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  • 1.
    Bautista, Rocí­o
    et al.
    University of Malaga.
    Villalobos, David, P.
    University of Malaga.
    Diaz-Moreno, Sara M
    University of Malaga.
    Cantón, Francisco, R.
    University of Malaga.
    Cánovas, Francisco, M.
    University of Malaga.
    Gonzalo Claros, M.
    University of Malaga.
    Toward a Pinus pinaster bacterial artificial chromosome library2007In: Annals of Forest Science, ISSN 1286-4560, E-ISSN 1297-966X, Vol. 64, no 8, p. 855-864Article in journal (Refereed)
    Abstract [en]

    Conifers are of great economic and ecological importance, but little is known concerning their genomic organization. This study is an attempt to obtain high-quality high-molecular-weight DNA from Pinus pinaster cotyledons and the construction of a pine BAC library. The preparation incorporates modifications like low centrifugation speeds, increase of EDTA concentration for plug maintenance, use of DNase inhibitors to reduce DNA degradation, use of polyvinylpyrrolidone and ascorbate to avoid secondary metabolites, and a brief electrophoresis of the plugs prior to their use. A total of 72 192 clones with an average insert size of 107 kb, which represents an equivalent of 11X pine haploid genomes, were obtained. The proportions of clones lacking inserts or containing chloroplast DNA are both approximately 1.6%. The library was screened with cDNA probes for seven genes, and two clones containing Fd-GOGAT sequences were found, one of them seemingly functional. Ongoing projects aimed at constructing a pinebacterial artificial chromosome library may benefit from the methods described here.

  • 2.
    Bjurhager, Ingela
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Ljungdahl, Jonas
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Wallstrom, Lennart
    Gamstedt, E. Kristofer
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
    Berglund, Lars A.
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
    Towards improved understanding of PEG-impregnated waterlogged archaeological wood: A model study on recent oak2010In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 64, no 2, p. 243-250Article in journal (Refereed)
    Abstract [en]

    To prevent deformation and cracking of waterlogged archaeological wood, polyethylene glycol (PEG) as a bulk impregnation agent is commonly applied. PEG maintains the wood in a swollen state during drying. However, swelling of wood can reduce its mechanical properties. In this study, the cellular structure of oak and cell wall swelling was characterized by scanning electron microscopy (SEM) of transverse cross-sections, and the microfibril angle of oak fibers was determined by wide angle X-ray scattering (WAXS). Samples of recent European oak (Quercus robur L) impregnated with PEG (molecular weight of 600) were tested in axial tension and radial compression. Mechanical tests showed that axial tensile modulus and strength were only slightly affected by PEG, whereas radial compressive modulus and yield strength were reduced by up to 50%. This behavior can be explained by the microstructure and deformation mechanisms of the material. Microfibril angles in tensile test samples were close to zero. This implies tensile loading of cellulose microfibrils within the fiber cell walls without almost any shear in the adjacent amorphous matrix. These results are important because they can help separate the impact of PEG on mechanical properties from that of chemical degradation in archaeological artifacts, which display only small to moderate biological degradation.

  • 3.
    Canales, Javier
    et al.
    University of Malaga.
    Ávila, Concepción
    University of Malaga.
    Cantón, Francisco
    University of Malaga.
    Pacheco-Villalobos, David
    University of Malaga.
    Díaz-Moreno, Sara
    University of Malaga.
    Ariza, David
    University of Cordoba.
    Molina-Rueda, Juan
    University of Malaga.
    Navarro-Cerrillo, Rafael
    University of Cordoba.
    Claros, M.
    University of Malaga.
    Cánovas, Francisco
    University of Malaga.
    Gene expression profiling in the stem of young maritime pine trees: detection of ammonium stress-responsive genes in the apex2011In: Trees, ISSN 0931-1890, E-ISSN 1432-2285, Vol. 26, no 2, p. 609-619Article in journal (Refereed)
    Abstract [en]

    The shoots of young conifer trees represent an interesting model to study the development and growth of conifers from meristematic cells in the shoot apex to differentiated tissues at the shoot base. In this work, microarray analysis was used to monitor contrasting patterns of gene expression between the apex and the base ofmaritime pine shoots. A group of differentially expressed genes were selected and validated by examining their relative expression levels in different sections along thestem, from the top to the bottom. After validation of the microarray data, additional geneexpression analyses were also performed in the shoots of young maritime pine treesexposed to different levels of ammonium nutrition. Our results show that the apex ofmaritime pine trees is extremely sensitive to conditions of ammonium excess or deficiency, as revealed by the observed changes in the expression of stress-responsivegenes. This new knowledge may be used to precocious detection of early symptoms of nitrogen nutritional stresses, thereby increasing survival and growth rates of young treesin managed forests. 

  • 4.
    Freitas, Flavio L. M.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Brazilian land use policies and the development of ecosystem services2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Concerns related to global environmental changes due to land use changes have been driving international communities towards more sustainable land use systems. Brazil is a country of global strategic importance in this matter considering that it is the nation with the largest extension of preserved tropical native vegetation, recognised for its ecosystem services and high and unique biodiversity. Expansion of forestry and agriculture is taking place rapidly in Brazil, partly over degraded pastureland, but also over native vegetation. Regulating policies to govern and limit this expansion is crucial to ensure the preservation of the ecosystems services provided by native vegetation.  This thesis aims at improving the understanding of the potential impacts of prevailing public and private policies in the conservation of nature in Brazil. For this end, the Land Use Policy Assessment (LUPA) model was employed to evaluate potential pathways of implementation of the land use policies. Paper 1 evaluated the effects of current private and public command and control regulations in the protection of above-ground carbon stocks, identifying the most relevant stakeholders holding carbon stocks. The findings suggest that about 10% of carbon stocks are unprotected, where other policy instruments based on the market will be mostly required. Paper 2 performed an assessment of the mechanism for offsetting the legal deficit of native vegetation among landholders, evaluating the different offsetting implementation practices and their impacts on nature protection and socio-economic development. The results indicate that the offsetting mechanism may have little or no additional effects on protection of native vegetation and its ecosystem services because most of the offsetting is likely to take place where native vegetation is already protected by current legislations. However, it is viable to maximise environmental and socio-economic returns from the offsetting mechanism.

  • 5.
    Freitas, Flavio L. M.
    et al.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Sparovek, Gerd
    University of São Paulo, Soil Dep..
    Mörtberg, Ulla
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Silveira, Semida
    KTH, School of Industrial Engineering and Management (ITM), Energy Technology, Energy and Climate Studies, ECS.
    Klug, Israel
    Food and Agriculture Organization of United Nations, Nutrition and Food Systems Division.
    Berndes, Göran
    Chalmers University, Energy and Environment.
    Offsetting legal deficits of native vegetation among Brazilian landholders: effects on nature protection and socioeconomic developmentManuscript (preprint) (Other academic)
  • 6.
    Gellerstedt, Göran
    KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Wood Chemistry and Pulp Technology.
    Professor Gosta Brunow (1936-2013) Obituary2014In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 68, no 2, p. 253-254Article in journal (Refereed)
  • 7. Hagström, Peter
    Biomass Potential for Heat, Electricity and Vehicle Fuel in Sweden2006Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The main objective of this thesis was to determine how far a biomass quantity, equal to the potential produced within the Swedish borders, could cover the present energy needs inSwedenwith respect to economic and ecological circumstances. Three scenarios were studied where the available biomass was converted to heat, electricity and vehicle fuel. Three different amounts of biomass supply were studied for each scenario: 1) potential biomass amounts derived from forestry, non-forest land, forest industry and community; 2) the same amounts as in Case 1, plus the potential biomass amounts derived from agriculture; 3) the same amounts as in Case 1, plus 50% of the potential pulpwood quantity.

    For evaluating the economic and ecological circumstances of using biomass in the Swedish energy system, the scenarios were complemented with energy, cost and emergy analysis.

    The scenarios indicated that it may be possible to produce 170.2 PJ (47.3 TWh) per year of electricity from the biomass amounts in Case 2. From the same amount of biomass, the maximum annual production of hydrogen was 241.5 PJ (67.1 TWh) per year or 197.2 PJ (54.8 TWh) per year of methanol.

    The energy analysis showed that the ratio of energy output to energy input for large-scale applications ranged from 1.9 at electric power generation by gasification of straw to 40 at district heating generation by combustion of recovered wood. The cost of electricity at gasification ranged from 7.95 to 22.58 €/GJ. The cost of vehicle work generated by using hydrogen produced from forestry biomass in novel fuel cells was economically competitive compared to today’s propulsion systems. However, the cost of vehicle work generated by using methanol produced from forestry biomass in combustion engines was rather higher compared to use of petrol in petrol engines.

    The emergy analysis indicated that the only biomass assortment studied with a larger emergy flow from the local environment, in relation to the emergy flow invested from society after conversion, was fuel wood from non-forest land. However, even use of this biomass assortment for production of heat, electricity or vehicle fuels had smaller yields of emergy output in relation to emergy invested from society compared to alternative conversion processes; thus, the net contribution of emergy generated to the economy was smaller compared to these alternative conversion processes.

  • 8. Hsieh, Y S Y
    et al.
    Liao, S F
    Yang, W B
    Biologically active polysaccharides in medicinal plants.2009In: New Zealand Journal of Forestry Science, Vol. 39, p. 217-223Article in journal (Refereed)
    Abstract [en]

    Biologically active polysaccharides from medicinal plants have been studied for many years. In addition to immuno-modulating effects, human clinical studies have shown that some polysaccharides have certain benefits for human health. Most studies have focused on the side chains of pectic rhamnogalacturonan I (RG-I), particularly the Type II arabinogalactans, which have been isolated and shown to have anti-complementary and other immuno-activities. These studies have provided valuable information about how carbohydrate moieties induce certain biological events.

  • 9. Hsieh, Y S Y
    et al.
    Paxton, M
    Ade, C P
    Harris, P J
    Structural diversity, functions and biosynthesis of xyloglucans in angiosperm cell walls.2009In: New Zealand Journal of Forestry Science, Vol. 39, p. 187-196Article in journal (Refereed)
    Abstract [en]

    Xyloglucans occur in the primary cell walls of all angiosperms where they are thought to have a structural role and be involved in the control of cell expansion. They also occur in the thick, non-lignified secondary cell walls of seeds of some species ofeudicotyledons where they serve as reserve carbohydrates. The xyloglucans in the primary cell walls of most eudicotyledons have similar structures with side chains containing galactose and fucose. However, in one group of eudicotyledons, the asterids, there is considerable structural variability in the xyloglucans, with many containing arabinose. There is also variability in the xyloglucans of the monocotyledons, with those in the family Poaceae containing no fucose and only small proportions ofgalactose. The xyloglucans of the thick, secondary cell walls of seeds are similar to those in the primary walls of most eudicotyledons, but contain no fucose. The functional significance of these structural variations is unknown. A number of genes and their encoded glycosyltransferases have been identified as being involved in the biosynthesis of the xyloglucans of the model eudicotyledon Arabidopsis thaliana. 

  • 10. Kännaste, A.
    et al.
    Laanisto, L.
    Pazouki, L.
    Copolovici, L.
    Suhorutšenko, M.
    Azeem, Muhammad
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. COMSATS Institute of Information Technology, Pakistan.
    Toom, L.
    Borg-Karlson, Anna-Karin
    KTH, School of Chemical Science and Engineering (CHE), Chemistry. University of Tartu, Estonia.
    Niinemets, Ü.
    Diterpenoid fingerprints in pine foliage across an environmental and chemotypic matrix: Isoabienol content is a key trait differentiating chemotypes2018In: Phytochemistry, ISSN 0031-9422, E-ISSN 1873-3700, Vol. 147, p. 80-88Article in journal (Refereed)
    Abstract [en]

    Diterpenoids constitute an important part of oleoresin in conifer needles, but the environmental and genetic controls on diterpenoid composition are poorly known. We studied the presence of diterpenoids in four pine populations spanning an extensive range of nitrogen (N) availability. In most samples, isoabienol was the main diterpenoid. Additionally, low contents of (Z)-biformene, abietadiene isomers, manoyl oxide isomers, labda-7,13,14-triene and labda-7,14-dien-13-ol were quantified in pine needles. According to the occurrence and content of diterpenoids it was possible to distinguish ‘non diterpenoid pines’ ‘high isoabienol pines’ ‘manoyl oxide – isoabienol pines’ and ‘other diterpenoid pines’. ‘Non diterpenoid pines’ ‘high isoabienol pines’ and ‘other diterpenoid pines’ were characteristic to the dry forest, yet the majority of pines (>80%) of the bog Laeva represented ‘high isoabienol pines’. ‘Manoyl oxide – isoabienol pines’ were present only in the wet sites. Additionally, orthogonal partial least-squares analysis showed, that in the bogs foliar nitrogen content per dry mass (NM) correlated to diterpenoids. Significant correlations existed between abietadienes, isoabienol and foliar NM in ‘manoyl oxide – isoabienol pines’ and chemotypic variation was also associated by population genetic distance estimated by nuclear microsatellite markers. Previously, the presence of low and high Δ-3-carene pines has been demonstrated, but the results of the current study indicate that also diterpenoids form an independent axis of chemotypic differentiation. Further studies are needed to understand whether the enhanced abundance of diterpenoids in wetter sites reflects a phenotypic or genotypic response.

  • 11.
    Lindström, Tom
    et al.
    KTH, School of Engineering Sciences (SCI), Solid Mechanics (Dept.). KTH, School of Engineering Sciences (SCI), Centres, VinnExcellence Center BiMaC Innovation. Innventia AB, Paper Chem & Nanomat Grp, Sweden.
    Aulin, Christian
    Market and technical challenges and opportunities in the area of innovative new materials and composites based on nanocellulosics2014In: Scandinavian Journal of Forest Research, ISSN 0282-7581, E-ISSN 1651-1891, Vol. 29, no 4, p. 345-351Article in journal (Refereed)
    Abstract [en]

    This communication is a review over the major market and technical challenges and opportunities for nanocellulosic materials on a large scale but in low-to-medium-end markets. Basically, the potential use of nanocellulose as a wet-end strength additive in papermaking has been known for decades, but not come into operation because of the high-energy costs of producing these materials. Cost performance compared to starch derivatives is one challenge, and the other is to design suitable dewatering/retention aid systems. Other paper applications are as a surface-sizing agent and as a barrier coating material. Major challenges are associated with the high viscosity of nanocellulosic materials and how to apply the nanocellulose in order to obtain good surface coverage. There are several opportunities in the nanocomposite markets. The packaging sector together with the automotive sector and the building sector constitute large potential markets. Challenges are related to the mixing of hydrophobic and hydrophilic materials so that a good dispersion of nanocellulose is obtained. Scaling up of nanocellulose production processes and procedures for nanocomposite manufacturing in order to obtain price-performance in the various applications remains, as expected, the largest challenge.

  • 12.
    Ohlsson, Anna B.
    et al.
    KTH, School of Biotechnology (BIO).
    Segerfeldt, Patrik
    KTH, School of Biotechnology (BIO). KTH, School of Chemical Science and Engineering (CHE), Chemistry.
    Lindström, Anders
    Dalarna University.
    Borg-Karlsson, Anna-Karin M.
    KTH, School of Chemical Science and Engineering (CHE), Chemistry, Organic Chemistry.
    Berglund, Torkel
    KTH, School of Biotechnology (BIO).
    UV-B Exposure of Indoor-Grown Picea abies Seedlings Causes an Epigenetic Effect and Selective Emission of Terpenes2013In: Zeitschrift für Naturforschung C - A Journal of Biosciences, ISSN 0939-5075, E-ISSN 1865-7125, Vol. 68, no 3-4, p. 139-147Article in journal (Refereed)
    Abstract [en]

    Terpenoids  are  involved  in  various  defensive  functions  in  plants,  especially  conifers.  Epi-genetic  mechanisms,  for  example  DNA  methylation,  can  infl uence  plant  defence  systems. The purpose of the present study was to investigate the infl uence of UV-B exposure on the release  of  terpenoids  from  spruce  seedlings  and  on  needle  DNA  methylation.  Ten-week-old  seedlings  grown  indoors  were  exposed  to  UV-B  radiation  during  4 h,  and  the  volatile compounds  emitted  from  the  seedlings  were  analysed.  Analysis  of  the  volatiles  1,  3,  and 22 d after this UV-B exposure showed that bornyl acetate, borneol, myrcene, and limonene contents increased during the fi rst 3 days, while at day 22 the level of emission had returned to the control level. UV-B exposure decreased the level of DNA methylation in needles of young  seedlings,  refl ected  in  methylation  changes  in  CCGG  sequences.  Exposure  of  young seedlings  to  UV-B  radiation  might  be  a  way  to  potentiate  the  general  defensive  capacity, improving their ability to survive in outdoor conditions. UV-B-induced defence is discussed in the light of epigenetic mechanisms.

  • 13.
    Ramachandran, Praveen
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Ismoilov, AbbosKTH, School of Industrial Engineering and Management (ITM), Machine Design (Dept.).Sellgren, UlfKTH, School of Industrial Engineering and Management (ITM).Löfgren, BjörnSwedish Forestry Research Institute, Skogforsk.Andersson, KjellKTH, School of Industrial Engineering and Management (ITM).
    MODEL-BASED ANALYSIS OF A TRACKED FORWARDER FOR SUSTAINABLE FORESTRY2015Conference proceedings (editor) (Other academic)
    Abstract [en]

    Cut-to-length logging (CTL) is a mechanized harvesting process where trees are delimbed and cut to length directly at the stump. CTL is typically a two-man, two-machine operation with a harvester felling, delimbing, and bucking trees, and a forwarder transporting the cut logs from the felling area to a landing area accessible by trucks, or trains. The main challenges for the manufacturers of forestry machines for CTL logging are to address new customer demands and tougher ergonomic and environmental legislations by finding means that: (1) further increase the harvesting and log transportation productivity, e.g. by enabling operation on eco-soils, (2) reduce the damage to the soil, e.g. by controlling the rut depth and preserving the root layer, (3) reduce exhaust emissions, e.g. by reducing the rolling resistance and evening the contact and tractive forces between all traction units and ground, and (4) reduce the daily vibration dosage for the machine operators, e.g. with efficient chassis and cabin suspension solutions.This paper presents a model-based study of a novel tracked medium-sized forestry machine. The machine is a standard eight-wheeled forwarder of bogie type with the four bogies replaced with four passively suspended track units adapted from an off-road military vehicle. The paper briefly summarize how a tracked forwarder can be modelled and simulated using multi-body simulation software like Adams ATV and how the performance parameters can be evaluated.

  • 14. Rappe George, M. O.
    et al.
    Hansson, L. J.
    Ring, E.
    Jansson, P. E.
    KTH, School of Architecture and the Built Environment (ABE), Sustainable development, Environmental science and Engineering, Land and Water Resources Engineering.
    Gärdenäs, A. I.
    Nitrogen leaching following clear-cutting and soil scarification at a Scots pine site – A modelling study of a fertilization experiment2017In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 385, p. 281-294Article in journal (Refereed)
    Abstract [en]

    Boreal forest stands fertilized with nitrogen (N) might be susceptible to elevated N leaching following clear-cutting, with consequences for water quality and soil acidification. Here, we studied a forest fertilization experiment with N, 165 Hagfors, in Sweden during the first six years (2006–2011) following clear-cutting. The N fertilization treatments were 0 kg ha−1 (0 N) and 450 kg ha−1 of N (450 N), supplied during 1981–1992 to a Scots pine (Pinus sylvestris L.) stand: the stand was harvested in March 2006. Following clear-cutting, disc trenching was performed and furrows (F), ridges (R) and areas in-between two furrows (IB) were created. We calculated the N leaching fluxes and ecosystem N budget during 2006–2011 as affected by previous N fertilization, disc trenching and interactions thereof, at Hagfors by the use of a process-based biogeophysical ecosystem model (CoupModel). The model was calibrated against measurements of soil water and temperature dynamics and previously reported measurements of N in soil solution, soil organic matter and vegetation biomass. Criteria for acceptance of model estimates were based on the range enclosed by the 95% confidence intervals of the mean of the field data used in calibration sampled at low frequency (1–2 occasions) and a combination of the mean error and the coefficient of the determination for variables sampled at a higher frequency (28–1921 occasions). The accepted model estimates of the mean annual leaching rates of N were 3.1 (range 1.4–22.7) and 2.4 (range 0.8–7.0) kg ha−1 of N year−1 in the treatments 0 N and 450 N, respectively, without disc trenching. Disc trenching increased N leaching during the regeneration phase, more so in the 450 N treatment (mean 6.1, range 1.9–16.7 kg ha−1 of N year−1) than in the 0 N treatment (mean 4.6, range 1.9–12.9 kg ha−1 of N year−1). Overall, differences in the posterior model parameter estimates between N treatments and disc trenched treatments F, R and IB were related to the soil physical component: the differences resulted in enhanced drainage in the disc trenched treatments. We conclude that vegetation biomass N accumulation controlled soil water N leaching, and disc trenching increased N leaching from the previously N fertilized plots at Hagfors by its effects on water drainage flow and vegetation N uptake. This finding warrants more research since N fertilization followed by soil scarification in boreal forests is a practice which may increase in the future.

  • 15. Wang, Yi-Qiang
    et al.
    Shen, Ji-Kang
    Berglund, Torkel
    KTH, School of Biotechnology (BIO), Biochemistry.
    Ohlsson, Anna B.
    KTH, School of Biotechnology (BIO), Biochemistry.
    Tang, Xiao-Feng
    Zhou, Zhai-Kui
    Wu, Ruo-Yan
    Zhou, Xiao-Hui
    Chen, Jie-Nan
    Analysis of expressed sequence tags from Ginkgo mature foliage in China2010In: TREE GENET GENOMES, ISSN 1614-2942, Vol. 6, no 3, p. 357-365Article in journal (Refereed)
    Abstract [en]

    Ginkgo biloba L. is a tree native to China, which has large importance within medicine and horticulture. The extracts from Ginkgo mature leaves with rich flavonoids and terpenoids are commonly used for a variety of folk remedies. We constructed a cDNA library derived from mature leaves of Ginkgo, which consisted of 8.12 x 10(5) clones with the insert length of 500-2,000 bp. We performed an analysis of expressed sequence tags (ESTs) and obtained partial sequences from 2,039 clones, which represented 1,437 unigenes consisting of 249 contigs and 1,188 singletons. The 2,039 ESTs were submitted to GenBank (dbEST) at NCBI and were assigned GenBank accession numbers from GE647881 to GE649919. The 1,235 cDNA clones out of 2,039 (60.1%) were assigned putative functions, and the remaining 804 clones were not similar to any known gene sequences in the databases. The five largest categories of Ginkgo clones were: "energy" (19.4%), "disease/defense" (16%), "metabolism" (11.3%), "unclassified proteins" (12.5%), and "secondary metabolism" (9%). The highly expressed transcripts in the cDNA library were some genes related to photosynthesis, disease/defense, and flavonoid biosynthesis, including ribulose-bisphosphate carboxylase small-chain gene, pathogenesis-related protein gene, light-harvesting chlorophyll a/b binding protein of photosystem gene, catalase gene, and phenylcoumaran benzylic ether reductase gene et al. Many genes with ESTs similar to photosynthesis, secondary metabolism, and stress-response genes were characterized. The analysis of ESTs indicates that it is a useful approach for isolating Ginkgo genes homologous to known genes. Our results provide new information about mature leaf-specific transcripts of Ginkgo.

  • 16.
    Wohletz, Gunnar
    KTH, School of Architecture and the Built Environment (ABE), Urban Planning and Environment, Geoinformatik och Geodesi.
    A GIS Model to Estimate a Sustainable Potential of Forest Fuel for Energy Generation in the Municipality of Växjö, Sweden2011Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Since the 1980s the municipality of Växjö in Southern Sweden has been increasingly focusing on using wood to produce energy for the region. A permanent and sustainable supply of wood material is therefore indispensable. The main source for this wood fuel is harvested wood from forests which can be used as energy, so-called forest fuel. The objective of this research is to develop a model to estimate a sustainable potential of forest fuel supply until the year 2050 for the municipality using a geographic information system (GIS). The model overall follows a top-down approach that consists of three sequential modeling steps which are generally applicable for biomass potential estimations: a theoretical, technical and the reduced technical potential. For input data the model uses georeferenced forest data (called kNN-Sweden) and topographic data about the study area to describe and narrow down the forest fuel potential by setting numerical or topographic (spatial) parameters for each modeling step. In this report forest data from 2005 has been used, which was obtained shortly before the storm ‘Gudrun’ hit and damaged great parts of the Swedish forest landscape. This factor might have resulted in slightly misleading estimated numerical modeling results concerning the actual future forest fuel supplies, but is not related to the overall layout of the model. The results show that the municipality of Växjö should be able to satisfy its demand for energy wood from harvested forest wood alone until around the year 2035, but might have shortages after that year until 2050 (and possibly beyond that). This thesis concludes that for the next 40 years the municipality of Växjö should not only rely on its annually available forest fuel capacity, but instead, different wood resources, such as recycled wood from constructions or furniture, have to be utilized or forest wood from years with surplus supply have to be stored for future tighter years. For more accurate results the modeling steps should be repeated with more recent forest data. The report also concludes that the estimation of the forest fuel potential in this study still lacks accuracy and that it is advised to treat the estimated numerical modeling results with caution. There’s still room for further improvement, and therefore possible error sources and suggestions for future work are listed.

  • 17.
    Wu, Sihong
    KTH, School of Architecture and the Built Environment (ABE), Land and Water Resources Engineering, Environmental Physics.
    Impact of cold climate on boreal ecosystem processes: exploring data and model uncertainties2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The impact of cold climate on physical and biological processes, especially the role of air and soil temperature in recovering photosynthesis and transpiration in boreal forests, was investigated in a series of studies. A process-based ecosystem model (CoupModel) considering atmospheric, soil and plant components was evaluated and developed using Generalized Likelihood Uncertainty Estimation (GLUE) and detailed measurements from three different sites. The model accurately described the variability in measurements within days, within years and between years. The forcing environmental conditions were shown to govern both aboveground and belowground processes and regulating carbon, water and heat fluxes. However, the various feedback mechanisms between vegetation and environmental conditions are still unclear, since simulations with one model assumption could not be rejected when compared with another.

    The strong interactions between soil temperature and moisture processes were indicated by the few behavioural models obtained when constrained by combined temperature and moisture criteria. Model performance on sensible and latent heat fluxes and net ecosystem exchange (NEE) also indicated the coupled processes within the system. Diurnal and seasonal courses of eddy flux data in boreal conifer ecosystems were reproduced successfully within defined ranges of parameter values. Air temperature was the major limiting factor for photosynthesis in early spring, autumn and winter, but soil temperature was a rather important limiting factor in late spring. Soil moisture and nitrogen showed indications of being more important for regulating photosynthesis in the summer period. The need for systematic monitoring of the entire system, covering both soil and plant components, was identified as a subject for future studies. The results from this modelling work could be applied to suggest improvements in management of forest and agriculture ecosystems in order to reduce greenhouse gas emissions and to find adaptations to future climate conditions.

  • 18. Zhu, Weizhen
    et al.
    Westman, Gunnar
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Chalmers University of Technology, Sweden.
    Theliander, Hans
    KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center. Chalmers University of Technology, Sweden.
    The molecular properties and carbohydrate content of lignins precipitated from black liquor2015In: Holzforschung, ISSN 0018-3830, E-ISSN 1437-434X, Vol. 69, no 2, p. 143-152Article in journal (Refereed)
    Abstract [en]

    Precipitation and utilization of lignin from black liquor (BL) offers many promising advantages to modern kraft pulp mills. A novel process, known as "LignoBoost", has recently been introduced as a process for separating lignin from BL; it results in lignins with a low ash and high dry solid content. There is a lack of knowledge regarding the influences of process parameters on the behavior of lignin in the precipitation step. In this study, the yield of precipitated lignin and its average molecular weight (MWt) and carbohydrate content were the focus. Nuclear magnetic resonance (NMR) analysis showed that the lignin yield increased at lower pH and temperatures or when the ion strength of BL was elevated. High yield lignins contained more low MWt components and such lignins have more phenolic OH and methoxy groups. Xylan content of the lignins decreased with decreasing pH and increasing temperature, but glucomannan content was virtually unaffected by the conditions of precipitation.

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