نتایج جستجو برای: juvenile wood
تعداد نتایج: 84737 فیلتر نتایج به سال:
The angle between helical windings of microfibrils in the secondary cell wall of fibers and the long axis is called microfibril angle (MFA). Stiffness of wood depends on variations in the MFA. The large MFA shows low stiffness, which is found in juvenile wood and this character make threes vulnerable to high winds breaking. Timber containing a high proportion of juvenile wood is unsuitable for ...
Strength Properties of Juvenile and Mature Wood of Twelve Families of Loblolly Pine (Pinus Taeda L.)
The wood mechanical properties of progeny from twelve open-pollinated parent trees were examined. Six families were from parents which had high wood specific gravity and six were from parents which had low wood specific gravity. Thirty-two-year-old trees, that had been planted at Many, Louisiana, were sampled and juvenile and mature wood test specimens were prepared. Maximum crushing strength, ...
The variability of wood properties is an important issue in the utilisation of wood and fibre. Over recent decades there has been increased emphasis on intensively managed, short rotation, plantation forestry, that produces larger proportions of so-called juvenile or core wood. This situation seems to have been aggravated by the shift to establishing forests on high-fertility farm sites, and ea...
Larvae of certain species of blowflies (Calliphoridae) can cause myiasis in frogs and toads, but there are few reports from North American amphibians. Of these, most are from toads (bufonids). In this study, we observe primary myiasis in a population of juvenile wood frogs, Rana sylvatica, collected on 22-23 August 2003, from southeastern Wisconsin and compare our observations with previous stu...
The evaluation of wood durability enables the definition of reliable parameters to predict the servicelife of wood-based products. This study aimed to evaluate the wood deterioration of four fast-growing eucalypts species (Eucalyptus botryoides, Corymbia citriodora, Eucalyptus paniculata e Eucalyptus tereticornis) exposed to three field tests (outdoor, flooded site and forest canopy) during 540...
The cohesion-tension theory of water transport states that hydrogen bonds hold water molecules together and that they are pulled through the xylem under tension. This tension could cause transport failure in at least two ways: collapse of the conduit walls (implosion), or rupture of the water column through air-seeding. The objective of this research was to elucidate the functional significance...
Four stands of 28-year-old radiata pine (Pinus radiata D. Don) grown in the eighth region (Biobio) of Chile were sampled to determine the effect of tree spacing on the microfibril angle. The samples were taken at two different stem levels of the tree, 2.5 m and 7.5 m, with increment strip taken in the Nothern direction. The four experimental stands were characterized by the following spacing 2x...
The aim of this study was to characterize the properties of juvenile and mature heartwood of Robinia pseudoacacia L. (black locust). The content, the composition, and subcellular localization of heartwood extractives were studied in 14 old-grown trees from forest sites in Germany and Hungary, as well as in 16 younger trees of four clone types. Heartwood extractives (methanol and acetone extract...
Juvenile-mature wood evaluation along the bole considering the influence of silvicultural treatments
Wood used for structural purposes has increased in the last decade Spain. However, as raw material, wood needs to comply with requirements that are not always present. Knowledge about quality from trees on stand is essential providing feedback forest managers and taking required actions obtain suitable silviculture treatments. Two of main species construction Spain, Pinus nigra sylvestris, have...
Near infrared (NIR) spectroscopy provides a rapid, non-destructive method for the estimation of several wood properties of increment cores. MR spectra are collected from adjacent sections of the same core; however, not all spectra are required for calibration purposes as spectra from the same core are autocorrelated. Previously, we showed that wood property calibrations that included a single s...
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