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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Effect on Climate Change on Maize Production in Zambia

Ngoma, Justine January 2008 (has links)
Maize is one of the crops that is grown by most farmers in Zambia being the staple food for the majority of Zambians. However, despite the crop being so important, its production is dependent on climatic conditions. This means that any change in climate can affect the production either negatively or positively. This research therefore, focused on determining how the change in temperature and rainfall affect maize production on the Copper belt, Eastern, Lusaka and Southern provinces of Zambia and investigate the main adaptation measures implemented by both the government and non-governmental sectors. Also, assess through the review of National Agricultural Policy and action plans, how the government has documented issues of climate change. In order to obtain the needed data, interviews were conducted with different officials from both the government and non-governmental sectors. However, from the estimate of the impact of temperature and rainfall on maize production, the results did not show with any significance that either temperature or rainfall has effect on maize production. In fact, it was found that quantifying the effects of climate change on maize production is not easy due to difficulties in quantifying other factors that may also have large impact on maize production. It was therefore, not possible to conclude whether or to what extent climate change has effects on maize production. However from the interviews conducted, it was found that both the government and non-governmental sectors have introduced different activities in their programmes to ensure that farmers are food secure, though the ministry of agriculture has no policy document on how to handle the problem of climate change to address different issues of the sector. In fact, most offices in the ministry do not have much documented information on climate change which could also be seen from the review of National Agricultural Policy and action plans where climate change issue has not been emphasized. Though both the Government and non-governmental sectors have implemented some adaptation measures, it cannot easily be concluded whether the implemented measures are adequate or not due to the fact that we are not sure of the expected effects in different parts of the country. Nevertheless, to enhance food security with or without adverse effects of climate change on maize production, it was recommended that members of staff at all levels under MACO should be trained in the area of climate change for them to have a wider understanding of the issue and work responsively and that much research should be done to open up the mind of the people and help policy makers make effective plans.
12

Studies on the competitiveness of wood : - market segmentation and customer need assessments

Jonsson, Ragnar January 2005 (has links)
Over the last decades, wood has encountered increasing competition from other building materials. Hence, it is relevant to study the underlying factors of material substitution. The market for repair and remodelling (R&R) is growing in importance. The end-consumer´s, or the household?s, assessments as to material selection are generally more crucial in R&R than in construction of new houses, a circumstance highlighting the importance of the end-consumer. Consequently, this thesis deals with material substitution within an end-consumer context. Proper market segmentation and targeting presuppose an understanding of why households differ as to material preferences. Prioritising customer needs in quality improvement and/or product development requires information as to the importance of different customer requirements or needs as well as the performance of wood, relative substitutes, in providing for these needs. The thesis proposes a coherent approach for market segmentation and for prioritising customer needs: (i) how to provide a basis for market segmentation and targeting, i.e., to extract the distinguishing features of different material preferences; (ii) how to extract information enabling the prioritising of customer needs, i.e., importance and performance information. Identifying prominent discriminating factors of building application material preference, in order to subsequently explain why households differ within and between samples/cultures as to material preferences, and finally assessing customer requirements or needs as to the importance and the performance of wood relative substitutes in fulfilling them, presuppose an approach for data collection and analysis, which in turn requires a theoretical frame of reference. Hence, in the thesis a theoretical framework and different methods, for extracting decisive preferential predictors and assessing customer needs respectively, are suggested and evaluated. A pronounced design profile and distinct material alternatives make floorcovering a good illustrative example. The results indicate that material substitution with an end-consumer focus should be studied within a contextual framework. Hence, the usage context, the type of room refloored and whether the dwelling is owned or not, seems to define the types of materials actively considered. Further, households obviously differ in how they perceive the concept of floorcovering in a given usage context, depending on the general life situation and individual experience. Data collection, with the aim of identifying distinguishing factors of building application material preferences, must thus handle the collection of data related to usage context as well as the general life situation and individual experience. To obtain a deeper understanding of the underlying motives open-ended questions are called for. Performance benchmarking as to customer requirements or needs should be relative competitors in the same market segment, i.e., close substitutes. The assessment of customer needs should allow analysis on benefit levels, as alternatives in material substitution most readily can be compared in terms of the more abstract benefits/consequences they provide rather than concrete attributes. The apparent causal complexity, resulting from contextual influences, severely limits the usefulness and adequacy of traditional, additive, statistical analysis. Multivariate projection methods like partial least square discriminant analysis (PLS-DA); in coping with collinear variables, as well as the Boolean approach of qualitative comparative analysis (QCA); enabling data reduction in a theoretically guided manner, have potential for handling multiple conjunctural causation when analysing material preferences. Furthermore, both methods are able to handle binary variables resulting from open-ended questions, dependent as well as independent. PLS-DA can, however, more readily than Boolean algebra capture contextual influences. Analysis by means of PLS-DA thus seem to provide the information necessary for market segmentation and targeting, i.e., the causes of preferential differences both between and within cultures: evaluative criteria and variables related to the context. The output from the analysis of material preferences serve as input to the subsequent assessment of customer needs, as to the make-up of customer needs and as to which materials constitute close substitutes, i.e., share usage context. Customer satisfaction modelling (CSM) using partial least squares (PLS) seems well adapted for extracting the information necessary for prioritising customer needs: the impact on customer satisfaction of the fulfilment of different customer requirements or needs, and the performance of wood, relative substitutes, in providing for these needs. A valuable asset of CSM is the ability to allow analysis on customer benefit as well as attribute level. Usage context and data connected with the life situation provide instruments for market segmentation and targeting. For example: according to the present results, users of wooden flooring in the Netherlands are house owners to a greater extent and generally have a higher household income than users of laminated flooring. One of the apparently salient reasons for choosing wood, the natural material property, is part of the intrinsic nature, character, of the material. This quality of wood could provide an edge on the close substitute, laminated flooring. The results presented in the thesis further indicate that practical, functional, benefits exert the greatest impact on customer satisfaction, for wooden flooring as well as its closest substitutes laminate and carpet. This is noteworthy, as the salient evaluative criteria for choosing wooden flooring, unlike the other materials studied, were of a non-practical nature. This circumstance highlights the necessity of considering substitutes to identify latent needs. A low cost over the life cycle and hygiene are apparently the most important benefits to improve for wooden flooring manufacturers, as importance is high and performance relatively low.
13

Ett verktyg för sågoptimering av kubb / A tool for saw optimization of small diameter logs

Karlsson, Eric, Sturesson, Brian January 2013 (has links)
I detta examensarbete har ett användarvänligt verktyg skapats för att möjliggöra undersökningar av värdeutfallet vid kubbsågning på VIDA Alvesta AB. Verktyget har skapats i Microsoft Excel som för många är en känd miljö. Just nu är det svårt att få lönsamhet inom sågverksbranschen. Råvaran är dyr och det tvingar sågverken att effektivisera sin produktion. Det här verktyget har vankantsandel som viktigaste variabel eftersom det maximerar värdeutbytet genom att använda maximalt tillåtna vankanter. En undersökning för produkten 47x100 har gjorts med avseende att dölja vankanter med hjälp av rundade hörn med radie 3 och 5 mm. Undersökningen visade att det går att dölja en större vankant genom att öka hörnradien från 3 till 5 mm. En ytterligare åtgärd som kan utföras för att utnyttja råvaran på ett bättre sätt är att minska på råmåtten. Om råmåttet minskas med 3 % kan en ekonomisk vinning erhållas.
14

Ekosystemansatsen : på nationell och regional nivå

Walter, Martina January 2006 (has links)
Att bevarandet av biologisk mångfald är en grundpelare för att nå en hållbar utveckling enades världens länder om i Konventionen om biologisk mångfald (CBD) som upprättades under toppmötet i Rio de Janeiro 1992. I konventionen förespråkas den s.k. ekosystemansatsen (EA), vilket är en strategi som innebär en helhetssyn på ekosystem. Syftet med denna uppsats är att undersöka i vilken grad EA tillämpas på nationell och regional nivå. Frågan är också om EA är en bra utgångspunkt för att upprätthålla biologisk mångfald på landskapsnivå samt vad som kan öka tillämpningen av EA på regional nivå. På nationell nivå analyserades två delar i miljömålspropositionen och på regional nivå analyserades de landskapsstrategier som sju län har fått i uppdrag av regeringen att upprätta i ett pilotprojekt. Min teoretiska utgångspunkt har varit ekosystemansatsen och dess principer och vägledande punkter. Metoden bestod av främst en kvantitativ innehållsanalys med kvalitativa inslag och som komplement utfördes fyra intervjuer. Resultatet visade att de delar av miljömålspropositionen som analyserades i hög grad följde ekosystemansatsen. En brist i propositionen var dock att det saknades riktlinjer om att det behövdes involvering av olika aktörer när den ursprungliga definitionen av landskapsavsnittet i strategierna skulle bestämmas. Att denna aspekt var implicit ledde troligtvis till det faktum att den även var implicit i landskapsstrategierna. Tillämpningen av EA i landskapsstrategierna skedde, trots att länsstyrelserna endast tillämpade den indirekt, i ganska hög grad och särskilt togs hänsyn till sociala aspekter som involvering av olika aktörer i själva processen och kontakt med vetenskapliga discipliner. Det som däremot var bristfälligt gällde tillämpningen av komplexa aspekter, vilka inte klart hade uttryckts i riktlinjerna till länsstyrelserna från regeringen. Dessa faktorer var beaktande av förvaltning av ekosystem inom ramen för dess funktion, processer i ekosystem samt adaptiv förvaltning. Alla intervjupersoner var överens om att EA är övergripande och ganska luddig, men det måste den vara för att gälla globalt. Av vikt är att konkretisera den på nationell och regional nivå. Ett förslag är att Naturvårdsverket i detta projekt ger tydliga riktlinjer angående tillämpningen av EA i landskapsstrategierna och att det är en tvåvägskommunikation mellan Naturvårdsverket och länsstyrelserna så att det blir en iterativ process. Genom en konkretisering kan tillämpningen av EA öka och därmed ett steg tas mot en hållbar utveckling. / The Convention on Biological Diversity (CBD) promotes the Ecosystem Approach (EA), which is a strategy that endeavours to take a comprehensive approach to managing ecosystems. The aim of this report is to study to what degree the EA is being followed on a national and regional level. A key question of the research is whether EA is conceptually sound and whether it has been operationalised effectively at both national and regional scale. Using articulated EA principles and operational guidelines from the CBD this study analyzed the Government's national environmental directive concerning biodiversity. The same approach was also applied to an analysis of several regional landscape strategies that are being developed as part of a pilot project. The results show that the national biodiversity directive is largely consistent with an EA. Although one area of inadequacy was the level of involvement by different stakeholders in the original decision about defining the landscape area in the pilot studies. This was also a weakness in the landscape strategies- perhaps because communication on this issue was not explicit in the directive from the government. The implementation of EA in the landscape strategies at the regional level was also found to be good, especially the participation from different stakeholders (especially local stakeholders) in the process and scientific institutions. However inadequate factors not represented in these strategies were complex ecological aspects such as principle 6 (ecosystem must be managed within the limits of their functioning) and operational guideline 1 (focus on the functional relationships and processes within ecosystems). Adaptive management (operational guideline 3), a relatively new approach in Sweden, was also found to be deficient. All the respondents agreed that the EA needed to be made more concrete on a national and regional level. A suggestion from the research to improve the development and adoption of the EA would be to develop iterative mechanisms between regional and national authorities to ensure national guiding principles are informed by more concrete regional experience. When the EA is implemented more effectively we will take one step further on the way to reaching a sustainable development.
15

Opportunities and obstacles in the certification process : A case study on the development of the organic production and agriculture in Babati, Tanzania

Klang, Linda January 2010 (has links)
Organic products have become more and more talked- about in today’s industrial world. The demand for organic products is increasing and the market is continuing to grow bigger. It is important to maintain what these products stand for, being environmental friendly, and to do so strict certification policies are needed. EU has today an international certification body called Regulation (EC) 834/2007 that needs to be followed for export to and within EU. Parts of Tanzania today have certification of some organic products but not in Babati, that lies in the northern of Tanzania in Manyara region where this case study was done. In Babati most of the farmers are smallholder farmers and many of them, founds it difficult to afford an international certification. For the smallholder farmers to get a certification there are two alternatives. One is to go together with other smallholder farmers and apply for a certification like EUs Regulation (EC) 834/2007 as a group and then get to pay lower fees. The other alternative is to go together and start local certification bodies that have fees that are adjusted to local farmers’ income. This case study was conducted between February and March of 2010 in villages around Babati and Babati town. Interviews were held with both organic- and non organic farmers. My goal was to find out if it was possible for Babati to develop the organic agriculture and have an organic market in the future. My conclusion ends up by perceiving that Babati has a very good chance of fulfilling the Regulation (EC) 834/2007 standards. However the farmers’ economical status is an obstacle for the farmers to get an international certification, because of the high cost in inspections and reinspections.  But through a local certification body that is adjusted to the smallholder farmers and the environment the farmers can get their certificate and the organic market can be developed in Babati.
16

DETERMINATION OF FREE STAND-ALONE PHOTOVOLTAIC POTENTIAL IN GERMANY BY GIS-BASED SITE RANKING

Shoshtari, Salahaldin January 2010 (has links)
<p>The purpose of this study is to find potential areas suitable for energy production using renewable sources. For this aim, accurate assessments are necessary. The assessments include geographical suitability, closeness of infrastructure and observing local and regional framework concerning the use of renewable sources together with environmental protection. In addition, economical factor is considered in such an assessment. In this study, the Photovoltaic (PV) production potential for Germany is considered. An accurate and complete data set is necessary in order to achieve reliable results. In addition, a powerful database management and strong analysis tools are required. Geographical Information System (GIS) is a tool for finding suitable sites for the photovoltaic production.Using GIS, energy generation planners are able to visualize solar densities throughout the considered area. In addition, they can find the optimal and most economical sites by the combination of solar potential with the information about land. In this study, data sources consist of meteorological and geographical conditions. Furthermore, all analyses have been performed using Arc GIS Desktop. This study demonstrates the possible places for photovoltaic plants and indicates suitable candidates according to weights and factors in multi criteria analysis. The solar radiation data is from year 1995 to 2005. Land cover data is according to Corine 2000 and the more detailed Raumordnungskataster (Rok) for Weser-Ems. Numerical results are reliable from a comparison point of view. This study demonstrates the sensitivity of the defined criteria with respect to electricity production. In particular, this study is useful to see the capabilities of GIS for site selection regarding photovoltaic plants.The purpose of this study is to find potential areas suitable for energy production using renewable sources. For this aim, accurate assessments are necessary. The assessments include geographical suitability, closeness of infrastructure and observing local and regional framework concerning the use of renewable sources together with environmental protection. In addition, economical factor is considered in such an assessment. In this study, the Photovoltaic (PV) production potential for Germany is considered. An accurate and complete data set is necessary in order to achieve reliable results. In addition, a powerful database management and strong analysis tools are required. Geographical Information System (GIS) is a tool for finding suitable sites for the photovoltaic production.Using GIS, energy generation planners are able to visualize solar densities throughout the considered area. In addition, they can find the optimal and most economical sites by the combination of solar potential with the information about land. In this study, data sources consist of meteorological and geographical conditions. Furthermore, all analyses have been performed using Arc GIS Desktop. This study demonstrates the possible places for photovoltaic plants and indicates suitable candidates according to weights and factors in multi criteria analysis. The solar radiation data is from year 1995 to 2005. Land cover data is according to Corine 2000 and the more detailed Raumordnungskataster (Rok) for Weser-Ems. Numerical results are reliable from a comparison point of view. This study demonstrates the sensitivity of the defined criteria with respect to electricity production. In particular, this study is useful to see the capabilities of GIS for site selection regarding photovoltaic plants.</p>
17

Above Ground Durability of Swedish Softwood

Blom, Åsa, Bergström, Mikael January 2005 (has links)
This thesis describes aspects of durability of Swedish softwood in above ground applications. The thesis consists of a summary of nine papers, which all aim to explain the existing variation in above ground microbial durability and moisture sensitivity of Norway spruce (Picea abies) and Scots pine (Pinus sylvestris). The methods used were two field tests, one accelerated durability test, and three water permeability tests. The main conclusions made in the study were that Norway spruce sapwood is more susceptible to discolouring fungi than heartwood. With respect to Scots pine, the only important factor for its natural durability above ground was whether the samples consisted of heartwood or of sapwood. There was also no systematic variation between pine heartwood from different stand origins in above ground conditions. Origin had no influence on durability in practice for neither spruce nor pine. Furthermore, in contradiction with traditional thinking, annual ring width and density had no influence on durability in any of the tests. The material came from two different samplings. The ‘old’ material was sampled in the beginning of the 1980s and consisted of Scots pine and Norway spruce from three different origins: the north, the central area, and the south of Sweden. The material was subjected to different handling conditions and surface and end-grain treatments. The ‘old’ material was used in a large above ground field test, carried out between 1985 and 1994. Unfortunately, the spruce sapwood and heartwood was not separated in this field test. In the field trial with the ‘old’ material, the most important factor for the durability of Norway spruce was the samples’ surface- and end-grain treatment. It was also observed that untreated spruce showed better durability than samples that were painted but without proper end-grain treatment. Samples originating from one of the stands were more sensitive towards air-drying than samples from the other two, which was reflected in a higher average moisture content and mass loss for the untreated samples. With respect to Scots pine, the most important factor was whether the sample consisted of heartwood or of sapwood. The heartwood samples were durable irrespective of their previous treatment. The Scots pine sapwood samples, on the other hand, had a very fluctuating moisture content if they were not surface- and end-painted. This was also reflected in higher mass losses in these samples. Even when properly surface- and end grain treated, the sapwood samples did not perform as well as the heartwood samples. The ‘new’ material consisted of Scots pine taken from six different stands, and Norway spruce from five different stands, all from areas in southern Sweden. The sampling was performed in order to achieve a large variation in wood properties. Thus, logs from areas with different climate and growth conditions were collected. This material was used for laboratory tests, and also for the second field test, which was evaluated after a test period of two years. In the second field test untreated Scots pine and Norway spruce samples from the ‘new’ material were investigated. Effects of origin and different tree diameters were examined. Furthermore, Scots pine was separated to heartwood and sapwood, and Norway spruce to mature and juvenile wood. The Norway spruce samples were sawn with vertical or horizontal annual rings. For the Norway spruce in the second field test, vertical annual rings were shown to be very beneficial for avoiding crack formation, while samples with horizontal annual rings displayed a large number of cracks. Despite this, the larger number of cracks did not result in a higher moisture content or more fungal discoloration. Juvenile wood had a slightly higher average discolouring fungal growth grading than the other spruce samples. For Scots pine, the only factor of importance was whether the samples consisted of heartwood or of sapwood. Annual ring width, density and origin had no significant effect on either fungal growth or moisture uptake. This observation held for both Norway spruce samples and Scots pine samples. An accelerated test was run in order to investigate Norway spruce sapwood and heartwood with respect to their differences in durability towards discolouring fungi and moisture uptake. The Mycologg method was used to accelerate fungal growth during a number of forced moisture cycles. The results showed that sapwood was much more sensitive to discolouring fungi than heartwood. Sapwood also recorded a higher average moisture content than heartwood. The differences that were observed between the types of samples were not due to annual ring width, density or origin. It was observed that Norway spruce sapwood samples and heartwood samples showed differences in liquid water permeability. This observation was made especially evident in a droplet absorption test. Water droplets were absorbed much faster on the sapwood samples in comparison with the heartwood samples. This higher affinity to water suggested that a sapwood surface would reach a higher moisture content than a heartwood surface. This observation provides a major explanation of why the sapwood samples showed poorer durability towards discolouring fungi in the Mycologg trials.
18

How Does Past Grazing and Surrounding Landscape Affect the Restoration Sucess of Deciduous Forests?

Ringselle, Björn January 2010 (has links)
The Swedish deciduous forest has been actively replaced by coniferous forest during the last two hundred years. In Färna Ekopark, Västmanland, this trend is being reversed by restorations of deciduous forests through the removal of coniferous trees in mixed forests. This field study investigates how successful these restorations have been for plant diversity and how they were affected by past grazing and the proportion of similar mixed and deciduous forest habitats in thesurrounding landscape. Plant species richness was investigated in 370 1m2-plots distributed over 37 sample areas and the surrounding landscape analyzed in a GIS. Results show that a few years after restoration there was higher plant species richness and lower homogenization, at the site scale, compared to the controls. When the restored sites were divided into two subgroups dependant on age, the 5-6 year old restoration displayed higher plot richness than the 2-4 year old restorations, but were also more homogeneous. Past grazing showed a generally positive effect on plant diversity, and these areas also responded with a larger increase of plant species richness and less homogenous plant populations after restorations compared to areas that had not been formerly grazed. The proportion of similar deciduous and mixed forest habitats (more than 40 % deciduous trees) inthe surrounding landscape showed no effect on the plant diversity of deciduous forests in general, though it did display a weak influence over the plot richness of restored deciduous forests without a history of grazing. When restoring deciduous forests to increase plant diversity it would therefore appear wise to focuson the formerly grazed deciduous forests. To take advantage of the beneficial effects to plot richness restored deciduous forests should have a high degree of deciduous and mixed forests within one kilometer. / Den svenska lövskogen har aktivt ersatts med barrskog under de senaste tvåhundra åren. I Färna Ekopark, Västmanland, försöker man vända denna trend genom att ta bort barrträd i blandskog ochpå så sätt restaurera lövskog. Denna fältstudie undersöker om restaureringarna har gett ökad växtdiversitet och hur restaureringarna har påverkats av tidigare bete samt andelen av liknande bland- och lövskogshabitat i det omgivande landskapet. Växtartantalet undersöktes med 370 1m2-rutor utspridda över 37 områden och det omgivande landskapet analyserades i ett GIS. Resultaten visar att några år efter restaurering hade områdena högre växtdiversitet och artsammansättningen var mindre likformig i jämförelse med kontrollerna. När de restaurerade områdena delades upp i två grupper, i avseende på ålder, uppvisade de 5-6 år gamla restaureringarna högre växtdiversitet i rutorna än de 2-4 år gamla restaureringarna, men artsammansättningen var även mer likformig. Tidigare bete visade en generellt positiv inverkar på växtdiversiteten och dessa områden fick en ännu större uppgång i artrikedom och ännu lägre likformighet i artsammansättningarna efter restaureringarna än de områden som inte hade betats tidigare. Andelen av liknande bland- och lövskogshabitat (mer än 40 % lövträd) i det omgivande landskapet uppvisade ingen effekt på växtdiversiteten hos lövskog generellt, men det fanns en svag påverkan på växtdiversiteten på rutnivå hos restaurerade lövskogar utan tidigare bete. När man restaurerar lövskog för att öka växtdiversiteten verkar det därför bra att fokusera på tidigare betade lövskogar. Om man vill ta tillvara på den positiva påverkan på växtpopulationerna som omgivande landskap kan ha bör restaurerade lövskogar ha en stor andel bland- och lövskog en kilometer runt omkring sig.
19

Managing timber procurement in Nordic purchasing sawmills

Helstad, Klara January 2006 (has links)
Procurement of sawlogs to purchasing sawmills represents a basic strategic business process. The properties of inbound sawlogs are decisive for the output of sawn products and the cost of raw material contributes substantially to the cost of the final product. Increasing customer orientation and new demands from powerful customers in the building and retail sectors entail new or accentuated demands on management of procurement. Managing raw material procurement and communicating needs to suppliers and logging machine operators are vital issues for sawmills in order to be competitive. The purpose of the thesis is to explore how purchasing sawmills manage procurement of sawlogs. The results are based on 46 in-depth interviews with people involved in the procurement process at seven softwood sawmills in Denmark, Finland and Sweden. The thesis identifies various types of supply uncertainties as well as process improvement and buffer activities that reduce uncertainties. However, the major obstacle in the procurement process is the power/dependence balance in the relationships with suppliers. Beyond doubt, it restricts the manageability of procurement and particularly bucking. The results suggest that there are a number of ways to improve management of procurement, which are currently not fully employed. The thesis provides four key strategic dimensions of the procurement process and suggests a general conceptual model of wood procurement to purchasing sawmills. Further research within the subject can usefully explore the link between procurement management and procurement strategy as well as the relation to other functions' strategies and the corporate strategy. The importance of the identified strategic dimensions of the procurement process needs to be quantified in order to provide normative suggestions.
20

Spiral Grain in Norway Spruce

Säll, Harald January 2002 (has links)
Wood is a major construction material that is used in many contexts, and for different purposes. Serious problems may arise, however, when moisture related deformations as twist occur in wood used in different types of building structures, joinery and furniture. Twist can be explained to a great degree by the helical deviation of the grain angle in relation to the longitudinal direction of the log or the sawn board. Wood fibres form a spiral within the tree, and this is a natural occurrence that is named spiral grain. The wood fibres close to the pith in Norway spruce form a left-handed spiral. In most trees the grain angle turns over to be right-handed with time. Sawn timber that exhibits large grain angles lead to problems of shape stability and stiffness in finished constructions. In this thesis the spiral grain in Norway spruce (Picea abies (L.) Karst.) was stated as well as the effect on sawn timber. The material was based on sample trees from Sweden and Finland. Samples were taken in twenty-two stands at different heights in tree. From six stands studs were sawn and dried for measuring twist and other deformations. The spiral grain was measured with the method scribe test on 390 log discs taken at the top-end of the logs. Account was given concerning changes in grain angle from pith to bark, regarding both increasing annual ring numbers and distance from pith. The development of grain angle over tree age was utilized to study whether annual growth, size of tree, height in tree as well as silvicultural treatments affected spiral grain. Moreover, the relation between grain angle and distance to pith (in mm) was used to forecast twist in sawn timber. The left-handed grain angle was at its greatest between the fourth and eighth annual rings. Thereafter for most trees the grain angle turned from left-handed to right-handed in a linear fashion, in a manner that was unique for each individual tree. The pattern of spiral grain differed significantly between different stands, regarding change of inclination with increasing age or distance from pith. The culmination of the grain angle close to the pith occurred at somewhat higher age higher up in the trunk. The grain angle decreased faster in top logs than it did in the butt logs. The largest trees within a stand had a grain angle that turned to right in a slower way than smaller ones. The thinning strength and type of thinning regime also affected the character of spiral grain in the remaining trees in a stand. There was an indication that strong thinnings, where fast growing trees are retained, may lead to more individuals in a stand that exhibit high grain angles under bark. With knowledge of the size and direction of the grain angle under bark, and the diameter of the log, calculations can be made that show how twisted the sawn timber will be after drying. This can be used for deciding whether an individual log can profitably be sawn and processed further or not. The grain angle under bark can be used to remove trees showing the greatest degree of spiral grain already in the first thinning. Silvicultural methods aiming at even and dense Norway spruce stands, which normally is practised in Scandinavia, will probably result in timber with relatively low risk concerning large grain angle and subsequent risk for twist in sawn wood.

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