal area or density for red spruce or other woody species. Climate data show that mean annual minimum, maximum, and summer temperatures have increased over the last 100 years. Dendroclimatological analyses indicated that red spruce growth was sensitive to both temperature and precipitation. Prior to the 1960s...

Expression of the β-glucosidase gene Pgβglu-1 underpins natural resistance of white spruce against spruce budworm

Mageroy, Melissa H; Parent, Geneviève; Germanos, Gaby; Giguère, Isabelle; Delvas, Nathalie; Maaroufi, Halim; Bauce, Éric; Bohlmann, Joerg; Mackay, John J
Fonte: BlackWell Publishing Ltd Publicador: BlackWell Publishing Ltd
Tipo: Artigo de Revista Científica
EN
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27.52%
Periodic outbreaks of spruce budworm (SBW) affect large areas of ecologically and economically important conifer forests in North America, causing tree mortality and reduced forest productivity. Host resistance against SBW has been linked to growth phenology and the chemical composition of foliage, but the underlying molecular mechanisms and population variation are largely unknown. Using a genomics approach, we discovered a β-glucosidase gene, Pgβglu-1, whose expression levels and function underpin natural resistance to SBW in mature white spruce (Picea glauca) trees. In phenotypically resistant trees, Pgβglu-1 transcripts were up to 1000 times more abundant than in non-resistant trees and were highly enriched in foliage. The encoded PgβGLU-1 enzyme catalysed the cleavage of acetophenone sugar conjugates to release the aglycons piceol and pungenol. These aglycons were previously shown to be active against SBW. Levels of Pgβglu-1 transcripts and biologically active acetophenone aglycons were substantially different between resistant and non-resistant trees over time, were positively correlated with each other and were highly variable in a natural white spruce population. These results suggest that expression of Pgβglu-1 and accumulation of acetophenone aglycons is a constitutive defence mechanism in white spruce. The progeny of resistant trees had higher Pgβglu-1 gene expression than non-resistant progeny...

Negative Feedbacks on Bark Beetle Outbreaks: Widespread and Severe Spruce Beetle Infestation Restricts Subsequent Infestation

Hart, Sarah J.; Veblen, Thomas T.; Mietkiewicz, Nathan; Kulakowski, Dominik
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 22/05/2015 EN
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27.52%
Understanding disturbance interactions and their ecological consequences remains a major challenge for research on the response of forests to a changing climate. When, where, and how one disturbance may alter the severity, extent, or occurrence probability of a subsequent disturbance is encapsulated by the concept of linked disturbances. Here, we evaluated 1) how climate and forest habitat variables, including disturbance history, interact to drive 2000s spruce beetle (Dendroctonus rufipennis) infestation of Engelmann spruce (Picea engelmannii) across the Southern Rocky Mountains; and 2) how previous spruce beetle infestation affects subsequent infestation across the Flat Tops Wilderness in northwestern Colorado, which experienced a severe landscape-scale spruce beetle infestation in the 1940s. We hypothesized that drought and warm temperatures would promote infestation, whereas small diameter and non-host trees, which may reflect past disturbance by spruce beetles, would inhibit infestation. Across the Southern Rocky Mountains, we found that climate and forest structure interacted to drive the 2000s infestation. Within the Flat Tops study area we found that stands infested in the 1940s were composed of higher proportions of small diameter and non-host trees ca. 60 years later. In this area...

Stochastic Model of Eastern Spruce Budworm (Lepidoptera: Tortricidae) Phenology on White Spruce and Balsam Fir

Lysyk, Timothy J.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
EN
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27.61%
Astochastic model of spruce budworm, Choristoneura fumiferana (Clemens), phenology on balsam fir, Abies balsamea (L.) Miller, and white spruce, Picea glauca (Moench) Voss, in northern Ontario was developed based on relationships between the proportion of budworms in each stage (second instar to adult) and accumulated degree-days (DO). Repeated calculations indicated that 8°C was a suitable threshold for degree-day calculations. Fifty percent of the population was in the second instar after 89 and 92 DO above 8°C on balsam fir and white spruce, respectively. Peak occurrence of instars three, four, five, and six, and of pupae, occurred on balsam fir after 108, 154, 204, 295, and 413 DD, respectively; peak occurrence of the same stadia on white spruce occurred after 103, 138, 186, 256, and 370 DD. Fifty percent adult emergence occurred at 467 and 437 DD for balsam fir and white spruce. Tests of the model with independent data showed that it simulated spruce budworm development excellently. Model performance was superior compared with a previously published spruce budworm phenology model.

Above-ground space sequestration determines competitive success in juvenile beech and spruce trees.

Kozovits, Alessandra Rodrigues; Matyssek, Rainer; Winkler, J. Barbro; G?ttlein, Axel; Blaschke, Helmut; Grams, Thorsten E. E.
Fonte: Universidade Federal de Ouro Preto Publicador: Universidade Federal de Ouro Preto
Tipo: Artigo publicado em periodico
EN_US
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A 2-yr phytotron study was conducted to investigate the intra- and inter-specific competitive behaviour of juvenile beech (Fagus sylvatica ) and spruce (Picea abies ). Competitiveness was analysed by quantifying the resource budgets that occur along structures and within occupied space of relevance for competitive interaction. Ambient and elevated CO2 and ozone (O3) regimes were applied throughout two growing seasons as stressors for provoking changes in resource budgets, growth and allocation to facilitate the competition analysis. The hypothesis tested was that the ability to sequester space at low structural cost will determine the competitive success. Spruce was a stronger competitor than beech, as displayed by its higher aboveground biomass increments in mixed culture compared with monoculture. A crucial factor in the competitive success of spruce was its ability to enlarge crown volume at low structural costs, supporting the hypothesis. Interspecific competition with spruce resulted in a size-independent readjustment of above-ground allocation in beech (reduced leaf: shoot biomass ratio). The efficient use of resources for above-ground space sequestration proved to be a parameter that quantitatively reflects competitiveness.

Nutrient pools in Sitka spruce and lodgepole pine forest biomass

Mangrinan, Eva Ros
Fonte: University of Limerick Publicador: University of Limerick
Tipo: info:eu-repo/semantics/doctoralThesis; all_ul_research; ul_published_reviewed; ul_theses_dissertations
ENG
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37.38%
peer-reviewed; Biomass harvesting may affect the nutrient pools of forests and impact negatively on forest ecosystems in the long-term. Appropriate knowledge regarding nutrient pools and potential nutrient removal is required for a good forest management to attain sustainable productivity. The main aims of this work were to give information of nutrient status (nitrogen N, phosphorus P, potassium K, calcium Ca, and magnesium Mg) of forests by studying a chronosequence Sitka spruce (Picea sitchensis (Bong.) Carr) and several mature Sitka spruce and lodgepole pine (Pinus contorta Dougl. var. latifolia) stands, and to determinate the potential nutrient removal in a site applying different harvest scenarios: stem-only harvest, stem-and-branch harvest and whole-tree harvest. The database of this study comes from selected and sampled forest harvest residue in brash bundles and from standing trees, which were divided in six components (needles, branches, deadwood, roots, stembark and stemwood). Nutrient concentrations of these samples were analysed. Both tree species showed that needles was the component with higher nutrient concentration, and stemwood that with the lowest. In general, nutrient concentration in a tree for both species was identified from large to lesser concentration: N > Ca > K > Mg > P. Nitrogen pool generally increased over time. Sitka spruce stands had larger nutrient pools than lodgepole pine stands. WTH system potentially removed approximately double the amount of nutrients than SOH system. Several investigators had suggested different percentages of harvest residues to be retained on site in order to manage the forest sustainably. More research will be needed to verify what amount of harvest residue and what type of it must be left on site.

Spruce bark beetle disturbance in the forest-tundra ecotones of southwest Yukon: impacts and predisposing factors

Mazzocato, Michelle
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
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As climate warms, phytophagous forest insects are expected to advance into previously unoccupied regions and/or experience population eruptions within their extant ranges. Already stressed by abiotic factors, arctic and alpine treeline environments will therefore become increasingly vulnerable to insect disturbances. Using vegetation surveys and dendrochronological techniques, we examined factors that may have predisposed the forest-tundra ecotones of southwest Yukon to spruce bark beetle (Dendroctonus rufipennis) infestation, and investigated the subsequent effects of insect disturbance on the growth and establishment of white spruce (Picea glauca). Specific objectives were to evaluate (i) the relationships between stand structure and variance in beetle-induced mortality and (ii) growth patterns between stands affected and relatively unaffected by the outbreak. Information on spruce size, reproduction and health, shrub cover, seedling density and size, stand density, and basal area was collected from three elevations at six sites, divided equally into three mortality classes. A subset of mature spruce individuals – both living and deceased – was sampled from one low-mortality and one medium-mortality site. Results demonstrated that hosts selected by spruce bark beetle were typically large individuals growing in dense stands...

Evaluation of the visual stress grading standard on French Spruce (Picea excelsa) and Douglas-fir (Pseudotsuga menziesii) sawn timber

ROBLOT, Guillaume; COUDEGNAT, Damien; BLERON, Laurent; COLLET, Robert
Fonte: EDP Sciences Publicador: EDP Sciences
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37.11%
We wish to thank J.C. Sève and S. Vives from Monnet-Sève sawmills who provided us with the two batches of boards. Acknowledgments also go to people from LaBoMap, especially J.C. Butaud who helped us during the tests. Finally, we thank L. Brancheriau from CIRAD, who assisted us with the data exploitation.; In this paper an evaluation of the visual grading standard for softwood sawn timber was made. • In order to do so, visual grading according to EN 518 and theoretical grading according to EN 338 and EN 384 (measurements of MOE, MOR and density) were applied to lumber. Two batches of 111 and 102 French boards were graded, respectively, of Spruce (Picea excelsa) and Douglas-fir (Pseudotsuga menziesii). For the visual grading the most discriminant criterion was noted: knots, cracks, wane, etc. • Finally, the results of the two grading methods were compared, and it was shown that the visual stress grading gave quite low results for our two French species.

No Evidence of an Impact on the Rhizosphere Diazotroph Community by the Expression of Bacillus thuringiensis Cry1Ab Toxin by Bt White Spruce▿†

Lamarche, Josyanne; Hamelin, Richard C.
Fonte: American Society for Microbiology (ASM) Publicador: American Society for Microbiology (ASM)
Tipo: Artigo de Revista Científica
EN
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27.66%
Nitrogen fixation is one of the most important roles played by soil bacterial communities, as fixation supplies nitrogen to many ecosystems which are often N limited. As impacts on this functional group of bacteria might harm the ecosystem's health and reduce productivity, monitoring that particular group is important. Recently, a field trial with Bt white spruce, which constitutively expresses the Cry1Ab insecticidal toxin of Bacillus thuringiensis, was established. The Bt white spruce was shown to be resistant to spruce budworm. We investigated the possible impact of these genetically modified trees on soil nitrogen-fixing bacterial communities. The trial consisted of untransformed controls, GUS white spruce (transformed with the β-glucuronidase gene), and Bt/GUS white spruce (which constitutively expresses both the Cry1Ab toxin and β-glucuronidase) in a random design. Four years after planting, soil samples from the control and the two treatments from plantation as well as from two natural stands of white spruce were collected. Diazotroph diversity was assessed by extracting soil genomic DNA and amplifying a region of the nitrogenase reductase (nifH) gene, followed by cloning and sequencing. Analysis revealed that nitrogen-fixing communities did not differ significantly among the untransformed control...

Silica-cast replicas for morphology studies on spruce and birch xylem

Persson, Per Valdemar; Fogden, Andrew; Hafren, Jonas; Daniel, Geoffrey; Iversen, Tommy
Fonte: National Herbarium and Botanic Gardens Publicador: National Herbarium and Botanic Gardens
Tipo: Artigo de Revista Científica
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Sol-gel mineralization has been used and evaluated as a tool for morphological studies on Picea abies and Betula verrucosa. Wood specimens and a pulped spruce sample were impregnated with a silica sol-gel and subsequently heated (calcined) to condense the