Iskanje po repozitoriju

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Povzetek: An inventory of tree microhabitats was done in two unmanaged forests (Kobile and Ravna gora forest reserves) and one managed beech forest in SE Slovenia. The purpose of this study was to determine the influence of forest management, natural disturbances, and tree characteristics on microhabitat patterns. Forest structure and microhabitats were recorded in systematically placed plots (500 m2 in size) across each area. In total, we inventoried 849 trees on 54 plots and 1833 tree microhabitats. The results showed that forest management had no significant influence on the abundance of microhabitats per tree, but there were differences regarding microhabitat type between managed and unmanaged sites. There were substantially more microhabitats related to standing dead and live habitat trees in unmanaged forest (e.g. woodpecker cavities, insect galleries and bore holes, branch holes, dead branches and fruiting bodies of fungi), whereas in managed forests there were more tree microhabitats related to management (e.g. exposed heartwood, coarse bark, and epiphytic plants). The results also indicate that disturbance, tree diameter, vitality, and species influence the density, diversity, and occurrence of tree microhabitats.
Ključne besede: forest management, biodiversity, tree microhabitats, beech forests, old-growth, veteran tree, natural disturbance, dead wood
Objavljeno v DiRROS: 08.07.2019; Ogledov: 6921; Prenosov: 2933
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Povzetek: In repressive protection of cultural/historical woodwork, microwaves have many advantages over conventional heating. The research%s objective was to examine conditions for eradication of house longhorn beetle larvae (Hylotrupes bajulus) in spruce wood (Picea abies) using microwaves. Larvae, inserted at different depths of spruce blocks containing 12% and 42% of moisture, were exposed to microwaves. Two apparatuses were used; a 750W commercial microwave chamber and a newly developed horn antenna microwave device with the power of 800W and a frequency of 2.45GHz, for targeted radiation. We discovered that the inner part of wood warmed up quicker than the surface heated to 65°C. For successful suppression larvae in the wood need to be heated to 54.5°C, for 10 seconds. The necessary exposure time increases with increasing thickness of wood. The surface of wood containing more moisture is heated quicker, but increased moisture slows down the penetration of microwaves into the wood specimen. Therefore, larvae in wood of lower moisture (12%) died faster, both those 20mm under surface (1.5min) and those at 130 mm of depth (10.5min).
Ključne besede: wooden objects, repressive wood protection, microwaves, heating, wood moisture content, house longhorn beetle, Hylotrupes bajulus
Objavljeno v DiRROS: 25.10.2017; Ogledov: 4891; Prenosov: 2873
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Povzetek: The assumption that non-stationary sorption processes associated with wood canbe evaluated by analysis of their transient system response to the disturbance developed is undoubtedly correct. In general it is, in fact, possible to obtain by time analysis of the transient phenomenon - involving the transition into an arbitrary new state of equilibrium - all data required for a credible evaluation of the observed system. Evaluation of moisture movement during drying or moistening requires determination of external moisture transfer resistance from or to wood surfaces, as well as internal resistance. Time-dependent changes in the moisture content of the spruce (Picea abies Karst.) samples of different thickness were monitored gravimetrically, during which the frequency of weighing was in accord with thespeed of moistening. It was assumed that quasi-isothermal sorption processes associated with wood could be evaluated as first order systems. The characteristic time constant ? determines, wholly and uniformly, the time dependence of the sorption process for the relevant sorption range of wood tissue. The connection between the time constant and the thickness of the sample measured in the direction of the material flux is potential, with the power depending solely on the relationship between the external mass transfer convection and internal diffusion resistance. To determine the said resistances or coefficients of mass transfer convection and diffusivity, the experiment must be carried out on samples of varying thickness. It is only in this way that the external mass transfer convection and internal diffusion resistance can be correctly distinguished.
Ključne besede: wood sorption, first order system, time constant, mass transfer, diffusivity
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4402; Prenosov: 1886
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Povzetek: The paper provides an answer to the question as to in what way and with which organizational steps a wood industry company can be (more) adaptable and successful in a rapidly changing (global) business environment. The purpose ofthe article is to form an organizational model of a globally oriented wood industry company, considering the three required model properties: repeatability, efficiency and productiveness, as well as practical applicability. Research is limited to actual state in Slovenian wood industry practice with some specifics that should be considered by other implications of the research. Practical applicability of the model is based on these findings and is ensured by making guidelines on the basis of which companies can organise their businesses. These guidelines include suggested measures forindividual areas of business organization with the intention of increasing adaptability and innovativeness of business operation, improving competitive ability, and the ability of constant improvement. The paper provides a new organizational approach, specialized for making wood industry companies successful in the changing business environment.
Ključne besede: adaptability, globalisation, model, organization, wood industry company
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4220; Prenosov: 1915
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Povzetek: The paper treats the processes involved in wood densification and provides a summary of the state-of-the-art, as presented in the literature, with regard to densification as achieved by compression, accompanied by some form of hydrothermal treatment. The viscoelastic nature of wood is discussed, togetherwith its thermal softening and typical stress-strain relationships. The properties of densified wood products depend, apart from processing parameters, on various anatomical features such as density, the percentage of late wood material, ray volume and the loading direction. The problems associated with wood stabilization after densification are also treated. Relevant examples of wood densification from fundamental research, and the results of applied studies significant for everyday practice, are presented. Aspecial focus is given on the process of viscoelastic thermal compression (VTC) of wood.
Ključne besede: wood, densification, softening, transverse compression, viscoelasticity, glass transition temperature
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4147; Prenosov: 1895
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