首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到10条相似文献,搜索用时 78 毫秒
1.
Forest owner cooperations (FOC) are bundling wood supply from small-scale forests and some also offer additional services, such as wood harvesting or planting. FOCs are growing throughout Europe in terms of the managed timber volume. The increasing timber demand of forest-based industries as well as the new, rapidly growing demand for energy plants could lead to an under-supply in the following years in Europe. Because of high harvesting arrears in small-scale forests, FOCs are seen as an opportunity to overcome this foreseen timber shortage. The paper maps out timber mobilisation strategies using the SWOT (Strengths, Weaknesses, Opportunities and Threats) approach.
Peter RauchEmail:
  相似文献   

2.
The practical application of the orientation distribution function (ODF), being the three-dimensional representation of the texture function, was presented. The investigations of the crystallograpically organized regions of wood were performed. The experimental methods of the X-ray diffraction were discussed in detail. The incomplete pole figures were measured in order to calculate the ODF. The dominant components of the crystallographical texture of wood were determined from the obtained ODF. The obtained texture function was also used to derive the complete pole figures, additional non-measurable figures as well as inverse pole figures. The figures were used to perform additional analysis of the crystallographical organization. The traditional concept of the microfibril angle was enhanced by defining two transformation parameters, i.e. a crystallographical axis and an angle of rotation.
Wiesław OlekEmail:
  相似文献   

3.
A model of public cost-sharing in private forest investment is proposed to describe the substitution between the private financing of investments and public investment assistance. The substitution depends on the curvature conditions of the forest investment function on forest stock. When the second-order investment effects are close to zero or when they do not exist, the funding substitution will not take place. A simultaneous econometric model for private and public funding employing forest incomes, forest income taxes, interest rates, investment scale and market wood price expectations as exogenous variables is estimated. The model estimation based on Finnish regional data in 1983–2000 rejects the substitution alternative. A 10% increase in private investment funding increases the demand for public funding at the same rate, but a 10% increase in public funds will increase the private funds supply by 2.5%. Significant income effects are found only in the case of private funding. In northern Finland, the scale effects are large for public financial assistance. The effects of the income tax reform on the private supply of funds are positive, especially for the new wood-sales profit taxation, whereas the interest rate and price expectation effects are negative.
Mikael LindenEmail: Phone: +358-13-2514225Fax: +358-13-2513290
  相似文献   

4.
Environmental concern accelerated development of new wood preservatives having low mammalian toxicity in addition to high protective effectiveness. PHN 130 and PHN 130 G have been developed recently by KOHMIX Ltd. in Japan as environmentally safe, fire-proof boron containing compounds. Beyond their proved fire-proof properties, stability of loaded chemical in wood at humid service conditions and decay resistance are required to be known for effective and broad use of these compounds in wood preservation. Results indicated that PHN imparted complete decay resistance to wood against brown- and white-rot fungi Tyromyces palustris and Coriolus versicolor, respectively. Protection efficacy of PHN also continued despite severe weathering conditions provided that impregnation is done by an undiluted solution. PHN 130 G appeared more effective than PHN 130 in this respect. However, both compounds were leachable from treated wood regardless of retention level or physical restriction of water access into wood by compression.This revised version was published online in April 2005 with a corrected date of receipt of the article.
Ergün BaysalEmail: Phone: +90-252-2238612Fax: +90-252-2238511
  相似文献   

5.
6.
The organization of wood cell wall components involves aggregates of cellulose microfibrils and matrix known as macrofibrils. A combination of field emission electron microscopy and environmental scanning electron microscopy was used to visualise the organization of macrofibrils in different cell wall types comparing normal and reaction wood of radiata pine and poplar as examples of a typical softwood and hardwood. The size of macrofibrils is shown to vary among cell wall types with the smallest structures occurring in the gelatinous layer of tension wood (14 nm) and the largest structures in the S2L layer of compression wood (23 nm). A positive correlation between macrofibril size and degree of lignification is observed, with macrofibrils apparently increasing in size in more highly lignified cell wall types. The fibrillar structure of the secondary wall varies from microfibril-sized structures of 3–4 nm up to large aggregates of 60 nm diameter. The size of macrofibrils also varies slightly among adjacent cells of the same cell wall type. Macrofibrils occur predominantly in a random arrangement, although radial and tangential lamellae may sometimes be seen in individual cells.
Lloyd DonaldsonEmail:
  相似文献   

7.
The behaviour of air-dried and fully saturated parallel strand lumber (PSL) was determined under both static and impact loading. It was found that the moisture content had a significant effect on peak stress and deformation, stress rate, time to failure, and fracture energy. In addition, the results from this study were combined with those from previous studies in order to obtain a more general relationship between strength and stress rate for air-dried PSL.
Sidney MindessEmail: Phone: +1-604-8224471Fax: +1-604-8226901
  相似文献   

8.
Impact of stochastic price and growth processes on optimal rotation age   总被引:1,自引:0,他引:1  
This paper analyses timber harvesting in the Finnish economic and wood production environment. Empirical evidence including stumpage prices, silvicultural costs, etc., since 1949 covers all non-industrial private forestry. Stumpage price and volume growth processes are proxied by GBMs. Optimal harvesting age solutions and numerical results recognising price drift, price and growth volatility, volume growth, value growth and stand establishment costs, as well as thinning benefits, are provided for Scots pine. Moreover, comparative static and sensitivity solutions, including numerical results, show the impact of the discount rate, price drift, and price and growth volatilities on optimal harvesting age. Price volatility prolonged harvesting age by some 5–9 years, and growth volatility by about 1–2, but negative price drift for discount rates from 5 to 2% fell by roughly 6–10 years. Ignoring the future thinning benefits prolonged the harvesting age only by 1–2 years, but ignoring future stand establishment costs reduced it by 2–4 years. Including the price drift and volatility violated the 70 year age limit in the Forest Act for discount rates exceeding 3.5%. The recommended harvesting age of 80 years could be established only by ignoring the price drift. In all, this study produces solutions and programs that can be incorporated into a forest management planning software product widely used in Finland (Hynynen et al. in For Ecol Manage 207(1–2):5–18, 2005).
Markku J. PenttinenEmail: Phone: +358-10-2112244Fax: +358-10-2112104
  相似文献   

9.
Acoustics provide opportunities for non-destructive evaluation of the mechanical properties of wood, especially stiffness. In this work, Fakopp 2D a time of flight (TOF) tool and WoodSpec a resonance-based system were used. In a scoping study on young Pinus radiata trees (aged 8–11) no systematic differences were found between the Fakopp acoustic velocity on opposite sides of young trees. These Fakopp values were then averaged and correlated with that from the equivalent log using WoodSpec. Finally stem and log values were correlated with acoustic velocity in outerwood and in corewood lumber. External measurements on the log (standing tree) correlated well with those for lumber cut adjacent to the bark and modestly for the corewood (R 2 of 0.89 and 0.74, respectively). In a separate study, the acoustic velocities were measured on standing trees in three adjacent stands aged 8, 16 and 26 and the data were used to construct a “Russian Doll” model to demonstrate the enormous range in wood stiffness within and between trees. The stiffest 20% of the population was estimated to be 146, 87 and 76% stiffer than the poorest 20% in the corewood (age 8), intermediate (age 16) and outerwood zone (age 26) respectively.
M. GrabianowskiEmail:
  相似文献   

10.
The effects of stocking on wood stiffness (MoE) for three Eucalyptus species are quantified using a 6-year-old trial established in New South Wales, Australia. An acoustic time-of-flight tool measured the velocity between two probes in the outerwood, from which the stiffness was estimated. Four stocking levels (714, 1,250, 1,667 and 3,333 sph) were examined. Stiffness varied significantly between all species, with E. cloeziana showing the highest stiffness (14.2–15.7 GPa), followed by E. pilularis (12.2–13.5 GPa) and E. dunnii (10.7–12.6 GPa). There was a stiffness increase (around 11%) between 714 and 1,250 stems/ha for all species but thereafter differences between stockings were not always significant. Trees were also assessed for basic density, dbh, total height, crown area, green crown height and stem slenderness (height/dbh). Only stem slenderness had a significant association (0.41 ± 0.17) with stiffness. These findings suggest that, where stiffness is a priority, forest managers could reduce establishment costs with low stockings (around 1,250 stems/ha).
Luis Alejandro ApiolazaEmail:
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号