| 1. |
- Ah Shenga, Pedro
(author)
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SAWING STRATEGIES FOR TROPICAL HARDWOOD SPECIES : Simulation studies based on industrial conditions of Mozambique
- 2016
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Doctoral thesis (other academic/artistic)abstract
- The harvesting of Mozambique tropical hardwood species is considerable higher than the natural regrowth in the forest and the stock is decreasing drastically. Therefore, it is important to improve the material recovery when the wood is refined (i.e., in sawing and further refinement to products such as joineries, furniture etc.) to reduce the waste and to re-utilize efficiently the by-products to increase the added value. The wood processing industry is an important means to boost the industries in the rural areas and also to generate incomes for the local communities by creating jobs and business opportunities.The majority of the logging that can be used for sawmilling in Mozambique is exported as roundwood due to the inability of companies to meet the product standards set for export and to generate profit. The lack of capabilities of the local sawmills to generate profit, also foments the illegal logging because of the higher price of roundwood for export which contributes to increase the number of unlicensed individuals in harvesting. This threatens the law enforcement and thus the degradation of the local wood industry. An alternative to increase the profit and empower the local community could be to export more refined wood products such as sawn timber, parquet, and veneer instead of the roundwood.The objective of the work was to investigate alternative sawing strategies of tropical hardwood species that could increase the profitability of the Mozambique wood industry in general and at sawmill in particular. The subject was approached using a database of virtual logs and together with a sawing simulator. The thesis has two main focus areas: (1) creating the log database with the corresponding algorithms for sawing simulation, and (2) investigations of alternative sawing strategies.The first focus was to build the database of surface-scanned logs and develop the algorithm for the saw simulation. The results are a database of 15 logs models describing the logs outer shape in which 10 jambirre (Millettia stuhlmannii Taub.) and 5 umbila (Pterocarpus angolensis DC.), and the algorithm for the sawing simulation. The algorithm use “brute force” i.e., determines all volume yields of sawn timber from the combination of all settings of log-positioning parameters (offset, skew and rotation) and selects the maximum value of volume yield. From simulation, using three sawing patterns (cant-sawing, through-and-through sawing and square-sawing) combined with two positioning parameters (offset and rotation) it was found that the sawing pattern has great impact on volume yield and that the square-sawing gave higher yield followed by through-and-through sawing pattern.The second focus was on alternative sawing strategies; having in mind that the optimal volume yield is achieved by aid of computerized production systems and that these resources are not yet in use in Mozambique. Hence, the objective was to find the positioning parameters that can be set manually and improve the volume yield. The result have shown that the rotation is the most affecting parameter followed by offset and skew, and that the volume yield can decrease by between 7.7% and 12.5% from the optimal positioning when the logs are manually positioned with the knowledge about the optimal log position. In another study, using crook-up or horns-down positioning as alternative to the optimal positioning, the volume yield decreases by between 10% and 13% from the optimal positioning. By using bucked logs , the optimal volume yield increased by between 8% and 13% in relation to full lengths logs, and the volume yield of bucked logs when using crook up positioning decreases 2% in relation to optimal positioning of full length logs.It is concluded that there is an unexploited value potential in the wood chain which can be reached using alternative positioning and modern measurement techniques and that the grading of wood will facilitate and improve the sawing process.
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| 2. |
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| 3. |
- Hesselman, Jonas, et al.
(author)
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Jämförelser mellan metoder för fastvolymbestämning av stockar
- 2009
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Reports (other academic/artistic)abstract
- In 2008 a new method for automatic measurement of solid volume under bark (m3sub) of sawlogs was introduced in southern Sweden. In this method the diameters at 10 cm intervals are used, thus producing a section-wise volume (m3sub-sw). The scanners used are programmed to leave out bumps and indents when diameters are calculated. The objective of the study was to compare this method with two other methods used on the Swedish wood market; a) volume based on top and butt end diameters (m3sub-tb) and b) volume based on top end diameters and conversion factors to solid volume (m3sub-cf). The conversion factors are arranged as a matrix based on diameter and length of the logs. Volume m3sub-tb is the most widely used method for measuring m3sub in Sweden. M3sub-cf is partly used for payment but more widely for planning purposes, for example when the logs are priced as a cylinder volume based on top end diameter. The study was performed on spruce (Picea abies). The three different volume estimates as well as the diameters obtained from the log scanners were evaluated on 435 manually measured control logs from five different mills. For an additional 180 000 automatically measured logs from four of the sawmills the m3sub-sw and m3sub-cf volume estimates were compared. The results showed only minor differences between the methods. The volume m3sub-sw was, for the 180 000 logs, 0.6 % greater than the volume m3sub-cf. The analysis of the matrix for conversion factors showed that, if the matrix was to be revised, this should be done as slightly increased factors for small diameter logs and for big diameter logs. However, it was concluded that it would mean less implications for the wood market if the section-wise volume could be reduced to make this volume equal to m3sub-tb and m3sub-cf. This to achieve that all three methods, given a sufficient number of representative logs, would give the same volume
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| 4. |
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| 5. |
- Hultnäs, Mikael, et al.
(author)
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Dual-Energy X-Ray Absorptiometry Analysis for the Determination of Moisture Content in Biomass
- 2010
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In: Journal of Biobased Materials and Bioenergy. - : American Scientific Publishers. - 1556-6560 .- 1556-6579. ; 4, s. 363-366
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Journal article (peer-reviewed)abstract
- The aim of the present study was to describe and validate a novel method able to fast, accurately and with a high precision determine the moisture content of biological materials ranging 10% to 70%. A calibrated Dual X-ray photon absorptiometry technique is validated against moisture content in wood chips. Conventional criteria such as the Pearson correlation coefficient, the root mean square errors of calibration and coefficient of variation were used for the evaluation of the method. The method is independent of the thickness and density of the object but dependent of the effective atomic number of the material. The results shows that this photon absorptiometric method gives accurate (<2%) and precise (<1%) results for moisture content determination in wood chips.
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| 6. |
- Hultnäs, Mikael, et al.
(author)
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Predicting the green density as a means to achieve the volume of Norway spruce
- 2013
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In: Scandinavian Journal of Forest Research. - : Informa UK Limited. - 0282-7581 .- 1651-1891. ; 28:3, s. 257-265
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Journal article (peer-reviewed)abstract
- All roundwood that arrives at pulp mills in Sweden is measured manually to obtain the volume. Shortened times between the harvest of the wood and its transportation to the mill have decreased the variation in the green density of wood and have increased the appeal of a method that combines the prediction of green density and weight scaling of the trucks with wood to obtain the volume. The aim of this article is to create a statistical model that can predict the green density of Norway spruce (Picea abies (L.) Karst.) pulpwood with the help of density data from earlier years for a certain mill and meteorological data from the wood supply area of the mill. To create the model to predict the green density, stepwise regression was used. The results showed that the model can explain the variation in green density by 89%, and can predict the density with a mean error of 00.019 ton/m3. The average standard deviation of the ratio between the measured observations and the predicted density was 7% on a yearly basis with variations over the year. From October to March, the model showed results that were at the same level to the result for the volume measurement performed in Sweden today.
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| 7. |
- Johansson, Tord, et al.
(author)
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Micropropagation and establishment of triploid birch and yield and wood properties
- 2006
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Reports (pop. science, debate, etc.)abstract
- A triploid birch (Betula pendula f. gigas) from Valls Hage, Gävle, Sweden has been cloned and micropropagated. Small (30 cm high), tall (90 cm) and magnum (> 120 cm) were produced and planted in the field in autumn or in next spring.Three localities were used: Hedemora, Sala and Uppsala. The experiments were located on former farmland. In a parcel, 25 seedlings of triploid birch was planted in a spacing of 3x3 m. Between the triploid seedlings, pendula birches (Betula pendula Roth) was planted. Close to the experiment a parcel with hybrid aspen (Populus tremula x Populus tremuloides) was planted. The same spacing as for triploid birch and mixed with pendula birch. Hybrid aspen was used as control.The percentage surviving seedlings differed between localities but also between planting years. As a mean 85-100% of the triploid birches planted five years ago were still alive. The highest triploid birches were found in Hedemora, 150-250 cm high. In Sala the heights differ between 120 and 160 cm and in Uppsala between 70 and 220 cm. The pendula birches were shorter, 75 to 200 cm high, and the aspens were 100 to 160 cm high.The diameter and height of older triploid birches was measured and compared with pendula birch. The triploid birches had grown faster than the pendula birches. A small group of triploid birches growing on a site in southern Sweden, Ekebo, had a a site index of 28-30 m (H40).Studies on wood qualities among others basic density and fibre length were made. There were no significant differences between the studied factors for triploid birch and pendula birch.Some practical implications were made.
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| 8. |
- Johansson, Tord, et al.
(author)
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Överlevnad och produktion hos triploid björk
- 2014
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Reports (other academic/artistic)abstract
- A triploid birch (Betula pendula f. gigas) from Valls hage, Gävle, Sweden has been cloned by micropropagation. Mini (8 cm), small (30 cm) and tall (90 cm) seedlings were produced and planted in autumn or in spring 2001-2004. Three localities were used: Hedemora (Lat. 60° 15’ N.), Sala (Lat. 59° 95’ N.) and Uppsala (Lat. 59° 58’ N.). The experiments were located on former farmland. In a parcel, 25 seedlings of triploid birch were planted in a spacing of 3x3 m. Silver birches (Betula pendula Roth) was planted between the triploid seedlings. Close to the experiment a parcel with hybridaspen (Populus tremula x Populus tremuloides) was planted. The same spacing as for triploid birch and mixed with silver birch. The percentage surviving seedlings differed between localities but also between planting years. As a mean 85-100 % of the triploid birches planted five years ago were still alive. The tallest triploid birches examined five years after planting were found on parcels planted in spring 2003: Hedemora, 297 and 323 cm tall, Sala 117 and Uppsala 162 and 202 cm. The silver birches growing on the same parcels were shorter than the triploid birches on trials in Hedemora and Sala, 284 and 306, 87 and 121 cm respectively, but taller in Uppsala: 191 and 245 cm. When the trials were examined 2014 the heights for triploid birch ranged between 5 and 10 meters in Hedemora, between 3 and 5 meters in Sala and around 8 meters in Uppsala. The tallest triploid birches were growing on parcels planted in spring 2003. Silver birches were taller or had the same height as triploid birches on all localities. The height of hybridaspens ranged between 4 and 11 meters in Hedemora, 3.5 and 4 meters in Sala and 6 and 8 meters in Uppsala. Silver birches mixed with hybridaspens growing in Hedemora and Sala had the same height as hybrid aspens but were taller than hybridaspens in Uppsala (10 m). Diameter at breast height ranged between 40 and 78 mm for triploid birch and 29 and 81 mm for silver birch in Hedemora; between 13 and 33 mm and 22 and 29 respectively in Sala and 58 and 60 mm and 72 and 84 mm respectively in Uppsala. The diameter and height of older triploid birches (28-51 years of age) was measured and compared with a silver birch tree. A triploid birch (51 years old) micropropagated from a birch in Edsbyn had a site index of 28 m (H50), a triploid birch from Ekebo 32 m and a 30-year-old silver birch 34 m. Over all the studies did not reveal any differences in growth between triploid birch and silver birch. Key words: Farmland, growth, hybrid aspen, micro propagation, plantation, silver birch, survival, triploid birch, height
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| 9. |
- Klemedtsson, Leif, 1953, et al.
(author)
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Skogaryd – Integration of terrestrial and freshwater greenhouse gas sources and sinks
- 2010
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In: 1st COST meeting ‘Belowground carbon in Europeanforest’, Birmensdorf, Switzerland, 26–28 January 2010..
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Conference paper (other academic/artistic)abstract
- Forests play an important role in the global carbon (C) cycle, and management as well as climate can cause major effects on the balance of C between the atmosphere and the plant/soil system. With re-gard to our commitments to the Kyoto and post-Kyoto actions on climate change, we need reliable predictions on how this balance is affected by management and climate. In 2006 the Skogaryd Research Forest was established in the southwest of Sweden (58°23’N, 12°09’E). The overall goal is to quantify net greenhouse gas (GHG) fluxes from drained spruce forest, by determining the individual fluxes and pools of C and nitrogen and elucidating their connection to site fertility, drainage status and abiotic parameters and then use the generated data in GHG models, for model validations and ultimately emissions predictions. During 2006-2009 the research has fo-cused on two sites, mineral and organic, dominated by Norway spruce (Picea abies). Both sites are drained fertile soils but with different land-use history that have affected their physical properties. Measurements includes: net ecosystem exchange of CO2, Shoot photosynthesis and respiration at different locations within the canopy, stem respiration, emissions of N2O and CH4 using manual cham-bers, soil respiration with automatic chambers including a trenching experiment where root-, mycelia-, and heterotrophic respiration are separated, fine root production using minirhizotrons, and mycelia production. The organic site also includes a wood ash experiment. From 2010 the research will be expanded to the whole watershed, from the mire system via streams, riparian zones, forests, to lakes and the subsequent exchange between the atmosphere and surface waters. Different terrestrial and limnic ecosystems will be linked holistically, using site specific tech-niques at different scales, from aircraft (km2) to chambers (m2) to create integrated models that can be used to quantify net GHG flux for management strategies.
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| 10. |
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| 11. |
- Nilsson, Daniel, 1985-, et al.
(author)
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Mätning av grotflis
- 2012
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Reports (other academic/artistic)abstract
- Handeln av grotflis, flis från grenar och toppar vid slutavverkning, har ökatkraftigt under de senaste åren. Inmätningen sker vanligtvis vidmottagningsplatsen och betalningen sker vanligen utifrån energiinnehåll meduppgift om fukthalt.Syftet med denna studie har varit att jämföra olika mätmetoder för grotflissom bygger på volym, vikt och olika sätt att uppskatta fukthalten. Den metodsom antas som facit bygger på 10 prover per container vilket innebär 30prover per leverans. Detta ”facit” har jämförts med sex alternativa sätt attberäkna lassens energivärde. En av metoderna är den som tillämpas av VMFSyd och en annan är en metod som bygger på en finsk modell att uppskattafukthalten. Studien är avgränsad till 44 leveranser grotflis, i huvudask frånbarrträd, under vinter och sommarförhållanden och transporten har skett iekipage om tre fliscontainrar.Medelfukthalten för de vinterkörda leveranserna bestämdes via 10 prov percontainer, LNU/SLU, till 39,3 % medan VMF Syd uppmätte enmedelfukthalt på 38,7 %, via den finska metoden uppskattades fukthalten förde vinterkörda leveranserna till 45,5 %. Medelfukthalten för desommarkörda leveranserna bestämdes av LNU/SLU till 27,9 %, av VMFSyd till 27,0 % meden uppskattningen via den finska metoden gav enmedelfukthalt på 30 %.De vinterkörda ekipagen hade enligt det antagna facit, LNU/SLU, ettenergiinnehåll i medeltal på 104,2 MWh medan energiinnehållet enligtfukthalten från VMF blev energiinnehållet i medeltal 105,7 MWh och dåfukthalten bestämdes med den finska metoden blev energiinnehållet imedeltal 90,8 MWh. För de sommarkörda leveranserna blev energiinnehålleti medeltal 110,8 MWh enligt LNU/SLU, 112,5 MWh enligt VMF Syd och105,7 MWh enligt den finska metoden.När det gäller de olika mätmetoderna visade det sig att M6, energivärde direkt ifrån mätsedel, var den bästa med en kvotspridning på 6,4 % ijämförelse med antaget facitvärde beräknat enligt LNU/SLU. Anledningentill detta är att denna mätning baseras på av fukthalten och beräknat effektivtvärmevärde för varje enskild leverans medan de andra bygger på ett beräknat”erfarenhetstal” för energiinnehåll per ton respektive per m3s förleveranserna i studien. Om mätningen istället baseras på erfarenhetstalistället för fukthaltsmätning visar resultaten att volymmätning ger en mindrekvotspridning, runt 10 %, jämfört med viktbaserad mätning där kvotspridningen hamnar på ca 17 % jämfört med facit. Fukthaltsmätningenligt den finska metoden ger en kvotspridning på ca 15 %.Volymminskningen under transport för alla leveranser i studien uppmättes imedeltal till strax över 2 % och resultaten visar också att den störstavolymminskningen, ca 70 %, sker redan under de första kilometrarna.Skillnaden mellan VMFs volymmätning och den mer noggrannavolymmätningen utförda av LNU/SLU visade sig vara endast 0,5 %. Men dålassen krattats för att möjliggöra denna mätning har även VMFs inmätningförenklats.
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| 12. |
- Nilsson, Daniel, et al.
(author)
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Mätning av grotflis
- 2012
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In: Research results (Swedish University of Agricultural Sciences, Department of Forest Products). - 1654-9759. ; , s. 1-5
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Other publication (pop. science, debate, etc.)abstract
- Syftet med denna studie har varit att jämföra olika mätmetoder för grotflis som bygger på volym, vikt och olika sätt att uppskatta fukthalten. Den metod som antas som facit bygger på 10 prover per container vilket innebär 30 prover per leverans. Facit har sedan jämförts mot 6 olika mätmetoder. Studien omfattar 44 leveranser grotflis, i huvudsak från barrträd, under vinter- och sommarförhållanden. Transporten till värmeverket har skett i ekipage om tre fliscontainrar. Denna redovisning är en förkortad version av projektets slutrapport, Rapport nr 21 vid institutionen för skogens produkter, SLU, Uppsala. Medelfukthalten för grotflisen i hela studien uppmättes till 35,2 % av LNU/SLU och 34,9 % av VMF Syd vilket är en skillnad på 0,3 %-enheter. Beräknas kvotspridningen för fukthaltsmätningarna blir den ca 10 % för VMF-mätning och ca 32 % för en finsk metod för skattning av fukthalt jämfört med LNU/SLU. Det effektiva värmevärdet varierar mellan 2,86 till 3,22 MWh/ton och mellan 0,97 och 1,01 Mwh per m3s. När det gäller de olika mätmetoderna visade det sig att mätmetod M6, energivärde direkt från VMFs mätsedel, var den bästa med en kvotspridning på 6,4 % i jämförelse med antaget facitvärde beräknat enligt LNU/SLU. Anledningen till detta är att denna mätning baseras på mätning av fukthalten och ett beräknat effektivt värmevärde för varje enskild leverans medan de andra mätmetoderna bygger på ett beräknat ”erfarenhetstal” för energinnehåll per ton respektive per m3s för leveranserna i studien. Om mätningen baseras på erfarenhetstal för fukthaltsmätning visar resultaten att volymmätning ger en mindre kvotspridning, runt 10 %, jämfört med viktbaserad mätning där kvotspridningen hamnar på ca 17 % jämfört med facit. Fukthaltsmätning enligt en finsk metod ger en kvotspridning på ca 15 %. Volymminskningen under transport för alla leveranser i studien uppmättes i medeltal till strax över 2 % och resultaten visar också att den största delen av volymminskningen, ca 70 %, sker redan under de första kilometrarna.
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| 13. |
- Nilsson, Daniel, et al.
(author)
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The importance of accurate measurement of comminuted logging residues’ moisture contents for small-scale forest owners
- 2016
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In: Drewno. - 1644-3985. ; 59:198, s. 99-110
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Journal article (peer-reviewed)abstract
- Bioenergy from logging residues is an important contributor to Swedish energysupplies. Thus, accurate measurements of delivered logging residues’ energycontents are very important for both sellers and buyers. Deliveries’ energycontents are highly correlated with their moisture contents, and thus aredetermined in southern Sweden (and elsewhere) by measuring their masses andmoisture contents. There is insufficient knowledge, however, about the variation inmoisture content within and between deliveries, and hence the minimum numberof samples needed to obtain the required precision. Thus, these variations wereexamined in detail in the presented study. Nested analysis of the variance of theacquired data shows that at least nine samples are required to obtain estimates ofa delivery’s moisture content with a 3% margin of error. For high volume trade,such as that between forest companies and the energy-conversion industry,current measurement practices are sufficiently accurate. For private forest ownersmaking single deliveries, however, higher precision is required as inaccuratemeasurements can strongly affect prices.
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| 14. |
- Nilsson, Josefin A., 1985-
(author)
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Juvenile birch in Sweden : Selected stem characteristics for interior and furniture applications
- 2019
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Licentiate thesis (other academic/artistic)abstract
- In response to the furniture industry’s growing demand for raw material, large volumes of juvenile silver birch and downy birch stems available from pre-commercial thinning operations in Sweden’s forests could offer solutions. However, such stems are not currently used on an industrial scale, and most research conducted on birch stems in general has neither focussed on young trees nor the potential use of the central stem part around the tree pith. The resulting lack of knowledge about the juvenile part of birch wood thus requires additional information about the material properties of birch, which could encourage its use for various purposes in the furniture and other industries.The initial literature review performed for this thesis has highlighted some properties of juvenile birch required for its use as a furniture material, as well as identified topics concerning the physical characteristics of juvenile birch about which knowledge is currently limited. Consequently, the objectives of this thesis were to explore some characteristics of juvenile birch—bark thickness, wood-to-bark bonding ratio after drying, variations in the density and width of growth rings, and anatomical growth response to fertilisation—in order to increase the knowledge.The material studied came from mixed birch and Norway spruce stands at two sites in southern Sweden, namely Asa and Toftaholm. The birch stems were naturally regenerated silver birch and downy birch, with breast height diameters between 30 and 83 mm. Fertilised and unfertilised silver birch trees were sampled at Toftaholm, whereas unfertilised stems of silver birch and downy birch were sampled at Asa. The characteristics of stems from the pith to bark (radial direction) and along the stem (longitudinal direction) were measured. The wood-to-bark bonding ratio on downy birch after drying was calculated as the percentage of the stem circumference with full contact between the wood and bark, while oven-dry density and basic wood density for silver birch were determined by using the water displacement method. The impact of ring width on wood density was statistically analysed, and an image analysis of the wood anatomy was conducted to elucidate their relationship.Amongst the results, bark thickness along the stem had the highest deviation in the section closest to the stump. Moreover, the wood-to-bark bonding ratio after drying measured for juvenile downy birch seemed to depend more on the stem’s diameter than the sampling height along the stem. Such results are relevant for processors seeking to estimate the volume of wood under the bark. The wood-to-bark bonding ratio was highest for diameters between 30 and 39 mm, and neither did that relationship correlate with the sampling height along the stem.Variation in wood density in the radial and longitudinal directions in juvenile silver birch suggested that such density negatively correlated with growth rate (ring width). That relationship held true for stems at each site and between the sites, irrespective of management or growing conditions. As expected, mean wood density was lower in fertilised trees than in unfertilised ones, and towards the bark, radial density increased more in trees that grew more slowly. At the same time, variation in longitudinal density in young silver birch trees was low. Quantitative wood anatomy studies confirmed that the fertilised juvenile birch had younger cambia, thinner cell walls, and fewer vessels per mm2 than unfertilised trees in the same diameter class.Overall, the knowledge generated in the study may facilitate the industrial use of juvenile birch stems and wood in interior and furniture applications. The role of wood anatomy in determining the mechanical performance of juvenile birch stems should be further examined, however, to possibly reveal new opportunities for the use of juvenile birch.
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| 15. |
- Nylinder, Mats, et al.
(author)
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Förändring av volym och vedvolymandel vid torkning av massaved
- 2014
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In: Research results (Swedish University of Agricultural Sciences, Department of Forest Products). - 1654-9759.
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Other publication (other academic/artistic)abstract
- Vid sommarlagring av massaved krymper bark och ved. Massaved som volymbestäms i travat och fast mått påverkas av om veden är rå eller torr. Betydelsen av detta kan tyckas marginell men endast någon procent har på större volymer betydelse i affärssamband och vid lagerinventeringar samt beräkning av massaindustrins vedåtgångstal i produktionsprocessen. Föreliggande studie är förhållandevis liten och skall ses som en förstudie till, beroende på utfall, en mer omfattande studie. Studien har genomfördes vid Frövifors Bruk då tre massavedstravar av tall, gran resp. björk följdes under en sommar. Hopsjunkningen, minskningen av tvärsnittsytan, var 2,0 % för tallen, 2,5 % för granen och 4,5 % för björktaven och därmed samma effekt på den travade volymen då längdkrympningen kan anses försumbar. De uppmätta värdena för hopsjunkning stämmer ganska väl för barrvirke med tidigare studier av barrvirke där man anger hopsjunkningen till mellan 1-3 %. Någon studie av hopsjunkningen i björktravar verkar inte ha genomförsts tidigare. Studien omfattar vidare en topp-rotmätning av en barrtrave och en björktrave före resp. efter torkning. Volymen under bark minskade med 1,5 % för barrtraven och 3,4 % för björtraven. I tidigare studier utförda hos SCA har man uppskattat volymminskningen för barrvirke under bark till nivå 1 %. I nämnda studie uppmättes volymminskningen på bark till 2-4 %.
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| 16. |
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| 17. |
- Nylinder, Mats, et al.
(author)
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Mätning av delkvistad energived
- 2014
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In: Research results (Swedish University of Agricultural Sciences, Department of Forest Products). - 1654-9759. ; , s. 1-2
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Other publication (pop. science, debate, etc.)abstract
- Delkvistad energived är ett sortiment som ökat men kan eventuellt inte mätas efter samma mall som massaved, d.v.s. travmätning med bedömning av vedvolymandel. Syftet med denna studie var därför att jämföra olika tänkbara mätmetoder. Fältarbetet har utförts vid Stora Ensos virkesterminal i Stockaryd och genomförts i samarbete med Stora Enso Bioenergi, Sydved och VMF Syd. För att belysa eventuella årstidvariationer delades studien upp i tre försöksperioder, vinter, vår/sommar och höst. Vinterstudierna utfördes i januari-februari, vår/sommar i juni-juli och höststudierna under september-oktober. Vid varje tillfälle har 10 slumpvist valda travar, totalt 30, inmätts.
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| 18. |
- Nylinder, Mats, et al.
(author)
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Mätning av delkvistad energived : vid Stora Ensos virkesterminal i Stockared i samarbete med Stora Enso Bioenergi, Sydved och VMF Syd
- 2014
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Reports (other academic/artistic)abstract
- Delkvistad energived är ett sortiment som ökat i omfattning under senare år. Detta sortiment kan eventuellt inte mätas efter samma mall som massaved, d.v.s. travmätning med bedömning av vedvolymandel. Syftet med denna studie var därför att jämföra olika mätmetoder. Fältarbetet har utförts vid Stora Ensos virkesterminal i Stockaryd och genomförts i samarbete med Stora Enso Bioenergi, Sydved och VMF Syd. För att belysa eventuella årstidvariationer delades studien upp i tre försöksperioder, vinter, vår/sommar och höst. Vinterstudierna utfördes i januari-februari, vår/sommar i juni-juli och höststudierna under september-oktober. Vid varje tillfälle har 10 slumpvist valda travar, totalt 30, inmätts. Försökstravarna samansättning varierade stort. Medellängden inom travarna varierade mellan 3,6 till 4,1 meter och var i genomsnitt omkring 3,8 meter. Antal stockar per trave varierade mellan 400 upp till 900 och i genomsnitt var andel löv 50 %. Torr-rådensitet uppmättes i genomsnitt till 444 kg/m3 med en variation mellan travarna på 405 till 532 kg/m3. Virkets rådensitet inklusive bark uppmättes till i genomsnitt 799 kg/m3 med en variation inom travar på i genomsnitt 84 kg. I den modell Stora Enso tagit fram varierar omräknings-talet, vikten inklusive bark i förhållande till volymen under bark, från ett minimivärde på 978 till ett maxvärde på 1098 kg per m3f. Fukthalten mättes på tre olika sätt: • Genom uttag av spån med motorsåg, 4 prov per trave • Genom bestämning för 20 trissor per trave • Genom bestämning av fukthalten i 10 flisprov per trave Följande fukthalt (%) uppmättes Medelvärde Std Std inom trave mellan travar Spånprov 39,9 3,2 6,2 Trissor 44,4 6,8 7,7 Flis 43,5 1,4 6,6 En jämförelse av bedömningen av andel löv på inkommande travar till mätstationen och andel löv uppmätt i VMFs stockmätning gav för ett linjärt samband en korrelationskoefficient på, r2 = 0,73. Detta bör betraktas som relativt bra med tanke på travarnas utseende, dimension och antal bitar. Om framtiden innebär att detta sortiment måste transporteras med täckta sidor eller i containrar torde en trädslagsbedömning vid en mätbrygga blir mer eller mindre omöjlig. Andel bark, grenar och toppar uppmättes till i genomsnitt för alla travar till 25,7 %. Andelen varierade mellan 10 till 40 % och standardavvikelsen mellan travar uppmätte still 7,0 % -enheter. Relativt stor osäkerhet råder i dessa beräkningar för en enskild trave då spridningen i rådensitet mellan trissor inom en trave är stor. För hela materialet 25,7 % bör dock uppskattningen vara tämligen väl underbyggd. Flisens fastvolym beräknades till i genomsnitt 42,6 % med mycket stora variationer mellan travarna, 34-50 %. Stora Ensos modell för skattning av volym ger i stort samma volym som VMFs beräkning av volymen stamved under bark. Den extra vikt som toppar under 1 cm diameter och vikten av grenar ”fångas” inte upp av Stora Ensos modell. Detta beror sannolikt på att Stora Ensos modell bygger på virke som varit fuktigare än virket i denna studie. Virket i denna studie hade en fuktighet på cirka 44 % medan klen massaved normalt har en fuktighet på över 50 %. I jämförelse med den totala volymen per trave ger Stora Ensos modell en underskattning av volymen med cirka 25 %. Kvotspridningen för Stora Ensos modell blir cirka 10 % vilket kan jämföras med dagens mätning av massaved som har en kvotspridning på mellan 3-5 %. Energivärdet per trave är i genomsnitt 22,5 MWh. Av studierna framgår att sambandet, korrelationen, mellan volym m3s och energivärde per trave är bättre än volymen enligt Stora Ensos modell. Stora Ensos modell ger en bättre skattning av energivärdet än en råvägning. En beräkning av mängden torrsubstans och virkets torrhalt baserat på flisen fukthalt ger den klart bästa skattningen av travarnas energivärde. Detta talar för att en kostnadseffektiv metod för att bestämma fukthalt skulle vara att föredra.
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| 19. |
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| 20. |
- Nylinder, Mats, et al.
(author)
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Timmer
- 2011
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Book (other academic/artistic)
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| 21. |
- Nylinder, Mats, et al.
(author)
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Torrhaltsbestämning av spånprov uttagna med motorsåg
- 2012
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In: Research results (Swedish University of Agricultural Sciences, Department of Forest Products). - 1654-9759.
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Other publication (pop. science, debate, etc.)abstract
- Intresset för att fastställa torrhalten i virke har ökat i och med att användning av virke till förbränning vuxit. Torr-halten är en grundläggande parameter för att fastställa energimängden och kvantiteten vid vägning. Under de senaste 20-30 åren har en rad metoder för uttag av torr-haltsprov provats såväl i Sverige som utomlands. De flestaav dessa bygger på olika tekniska utformningar av provtagningsutrustning för att få representativa prov. Variationen i torrhalt inom stamved och mellan stockar talar för att man inte bör inrikta utveckling mot att söka utveckla metoder som har så god noggrannhet och pre-cision för ett enskilt prov utan finnaen metod som är robust för en trave som helhet. En sådan metod kan vara att göra en enkel provsamlingsfickaför en standardmo-torsåg och ta ett antal ”snitt” i en trave för att få spån från så många stockar som möjligt i traven. Syftet med denna studie är att för en sådan lösning få en uppfattning om vilka avvikelser som föreligger mellan torrhalten i spån från en motorsåg och intilliggande ved.För att klarlägga detta uppsamlades spån från ett helt sågsnitt intill en trissa och ett halvt snitt på andra si-dan trissan innan denna sågades fram. Det halva snittets djup i stocken bestämdes genom en visuell bedömning av halva stockdiametern. Spånet från sågen uppsamla-des i en spånfickakopplad till motorsågen som byggdes för denna studie.För att minimera eventuell risk för uttorkning av speci-ellt spån, men även av trissorna, vägdes proven i direkt anslutning till provtagningen i skogen. För att belysa vedens betydelse för provtagningen togs prov av olika trädslag, virke av olika dimensioner, ofruset och fru-set virke samt lagrat virke. Detta projekt genomfördes inom ramen för FoU-programmet ”Effektivare skogs-bränslesystem” som drivs av Skogforsk.Resultatet av studien visar att ingen signifikantskill-nad kunde påvisas mellan torrhalten i spån från halva snitt, hela snitt eller i mellanliggande trissa. Endast för färsk ek och lagrad klen ek gav de tre metoderna olika torrhalt. För dessa ekprov uppmättes högre torrhalt i spånet än i trissorna. Det avvikande resultatet för ek är litet vad gäller uppmätta medelvärden och avvikel-serna är inte de samma mellan metoderna för de olika försöksleden. Ytterligare studier bör därför genomföras för tyngre trädslag likt ek.Sammanfattningsvis talar resultatet i denna studie för att en konventionell motorsåg men spånsmalare kan användas som redskap för att insamla prov i rundved för torrhaltsbestämning.
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| 22. |
- Swenson, Ulf, et al.
(author)
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Phylogenetic position and reinstatement of Gayella (Sapotaceae), a monotypic genus endemic to Chile with an Eocene origin in continental Australia
- 2023
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In: Taxon. - : Wiley. - 0040-0262 .- 1996-8175. ; 72:2, s. 360-374
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Journal article (peer-reviewed)abstract
- PouteriasplendensistheonlynativespeciesofSapotaceaeinChile,aspeciesonceplacedinthemonotypicgenusGayella and known as G. valparadisaea, but for a long time treated as a Pouteria. In a phylogenetic analysis, this species was placed in an Australasian clade, not with its presumed relatives in South America. We used Bayesian inference under a relaxed molecular clock in BEAST, nuclear ribosomal DNA (ETS, ITS), the nuclear gene RPB2, indel information, and 201 terminals to find the closest rel- ative of P. splendens and to estimate the age of the disjunction between Australasia and South America. The taxon has an isolated phylogenetic position, being part of the cladeʼs backbone, and is placed with weak support as sister to Van-royena, another monotypic genus, but endemic to Australia. Our results justify reinstatement of Gayella with its single species G. valparadisaea. Gayella has a unique combination of morphological features including alternate, opposite or 3-whorled leaves, often on the same plant, a usually 6-lobed, rotate corolla with revolute corolla lobes giving the flower a star-like appearance, lacerate to dentate staminodes, and yellow-orange-red fruit with plano-convex cotyledons and an exserted radicle below the cotyledon commissure. The split between Gayella and Van-royena is estimated to the late Eocene at about 40.0 Ma (50.5–25.3 Ma). The hypothesis that the presence of Gayella in South America is a result of vicariance is consistent with the timing of the geological splits of southern Gondwana, as well as with evidence from fossil pollen, but long-distance dispersal is an alternative explanation that cannot be excluded. Gayella is restricted to an area with a Mediterranean-type climate in coastal central Chile, where it occurs in rocky places, ravines, and gullies, usually below 100 m altitude within reach of sea mist. Gayella valparadisaea is a rare plant, listed as Endangered (EN) in Chile, but it does not occur in any protected area. Considering the isolated phylogenetic position of this old lineage, we urge the Chilean authorities to increase the efforts towards protection of this species.
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| 23. |
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| 24. |
- Wallin, Anita, et al.
(author)
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Träd- och virkesegenskaper hos två kloner av mikroförökad masurbjörk
- 2005
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Reports (other academic/artistic)abstract
- The curly birch (Betula pendula var. carelica) has a wood that deviates from the non-curly form of birch. The curly birch has wavy lines or grains in the wood.The masur formation is genetically controlled by sexual crossing or can eventually be formed by new formations of curly birches. Each individual has a unique pattern of curly-grained wood. In order to preserv the same pattern in many trees vegetative propagation has to be utilized. Rooting of birch cuttings is more or less impossible. Micropropagation is a more efficient method than grafting or inoculation.Cloning of curly birch would be a possibility to produce trees with a predetermined stucture of the wood and in large quantities. In the light of these facts one need a model to characterize the wood and to make sure that the individuals from the same clone give a similar wood.In 1985 three different curly birches and one non-curly birch were micropropagated in an examination work supervised by Anita Wallin. Of each clone about 15 micropropagated plants were planted and fenced.The aim of this study was to classify the curly-grained wood and to compare the wood from 5 trees in two different micropropagated curly birches.Wood characteristics. The difference is great between the wood structure of the cross-section of fully developed masur rose in the two clones. The disturbances of the wood are more extensive in M3 and the angle somewhat more acute in M3 than in M1.The utility of the clones in industríal trade. There is a great difference in prerequisite for industrial processing of the wood. Clone M1 yields relatively straight and long logs with homogenous wood structure, compared to M3. Clone M1 would be usable in veneer turnings and veneer cuttings as the veneer surface would be uniform all over.Micropropagation foir efficient curly-grained wood producation. Cloning of curly birch by micropropagation is proven to be a reliable method to obtain many individuals with the same stem form and equivalent masur quality.
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| 25. |
- Woxblom, Ann-Charlotte, et al.
(author)
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Industrial utilizaton of hardwood in Sweden
- 2010
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In: Broadleaved Forests in Southern Sweden: Management for Multiple Goals. - 9781405188869 ; :53, s. 43-50
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Book chapter (peer-reviewed)abstract
- This paper is intended to provide an overview of hardwood resources and use in Sweden today. Sweden has about 23 million ha of productive forest land (production > 1 m3 ha–1 yr–1) and is an important country with respect to the production of pulp, paper and sawn softwood timber. An increased demand for hardwood by the pulp industry and new perspectives on deciduous forests, regarding them not only as a source of raw materials but also as ecosystems with a rich biodiversity and places for human recreation, has resulted in a growing interest in the sustainable management of deciduous forests. The total stock of wood in Sweden’s forests amounts to about three billion m3sk (cubic metres standing volume incl. bark and tops). The stock of hardwood has increased from ca 300 million m3sk in 1920, to roughly 500 million m3sk today; ca 17% of the total stock of wood in Sweden. Birch is the dominant deciduous species, accounting for nearly 70% of the hardwood volume. Birch, aspen, alder, oak and beech collectively represent 94% of the total stock of hardwood. The total amount of hardwood used for industrial purposes in Sweden is ca 7.6 million m3sub (cubic metres solid wood excl. bark and tops) yr–1. Hardwood accounts for ca 20% of the wood consumption in the pulp industry and <1% in the sawmill sector. The main consumer of birch, aspen, beech and alder is the pulp industry. Birch, beech and alder are also used, to a large degree, in the sawmill industry. Oak and ash are used mainly in the sawmill industry. During the last 25 yr there has been an increased demand for oak, ash and beech for flooring
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