| 1. |
- Lidestav, Gun, et al.
(author)
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Introducing gender in studies on management behaviour among non-industrial private forest owners
- 2000
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In: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 15:3, s. 378-386
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Journal article (peer-reviewed)abstract
- The genderization of non-industrial private forest (NIPF) ownership creates different conditions for male and female forest owners. To compare male and female forest management behaviour and to examine whether observed differences should be understood in terms of gender, data from the Swedish National Board of Forestry's interview inquiry were used. Differences in frequency of harvesting and silvicultural operations were examined by binary logistic regression and differences in harvesting volume were tested by a multiple regression analysis. In all analyses sex of the owner was introduced as one of the explanatory variables. The sex of the owner was found to have a significant effect on the frequency of harvesting, cleaning and supplementary planting, but not on planting and mechanized scarification. In the cases when the sex of the owner was a significant factor, the degree of activity among the female owners was found to be lower. Results regarding harvested volumes did not expose ally significant differences in harvesting management strategies between male and female owners.
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| 2. |
- Eklund, Leif, et al.
(author)
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Spiral grain from an environmental, genetic and economical point of view
- 2000
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In: The Tree.
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Conference paper (other academic/artistic)abstract
- Characteristic of wood is that its behavior is strongly orthotropic due to the internal structure of the material and dependent on moisture and temperature. In addition, the material is characterized by a strong variation of the properties in the radial direction. Another important property that affects the behavior of wood is spiral grain, causing the direction of the fibers to deviate from the longitudinal direction of the tree. It is hardly possible to assess spiral grain in the woods, no rejection of severe spiraled trees are done before the log arrives into the sawmill. If a method for on site rejection is available, and the severest spiraled trees, 2-10%, could be avoided in the shipment to the sawmill substantial money could be saved in the forest industry. The causes of spiral grain have been thoroughly discussed through the years and the debate about the environmental and genetic impact on the phenomenon is still not settled. We present evidence for a direct effect of wind on the degree of spiral grain. We also present evidence for a putative thinning effect on spiral grain that is probably connected to wind. Additionally we also present evidence for a strong genetic impact on the formation of spiral grain in conifer trees. In another study mechanical properties such as shape stability has been investigated for the same trees. In some of the logs it may therefore be possible to quantify the relation between spiral grain and distortion in sawn timber.
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| 3. |
- Eklund, Leif, et al.
(author)
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The influence of wind on spiral grain formation in conifer trees
- 2000
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In: Trees. - : Springer. - 0931-1890 .- 1432-2285. ; 14, s. 324-328
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Journal article (peer-reviewed)abstract
- The correlation between spiral grain formationand crown asymmetry was investigated in 18 Scots pine(Pinus sylvestris L.) and 17 Norway spruce [Picea abies(L.) Karst.] trees selected from clones of each speciesgrowing in the south of Sweden. The angle between thelongitudinal direction of the tracheids in the outermostyear ring compared to the longitudinal direction of thestem was measured by scribing lines which followed thedirection of the tracheids. The crown asymmetry wasmeasured by taking photographs of the trees followed bya simple picture analysis of the tree. Wind data for thegrowing seasons of 1997 and 1998 were obtained fromthe Swedish Meteorological and Hydrological Institute.The results showed a significant correlation between theangle of the tracheids compared to the stem longitudinaldirection going from a left-handed angle if the trees hada crown projected to the north towards a right-handedangle the more the crown projects to the south.
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| 4. |
- Kifetew, Girma, 1950-, et al.
(author)
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Material damage due to electron beam during testing in the environmental scanning electron microscope (ESEM).
- 2000
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In: Wood and Fiber Science. - 0735-6161. ; 32:1, s. 44-51
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Journal article (peer-reviewed)abstract
- This study describes the development of cell-wall damage, i.e., the creation of cracks across or in the vicinity of pits during the testing of twenty microtomed spruce (Picea abies karst.) samples in the Environmental Scanning Electron Microscope (ESEM). Samples were investigated both in an unloaded condition and under a constant tensile load and at different moisture levels. Regions of the moisture-cycled samples that had been exposed to an electron beam during image acquisition showed damage running through pits and their surroundings. Specimens loaded in the green condition and dried in the chamber for 2 h without beam exposure except during imaging showed no noticeable cell-wall damage. The results indicate that the electron beam may be a major source of damage initiation. Therefore, it is essential to note the circumstances of the rest when explaining the observations made in ESEM studies.
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| 5. |
- Kliger, Robert, et al.
(author)
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STUD: Improved Spruce Timber Utilizations : Prediction of Twist and Industrial Validation. Sub-task B9.1.
- 2000
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Reports (other academic/artistic)abstract
- It has been shown that the number of straight battens after drying can be easily increased by avoiding converting logs with a somewhat large left-hand spiral grain measured under bark and by avoiding converting the central cylinder of logs with a diameter about 50 mm around the pith. It is assumed that more than 10% of the trees (Norway spruce) exceed a spiral grain angle of 3° measured under bark. Between 80% and 90% of the studs from these trees displayed an unacceptable amount of twist (3°). It should be of great interest for the sawmill industry to be able to reject logs with respect to their overly large spiral growth in order to improve the straightness of sawn lumber in service (at low moisture content).Other conclusion drawn from this study is that the spiral grain angle and the annual ring curvature of the stud can predict twist. If it is possible to measure effectively spiral grain angle on the logs or on the sawn timber prior to drying the twist-prone material would be possible to sort out and thus increase the value of the timber products. Simple models expressed in diagram form can produce enough information about twist to be a useful tool for improving the number of straight studs after drying.Over 90% of the studs sawn closer than 50 mm from the pith from five trees displayed unacceptable twist when dried to 12% moisture content. All the studs sawn from a tree (five logs) with a left-hand spiral grain of about 15° displayed very large twist after drying and they were all classified as rejects, independent of the grading criterion.
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