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Spruce Trees (spruce + tree)
Selected AbstractsAtomic force microscopic analysis of hydrogen peroxide bleached kraft northern black spruce fibresJOURNAL OF MICROSCOPY, Issue 2 2005M. A. POGGI Summary Hydrogen peroxide is a potent, relatively inexpensive oxidant that chemically degrades chromophoric components in pulps and textiles. Oxidation of cellulose is a byproduct of this process step that decreases the tensile strength of individual fibres. The residence time of pulp in the bleaching reactor must be optimized to achieve the desired brightness and minimizing fibre degradation. To evaluate the impact of peroxide bleaching at the microfibrillar level, a single black spruce tree was chosen and kraft pulped. Peroxide bleaching was conducted via benchtop polyethylene bag bleaching in a temperature-controlled waterbath. Atomic force microscopy (AFM) topographical images acquired before and after the bleaching step show dramatic changes in fibre structure consistent with delignification and defects in the surface topography. This was further verified by X-ray work at Brookhaven National Laboratory, NY, U.S.A. [source] Fungi isolated from Picea abies infested by the bark beetle Ips typographus in the Bia,owie,a forest in north-eastern PolandFOREST PATHOLOGY, Issue 2 2010T. Kirisits Summary The assemblage of fungi occurring in the sapwood of Norway spruce (Picea abies) and in bark beetle galleries following attack by the Eurasian spruce bark beetle Ips typographus was investigated in the Bia,owie,a forest in north-eastern Poland. Fungi were isolated from blue-stained sapwood of beetle-infested spruce trees in June 2002, and a few isolates were also obtained from ascospores and conidia taken from perithecia and asexual structures occurring in the gallery systems of the insects. The mycobiota of I. typographus in the Bia,owie,a forest was dominated by ophiostomatoid fungi, which were represented by seven species. Four species, including Ceratocystis polonica, Grosmannia penicillata, Ophiostoma ainoae and Ophiostoma bicolor were isolated at high frequencies, whereas three other taxa, Ceratocystiopsis minuta, Ceratocystiopsis alba and a Pesotum sp. were rare. The anamorphic fungus Graphium fimbriisporum and yeasts also occurred occasionally. In addition, the basidiomycete Gloeocystidium ipidophilum was relatively common. The pathogenic blue-stain fungus C. polonica was the dominant fungal associate of I. typographus in the Bia,owie,a forest, which is consistent with a previous study at this area in the 1930s. Ceratocystis polonica was the most frequently isolated species at the leading edge of fungal colonization in the sapwood and had on an average penetrated deeper into the wood than other fungal associates. This suggests that it acts as a primary invader into the sapwood after attack by I. typographus in the Bia,owie,a forest, followed by O. bicolor, O. ainoae, G. ipidophilum and G. penicillata. Thus far, the Bia,owie,a forest is one of the few areas in Europe, where C. polonica has been reported as a dominate fungal associate of I. typographus. [source] Response of soil surface CO2 flux in a boreal forest to ecosystem warmingGLOBAL CHANGE BIOLOGY, Issue 4 2008DUSTIN R. BRONSON Abstract Soil surface carbon dioxide (CO2) flux (RS) was measured for 2 years at the Boreal Soil and Air Warming Experiment site near Thompson, MB, Canada. The experimental design was a complete random block design that consisted of four replicate blocks, with each block containing a 15 m × 15 m control and heated plot. Black spruce [Picea mariana (Mill.) BSP] was the overstory species and Epilobium angustifolium was the dominant understory. Soil temperature was maintained (,5 °C) above the control soil temperature using electric cables inside water filled polyethylene tubing for each heated plot. Air inside a 7.3-m-diameter chamber, centered in the soil warming plot, contained approximately nine black spruce trees was heated ,5 °C above control ambient air temperature allowing for the testing of soil-only warming and soil+air warming. Soil surface CO2 flux (RS) was positively correlated (P < 0.0001) to soil temperature at 10 cm depth. Soil surface CO2 flux (RS) was 24% greater in the soil-only warming than the control in 2004, but was only 11% greater in 2005, while RS in the soil+air warming treatments was 31% less than the control in 2004 and 23% less in 2005. Live fine root mass (< 2 mm diameter) was less in the heated than control treatments in 2004 and statistically less (P < 0.01) in 2005. Similar root mass between the two heated treatments suggests that different heating methods (soil-only vs. soil+air warming) can affect the rate of decomposition. [source] Colonization of storm gaps by the spruce bark beetle: influence of gap and landscape characteristicsAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2010Leif Martin Schroeder 1After storm disturbances, there is a risk for degradation of the quality of fallen trees, and for subsequent tree mortality caused by the spruce bark beetle Ips typographus (L.) (Coleoptera: Curculionidae). Models assessing the risk for bark beetle colonization of different kinds of storm gaps would be a valuable tool for management decisions. 2The present study aimed to determine which gap and landscape characteristics are correlated with the probability of colonization of wind-felled Norway spruce trees by I. typographus. 3The study included 36 storm gaps, varying in size from three to 1168 wind-felled spruces, created by the storm Gudrun in southern Sweden in January 2005. 4In the first summer, on average, 5% of the wind-felled spruces were colonized by I. typographus. The percentage of colonized wind-felled trees per gap was negatively correlated with the total area of storm gaps within 2000 m in the surrounding forest landscape. 5In the second summer, the proportion of colonized trees increased to 50%. Both gap (mean diameter of wind-felled trees and basal area of living spruce trees) and landscape variables (amount of spruce forest) were significantly correlated with colonization percentage and explained almost 50% of the variation between gaps. 6There was no relationship between gap area and colonization percentage. This implies that landscapes with many large storm gaps, where logging resources will be most effectively used, should be salvaged first. [source] Influence of boreal forest succession and dead wood qualities on saproxylic beetlesAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2007Joshua M. Jacobs Abstract 1,Saproxylic insects, a functional group dominated by beetles, are dependent on dead or moribund trees as habitat elements. 2,Although there are few studies of saproxylic insects from the North American boreal zone, European studies demonstrate that forest harvest can lead to a biologically significant decrease in saproxylic beetle diversity. 3,We studied saproxylic beetles in the North American boreal mixedwood forest using flight intercept traps established on naturally dead and girdled trembling aspen and spruce trees along a successional gradient of undisturbed stands from deciduous to coniferous overstory trees. 4,Composition and diversity of beetle assemblages differed among forest successional types. 5,Snag age class was an important determinant of composition for saproxylic beetle assemblages. 6,Multivariate regression analysis of these data indicated that saproxylic beetles are responding to changes in coarse woody debris, and not to the relative densities of canopy tree species, although these variables are strongly correlated. 7,Coarse woody debris management should be a primary concern in forest management plans seeking to conserve saproxylic organisms and the critical ecosystem functions (i.e. nutrient cycling) in which they participate. [source] Consistency of resistance to attack by the green spruce aphid (Elatobium abietinum Walker) in different ontogenetic stages of Sitka spruceAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 2 2003S. Harding Abstract 1,The susceptibility of different genotypes of 29-year-old Sitka spruce to damage by the green spruce aphid, Elatobium abietinum, was investigated in a progeny trial where aphid damage on individual trees had previously been assessed twice in an earlier stage of ontogenetic development. The progeny trial comprised 14 open-pollinated families originating from a clonal seed orchard that had been established using mature spruce trees selected for aphid resistance. 2,Previous investigations had demonstrated that resistance was inherited by the offspring, and that differences in resistance between progenies of the individual orchard clones were highly significant. 3,Susceptibility to aphid attack was recorded as the percentage loss of previous year's needles. Differences in susceptibility recorded between the juvenile trees were found to persist after the trees had developed into the closed-canopy, sexually reproducing stage. Needle loss of the families was significantly less than that of the reference population of Sitka spruce. 4,Hybrids between Sitka spruce and white spruce were defoliated more heavily than pure Sitka spruce, and the difference increased with age. 5,Family heritability of resistance was estimated as 0.60 compared to 0.73 when the trees were assessed in the juvenile stage. The genetic correlation based on family means between damage in the juvenile and sexually reproducing stand was high (0.83), indicating a high consistency of resistance to the aphid over years and ontogenetic stages. 6,A skewed distribution of defoliation indicated that major genes are involved in the expression of resistance, and that the genetics behind resistance has a nonadditive component. [source] Bootstrapping data with multiple levels of variationTHE CANADIAN JOURNAL OF STATISTICS, Issue 4 2008Christopher A. Field Abstract The authors consider general estimators for the mean and variance parameters in the random effect model and in the transformation model for data with multiple levels of variation. They show that these estimators have different distributions under the two models unless all the variables have Gaussian distributions. They investigate the asymptotic properties of bootstrap procedures designed for the two models. They also report simulation results and illustrate the bootstraps using data on red spruce trees. Rééchantillonnage de données à variation multiniveau Les auteurs s'intéressent à des estimateurs généraux des paramètres de moyenne et variance dans le modèle à effets aléatoires et le modèle de transformation pour des données à variation multiniveau. Ils montrent que la loi de ces estimateurs dépend du modèle sauf si toutes les variables sont gaussiennes. Ils explorent les propriétés asymptotiques de procédures bootstrap propres aux deux modèles. Ils présentent des résultats de simulation et illustrent l'emploi de ces bootstraps à l'aide de données sur l'épinette rouge. [source] | ||||||||||