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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Trees 10 (1996), S. 239-246 
    ISSN: 1432-2285
    Schlagwort(e): Bending stress ; Stem shape ; Radial growth rate ; Eucalyptus regnans
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract A glasshouse experiment investigated the effect of bending stress on stem radial and height growth and stem taper ofEucalyptus regnans seedlings. Eighteen-week-old, potted seedlings were bent continuously for 8 weeks with a static bending stress. The bending treatment was then removed and the seedlings grown for another 12 weeks. Other seedlings were stayed vertically throughout the experiment whilst control seedlings were neither bent nor stayed. Seedlings were rotated every 2 days to prevent reaction wood developing asymmetrically in the stems of bent trees. Bent trees had higher radial growth rates, developed more tapered stems and had higher safety factors (the ratio of stem radius to the minimum radius required to prevent the tree toppling over) than unbent seedlings. They produced a band of tension wood in their stems and ceased height growth whilst bent. When bending ceased, they resumed normal radial and height growth. Unbent trees developed more cylindrical stems. There were no differences in growth behaviour between stayed and control trees. Bent and unbent trees all developed a butt swell, the taper of which was not affected by treatment. It was concluded that bending stress has substantial effects on both the size and taper of tree stems. However, the development of butt swell is independent of the bending stress applied. The results were considered in relation to biomechanical theories of tree stem development.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Trees 8 (1994), S. 151-159 
    ISSN: 1432-2285
    Schlagwort(e): Pinus radiata ; Stem deformation ; Nitrogen, elasticity ; Compression wood ; Stem form
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary The occurrence of stem deformation in Pinus radiata plantations has been examined previously in terms of the factors leading to the onset of bending symptoms. In this study the influence of seedling family and nitrogen availability on the ability of seedlings to recover from deformation was investigated under glasshouse conditions. Seedlings from four families ranging from resistant to susceptible to stem deformation were used. Stem deformation was induced by loading stems with a known weight and comparing bending moments and rates of recovery. Significant differences between families were found with more susceptible families exhibiting greater initial magnitudes of stem lean. Similarly these families also exhibited greater rates of apical elongation following bending despite the larger stem leans. This resulted in more exaggerated stem bends as a consequence of the recovery of the lower stem pushing the upper stem away from the vertical. The strength characteristics of the stems could not explain differences between families. Susceptibility to stem deformation was explained more by stem slenderness expressed as stem height to root collar diameter.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Wood science and technology 25 (1991), S. 7-14 
    ISSN: 1432-5225
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft , Maschinenbau
    Notizen: Summary Lignin topochemistry of tracheid walls from a deformed, copper deficient Pinus radiata (D. Don) tree was examined by linescan and point analyses using a Scanning Electron Microscope and Energy Dispersive Spectrometry. Both opposite and compression wood had abnormal lignin distributions compared to those observed in normal wood from a straight tree. Lignin contents in the compound middle lamella were lower than lignin contents in the secondary wall in both opposite and compression wood tracheids.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Trees 10 (1996), S. 239-246 
    ISSN: 0931-1890
    Schlagwort(e): Key words Bending stress ; Stem shape ; Radial growth rate ; Eucalyptus regnans
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract  A glasshouse experiment investigated the effect of bending stress on stem radial and height growth and stem taper of Eucalyptus regnans seedlings. Eighteen-week-old, potted seedlings were bent continuously for 8 weeks with a static bending stress. The bending treatment was then removed and the seedlings grown for another 12 weeks. Other seedlings were stayed vertically throughout the experiment whilst control seedlings were neither bent nor stayed. Seedlings were rotated every 2 days to prevent reaction wood developing asymmetrically in the stems of bent trees. Bent trees had higher radial growth rates, developed more tapered stems and had higher safety factors (the ratio of stem radius to the minimum radius required to prevent the tree toppling over) than unbent seedlings. They produced a band of tension wood in their stems and ceased height growth whilst bent. When bending ceased, they resumed normal radial and height growth. Unbent trees developed more cylindrical stems. There were no differences in growth behaviour between stayed and control trees. Bent and unbent trees all developed a butt swell, the taper of which was not affected by treatment. It was concluded that bending stress has substantial effects on both the size and taper of tree stems. However, the development of butt swell is independent of the bending stress applied. The results were considered in relation to biomechanical theories of tree stem development.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Publikationsdatum: 2011-11-24
    Beschreibung: The tropical conifer Callitris intratropica (Cupressaceae) produces clear annual growth rings, and has been shown to be potentially useful for understanding past climate variability in northern Australia. As climate patterns in this region become less predictable, an understanding of plant responses to different weather patterns is of importance. In this paper, we examine tree water relations using a parameter here called tree water deficit ( D ), determined from de-trended stem size variability in densely grown (‘grove’) and isolated trees. This parameter provides an integrated measure of the trees' response to water supply and demand under constantly changing environmental conditions. The work, conducted over 12 months, found that daily variation in tree water deficit was determined mainly by soil water availability, but temperature and relative humidity contributed more to the variability over some periods. Isolated and grove trees exhibited quite distinct patterns of D development during the year, but particularly during the transition between the dry and wet seasons. The results of this work suggest that the dendrochronological interpretation of tree rings in the context of strongly seasonal water availability should incorporate an understanding of the development of seasonal drought in isolated trees compared with trees experiencing strong intra-specific competition. Different responses based on the ecological situations of the trees will affect their patterns of stem growth, and ultimately the climatic information that is incorporated in ring width variability.
    Print ISSN: 0829-318X
    Digitale ISSN: 1758-4469
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Publikationsdatum: 2013-01-22
    Beschreibung: Although tree-ring-width chronologies have been widely used for temperature reconstructions, there are many sites around the world at which there is little evidence of a clear climate signal in the ring-width chronologies. This is the case with the long-lived conifer Huon pine ( Lagarostrobos franklinii (Hook. F.) Quinn), endemic to Tasmania, Australia, when the species grows at low elevation. In this study, we developed chronologies of several wood properties (e.g., tracheid radial diameter, microfibril angle) from Huon pine growing at a low-elevation site. We found that despite the absence of a climate signal in the ring-width chronologies, there were significant correlations between wood density, tracheid radial diameter and microfibril angle and temperature, stream flow and a drought index, enabling the development of robust chronologies. This novel finding suggests that chronologies based on these wood properties may have important potential for climate reconstructions from sites and species that have not yet been realized. In particular, a relatively extensive resource of ancient, low-elevation Huon pine in western Tasmania, in which climate signals have not been found using ring widths, may now be useful as part of the broader effort to reconstruct Southern Hemisphere climate.
    Print ISSN: 0829-318X
    Digitale ISSN: 1758-4469
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Publikationsdatum: 1989-01-01
    Beschreibung: Pinusradiata may exhibit moderate to severe stem deformity (Toorour syndrome) when planted on ex-pasture sites in southern Australia. However, the deformity does not occur on ex-eucalypt forest sites unless N fertilizer is applied. While the symptoms of Toorour syndrome are visually similar to those induced by Cu deficiency, the syndrome is associated with high foliar Cu concentrations (and concentrations of Mn and Zn). Furthermore, although Cu-deficient trees typically exhibit lower stem lignin concentrations than nondeformed trees, there is no apparent reduction in the stem lignin concentrations of trees exhibiting Toorour syndrome. Unlike Cu deficiency, the syndrome is not alleviated by Cu fertilizer applications. From comparisons of soil chemical properties between ex-pasture (deformed) and ex-eucalypt (nondeformed) sites, across a range of soil types and lithologies, it is concluded that (i) the syndrome is associated with previous land use rather than soil type or lithology, (ii) the syndrome is associated with the high fertility of ex-pasture soils, in particular, high NO3-N production, relative nitrification, and Mn availability, and (iii) it is unlikely that the syndrome is a consequence of single trace element or other element deficiencies.
    Print ISSN: 0045-5067
    Digitale ISSN: 1208-6037
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Publikationsdatum: 2010-01-01
    Beschreibung: The relative importance of density, acoustic velocity, and microfibril angle (MFA) for the prediction of stiffness (MOE) and strength (MOR) has not been well established for Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco). MOE and MOR of small clear specimens of mature wood were better predicted by density and velocity than by either variable alone (183 trees 〉20 years old, six specimens per tree, 1087 specimens total). Specimens sampled around the stem circumference had similar density (intraclass correlation coefficient t = 0.74) but not MOE (t = 0.40) or acoustic velocity (t = 0.32), indicating benefits from sampling several circumferential positions. For MOE, the path coefficients (β) were moderate for density and velocity. For MOR, β was only high for density. End-matched samples of one specimen per tree were analyzed with SilviScan. Simple correlations with MOE were highest for density (r = 0.67) and then acoustic velocity2 (0.53), MFA (–0.50), earlywood MFA (–0.45), and latewood proportion (0.40). Most correlations were weaker for MOR. Density had a higher β than did MFA for either MOE or MOR. In more complex path models, latewood proportion and latewood density were the most important contributors to MOE and MOR, and MFA was relatively unimportant. The path analyses showed what simple correlation did not: that latewood proportion has strong predictive value for Douglas-fir mature wood quality.
    Print ISSN: 0045-5067
    Digitale ISSN: 1208-6037
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 2008-08-01
    Print ISSN: 0829-318X
    Digitale ISSN: 1758-4469
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2011-05-10
    Print ISSN: 0829-318X
    Digitale ISSN: 1758-4469
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Publiziert von Oxford University Press
    Standort Signatur Erwartet Verfügbarkeit
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