Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2009
Abstract
Wood modification with furfuryl alcohol is an extensively investigated process and already produced commercially. Furfurylated wood is in the focus of a European project on its use for the production of high performance windows. Different wood species were treated with furfuryl alcohol and tested on water uptake, dimensional changes, leaching in water, resistance to fungal degradation, and ecotoxicity. The results show a reduced water uptake and a reduced swelling of the furfurylated wood samples. A high resistance against fungal attack of the treated wood samples can be shown. A low amount of furfuryl alcohol was leached out and the water samples of two different leaching tests showed in general low toxicity. Southern yellow pine showed good results in all of the tests and has potential for the production of window frames according to the tests performed.
Abstract
In recent years the market share for wooden window products has continuously decreased in Europe. Plastics and aluminum have partly replaced wooden window constructions. Service life and maintenance costs lead the customer to a preferable use of other materials than wood. Additionally the use of tropical hardwoods is decreasing because the market demands sustainable alternatives. A transnational research project is initiated to evaluate the use of an alternative wood material for the production of wooden windows. This project involves both, industry and research institutes from Germany, Sweden and Norway. The objective is to establish Kebony furfurylated wood within the window market of the involved countries. Furfurylation of wood using European timbers has been a research topic for many years and is already commercially produced for different applications. The treatment improves dimensional stability, durability and some mechanical properties. This paper presents the first part of the project, where wood properties such as dimensional stability, water sorption, ecotoxicity, capillary water uptake and water vapor diffusion are evaluated.
Authors
Peder GjerdrumAbstract
The Scots pine is one of the most important raw materials for the wood industry. The pine is straight and strong, and easily preservation treated. The objective of this study was to describe and analyse the accuracy of diameter observations by varying technologies, and to have a first indication for the applicability of RFID tracing logs in the pole industry. Observations were made on barked poles with calliper, 2D scanner and 3D scanner. The local variation in diameter can be indicated by a standard deviation of 3 to 5 mm for repeated observation in almost the same location, and the same magnitude for actual diameter profile deviation from a smoothed profile. In a 3D scanner, the amount of observed data is huge, making it a challenge to analyse, verify and calibrate the equipment. Nevertheless, the accuracy seems acceptable for observations on barked logs. The RFID technology might find uses in permanent applications, but it is still rather work consuming and expensive, and the commercial profit has so far not been identified.
Authors
Peder Gjerdrum Jarl-Gunnar SalinAbstract
The Scots pine is widely used for pressure-treated transmission poles. Prior to preservation treatment, all capillary water must be dried off. Natural seasoning in open-air predominates, which implies that most drying takes place during the dry spring and warm summer seasons. The inventory of drying poles represents considerable value in a company’s balance sheet and risk of downgrading. There is risk both for keeping higher inventory than optimal and for treating poles that would not be dried sufficiently. Knowledge of drying times during the annual seasons has been insufficient. The objective of this study has been to work out a model for pole drying, based on a description of the pole itself and climatic observations during drying. The model has then been used to predict optimal drying times for various pole types and climatic conditions, for roofed or sheltered pole inventories, for assisted drying, etc.
Abstract
No abstract has been registered
Authors
Kjersti Holt HanssenAbstract
We studied the growth of Norway spruce and Scots pine seedlings in the understory, using three sites with selective cutting and group fellings in SE Norway. Seedlings were planted in plots with and without trenching in gaps of four different sizes, ranging from 20 m2 to 500 m2 and giving light levels from around 20 to 75 % of open sky. After tree years seedlings were dug up and measured. Vegetation cover was also registered. Growth of both species was positively and significantly correlated with increasing gap size. This applied for height, diameter, shoot volume, needle length and needle number as well as total dry weight. However, trenching also had a clear and significant positive effect on the same growth parameters. The growth of some weed species, especially wavy hair-grass (Deschampsia flexuosa) also increased significantly with both gap size and trenching. The results show that competition for both light and below-ground resources matters for understory seedling growth under the studied conditions.
Abstract
European ash (Fraxinus excelsior), also known as common ash, occurs naturally inland in lower areas of southeastern Norway and along the southern coast of the country. It is important both as a forest and ornamental tree. During the last decade, dieback has become a disastrous disease on F. excelsior in many European countries. The anamorphic fungus Chalara fraxinea T. Kowalski (1), described for the first time from dying ash trees in Poland, is now considered the cause of ash dieback (2). In May of 2008, C. fraxinea was isolated from 1.5 m high diseased F. excelsior in a nursery in Østfold County in southeastern Norway. Symptoms included wilting, necrotic lesions around leaf scars and side branches, and discoloration of the wood. From symptomatic branches, small pieces (approximately 1 cm3) were excised in the transition area between healthy and discolored wood. After surface sterilization (10 s in 70% ethanol + 90 s in NaOCl), the pieces were air dried for 1 min in a safety cabinet, cut into smaller pieces, and placed on media. The fungus was isolated on potato dextrose agar (PDA) and water agar (WA). On PDA, the cultures were tomentose, light orange, and grew slowly (21 mm mean colony diameter after 2 weeks at room temperature). Typical morphological features of C. fraxinea developed in culture. Brownish phialides (14.8 to 30.0 [19.5] × 2.5 to 5.0 [4.1] μm, n = 50) first appeared in the center of the colonies on the agar plugs that had been transferred. The agar plugs were 21 days old when phialides were observed. Abundant sporulation occurred 3 days later. Conidia (phialospores) extruded apically from the phialides and formed droplets. Conidia measured 2.1 to 4.0 (3.0) × 1.4 to 1.9 (1.7) μm (n = 50). The first-formed conidia from each phialide were different in size and shape from the rest by being longer (6 μm, n = 10) and more narrow in the end that first appeared at the opening of the phialide. Internal transcribed spacer sequencing confirmed that the morphological identification was correct (Accession No. EU848544 in GenBank). A pathogenicity test was carried out in June of 2008 by carefully removing one leaf per plant on 10 to 25 cm high F. excelsior trees (18 trees) and placing agar plugs from a 31-day-old C. fraxinea culture (isolate number 10636) on the leaf scars and covering with Parafilm. After 46 days, isolations were carried out as described above from discolored wood that had developed underneath necrotic lesions in the bark and subsequently caused wilting of leaves. All the inoculated plants showed symptoms, and C. fraxinea was successfully reisolated. No symptoms were seen on uninoculated control plants (eight trees) that had received the same treatment except that sterile PDA agar plugs had been used.
Authors
Jarl-Gunnar Salin Peder GjerdrumAbstract
Wooden poles are frequently used for power and telecommunication lines. After creosote preservation the durability is secured for many decades. This study is related to a Norwegian plant where such poles are produced using Scots pine. Prior to the preservation process the poles have to be dried to a moisture content below the fibre saturation point everywhere in the pole. This is done outdoors in open stacks of poles, i.e. as air-drying. A problem is caused by the difficulties to determine when the target moisture content has been reached. The inventory of drying poles represents considerable value in a company\"s balance sheet and risk of downgrading. Knowledge of drying times during the annual seasons has been insufficient, and no efficient method is known for accurately observing the MC through the various parts of the poles.....
Abstract
Evaluation of climate change consequences and national carbon reporting such as under the Kyoto protocol require long-term monitoring of carbon fluxes. We report on an ongoing project aimed at a national-level assessment of the terrestrial carbon sequestration potential under present conditions and under various climate and land use change scenarios, in particular in terms of their temperature effect. We develop empirical models for national soil carbon stock assessment and evaluate process-based soil carbon models for prediction of future carbon dynamics.....
Abstract
The CO2 uptake of the terrestrial biosphere (Gross Primary Productivity, GPP) plays a key role in the global carbon balance. This carbon flux cannot be determined directly on a global scale. Yet, the remotely sensed Fraction of Absorbed Photosynthetically Active Radiation (FAPAR) is a valuable proxy for GPP. This study aims at characterizing global FAPAR dynamics on different temporal scales and extracting corresponding spatial structures. The time series were analyzed to uncover the presence and extent of trends, and to identify quasi-oscillatory patterns from intra- to interannual time scales....