| 1. |
- Bhatt, Isha M, et al.
(författare)
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Anatomical changes in the cell-wall structure of Leucaena leucocephala(Lam.) de Wit as caused by the decay fungi Trametes versicolorandTrametes hirsuta
- 2015
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Ingår i: Southern Forests, a journal of forest science. - : National Inquiry Services Center (NISC). - 2070-2620 .- 2070-2639. ; 77:4, s. 297-303
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Tidskriftsartikel (refereegranskat)abstract
- The structural changes in the cell wall and delignification pattern caused by Trametes versicolor and Trametes hirsuta in the sap wood of Leucaena leucocephala were examined by light and confocal laser scanning microscopy. The in vitro decay test was conducted for 12 weeks. Both species of Trametes used in this study caused anatomical characteristics specific to simultaneous white rot. Formation of boreholes, erosion troughs, erosion channels with U-shaped notches in tangential sections and thinning of cell walls were evident in the wood inoculated with each of the fungal species. Cell separation due to removal of middle lamellae occurred at the early stages of infection (30 d) with T. versicolor. In contrast, middle lamellae remained intact in wood inoculated with T. hirsuta and showed cell separation due to degradation of the outer layer of the secondary wall and degradation of the middle lamellae observed only in severely decayed wood at late stages. Confocal microscopy revealed the delignification pattern particularly from cell corners and vessel walls at an advanced stage of decay, indicating strong ligninolytic activity of both species in the sapwood of L. leucocephala.
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| 2. |
- Lundqvist, Sven-Olof, et al.
(författare)
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Comparison of wood, fibre and vessel properties of drought-tolerant eucalypts in South Africa
- 2017
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Ingår i: Southern Forests, a journal of forest science. - : National Inquiry Services Center (NISC). - 2070-2620 .- 2070-2639. ; 79:3, s. 215-223
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Tidskriftsartikel (refereegranskat)abstract
- Three drought-tolerant eucalypt genotypes have been investigated for a broad spectrum of properties to provide a basis for comparison on their suitability for various end-uses. The genotypes included were a Eucalyptus grandis × E. camaldulensis hybrid, E. gomphocephala and E. cladocalyx, selected based on previous studies that indicated good potential to tolerate arid conditions, reasonably good volume growth and straightness of stems. In this study, information was added on differences between species and parts of stems in growth (volume and biomass) and properties of wood (density and stiffness), fibres (dimensions and microfibril angle) and vessels (size and numbers). We found high wood densities and stiffness values for E. cladocalyx and E. gomphcephala, making them suitable for construction wood. Logs from the mid-part of the stem had the best timber properties, as the butt logs showed the highest microfibril angle and lowest wood stiffness due to longitudinal juvenility. Such juvenility was also to some degree observed for wood density and fibre length. The information gained will be especially helpful for selecting species and processing options for small farm and community plantations for producing higher-value products that may be sold to generate much-needed income as well as for local uses, such as fuelwood and charcoal. © 2017 The Authors
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| 3. |
- Nilsson, Oscar, et al.
(författare)
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Growth and modulus of elasticity of pine species and hybrids three years after planting in South Africa
- 2020
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Ingår i: Southern Forests, a journal of forest science. - : Taylor & Francis Group. - 2070-2620 .- 2070-2639. ; 82:4, s. 367-376
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Tidskriftsartikel (refereegranskat)abstract
- Growth data and modulus of elasticity (MOE) of 11 different pine species and hybrids were examined at six sites in three regions in South Africa. Growth traits and three MOE variables were measured at three years of age in order to evaluate whether other potential pine species were more suitable than the current commercial species. There were strong observed species differences for all three MOE variables both within and across the four sites measured for wood properties, with across-site MOE ranging from 3.03 to 6.40 GPa. Green density varied among species, and an assumed constant green density of 1 000 kg m-3 underestimated MOE for species with a very high green density; similarly, for species with a very low green density, MOE was overestimated. Although survival was poor at several sites, the data shows that there are alternative pine species that exhibit comparable growth rates to the current commercial species. For estimating MOE, it is concluded that assuming a constant green density generally does not affect the species ranking, but if the aim is to find the 'true' MOE, sampling in the field to determine the appropriate green density is needed.
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| 4. |
- Phiri, Darius, et al.
(författare)
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Biomass equations for selected drought-tolerant eucalypts in South Africa
- 2015
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Ingår i: Southern Forests, a journal of forest science. - : National Inquiry Services Center (NISC). - 2070-2620 .- 2070-2639. ; 77:4, s. 255-262
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Tidskriftsartikel (refereegranskat)abstract
- In the water-scarce environment of South Africa, drought-tolerant eucalypt species have the potential to contribute to the timber and biomass resource. Biomass functions are a necessary prerequisite to predict yield and carbon sequestration. In this study preliminary biomass models for Eucalyptus cladocalyx, E. gomphocephala and E. grandis x E. camaldulensis from the dry West Coast of South Africa were developed. The study was based on 33 trees, which were destructively sampled for biomass components (branchwood, stems, bark and foliage). Simultaneous regression equations based on seemingly unrelated regression were fitted to estimate biomass while ensuring additivity. Models were of the classical allometric form, ln(Y) = a+x(1)ln(dbh)+x(2)ln(h), of which the best models explained between 70% and 98% of the variation of the predicted biomass quantities. A general model for the pooled data of all species showed a good fit as well as robust model behaviour. The average biomass proportions of the stemwood, bark, branches and foliage were 60%, 6%, 29% and 5%, respectively.
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