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1
Ansari-Renani, Hamid Reza. "Follicle shutdown and wool staple strength : a thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy". Title page, contents and abstract only, 1996. http://web4.library.adelaide.edu.au/theses/09ANP/09anpa617.pdf.
Testo completo
2
Bray, Megan. "Regulation of wool and body growth : nutritional and molecular approaches". Title page, contents and abstract only, 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phb8267.pdf.
Testo completoAbstract (sommario):
"May 2002" Includes bibliographical references (leaves 148-164) Describes a series of novel experiments designed to enhance our understanding of nutrient utilisation for growth of wool and the whole body.
3
Nancarrow, Michelle Jane. "The role of polyamines in cellular and molecular events in the wool follicle". Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phn1756.pdf.
Testo completoAbstract (sommario):
Bibliography: leaves 255-280. In vivo and in vitro investigations of the hypothesis that polyamines and their synthetic enzymes have a role in regulation of cellular and molecular processes in the follicle. The activity of ornithine decarboxylase (ODC), the rate limiting polyamine biosynthetic enzyme, is demonstrated in wool follicle homogenates.
4
Moore, Anthony G., University of Western Sydney e School of Science. "The role of the extracellular matrix in wool follicle development". THESIS_XXXX_SS_Moore_A.xml, 1999. http://handle.uws.edu.au:8081/1959.7/389.
Testo completoAbstract (sommario):
Molecular and behavioural characterisation of ovine dermal papilla cells performed in this study indicate they synthesise a highly specialised extracellular matrix (ECM). This is conserved between different species and distinguishes papilla cells from dermal fibroblasts with which they have a common origin. The composition of the dermal papilla ECM is temporally and spatially regulated during wool follicle development. It was shown that the ECM associated with dermal papilla cells in foetal sheep skin becomes specialised in regard to chondroitin sulphate synthesis prior to the appearance of follicle primordia. Chrondroitin sulphate and fibronectin were present in the ECM of dermal papilla cells throughout follicle development and during fibre production. Cellular differentiation antigen 44 was present in the ECM od papilla cells exclusively during the formation of dermal papilla, while laminin was present in the dermal papilla ECM of fibre producing follicles only. Co-operation between chondroitin sulphate, fibronectin, and CD44 in regulating the agrregative and proliferative behaviour of papilla cells was demonstrated in culture. Finally, the inhibition of proteoglycan synthesis in newborn mouse skin was found to disrupt the growth of existing follicles and the generation of new ones. Together these findings demonstrate that chondroitin sulphate is intimately associated with the earliest interactions between epithelial and mesenchymal cells during the formation of follicle primordia. It is likely that the interactions specifically involve fibronectin and CD44, and possibly other ECM molecules which have he effect of regulating the behaviour of papilla cellsDoctor of Philosophy (PhD)
5
Barnes, Anne Louise. "The effect of lupinosis on reproduction and wool growth of the merino ewe". Thesis, Barnes, Anne Louise ORCID: 0000-0002-7227-230X (1993) The effect of lupinosis on reproduction and wool growth of the merino ewe. PhD thesis, Murdoch University, 1993. https://researchrepository.murdoch.edu.au/id/eprint/41883/.
Testo completoAbstract (sommario):
Lupinosis, a mycotoxicosis caused by phomopsins produced on lupin plants (Lupinus spp.) by Phomopsis leptostromiformis, is a disease of economic importance in W estem Australia. Preliminary studies and anecdotal reports indicated detrimental effects of lupinosis on reproduction and wool growth of ewes. The research described in this thesis was conducted to confirm experimentally the existence and magnitude of these effects on production, and to determine the stages of the reproductive cycle sensitive to phomopsin intoxication.
Mice were used to assess the effects of phomopsins on ovulation rate and on the early preimplantation embryo. Administration of phomopsins to female mice before ovulation reduced the number of mice mating and the number of embryos recovered. Culture of two-cell mouse embryos in medium containing phomopsins reduced the number developing to the blastocyst stage, with the embryos most sensitive to the effects of phomopsins before compaction and formation of the blastocoele.
Ovulation rate was depressed and wastage of ova was increased by the administration of phomopsins to ewes for 14 days before and 14 days after oestrus, resulting in 39 less lambs produced per 100 ewes than in the control groups.
The survival and growth of embryos/foetuses was reduced in ewes injected with phomopsins from approximately day 8 to 58 of pregnancy. Lamb marking rates were 10-20% less from phomopsin-treated ewes than from control ewes.
The wool production of ewes was significantly depressed by lupinosis. Length growth rate and mean fibre diameter were reduced after administration of phomopsins, and took up to 69 days to recover. The annual wool growth of the ewes was variable, and pregnancy and lactation reduced the quality and quantity of wool grown. There were reductions in clean fleece weight, yield, mean fibre diameter and staple strength, and changes in position of break attributable to administration of phomopsins.
Phomopsin intoxication significantly depressed the reproductive performances of ewes at all stages of the reproductive cycle examined, and reduced the quantity and quality of wool grown by the ewes.
6
Relf, Bronwyn Lee, University of Western Sydney e School of Science. "Isolation and characterisation of genes expressed in the wool follicle". THESIS_XXX_SS_Relf_B.xml, 1999. http://handle.uws.edu.au:8081/1959.7/529.
Testo completoAbstract (sommario):
Wool from Merino sheep is an important component of the Australian economy. However, little is known of the mechanisms within the wool follicle that regulate fibre production. The aim of the research described here was to identify and characterise some of the genes expressed in the follicle.A highly expressed gene has been identified from skin and sequenced. The information obtained on this gene suggests that it might be of use in future transgenic studies. Two cDNA libraries were constructed. The first was constructed using small amounts of total RNA from skin and PCR methodology, following a published method. A second cDNA library was then produced from adult mid-flank skin using a commercially available kit. A pool of 420 potential wool follicle specific transcripts were identified from this adult mid-flank skin cDNA library using a combination of differential and subtractive screening. Clone 1-25 was chosen as the focus for the remaining work described in this thesis. Expression of clone 1-25 was detected at all stages of wool follicle development and was localised to the wool follicle bulb, inner root sheath, outer root sheath, epidermis, but not the dermis or dermal papilla. The function of clone 1-25 is as yet unknown. However, from its expression in the wool follicle, and studies by other groups, it appears that it may play a role in inducing differentiationDoctor of Philosophy (PhD) (Biological Sciences)
7
Lee, William (Chun-To). "Harvesting Philosopher's Wool: A Study in the Growth, Structure and Optoelectrical Behaviour of Epitaxial ZnO". Thesis, University of Canterbury. Electrical and Computer Engineering, 2008. http://hdl.handle.net/10092/2507.
Testo completoAbstract (sommario):
This thesis is about the growth of ZnO thin films for optoelectronic applications. ZnO thin films were grown using plasma assisted molecular beam epitaxy and were studied using various conventional and novel characterisation techniques. The significance of different growth variables on growth efficiency was investigated. The growth rate of ZnO films was found to be linearly dependent on the Zn flux under O-rich growth conditions. Under Zn-rich conditions, the growth rate was dependent on both atomic and molecular oxygen flux. By characterising the oxygen plasma generated using different RF power and aperture plate designs and correlating the results with the growth rates observed, it was found that atomic oxygen was the dominant growth species under all conditions. Molecular oxygen also participated in the growth process, with its importance dependent on the aperture plate design. In addition, an increase in growth temperature was found to monotonically decrease the growth rate. A growth rate of 1.4 Å/s was achieved at a growth temperature of 650 ℃ by using an oxygen flow rate of 1.6 standard cubic centimetres utilising a plasma source with a 276 hole plate operating at 400 W, and a Zn flux 1.4✕10¹⁵ atoms/cm²⋅s. Characterisation of the MBE grown thin films revealed that the qualities of ZnO thin films were dependent on the growth conditions. Experimental evidence suggested that a maximum adatom diffusion rate can be achieved under Zn-rich conditions, giving samples with the best structural quality. O-rich conditions in general led to statistical roughening which resulted in rough and irregular film surfaces. Experimental results also suggested that by increasing the atomic oxygen content and decreasing the ion content of the plasma, the excitonic emission of the ZnO thin films can possibly be improved. It was also found that the conductivity of the films can possibly be reduced by increasing the plasma ion content. By investigating the evolution of the buffer layer surface during the early stages of growth, dislocation nucleation and surface roughening were found to be important strain relief mechanisms in MBE grown ZnO thin films that affected the crystal quality. The usage of LT-buffer layers was found to improve substrate wetting, and was shown to significantly reduce dislocation propagation. Further strain reduction was achieved via the application of a 1 nm MgO buffer layer, and a significant reduction of carrier concentration and improvement in optical quality was subsequently observed. A carrier concentration of <1✕10¹⁶ cm⁻³ and a near band emission full width half maximum of 2 meV was observed for the best sample. The study of electrical characteristics using the variable magnetic field Hall effect confirmed the existence of a degenerate carrier and a bulk carrier in most MBE grown ZnO thin films. The bulk carrier mobility was measured to be ~120 - 150 cm²/Vs for most as-grown samples, comparable to the best reported value. A typical bulk carrier concentration of ~1✕10¹⁶ - 1✕10¹⁸ cm⁻³ was observed for as-grown samples. Annealing was found to increase the mobility of the bulk carrier to ~120 - 225 cm²/Vs and decrease the bulk carrier concentration by two orders of magnitude. Using time resolved photoluminescence, it was found that the radiative recombination in MBE grown ZnO thin films was dominated by excitonic processes, and followed a T³⁄² trend with temperature. A maximum radiative lifetime of 10 ns was observed for as-grown samples. The non-radiative lifetime in ZnO thin films was dominated by the Shockley-Read-Hall recombination processes. The modelling of the temperature dependence of the non-radiative lifetime suggested that an electron trap at ~0.065 eV and a hole trap at ~0.1 eV may be present in these samples. The application of time resolved photoluminescence also allowed the direct observation of carrier freeze-out in these ZnO films at low temperature.
8
Moore, Anthony G. "The role of the extracellular matrix in wool follicle development". Thesis, View thesis, 1999. http://handle.uws.edu.au:8081/1959.7/389.
Testo completoAbstract (sommario):
Molecular and behavioural characterisation of ovine dermal papilla cells performed in this study indicate they synthesise a highly specialised extracellular matrix (ECM). This is conserved between different species and distinguishes papilla cells from dermal fibroblasts with which they have a common origin. The composition of the dermal papilla ECM is temporally and spatially regulated during wool follicle development. It was shown that the ECM associated with dermal papilla cells in foetal sheep skin becomes specialised in regard to chondroitin sulphate synthesis prior to the appearance of follicle primordia. Chrondroitin sulphate and fibronectin were present in the ECM of dermal papilla cells throughout follicle development and during fibre production. Cellular differentiation antigen 44 was present in the ECM od papilla cells exclusively during the formation of dermal papilla, while laminin was present in the dermal papilla ECM of fibre producing follicles only. Co-operation between chondroitin sulphate, fibronectin, and CD44 in regulating the agrregative and proliferative behaviour of papilla cells was demonstrated in culture. Finally, the inhibition of proteoglycan synthesis in newborn mouse skin was found to disrupt the growth of existing follicles and the generation of new ones. Together these findings demonstrate that chondroitin sulphate is intimately associated with the earliest interactions between epithelial and mesenchymal cells during the formation of follicle primordia. It is likely that the interactions specifically involve fibronectin and CD44, and possibly other ECM molecules which have he effect of regulating the behaviour of papilla cells
9
Scobie, David Roger. "Short term effects of stress hormones on cell division rate in wool follicles : a thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy". Title page, abstract and contents only, 1992. http://web4.library.adelaide.edu.au/theses/09PH/09phs421.pdf.
Testo completoAbstract (sommario):
Includes bibliographical references (leaves 183-207) A local intradermal technique using colchicine to estimate cell division rate in wool follicles is refined and used throughout the thesis. Statistical methods used to analyse data obtained with this method are described and discussed. The implications of the findings are of great significance to research into the influence of physiological changes on wool production, and suggest experiments should be conducted under controlled environmental conditions, with a minimum of stress imposed on the animals.
10
Vedegytė, Vaida. "Ūkio dydžio įtaka avių produktyvumui". Master's thesis, Lithuanian Academic Libraries Network (LABT), 2014. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2014~D_20140618_233058-29401.
Testo completoAbstract (sommario):
Temos aktualumas. Avininkystė Lietuvoje yra svarbi žemės ūkio sritis. Šio sektoriaus plėtrai šalyje yra palankios gamtinės sąlygos, susiformavusios gyvulių auginimo tradicijos, sukaupta patirtis. Gyvulininkystės sektorius yra daugiašakė ir įvairiapuse produkcija pasižyminti veikla, reikšminga Lietuvos gyventojams daugeliu ekonominių ir socialinių aspektų. Šis sektorius yra reikšmingas, aprūpinant Lietuvos vartotojus įvairiais maisto produktais bei svarbus Lietuvos eksporto šaltinis. Gyvūninės kilmės produktai yra svarbi subalansuotos mitybos dalis. Juose yra daug žmogaus organizmui reikalingų maisto medžiagų, vitaminų ir mineralų. Lietuvos Respublikos žemės ūkis atlieka svarbią ekonominę, socialinę, gamtosauginę ir etnokultūrinę funkciją, todėl laikomas prioritetine ūkio šaka. Jis pajėgus aprūpinti šalies gyventojus visais kokybiškais maisto produktais ir dalį jų eksportuoti. Nors ir lėtai, avininkystės sektorius plečiasi. Auga mėsos paklausa, atsigauna ir vilnos bei kailių perdirbėjai.
Vidutinis avių ūkis Lietuvoje, palyginti su vakarų šalimis, dar yra labai mažas. Dauguma augintojų laiko nedaug avių. O tų žmonių, kuriems avininkystė yra verslas, tėra vos kelios dešimtys. Tačiau mažieji augintojai pamažu didina savo bandas.
Įdiegus pažangias intensyvaus avių auginimo technologijas, auginant perspektyvias krypties avių veisles, galima tikėtis šio verslo sėkmės.
Darbo objektas: skirtingą skaičių avių turintys ūkiai.
Darbo tikslas: išanalizuoti ūkio dydžio įtaką avių... [toliau žr. visą tekstą]Relevance of the thesis. Shepherding has an important place in Lithuania‘s agriculture. There are suitable enviromental conditions, established cattle herding traditions and accumulated experience needed for this sector‘s further development in the country. The area of animal husbandry is activity known for its multisectoral and multifaceted production, many aspects of which has great economical and social significance for Lithuanians. This area is also very significant when providing Lithuanian consumer with eatables, furthermore it is very important branch of Lithuania‘s export. Products of animal origin takes big part in a balanced diet. They contain many components, vitamins and minerals which human body requires daily. Husbandry has important economical, social, enviromental and ethnocultural function in the Republic of Lithuania, thus it has priority in Lithuania‘s economy. It has capability not only to provide quality eatables for citizens, but also to export some. Sheepherding sector is growing, even though the growth rate is not very pronounced. The demand for meat grows; wool and fur processors are recovering. In Lithuania average sheep farm is very small when comparing with farms in other western countries. Most livestock owners don‘t have a lot of sheep. Furthermore, there are only few who make business out of it. However the small farmers seem to be increasing their flocks. If this business were introduced to advanced sheep herding technologies as well as... [to full text]
11
Verikios, George. "Understanding the world wool market : trade, productivity and grower incomes". University of Western Australia. School of Economics and Commerce, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0064.
Testo completoAbstract (sommario):
[Truncated abstract] The core objective of this thesis is summarised by its title: “Understanding the World Wool Market: Trade, Productivity and Grower Incomes”. Thus, we wish to aid understanding of the economic mechanisms by which the world wool market operates. In doing so, we analyse two issues trade and productivity and their effect on, inter alia, grower incomes. To achieve the objective, we develop a novel analytical framework, or model. The model combines two long and rich modelling traditions: the partial-equilibrium commodity-specific approach and the computable-general-equilibrium approach. The result is a model that represents the world wool market in detail, tracking the production of greasy wool through five off-farm production stages ending in the production of wool garments. Capturing the multistage nature of the wool production system is a key pillar in this part of the model . . . The estimated welfare gain for China is 0.1% of real income; this is a significant welfare gain. For three losing regions Italy, Germany and Japan the results are robust and we can be highly confident that these regions are the largest losers from the complete removal of 2005 wool tariffs. In both wool tariff liberalisation scenarios, regions whose exports are skewed towards wool textiles and garments gain the most as it is these wool products that have the highest initial tariff rates. The overall finding of this work is that a sophisticated analytical framework is necessary for analysing productivity and trade issues in the world wool market. Only a model of this kind can appropriately handle the degree of complexity of interactions between members (domestic and foreign) of the multistage wool production system. Further, including the nonwool economy in the analytical framework allows us to capture the indirect effects of changes in the world wool market and also the effects on the nonwool economy itself.
12
Shepard, Robert Michal. "Tree Rings In Velvet Mesquite (Prosopis velutina Woot.): An Exploratory Study of Wood Anatomy, Crossdating, Climate-Growth Relationships, Life History, and Above-Ground Biomass". Thesis, The University of Arizona, 2015. http://hdl.handle.net/10150/605122.
Testo completoAbstract (sommario):
Velvet mesquite (Prosopis velutina Woot.) is a common tree in semi-arid, southwestern U.S. savanna ecosystems. While there are studies that examine some of the physiological and ecological aspects of this tree (response to fire, net ecosystem exchange, encroachment into grasslands, yearly growth through dendrometer bands, among others), the wood anatomical features of a growth ring, suitability for dendrochronological research, life history, and above-ground biomass through time are knowledge gaps that can be filled. The purpose of this study was to examine these gaps in order to better understand the role of velvet mesquite in these ecosystems. Wood anatomical analysis showed that velvet mesquite has a semi-ring porous structure and termination of the growth ring is indicated by a small band of parenchyma. Visual crossdating of velvet mesquite was successful but a complex growth habit, with both eccentric and lobate growth, combined with ecological pressures hampered statistical validation of the chronology. Seasonal climate-growth analysis of dated rings showed a strong positive correlation to previous year September and October precipitation and a strong positive partial correlation to previous year September and August mean temperature. Life history through growth curve analysis showed no age related growth trend (either s-shaped or log normal) indicating the maximum age of velvet mesquite stems sampled (130 years old) can become much older with many releases and few suppressions. Above-ground biomass of these trees are low compared to higher elevation forest biomass, but similar to other savanna ecosystems of the southwest. The use of velvet mesquite in dendrochronological research would greatly benefit from a complete analysis of wood anatomy, and addition of more samples from various locations to verify dates and begin building more reliable chronologies for this species across its range. These additions would allow for a greater understanding of stand and tree level responses through suppressions and releases, and understand the biomass accumulated above-ground through time.
13
Desjarlais, Justin J. "An Examination of Crack Growth in Wood-FRP Bonds". Fogler Library, University of Maine, 2007. http://www.library.umaine.edu/theses/pdf/DesjarlaisJJ2007.pdf.
Testo completo
14
Gelbrich, Jana. "Bacterial wood degradation : a study of chemical changes in wood and growth conditions of bacteria /". Göttingen : Sierke, 2009. http://d-nb.info/996395377/04.
Testo completo
15
Di, Lucca Carlos Mario. "Juvenile - mature wood transition in second-growth coastal Douglas-fir". Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26244.
Testo completoAbstract (sommario):
The transition from old-growth to second-growth British Columbia coastal Douglas-fir has resulted in reduction of log size and increased proportion of juvenile (core or crown-formed) wood. Determination of the zone of transition from juvenile to mature wood is critical to the definition of wood quality and timber value.
Thirteen unpruned, two pruned second-growth, and two unpruned plantation-grown coastal Douglas-fir trees were sampled to analyze the hypothesis that the transition in relative density from juvenile to mature wood occurs at the base of the live crown. X-ray densftometric techniques were utilized to determine yearly pith to bark relative density data of five cross-sectional discs from each tree. Segmented linear regression techniques were utilized to estimate the juvenile - mature wood transition age from the data.
The average number of growth increments from the pith at which juvenile - mature wood transition occurred on sections sampled at breast height, 20 percent and 40 percent of total height was 22.18.
When the hypothesis was tested on unpruned trees, before and after harvest, the juvenile - mature wood transition occurred below the base of the live crown. When the hypothesis was tested on pruned trees, the transition occurred at the base of the live crown, which represented the upper limit of pruning height.
This information may provide a greater insight into juvenile - mature wood transition. It will likely assist in the determination of wood quality and economic value of forest products manufactured from second-growth coastal Douglas-fir.Forestry, Faculty of
Graduate
16
Saumure, Raymond A. "Growth, mutilation, and age structure of two populations of wood turtles, Clemmys insculpta, in southern Québec". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq29779.pdf.
Testo completo
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Love, Jonathan William Tylden. "New insights into ethylene signalling and wood development". Umeå : Depatment of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 2009. http://epsilon.slu.se/200988.pdf.
Testo completo
18
Janssens, Marc. "Fundamental thermophysical charecteristics of wood and their role in enclosure fire growth". Online version, 1991. http://dds.crl.edu/CRLdelivery.asp?tid=13140.
Testo completo
19
Perold, Maurits. "The effect of sodium lauryl sulphate on blue stain, mould growth and surface properties of SA pine". Thesis, Stellenbosch : University of Stellenbosch, 2006. http://hdl.handle.net/10019.1/2003.
Testo completoAbstract (sommario):
Thesis (MScFor (Forest and Wood Science))--University of Stellenbosch, 2006.Producing high quality end products, rather than focusing on volume production, is slowly but surely becoming the main driving force in the wood processing industry of South Africa. Drying defects such as surface checks and discolouration by yellow stain and kiln brown stain are major factors in softwood timber downgrades when selecting furniture grade timber. Previous efforts to control these defects have focused on schedule adaptation, but as the industry is still mainly concerned with volume production, and because of the varying lumber price, longer schedules to control these drying defects have not yet been that attractive for the larger sawmills. In ongoing research in this laboratory, a dip treatment of freshly sawn softwood boards in an aqueous solution containing a surfactant called sodium lauryl sulphate (SLS) was used to try to influence the mechanism involved in the development of these stains. Further, complementary research is reported in this study. Firstly, the possibility of using SLS solutions to control surface mould development and bluestain was investigated. Results showed that SLS did control the development of blue stain and mould growth in open-stacked boards for up to three weeks, using concentrations as low as 0.1%, and up to two weeks in closed-stacked timber when using concentrations of 0.2%. Secondly, it was investigated whether SLS treatment would have a detrimental effect on downstream product quality; in particular, kiln dried boards and glued components for furniture manufacturing. Since SLS influenced fluid water flow during kiln drying, the treatment could have exacerbated the occurrence of surface checking due to altered moisture distribution profiles. Results of this investigation showed that the SLS treatment did not result in increased surface checking. Thirdly, as furniture quality timber treated with SLS would be glued, (and also finished with surface coatings), it was further considered important to determine if SLS treatment influenced adhesion properties of wood surfaces. Based on shear test results, it was established that SLS did not influence the adhesion properties of wood when glued with two most commonly used glues in the furniture industry i.e. polyvinyl acetate (PVAc) and urea formaldehyde (UF).
20
Aebischer, Danille P. "Basic density and shrinkage of oak in relation to wood structure and cambial age". Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285465.
Testo completo
21
Bienz, Penelope. "Genetic variation of growth, form and wood properties of European beech (Fagus sylvatica L.)". Thesis, Bangor University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285466.
Testo completo
22
Lindner, Gerard Eckard. "Development of potential height growth and diameter increment models for the parameterisation of an individual tree growth model for Pinus elliottii plantations in South Africa". Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86621.
Testo completoAbstract (sommario):
Thesis (MScFor)--Stellenbosch University, 2014.ENGLISH ABSTRACT: Individual tree models, as opposed to stand models, have the potential to greatly improve sensitivity of forest growth models to changing conditions such as silvicultural amendments, irregular stand structures, etc. It was the purpose of this study to extend two sub-components of a European individual tree growth model to introduce individual tree growth modelling concepts in South Africa using Pinus elliottii as a study species. Two main objectives were established: Modelling the potential height of stands across different site qualities and modelling diameter increment using a potential modifier approach with a combination of competition indices that change in importance according to the edaphic conditions of the site. Potential height modelling used three steps in order to achieve this objective. The first was to compare site index models based on different model fitting techniques, namely nonlinear least squares, generalised nonlinear least squares and nonlinear mixed effects models. The nonlinear mixed effects model proved to be superior in terms of achieving the principles of regression assumptions and model fit for the data range observed. The second step was to fit potential height using nonlinear quantile regression on observed spacing trial height measurements. This proved to be a robust technique able to capture potentials according to the defined Chapman-Richards model structure. The final step was to use the predicted site index as a site classification variable in order to predict potential height. While some small deviation occurred, potential height seems to be well correlated to site index and validation on selected sites suggested that site index can be used to model potential height until a more sophisticated site classification model is used for future improvement of the model. Diameter increment modelling followed six major steps in order to apply the full parameterisation methodology of an age-independent diameter increment model dependent on tree diameter and competition. Diameter increment potentials were fit using site index as a predictor of the potential height curves. Multiple competition indices were tested on two sites to obtain a combination of two indices, which can capture overtopping and local crowding effects. Principle components analysis and variance inflation factors calculation were applied to test for collinearity between indices. Suitable combinations were tested resulting in a combination of the KKL and Local Basal Area competition indices. Changing importance of the two indices were observed on the two sites tested indicating a shift in the mode of competition according to a water gradient. These were combined in a deterministic potential modifier model, which mimicked competitive stages over age; however the validation showed a skewed distribution, which was not sensitive to stand density gradients. A stochastic model was constructed to model variance from observed residual plots using linear quantile regression to determine bounds for a truncated normal distribution which generates random deviates for a predicted increment. The stochastic element significantly improved the performance and sensitivity of the model, however the model was still not sensitive enough at very high and very low spacing densities. All in all two key models for an adaptation of an individual tree growth simulator to South African conditions were successfully demonstrated. The two main objectives were achieved; however some indicated improvements could be made, especially for the competition indices where the sensitivity of competition to changing resource limitation according to site and temporal scales needs to be further investigated. Furthermore, the full set of models for simulating individual tree growth still needs to be applied. Overall, as a methodological approach, the study outlined problems and future improvements, introduced new concepts and can serve as a guideline for future parameterisation of an individual tree growth model.
AFRIKAANSE OPSOMMING: In vergelyking met vakgroeimodelle, het individuele-boomgroeimodelle die potensiaal om die sensitiwiteit van plantasiegroeimodelle vir veranderende omstandighede soos aanpassings in boskultuur, onreëlmatige vakstrukture, ensovoorts, drasties te verbeter. Die doel van hierdie studie was om twee subkomponente van ‘n Europese individuele-boomgroeimodel uit te brei om sodoende individuele-boomgroei modelleringskonsepte in Suid-Afrika bekend te stel. Pinus elliottii is gebruik as studiespesie. Twee hoofdoelstellings is bepaal. Eerstens, die modellering van hoogtegroei potensiaal van opstande oor verskeie vlakke van groeiplek kwaliteit. Tweedens, die modellering van deursnee-aanwas deur gebruik te maak van ‘n potensiaal matigingsbenadering “potential modifier approach“ met ‘n kombinasie van kompetisie-indekse waarvan die belangrikheid verander volgens die edafiese toestande van die groeiplek. Die hoogtepotensiaalmodellering bestaan uit drie stappe. Tydens die eerste stap word groeiplek bonniteitsmodelle vergelyk op grond van verskillende modelpassingstegnieke, naamlik nie-lineêre minimum kwadrate, algemene nie-lineêre minimum kwadrate en nie-lineêre gemengde effek modelle. Laasgenoemde het die beste gevaar in terme van die beginsels van regressiemodelle asook die mate waarin die model die waargeneemde data pas. Tweedens is hoogtegroei potensiaal gemodelleer deur nie-lineêre kwantielregressie op waargeneemde hoogtes van spasiëringseksperimente toe te pas. Die metode is robuust en in staat om potensiale volgens die gedefinieerde Chapman Richards modelstruktuur vas te vang. Laastens is die voorspelde bonniteits indeks as ‘n groeiplek klassifasie veranderlike gebruik om sodoende die hoogtegroei potensiaal te voorspel. Alhoewel klein afwykings voorgekom het, blyk hoogtegroei potensiaal goed gekorreleer te wees met bonniteits indeks. Uit validasie op geselekteerde groieplekke blyk dit dat bonniteits indeks gebruik kan word om hoogtegroei potensiaal te modelleer totdat ‘n meer gesofistikeerde groeiplek klassifikasiemodel beskikbaar is wat die model verder sal kan vebeter. Die volledige parametriseringsmetodiek van ‘n ouderdoms-onafhanklike deursnee-aanwas model wat afhanklik is van boomdeursnee en kompetisie bestaan uit ses hoof prosesse. Nie-lineêre kwantielregressie is gebruik om deursnee-aanwaspotensiale te pas vir verskeie groeiplekke. Dié is gekombineer met ‘n bonniteits indeks om ‘n nuwe model te vorm waarmee hoogtegroeipotensiaal kurwes voorpel kon word. Daar is met veelvuldige kompetisie-indekse op twee groeiplekke geëksperimenteer om ‘n kombinasie van slegs twee indekse te vind wat die effekte van oorskaduwing en plaaslike verdringing kan vasvang, te vind. Hoof komponent analise “Principle components analysis” en variansie inflasie faktore berekening “variance inflation factors calculation” is gebruik om vir kollineariteit tussen die indekse te toets. Gepaste indekskombinasies is getoets. ‘n Kombinasie van die KKL en plaaslike basale oppervlakte “Local Basal Area” kompetisie-indekse het die beste resultate gelewer. Die twee indekse is as volg geselekteer. Veranderings in die belangrikheid van elk van die indekse is waargeneem op die twee toetspersele. Dit dui op ‘n verskuiwing in die modus van kompetisie afhangend van ‘n watergradiënt. Die twee indekse is gekombineer in ‘n deterministiese potensiaal matigings model wat die kompeterende stadiums oor ouderdom naboots. Validasie het egter ‘n skewe verdeling wat nie sensitief vir opstandsdigtheidsgradiënte is nie, gewys. ‘n Stogastiese model is ontwikkel om variansie in die residuele grafieke te modelleer. Lineêre kwantielregressie is gebruik om grense vir ‘n afgestompte normaalverdeling wat ewekansige afwykings vir ‘n voorspelde aanwas te bepaal. Die stogastiese element het die prestasie van die deterministiese model merkbaar verbeter. Selfs met die stogastiese element, is die model egter steeds nie sensitief genoeg vir baie hoë en baie lae opstandsdigthede nie. Ter opsomming is twee modelle vir ‘n aanpassing van ‘n individuele-boomgroeisimuleerder vir Suid- Afrikaanse toestande suksesvol gedemonstreer. Die twee hoofdoelstellings is bereik. Daar is egter steeds ‘n paar aangeduide verbeterings wat aangebring kan word. Die sensitiwiteit van die kompetisie-indekse op hulpbronbeperkings wat verander op grond van die ruimtelike en temporale skale moet veral verder bestudeer word. Verder moet die volle stel modelle wat benodig word om individuele-boomgroei te modelleer nog toegepas word. As ‘n metodologiese benadering, het die studie probleme uitgewys en toekomstige verbeterings aangedui, nuwe konsepte bekendgestel en kan dus dien as ‘n riglyn vir toekomstige parametrisering van individuele-boomgroeimodelle.
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Hart, James Foster. "Wood quality and growth characterization across intra- and inter-specific aspen hybrid clones". Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/43940.
Testo completoAbstract (sommario):
Trembling aspen (Populus tremuloides Michx) is Canada’s most abundant poplar species; it is native, found nationwide, and is an ecologically and economically important hardwood species. As the demand for raw material continues to rapidly increase, there is an incentive to improve tree quality and growth rates through breeding, particularly in fast-growing species suitable for the Canadian landscape. Hybridization is considered one of the best options to accelerate tree productivity and improve wood quality. Two aspen species showing particular promise for hybridization with trembling aspen are European aspen (P. tremula) and Chinese aspen (P. davidiana) because their native climates are similar to that of western Canada.
In 2003, poplar clones were planted in Athabasca, Alberta from the following species crosses: open pollinated (OP) P. tremuloides (NN), OP P. davidiana (CC), P. tremula × P. tremula (EE), P. tremula × P. tremuloides (EN), and P. tremuloides × P. davidiana (CN). In, November 2010, growth measurements and core samples were taken from the clones. Productivity was quantified through analysis of stem volume. Wood quality attributes were quantified via an assessment of fibre length, fibre width, coarseness, wood density, microfibril angle, total cell wall carbohydrate and lignin content, and lignin composition. Comparisons of the mean values for each attribute were made between crosses using generalized linear model least squares means tests.
The NN cross had lower volume growth than the CC and EE crosses. The EN and CN crosses had greater volume than the NN cross. The NN cross had shorter fibre length, but greater syringyl-guaiacyl ratio (S:G) relative to the CC cross. It also had lower density and S:G compared to the EE cross. The EN cross had longer, wider fibres and a greater carbohydrate concentration compared to the NN cross. The CN cross had greater fibre length and lignin concentration, but lower S:G compared to the NN cross. The results indicated that the inter-specific crosses were more desirable wood sources than the pure P. tremuloides cross. Specifically, the P. tremula x P. tremuloides cross showed the best potential to improve future generations of aspen on the Canadian landscape.
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Myronycheva, Olena. "Characterization of Mould Fungi Growth on Scots Pine Sapwood Surfaces". Licentiate thesis, Luleå tekniska universitet, Träteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-73793.
Testo completo
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Tarelkin, Yegor. "Radial Patterns of Wood Features Reveal Site-Specific Tree Growth Dynamics in the Congo Basin". Doctoral thesis, Universite Libre de Bruxelles, 2018. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/273503.
Testo completoAbstract (sommario):
Les forêts tropicales couvrent environ 7% de la surface terrestre et stockent environ 25% du carbone terrestre. Elles jouent un rôle important dans les cycles biogéochimiques et fournissent divers services écosystémiques. Cependant, elles sont menacées par l’activité anthropique et le changement climatique. Il y a un besoin pressant de mieux comprendre les effets du changement climatique sur la croissance des arbres afin de mieux estimer son impact sur la composition des forêts et leur capacité à fournir leurs services.Jusqu’à récemment, les réponses des forêts aux changements climatiques ont été étudiées via des expérimentations en laboratoire ou en rapportant les changements à l’échelle des populations. Cependant, notre connaissance de l’influence des changements climatiques graduels sur la croissance ligneuse reste limitée. L’étude des cernes de croissance a permis la reconstruction du climat passé et l’étude de son influence sur la dynamique de croissance des arbres dans les régions tempérées. Son application dans un contexte tropical reste cependant limitée par l’absence d’une saisonnalité marquée des facteurs limitants la croissance. La distinction des cernes de croissance chez les espèces tropicales est très variable et des études supplémentaires sont nécessaires pour correctement les identifier et les utiliser dans les études dendrochronologiques.Dans cette thèse, nous explorons le potentiel d’utilisation de l’anatomie et de la densité du bois dans l’étude des réponses des arbres aux changements climatiques. Nous évaluons la variabilité anatomique du coeur à l’écorce et la manière dont le climat l’influence. Le travail est subdivisé en trois chapitres, chacun répondant à une question spécifique. Plus particulièrement, nous avons étudié (i) la variabilité de la distinction et de l’anatomie des cernes de croissance dans les tropiques, (ii) la relation entre l’anatomie et la densité du bois ainsi que son potentiel d’utilisation comme un proxy pour estimer variabilité anatomique et (iii) l’influence de la saisonnalité des précipitations sur la rythmicité de la croissance des arbres via leurs profils de densité du bois.En premier lieu, nous avons décrit les traits anatomiques impliqués dans la démarcation des limites des cernes de croissance et évalué leur contribution à la distinction des cernes. Nous avons constaté une grande variabilité intra et interspécifique et mis en avant le fait que les définitions actuelles de la distinction des cernes ne décrivent pas suffisamment la complexité de l’anatomie du bois dans les tropiques. Au lieu de se concentrer sur la détection des cernes, nous proposons d’étudier la variabilité des traits anatomiques depuis le coeur jusqu’à l’écorce dans le but de reconstruire la croissance ligneuse passée et estimer les effets du climat.Ensuite nous avons automatisé les mesures de proportions de parenchyme et de vaisseaux ainsi que le ratio lumen/diamètre total des fibres dans le plan transversal de la moelle à l’écorce. Nous les avons étudiés en parallèle avec des profils à haute résolution de la densité du bois de huit espèces. Nous avons montré que la densité du bois est influencée par l’anatomie des fibres et que la relation entre l’anatomie et la densité du bois dépend de l’espèce. Notre étude suggère qu’il est possible d’utiliser les profils de la densité du bois comme un proxy pour étudier la variabilité de l’anatomie du bois.Finalement, nous avons utilisé les profils de densité afin de comparer les patterns de croissance ligneuse de 13 espèces le long d’un gradient de précipitation. Nous avons utilisé l’analyse en ondelettes afin de dériver trois descripteurs de croissance :la régularité, la périodicité et l’amplitude des variations. Nous avons montré que la saisonnalité de précipitations influence la régularité de la croissance ligneuse et que les variations sont plus abruptes dans les sites avec une saisonnalité plus marquée. Nous avons aussi montré que les espèces décidues et sempervirentes ne réagissent pas de la même façon aux variations des patterns de précipitations.Nous pensons que ces résultats vont favoriser l’émergence d’outils prometteurs pour étudier la croissance des arbres et sa relation avec le climat. L’automatisation des mesures des traits anatomiques et l’utilisation des profils de densité du bois comme proxies vont aider à diminuer le temps de traitement des échantillons et augmenter leur nombre ainsi que la puissance des traitements statistiques. Par la description très fine des signaux cycliques qu’elle permet, l’analyse en ondelettes ouvre de nouvelles perspectives pour la description des profils de variation de la densité du bois et donc l’interprétation de la dynamique de croissance des arbres.Doctorat en Sciences agronomiques et ingénierie biologique
info:eu-repo/semantics/nonPublished
26
Schrader, Jarmo. "Developmental biology of wood formation : finding regulatory factors through functional genomics /". Umeå : Dept. of Forest Genetics and Plant Physiology, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/s292.pdf.
Testo completo
27
Ngubeni, Ntombizodwa. "Bark re-growth and wood decay in response to bark stripping for medicinal use". Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97040.
Testo completoAbstract (sommario):
Thesis (MSc)--Stellenbosch University, 2015.ENGLISH ABSTRACT: Plants have been used for centuries to treat a wide range of ailments in the history of all civilizations. However, a growing interest in medicinal plants requires appropriate management to prevent over-exploitation of target species. The challenge for scientists is to find equilibrium between resource exploitation and the maintenance of viable populations of target species. Sustainability of use requires an understanding of the ecological, economic and socio-cultural aspects of resource use and the interaction between these factors. This research focuses on the ecological and socio-cultural aspects required to underwrite species-specific sustainable harvesting systems for bark used for traditional medicine. The social survey conducted in the form of structured interviews with traditional healers reported 69 plant species used for medicinal purposes in the southern Cape. The results suggested that resource users are aware of the increase in demand for medicinal plants in general, attributing this to an increasing recognition of traditional medicines and increasing prevalence of diseases. Ocotea bullata (Endangered), Curtisia dentata (Nearly Threatened) and Rapanea melanophloeos (Declining), as well as Siphonochilis aethiopicus (Critically Endangered), Elaeodendron transvaalense (Near Threatened) and Cassipourea flananganii (Endangered) that do not occur in the area naturally, were identified as species in high demand for their medicinal bark properties. Given the high demand and concerns about over-exploitation, a need for further ecological research to develop sustainable harvest systems was identified. Two species, O. bullata and C. dentata, were selected from an earlier study on the response of several species to bark stripping, that was confined to a study period of three years after treatment. With this current study tree response to bark stripping and harvesting impact were assessed over a period of ten years to reveal the intra and inter-specific difference of wound occlusion (wound closure through bark-regrowth) and the anatomical decay consequences of bark stripping. This is, to the knowledge of the author, the first study to evaluate the structural-tree pathogen interaction following bark stripping on medicinal tree species in Africa. The results revealed species-specific differences in terms of both wound closure and efficiency in decay containment. O. bullata had a significantly better wound occlusion rate and a lower extent of decay. The relationship between tree diameter growth and the rate of wound occlusion allowed for the formulation of a preliminary model that will assist forest managers in developing bark harvest systems. Smaller trees showed poor bark regrowth and a significantly higher mortality, which suggest that a minimum tree size for harvesting needs to be stipulated in the harvest prescriptions. In contrast, C. dentata showed a much higher volume of decay within the stem, poor bark regrowth and a significantly higher mortality of bark-stripped trees. In conclusion, the harvesting of bark for C. dentata through bark stripping is not viable, and alternatives should be explored. O. bullata has a much greater potential for strip harvesting, both in terms of bark regrowth and the containment of wood decay following wounding.
AFRIKAANSE OPSOMMING: Beskawings gebruik al vir eeue plante vir die behandeling van ‘n verskeidenheid van kwale. Die toenemende belangstelling in medisinale plante vereis egter oordeelkundige bestuur om die oorbenutting van teikenspesies te voorkom. Die uitdaging vir wetenskaplikes is om 'n balans tussen die benutting van hulpbronne en die handhawing van lewensvatbare populasies van teikenspesies te bewerkstellig. Standhoudende benutting vereis insig in die ekologiese, ekonomiese en sosio-kulturele aspekte van hulpbronbenutting, en die interaksie tussen hierdie faktore. Hierdie navorsing fokus op die ekologiese en sosio-kulturele aspekte wat nodig is om spesie-spesifieke, standhoudende oesstelsels vir bas wat vir tradisionele medisyne gebruik word, te onderskryf. Die sosiale opname, in die vorm van gestruktureerde onderhoude met tradisionele genesers, dui op 'n totaal van 69 plantspesies wat vir medisinale doeleindes in die Tuinroete gebruik word. Gebruikers is oor die algemeen bewus van die toenemende vraag na medisinale plante, en skryf dit toe aan groter erkenning van tradisionele medisyne en ‘n toename in siektes. Ocotea bullata (Bedreig), Curtisia dentata (Byna bedreig) en Rapanea melanophloeos (Afnemend), asook drie spesies wat nie natuurlik in die gebied voorkom nie, Siphonochilis aethiopicus (Kritiek bedreig), Elaeodendron transvaalense (Byna bedreig) en Cassipourea flananganii (Bedreig), is geïdentifiseer as spesies in groot aanvraag weens hul medisinale eienskappe. Die hoë aanvraag en kommer oor oorbenutting het gelei tot die behoefte vir verdere ekologiese navorsing vir die onwikkeling van oesstelsels vir die spesies. Twee spesies, O. bullata en C. dentata, is geselekteer van ‘n vroeëre studie oor die reaksie van verskeie spesies op basstroping wat beperk was tot ‘n studieperiode van drie jaar na behandeling. Die huidige studie was daarop gemik om die reaksie en impak oor ‘n periode van 10 jaar na behandeling te bepaal, en die intra- en inter-verskille van wond sluiting (wond sluiting deur die hergroei van die bas) en anatomiese verrotting na basstroping te beskryf. Dit is, tot die kennis van die outeur, die eerste studie om die struktuur-boompatogeen interaksie na basstroping op medisinale boomsoorte in Afrika te beskryf. Die resultate dui op spesie-spesifieke verskille in beide wond en die beperking van houtverrotting. O. bullata het ‘n betekenisvolle hoër tempo van wondsluiting en effektiwiteit in die beperking van houtverrotting. Die korrelasie tussen boomdeursnee-aanwas en die tempo van wondsluiting het die ontwikkeling van ‘n voorlopige model om bosbestuurders te help met die ontwikkeling van oesvoorskrifte, moontlik gemaak. Kleiner bome toon swak bas-hergroei en betekenisvolle hoër mortaliteit, wat aandui dat ‘n minimum grootte vir oesbome neergelê behoort te word in oesvoorskrifte. In teenstelling toon C. dentata ‘n baie groter mate van houtverrotting, het swak bas-hergroei, en ‘n betekenisvolle hoër mortaliteit van gestroopte bome. Ter afsluiting, die oes van C. dentata deur basstroping is nie lewensvatbaar nie en alternatiewe behoort ondersoek te word. O. bullata het ‘n groter potensiaal vir standhoudende basstroping, beide in terme van bas-hergroei en die beperking van houtverrotting na oes.
28
Adams, Steven Henry. "The impact of changing climate on tree growth and wood quality of Sitka spruce". Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/5121/.
Testo completoAbstract (sommario):
The recent trend in climate has shown that UK temperatures are increasing, summers are getting drier and winters are getting wetter. It is thought that this trend is set to continue for the foreseeable future and that this will have an impact on the growth and quality of timber in the UK. Sitka spruce (Picea sitchensis (Bong.) Carr) is one of the most widely planted and important commercial tree species in the UK but our knowledge of tree growth and wood properties is based on tree growth in the climate of the past 40 – 80 years. The rotation time for Sitka spruce is approximately 40 years so trees planted now will mature in the 2050s, when the climate could be different from today leading to impacts on the quality and quantity of the wood being produced. This project aims to predict the effect that changes in climate will have on Sitka spruce, by looking not only at growth but also at different properties of the wood and their susceptibility to any change in climate. This information could then be used to help make decisions as to whether Sitka spruce is the best tree to be planting now, at any specific site in the UK, to obtain the best quality wood in the future. The effect of seasonally changing weather on growth was measured at two sites by the use of LVDT point dendrometers to record changes in the radius of the tree stems. The data were compared to meteorological data collected from the site and from local weather stations, to determine how weather affected the growth of the trees. Data collection from the site at Griffin Forest near Aberfeldy was initiated in 2008 as part of a long term project at that site. Measurements taken during 2008 and 2009 were used as part of a previous PhD study and continued as part of the present study from 2010. The second site was newly established at Harwood Forest in Northumberland, northern England. At both sites the onset of growth at the beginning of the season was found to correspond to temperature >5°C. Deficit of soil moisture was found to decrease the growth rate during the peak growth period. Radial density, radial growth and the radial profile of longitudinal stiffness were investigated by analysing increment core samples taken from sites covering the full latitudinal range that Sitka spruce grows in Great Britain, with the aim of quantifying the effect of site factors such as latitude, longitude, initial spacing and elevation. The cores were measured from density and ring width using an ITRAX x-ray densitometer and analysed using Windendro software. Stiffness was investigated using acoustic velocity measurements taken directly on the increment cores using an ultrasonic scanner, modified to measure cores. A wide range of published radial growth models and a smaller number of radial density models were explored to see which were able to describe the data and compared to simpler linear segmented models. The sample population was found to be highly variable and the ability of the models to predict ring width or density from ring number alone was limited. Improved prediction of density was possible when ring width was included along with ring number as a predictor. The linear segmented models were found to be able to predict growth and density from ring number alone and this provides a useful and powerful tool. In practice ring width may not always be available and so there is a need for models which can predict density from ring number alone. Ring width was found to be negatively correlated with density, although the nature of the relationship was different between juvenile and mature wood. Most of the variation in both density and growth was between trees at the same site. Initial spacing was found to be the only significant effect on growth and then only by having a positive effect on the growth rate of the juvenile wood, which had a knock on effect on the size of the trees at the end of the juvenile phase. Both spacing and latitude were found to have significant effects on the mean density of the juvenile wood with spacing having a negative effect and latitude a positive effect. In the mature wood, cambial age was found to be the only significant effect on radial density.
29
Enefalk, Åsa. "Fine stream wood : effects on drift and brown trout (Salmo trutta) growth and behaviour". Doctoral thesis, Karlstads universitet, Institutionen för miljö- och livsvetenskaper, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-44537.
Testo completoAbstract (sommario):
Stream ecosystems and their riparian zones have previously been regarded as two different ecosystems, linked through numerous reciprocal subsidies. Today, ecologists agree that the stream and the riparian zone should be regarded as one system, the stream-riparian ecosystem, which is characterised largely by the subsidies between land and water. The terrestrial subsidies to the stream affect stream-living biota in several ways, some of which are well-known while others less so. The input of wood to the stream from the riparian zone is believed to play an important role in the population dynamics of stream-living fish. In this doctoral thesis, I explore effects of fine stream wood (FW, <10 cm diameter) on wild stream-living young-of-the-year brown trout (Salmo trutta) by reporting and discussing results from laboratory, semi-natural and field experiments. My results show that the local density of drifting prey is higher in the presence of FW than in its absence, and also that young-of-the-year brown trout decrease their diurnal foraging time and prey capture success when FW is added to their habitat. I show that trout decrease their swimming activity in the presence of FW, aggregate in FW bundles, and have lower growth rates than trout without FW access. Also, the degree of sheltering in FW bundles was higher during day than at night in a study performed at low water temperatures; moreover, the presence of an ectothermic nocturnal predator (burbot, Lota lota) did not affect the degree of sheltering in FW bundles by trout. Taken together, my results indicate that young-of-the-year brown trout with access to FW bundles spend considerable amounts of time sheltering in the FW, and by doing so they miss the opportunity for higher growth and foraging rates outside of the shelter. The most probable explanation for this behaviour is that growth is traded off against survival, i.e., the predation risk is higher outside of the shelter.Stream ecosystems and their riparian zones have previously been regarded as two different ecosystems, linked through numerous reciprocal subsidies. Today, ecologists agree that the stream and the riparian zone should be regarded as one system, the stream-riparian ecosystem, which is characterised largely by the subsidies between land and water. In this doctoral thesis, I explore one such subsidy – the input of fine stream wood (FW) to streams. Wild stream-living young-of-the-year brown trout (Salmo trutta) was chosen as study species. My results show that the local density of drifting prey is higher in the presence of FW than in its absence, and that young-of-the-year brown trout decrease their diurnal foraging time and prey capture success when FW is added to their habitat. I show that trout decrease their activity in the presence of FW, aggregate in FW bundles, and have lower growth rates than trout without FW access. Taken together, my results indicate that young-of-the-year brown trout spend considerable amounts of time in FW bundles, and by doing so they miss the opportunity for higher growth and foraging rates outside of the shelter. The most probable explanation for this behaviour is that growth is traded off against survival.
Artikel 3 publicerades i avhandlingen som manuskript med samma titel.
30
Mwitwa, Jacob Pacific. "Growth and physiological parameters related to shoot dieback in Pterocarpus angolensis DC seedlings". Thesis, Stellenbosch : Stellenbosch University, 2004. http://hdl.handle.net/10019.1/20431.
Testo completoAbstract (sommario):
Thesis (PhD)--Stellenbosch University, 2004.ENGLISH ABSTRACT:Six experiments, five in the glasshouse and one in the field near Nelspruit, were carried out to ascertain the effect of factors related to shoot die-back, and of water treatments on the growth and physiological responses of Pterocarpus angolensis seedlings. The study was undertaken to broaden the knowledge and understanding of the phenomenon of shoot die-back in order to enhance our ability to regenerate the species. The following experiments were carried out (a) Assessment of biomass accumulation; anatomical characteristics of the shoot apical meristem; foliar, stem and root concentration of micro- and macronutrients associated with each phenophase, (b) Effect of seedling age and seed source on the occurrence of shoot die-back under field conditions; (c) Water treatment effects on ChI. afluorescence traits of£'. angolensis seedlings obtained by assessing the fluorescence yield of photosynthetic samples subjected to dark- and light-adaptation; (d) Genetic variation in shoot die-back and other traits of sixteen halfsib families of £.. angolensis from Malawi, Namibia and Zambia grown over two die-back seasons. Experiments conducted revealed the following 1. Patterns of growth observed in phenophases are indicators of seasonal changes in annual biomass allocation to the shoot and root. Phenophases such as leaf loss and stem senescence, whether shoot die-back occurs completely or not, are directly related to the decline in above-ground biomass and declined rate of increase in root biomass respectively. Leaf flush, expansion and maturation result in increased biomass accumulation whilst shoot die-back has a minimal downregulatory effect on root biomass accumulation compared to the shoot. Shoot dieback is not sudden, therefore from the first day of germination, seedlings synchronise growth and development with the occurrence of shoot die-back. 2. Phenophasic concentration of foliar N, Ca and Mg, stem Fe and Cu and root concentrations of P, K, Mg, Fe and B are associated with shoot die-back. Patterns of mineral nutrient concentration obtained in foliage and roots but to a lesser extent in the stem, may be related to nutrient remobilisation during shoot dieback. Higher relative mineral nutrient changes during leaf yellowing and shoot die-back may be an indication of the removal of significant volumes of mobile nutrients from senescing tissues. 3. The volume of the shoot apex of E. angolensis remains constant during different phenophases which points to seasonal uniformity in the size of the apical dome. Changes in phenology associated with declined growth, or shoot die-back, is revealed through declined cell number in the tunica which is a reflection of declined mitotic activity. 4. Shoot die-back occurs in all seedlings from nursery stock planted under field conditions and all seedlings of up to two years experience complete shoot dieback. Shoot die-back takes place irrespective of seed source or the age of nursery stock that is planted. Survival after the first shoot die-back is normally low. Water treatments had no significant effect on the function of PSIJ reaction centres of P. angolensis nursery seedlings. In the case of both dark- and light-adapted leaves, water treatment had no significant effect on the measured Chi. a fluorescence parameters or the calculated parameters (specific activities, phenomenological fluxes, structure-function and performance indexes and drivingforces). 5. Water treatments affect the shape of ChI. a fluorescence transients of lightadapted compared to that of dark-adapted photosynthetic samples of E. angolensis. No significant water treatment effect was obtained for extracted and technical Chi. afluorescence parameters, specific fluxes, quantum efficiencies and phenomenological fluxes. Quantum yield, relative electron transport and quantum yield limitation, de-excitation rate constants, structure-function, performance indexes and driving forces were also not significantly different across water treatments.6. Genetic variation was observed to exist among 16 halfsib families from Malawi, Namibia and Zambia. High heritabilities were obtained for shoot die-back and other traits, indicating that shoot die-back is genetically controlled. The trait is passed from parents to offspring and it is highly probable that it occurs, throughout its natural range, in all seedlings. Since shoot die-back is genetically programmed, it remains crucial to the ability of a seedling to regenerate in the following rainy season
AFRIKAANSE OPSOMMING:Ses eksperimente, vyf in die glashuis en een in die veld naby Nelspruit, is uitgevoer om die effek van faktore wat verwant is aan die terugsterwing van lote op saailinge, sowel as om die effek van waterstres op die groei en fisiologiese responsies van Pterocarpus angolensis saailinge, te ondersoek. Die studie is ondemeem om die kennis en begrip aangaande die regenerasie-dinamika van die spesies te verbeter. Die volgende eksperimente is uitgevoer: (a) Evaluering van die effek van jisiologiese veranderings op biomassa; blaar-, stam- en wortelkonsentrasies van spoor- en makro-voedingselemente, en anatomiese eienskappe van die apikale meristeem van die lote. (b) Effek van saailingouderdom en saadbron op die voorkoms van lootterugsterwing onder veldtoestande. (c) Waterbehandelingseffekte op Chi. ajluorisensie eienskappe van ,e. angolensis saailinge wat verkry is deur die jluorisensie te evalueer van fotosintesemonsters wat aan donker- en lig-adaptasies onderwerp is. (d) Genetiese variasie in loot-terugsterwing en ander groei-eienskappe van 16 halfsib families van ,e. angolensis vanaf Malawi, Namibia en Zambia wat gekweek is oor twee terugsterj-seisoene. Die eksperimente het die volgende aan die lig gebring: 1. Groeipatrone waargeneem gedurende die fenofases is indikatore van seisoenale veranderings in jaarlikse biomassa allokasies aan die loot en die wortels. Fenofases soos blaarverlies en lootafsterwing, ongeag of loot-terugsterwing volledig is of nie, is direk verwant aan die afname in bogrondse biomassa en afnemende tempo van toename in wortelbiomassa respektiewelik. Bottende blare, vergroting en rypwording van blare lei tot toenemende biomassa akkumulasie terwyl loot-terugsterwing 'n minimale afskalende effek op akkumulasie van wortelbiomassa het in vergelyking met die van die loot. Loot-terugsterwing is nie skielik, met ander woorde vanaf die eerste dag van ontkieming sinchroniseer saailinge groei en ontwikkeling met die voorkoms van loot-terugsterwing. 2. Fenofase konsentrasies van en veranderings in blaar N en Ca en loot Fe, asook veranderings in waargenome wortel N, K, Ca, Mn, Cu, Zn en B is sterk geassosieer met loot-terugsterwing. Patrone van minerale voedingselementkonsentrasies wat in blare en wortels, en in minder mate in die loot, verkry is, mag direk verwant wees aan hermobilisering van voedingselemente gedurende loot-terugsterwing. Hoe relatiewe minerale voedingselementveranderings gedurende die vergeling van blare en lootterugsterwing mag 'n indikasie wees van die verwydering van betekenisvoUe hoeveelhede mobiele nutriente vanaf sterwende weefsel. 3. Die volume van die groeipunt van r. angolensis bly konstant gedurende verskillende fenofases wat dui op seisoenale uniformiteit in die grootte van die apikale koepel. Veranderings in fenologie ge-assosieer met afnemende groei, of loot-terugsterwing, word gerejlekteer deur afnemende selgetaUe in die tunika wat dui op afnemende mitotiese aktiwiteit. 4. VoUedige loot-terugsterwing kom voor in aUe saailinge vanaf die kwekery wat in die veld geplant word tot op die ouderdom van twee iaar. Dit kom voor angeag van saadbron of ouderdom van saailinge ten tye van planting. Oorlewing na aanvanklike loot-terugsterwing is normaalweg laag. 5. Water behandelings het geen beduidende effek op die funksie van PSII reaksiesentra van r. angolensis kewekery-saailinge gehad. Vir beide donker- en lig-aangepaste blare is geen beduidende waterbehandelingseffek verkry vir waargenome ChI. a jluoresensie parameters of die berekende parameters (spes ifieke aktiwiteite, jenomenologiese jlukse, struktuur-funksie-indekse, "perjormance-indekse oj" driving forces" ). 6. Genetiese variasie tussen 16 halfsibfamilies vanaf Malawi, Namibie en Zambie is verkry vir loot-terugsterwing en ander groei-eienskappe. Dit dui op genetiese beheer van terugsterwing en dat die eienskap oorerjbaar is, en waarskynlik in die hele natuurlike verspreidingsgebied van die spesies in aUe saailinge voorkom. Aangesien loot-terugsterwing gene ties geprogrammeer is, is dit noodsaaklik vir die vermoe van die plant om in die volgende reenseisoen te regenereer.
31
Panyushkina, Irina, Nurjan Mukhamadiev, Ann Lynch, Nursagim Ashikbaev, Alexis Arizpe, Christopher O’Connor, Danyar Abjanbaev, Gulnaz Mengdіbayeva e Abay Sagitov. "Wild Apple Growth and Climate Change in Southeast Kazakhstan". MDPI AG, 2017. http://hdl.handle.net/10150/626428.
Testo completoAbstract (sommario):
Wild populations of Malus sieversii [Ldb.] M. Roem are valued genetic and watershed resources in Inner Eurasia. These populations are located in a region that has experienced rapid and on-going climatic change over the past several decades. We assess relationships between climate variables and wild apple radial growth with dendroclimatological techniques to understand the potential of a changing climate to influence apple radial growth. Ring-width chronologies spanning 48 to 129 years were developed from 12 plots in the Trans-Ili Alatau and Jungar Alatau ranges of Tian Shan Mountains, southeastern Kazakhstan. Cluster analysis of the plot-level chronologies suggests different temporal patterns of growth variability over the last century in the two mountain ranges studied. Changes in the periodicity of annual ring-width variability occurred ca. 1970 at both mountain ranges, with decadal-scale variability supplanted by quasi-biennial variation. Seascorr correlation analysis of primary and secondary weather variables identified negative growth associations with spring precipitation and positive associations with cooler fall-winter temperatures, but the relative importance of these relationships varied spatially and temporally, with a shift in the relative importance of spring precipitation ca. 1970 at Trans-Ili Alatau. Altered apple tree radial growth patterns correspond to altered climatology in the Lake Balkhash Basin driven by unprecedented intensified Arctic Oscillations after the late 1970s.
32
Bertschi, Allan. "The growth response of Assiniboine poplar and Harrington barley to wood ash add[i]tions". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0014/MQ60102.pdf.
Testo completo
33
Mörling, Tommy. "Effects of nitrogen fertilisation and thinning on growth and clear wood properties in Scots pine /". Umeå : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5618-5.pdf.
Testo completo
34
John, L. S. "The genetics of growth and wood density in Sitka spruce estimated using mixed analysis techniques". Thesis, University of Edinburgh, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.653022.
Testo completoAbstract (sommario):
This study estimated the variance and covariance components for growth (height and diameter) and wood density within a randomly selected population of Sitka spruce (Picea sitchensis, (Bong.) Carr.) trees known to derive from a single origin. Open-pollinated progeny from the original ortets had previously been planted in a replicated trial and assessed periodically for height, diameter and wood density (indirectly using the Pilodyn) from 1 to 19-years old; 23-year diameter was collected during the study period. Increment cores were also collected from a representative sub-sample of trees identified using a genotypic selection ellipse. Ring-by-ring wood density analysis was carried out using X-ray densitometry. Variance and covariance components for all height, diameter and wood density assessments were estimated using Restricted Maximum Likelihood (REML). Family heritability for growth traits varied little over a 23-year period (1-year height = 0.61; 23-year diameter = 0.57). Individual tree heritability was more variable, reaching a peak at 7-year height (0.38) and then falling with age to 17-year diameter (0.12). Optimum family and individual tree selection ages for growth were found to be 5-year and 9-year height (breeding goal of 23-year diameter), and 3-year and 7-year height (breeding goal of 40-year diameter) from planting respectively; the latter were estimated with the use of a Lambeth regression equation. Wood density was found to be more heritable than growth at equivalent ages, although estimates decreased with increasing age (individual tree heritability of the outer 4 rings at 9 and 22-years old of 0.85 and 0.34 respectively). Precision and accuracy of estimated variance components and heritabilities were unacceptable unless the traits used to calibrate the selection ellipse were included as covariates. Genetic correlations between all juvenile ring-groupings and the selection goal (outer 4-rings at 22-years from planting) were near unity. The optimum family and individual tree selection age for wood density was found to be the outer 4-rings at 9-years from planting.
35
Lee, Stephen J. "Genetics of growth and wood density in Sitka spruce estimated using mixed model analysis techniques". Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/15201.
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36
Hellgren, Jenny Maria. "Ethylene and auxin in the control of wood formation /". Umeå : Dept. of Forest Genetics and Plant Physiology, Swedish Univ. of Agricultural Sciences, 2003. http://epsilon.slu.se/s268.pdf.
Testo completo
37
Faias, Sónia Maria Marques Pacheco. "Using neighbourhood vegetation information on cork oak growth and yield modelling". Doctoral thesis, ISA, 2020. http://hdl.handle.net/10400.5/21227.
Testo completoAbstract (sommario):
Doutoramento em Engenharia Florestal e dos Recursos Naturais / Instituto Superior de Agronomia. Universidade de LisboaThe present work contributes to information regarding the competition on the tree and cork growth, by evaluating the neighbourhood vegetation and local tree density impact. From a specific trial established to compare the effect on the tree of different understory management options, along a cork rotation cycle of 9 years, cork samples were taken at the beginning and at the end of the cycle on trees within lagged cycles. Former results revealed no effect on cork annual growth and wood increment for the trees growing under lupine periodical seeding. When analysing the interaction between cork ring age and understory operations, different thresholds were linked to the shrubs’ maintenance and the lupine seeding. Later, this trial was monitored to compare the shrubs’ maintenance versus removal with or without NP soil fertilization. On the set of selected trees, diameter increment was monthly monitored, as well as, leaves nutrients seasonal variability, and differences were found in the treatment with soil fertilization. Data gathered from a Portuguese network of permanent plots across the cork oak species distribution area was used to model tree variables including the site characteristics. Focusing the analysis on young plantations and never debarked stands, the relationship of the diameter relative growth rate over tree dimension showed signs of inter-tree competition before the first cork extraction in older high-density stands. A crown width model developed with a fixed-effect approach was applied using national forest inventory datasets. Subsequently, a decrease in crown cover was identified in Portugal over ten years. Using the Portuguese dataset with a Spanish dataset, a diameter increment model was developed applying two methodologies: age-independent difference equations and potential growth times a modifier. This Iberian dataset allowed testing the inclusion of stand variability associated with climate and soil site conditions
O presente trabalho contribui com informação sobre competição, avaliando o impacto da vegetação vizinha e da sua densidade, no crescimento da árvore e da cortiça. Para comparar o efeito na árvore da gestão do subcoberto, durante um ciclo de descortiçamento (9 anos), foram recolhidas amostras de cortiça, no início e final do ciclo, em árvores sujeitas a ciclos desfasados num ensaio específico. Primeiramente não foi encontrado efeito no crescimento anual da cortiça e no incremento em madeira entre árvores sujeitas a diferente gestão. Mas analisando a interação entre a idade do anel de cortiça e as operações realizadas, foram associados diferentes limites à manutenção dos arbustos e à sementeira de tremocilha. Este ensaio foi continuado para comparar a manutenção com a remoção dos arbustos, com ou sem fertilização NP do solo, monitorizando um conjunto de árvores selecionadas. Analisando o registo do incremento em diâmetro mensal e da variabilidade sazonal dos nutrientes das folhas, foram encontradas diferenças no tratamento com fertilização do solo. Os dados recolhidos numa rede de parcelas permanentes localizadas na área de distribuição de sobreiro em Portugal, foram utilizados para analisar e modelar variáveis arbóreas. Abordando apenas dados de plantações jovens e povoamentos não descortiçados, a relação entre a taxa de crescimento relativo em diâmetro com a dimensão da árvore mostrou sinais de competição nas árvores não descortiçadas, em povoamentos adultos de elevada densidade. Foi desenvolvido um modelo predição do diâmetro da copa que aplicado aos dados do inventário florestal nacional, indicaram uma diminuição da percentagem de coberto, num horizonte de dez anos. Juntando a este conjunto, dados de parcelas espanholas, foi desenvolvido um modelo para o incremento em diâmetro, com a inclusão da variabilidade local associada ao clima e ao solo, abordando duas metodologias: equações às diferenças independentes da idade e potencial de crescimento multiplicando um modificador
N/A
38
Ono, Kazuko. "Evaluation of the Nutritional Requirement and Wood Decay Properties of a Termite Mushroom, Termitomyces eurrhizus". 京都大学 (Kyoto University), 2017. http://hdl.handle.net/2433/225646.
Testo completo
39
Forsberg, Daniel. "Warp, in particular twist, of sawn wood of Norway spruce (Picea abies) /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5853-6.pdf.
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40
Lindeberg, Johan. "X-ray based tree ring analyses /". Umeå : Dept. of Silviculture, Swedish Univ. of Agricultural Sciences, 2004. http://epsilon.slu.se/s299.pdf.
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41
Ackerman, Simon Alexander. "The effect of irregular stand structures on growth, wood quality and its mitigation in operational harvest planning of Pinus patula stands". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/85874.
Testo completoAbstract (sommario):
Thesis (MScFor)--Stellenbosch University, 2013.ENGLISH ABSTRACT: The practice of combining row and selective thinning in commercial pine plantation silviculture carries the risk of unwanted irregularities in tree distribution within the stand. This situation is aggravated with poor tree selection during marking. The potential consequences of poor tree selection are gaps created along row removals, which are necessary for access to harvesting operations. These gaps lead to spatially asymmetric growing space among adjacent trees. The effect of irregular stand structures on tree morphology and growth are investigated in this study, and are based on two stands of Pinus patula, (Schiede ex Schlechtendal et Cham.) in Langeni plantation, South Africa. This study focuses on two aspects. Firstly, a comparison between trees grown in all-sided and one-sided spatial competition situations in order to assess if there are differences in growth and selected quality parameters. Secondly, the mitigation of irregular structures using a simulation based study on changing the planting geometry in order to investigate the effect on harvesting in terms of stand impact, simulated harvesting productivity and harvesting system costs. Results showed that trees grown in an irregular competitive status have significantly larger crown diameters, crown lengths, longer and thicker branches, disproportionately one sided crown growth and a reduction in space-use efficiency. Simulations indicated that changing planting geometry from the current 2.7m x 2.7m to 2.3m x 3.1m and 2.4m x 3m would result in up to a 20% reduction of machine trail length and fewer rows being removed for machine access. The simulation of harvesting thinnings showed that various planting geometry alternatives increased harvesting productivity by 10% to 20% and reduced overall thinning harvesting cost by up to 11%. This study successfully investigated the factors that potentially negatively affect saw timber quality and volume production of the stand at final felling. It also illustrated the applicability of simulation methods for testing harvesting scenarios and developing economically viable alternatives.
AFRIKAANSE OPSOMMING: Die praktiese kombinasie van ryuitdunning en seleksiedunning in kommersiële denneplantasies dra die risiko van ongewensde onreelmatighede in die verspreiding van bome in die opstand. Hierdie situasie word vererger deur swak boomseleksie tydens die merk van dunnings. Die potensiële gevolge van swak boomseleksie is die ontstaan van onreelmatige gapings tussen boomkrone, veral langs die rydunnings, wat nodig is vir toegang tydens die ontginning van die hout. Dit lei daartoe dat die bome langs die dunningsrye asimmetriese ruimtes het om in te groei. Die effek van onreelmatige opstandstrukture op boom-morfologie en -groei word in hierdie studie ondersoek in twee Pinus patula, (Schiede ex Schlechtendal et Cham.) vakke te Langeni plantasie, Suid-afrika. In die studie word daar gefokus op twee aspekte. Eerstens word bome wat onder toestande van eweredige ruimetlike kompetisie groei vergelyk met die wat onder toestande van eensydige ruimtelike kompetisie groei om sodoende vas te stel of daar verskille is in die groeipatroon aan die hand van geselekteerde gehalteparameters. Tweedens word daar gefokus op die verbetering van onreelmatige opstandstrukture deur gebruik te maak van ’n simulasie-gebasseerde studie om veranderinge in die aanplantingsgeometrie te ondersoek met die doel om die effek van plantspasieering op ontginningsimpakte, gesimuleerde ontginningsproduktiwiteit en -sisteem koste te bepaal. Die resultate het getoon dat bome wat onder toestande van onreelmatige spasieering en kompetisie groei krone met groter deursnee asook langer lengtes ontwikkel, langer en dikker takke het, disproporsionele, eensydige kroongroei en ’n reduksie in ruimte-gebruik toon, wat die groeidoeltreffendheid nadelig beinvloed. Simulasies met betrekking tot die verandering in boomaanplantgeometrie vanaf die huidige 2.7m x 2.7m na 2.3m x 3.1m en 2.4m x 3m het gedui op ’n reduksie van 20% in die masjienpadafstand en na minder rye wat uitgehaal moes word om die toegang van masjiene moontlik te maak. Die simulasie van die ontginning van dunnings het getoon dat verskillende aanplantgeometriealternatiewe die ontginningsproduktiwiteit met 10% tot 20% verbeter het, en die algehele dunningsoeskoste met tot 11% verminder het. In hierdie studie is die faktore, wat die gehalte van saaghoutkwaliteit en volume tydens die finale oes van die plantasie potensieel negatief mag beinvloed, suksesvol ondersoek. Dit illustreer ook die geskiktheid van simulasietoepassings vir die toets van ontginningsalternatiewe en die ontwikkelling van meer ekonomies voordelige praktyke .
42
Reinmann, Andrew B. "Effects of Harvesting on Nutrient Cycling, Red Spruce Radial Growth, and Dendrochemistry 30 Years after Harvesting in Northern Maine, USA". Fogler Library, University of Maine, 2006. http://www.library.umaine.edu/theses/pdf/ReinmannAB2006.pdf.
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43
Pape, Rolf. "Effects of thinning on wood properties of Norway spruce on highly productive sites /". Uppsala : Swedish Univ. of Agricultural Sciences (Sveriges lantbruksuniv.), 1999. http://epsilon.slu.se/avh/1999/91-576-5622-3.pdf.
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44
Larsson, Pontus, e Fredrik Möller. "How to Achieve Profitable Growht for SME:s : A Study of the Swedish Wood Industry". Thesis, Linköpings universitet, Institutionen för ekonomisk och industriell utveckling, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166062.
Testo completoAbstract (sommario):
Profit and growth are the pillars of all business enterprises. The Swedish wood industry has historically been characterized by pressured margins and marginal growth, and in particular SME's have had many challenges in regard to long-term success. It is thus interesting and essential to understand more specifically how SMEs in the Swedish wood industry can navigate the challenges in the industry, and thus generate profitability and growth. Against this background, this study aimed to describe and analyze what strategies and associated key activities SMEs in the wood industry can work with to generate profitable growth. In order to gain a deeper understanding of the concepts of growth and profitability, a literature study was first conducted to establish influencing factors for these. With a clear basis for strategy and market influence as main drivers, a theoretical basis for strategic positioning and growth strategies were then identified, strengthened by research showing how industry factors affect the context and how SMEs specifically are affected. For strategic positioning, cost leadership, differentiation and focus strategies were examined. Furthermore, the growth strategies were divided into organic and non-organic. Market penetration, market development, product development and diversification were investigated for organic growth strategies. The non-organic strategies dealt with two different types of acquisitions: consolidating acquisitions and diversifying acquisitions. These types of acquisitions were then supplemented with further studies on resource and synergy perspectives in acquisitions. Based on these theoretical areas, an analytical model was created with associated research questions to enable answers to the purpose of the study. In order to nuance the theoretical perspective, qualitative interviews were conducted with company executives with backgrounds in different parts of the wood industry. A variable-based cross-sectional analysis of collected empirical data was conducted to compare the different interview subjects' perspectives on the established theoretical concepts, in order to put these growth strategies in context with SME's in the Swedish wood industry. The study showed that the theoretical frameworks were not fully applicable in the wood industry, which resulted in an updated framework that considers the specific conditions of the wood industry. The study shows that it is essential that SMEs work with clear niches as a foundation and as a target for strategic positioning. This position is usually achieved through customer engagement, value adding and market knowledge. The study shows that it is essential, especially from a long-term perspective, that SMEs have clear organic growth strategies. In addition, companies can supplement the organic operations with non-organic strategies, which aim to strengthen the strategic position and create better conditions for future organic growth. Organic growth strategies fall into two categories for the wood industry: sales-oriented and value adding-oriented, where value adding strategies are the leading strategies for successful SMEs today. Sales-oriented strategies place requirements in the categories of raw material supply, market segmentation, and the correct use of sales channels. Value adding strategies place demands on customer engagement, ensuring raw material quality and establishing refined products in new markets. Non-organic strategies, both consolidating and diversifying, are well-used and potentially successful for SMEs in the wood industry. Furthermore, it is clear that diversification and consolidation through acquisitions are not necessarily separate, but should instead be encouraged to be carried out in symbiosis. Acquisition strategies have specific activities linked to the establishment of acquisition strategy, target search, analysis of identified targets and ensuring key personnel.
45
Bando, Takashi. "Development for Farsite Fire Growth Simulation for fhe Hardwood Forest in South Eastern Ohio". Ohio University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1243901740.
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46
Yildirim, Kubilay. "Inheritance Of Wood Specific Gravity And Its Genetic Correlation With Growth Traits In Young Pinus Brutia Progenies". Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12609264/index.pdf.
Testo completoAbstract (sommario):
In long term, to discover the genes responsible for wood production, genetic control of wood specific gravity (WSG) in Pinus brutia Ten. (Turkish red pine) open pollinated Ceyhan progeny trial, which was established with the seeds collected from 168 clones originated from six clonal Turkish red pine seed orchards was studied. Wood samples were taken by destructive sampling during the rouging of this trial at the age of seven. Specifically(1) to examine the magnitude of family differences and its components for wood specific gravity (WSG) and growth traits (height, diameter and stem volume)
(2) to determine WSG inheritance and its genetic correlation with growth traits
and (3) to estimate breeding values of 168 families for the WSG and to predict genetic gain if selection is based on phenotypic, rouged and genotypic seed orchard by reselecting the best parents with respect to WSG. Differences among the 168 families for mean WSG was large (ranged from 0.35 to 0.44), as indicated by high individual (0.42+0.07) and family mean (0.55+0.03) heritabilities. Family differences and high heritabilities were also observed for all growth traits. Genetic correlations between WSG and growth traits were statistically insignificant (near zero), while low and insignificant negative phenotypic correlations among the same traits were observed. Realized genetic gain for single trait selection at age seven was insignificant (0.37 %) for WSG and 8.4 % for stem volume in phenotypic seed orchards. Average genetic gain in breeding zone after roguing, by leaving the best 20 clones in each seed orchard, reached 1.7 % for WSG and 16.1 % for stem volume. Genetic gain (relative to controls) at the age of seven obtained from the first generation genotypic seed orchards consisting the best 30 clones was estimated 5.2 % for WSG and 35 % for stem volume. Multi-trait selection was also proposed in this study for the same traits. Selection of best 10 families for the highest WSG and stem volume breeding values produce 5.6 % genetic gain for WSG and 27.7 % genetic gain for stem volume. For the future, the 168 families with known phenotypic and genotypic values regarding to WSG will be screened for the genes responsible for wood production.
47
Peszlen, Ilona. "Influence of site, clone, age, and growth rate on wood properties of three Populus X Euramericana clones". Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40146.
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48
Dunham, Roger Allen. "The influence of growth rate on the wood and stem properties of silver birch (Betula pendula Roth.)". Thesis, University of Aberdeen, 1996. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU079039.
Testo completoAbstract (sommario):
The consequences of using low stocking density as a management tool to increase individual tree growth rate of silver birch, and thereby shorten rotation length, were investigated. Low stocking density was found to result in greater diameter and basal area increment but may also result in trees with larger branches, a shorter length of clear bole, and possibly a reduced total height. The rapid growth had little effect on wood properties. Grain angle was unaffected, longitudinal shrinkage increased slightly, but conversely transverse and volumetric shrinkage declined. Density was not affected directly, but the increased proportion of juvenile wood in rapidly grown trees was estimated to result in a 5% reduction in density compared with conventionally managed trees. While fast growth resulted in only a slight decline in the strength and stiffness of small clear wood specimens, a reduction of about 30% in these properties was found for large beams. This reduction in strength was correlated with high knot and grain angle values for the timber. Modulus of rupture was found to be correlated with modulus of elasticity for both small clear specimens and for beams, suggesting the possibility of machine stress grading of birch. Hardness was generally unaffected by growth rate. All the timber tested was suitable for typical domestic flooring. The use of low stocking density to reduce rotation lengths therefore appears to be technically feasible, allowing the production of 30 cm trees in as little as 40 years, although an economic appraisal of the practice was not performed. If, however, knot free timber is required then pruning will be necessary to remove the large branches that otherwise would persist on widely spaced trees. Following the removal of branches, rapid occlusion of branch scars can be expected and the production of a large volume of clear timber.
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Jonsson, Christian. "Detection of annual rings in wood". Thesis, Linköping University, Department of Science and Technology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-15804.
Testo completoAbstract (sommario):
This report describes an annual line detection algorithm for the WoodEye quality control system. The goal with the algorithm is to find the positions of annual lines on the four surfaces of a board. The purpose is to use this result to find the inner annual ring structure of the board. The work was done using image processing techniques to analyze images collected with WoodEye. The report gives the reader an insight in the requirements of quality control systems in the woodworking industry and the benefits of automated quality control versus manual inspection. The appearance and formation of annual lines are explained on a detailed level to provide insight on how the problem should be approached. A comparison between annual rings and fingerprints are made to see if ideas from this area of pattern recognition can be adapted to annual line detection. This comparison together with a study of existing methods led to the implementation of a fingerprint enhancement method. This method became a central part of the annual line detection algorithm. The annual line detection algorithm consists of two main steps; enhancing the edges of the annual rings, and tracking along the edges to form lines. Different solutions for components of the algorithm were tested to compare performance. The final algorithm was tested with different input images to find if the annual line detection algorithm works best with images from a grayscale or an RGB camera.
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Jackson, Brian Eugene. "Chemical, Physical, and Biological Factors Influencing Nutrient Availability and Plant Growth in a Pine Tree Substrate". Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29491.
Testo completoAbstract (sommario):
Pine tree substrate (PTS) produced from freshly harvested loblolly pine (Pinus taeda L.) trees has potential for replacing or reducing the use of aged pine bark (PB) and peat moss as container substrates for horticulture crop production. The objective of this work was to determine the factors influencing nutrient availability in PTS compared to PB or peat substrates. Chapter two reports data on the response of japanese holly and azalea to fertilizer rate when grown in PTS and PB. This study demonstrated that an additional 2.4 kgâ m-3 of Osmocote Plus (15N-3.9P-10K) controlled release fertilizer is required for both species when grown in PTS compared to PB. Data are reported in chapter three on the effects of fertilizer rate, substrate particle size, and peat amendment on growth and floral quality, and on post-production time-to-wilting of poinsettias. Data from this work show that PTS requires an additional 100 mgâ L-1 N to grow poinsettias comparable to plants grown in peat unless the particle size of PTS was decreased or 25% peat was added, in which case no additional fertilizer was needed. Results also indicated that PTS shrinkage was similar to that of peat, and that post-production time-to-wilting in PTS plants was similar as plants grown in peat. Data in chapter four compares nitrogen (N) immobilization rates, substrate carbon dioxide (CO2) efflux levels, and nutrient leaching in peat, PB, and PTS over time. Data from these studies indicated that more N immobilization occurs in PTS than in PB or peat and that the substrate CO2 efflux levels (estimate of microbial activity) corresponds to N immobilization in all substrates. Nutrient availability, changes in physical and chemical properties, substrate shrinkage, and microbial activity in PTS compared to PB during long-term nursery production are reported in chapter five. Results showed that substrate nutrient levels remain lower in PTS and that pH levels of PTS decrease considerably over two growing seasons compared to PB. Results also indicate that PTS does decompose over time in containers, but substrate shrinkage of PTS is similar to that of PL and PB during crop production.Ph. D.