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.
2011
Authors
Tore Filbakk Raida Jirjis Juha Nurmi Olav Albert HøibøAbstract
Increased use of pellets has resulted in a shortage of the traditional raw materials required for pellet making, including saw dust, shavings and cuttings from saw mills. Therefore, the pellets industry has started to look for alternative raw materials. Limited consumption of pulpwood from Scots pine (Pinus sylvestris L.) in Norway has made it a potential raw material for the pellets industry. A study on how bark content affects the quality of pellets is reported in this paper. Pellets from pinewood containing zero, five, 10, 30 and 100 percent bark were produced, and their quality parameters were evaluated. Combustion tests were also performed on the produced pellets. Pellets made from pure bark had the best mechanical properties compared with pellets made of wood containing various concentrations of bark. The differences were not substantial and the durability for all chosen assortments was in the same quality class in the CEN standard. A positive effect off the amount of steam added was found. The bulk densities of the blend pellets were higher than those of pure wood and bark. The ash content increased with the amount of bark in the pellets. There were no problems with sintering when the bark content was low (five and 10 percent). For pure bark pellets some sintering was registered.
Abstract
Timber constructions are often built in combination with other materials such as concrete. These materials can influence the timber construction. Moist concrete can e.g. lead to development of molds which creates an unhealthy living area for people. Furthermore, moisture in wood buildings can negatively affect the wood material, which can lead to negative biological activity in timber and possible reduction of strength properties of timber constructions. The present paper introduces a new innovative method of timber protection and describes the influence of moisture on wood and concrete. The new environmental friendly system for protection of timber has been tested on wood destroying fungi and termites. It can be shown that wood protection by means of electro osmotic pulsing technology can preserve wood in laboratory trials. The wood moisture content is reduced when the protection system is installed. Trials on protected wood against subterranean termites showed lower wood moisture content after test of protected samples compared to untreated samples. However, termite activity could not be reduced to a larger extend as the termite living surroundings were not included. It could be shown that humidity in pores of concrete in cellar walls is reduced using electro osmotic pulsing. The drying of concrete when combined with timber constructions can additionally help to reduce timber degradation as all protection measures that lead to a drier building are positive for fungi and subterranean termite control.
Authors
Vilnis Skipars Mari Kjos Baiba Krivmane Nina Elisabeth Nagy Ilze Gaile Danis Rungis Carl Gunnar FossdalAbstract
In Latvia and other Nordic countries Scots pine (Pinus sylvestris L.) is an economically important tree species, and the losses incurred by Heterobasidion annosum, a fungi that causes root rot in pines, are significant. Here we present results about candidate resistance gene expression using laser captured samples from different tissue types of one year old Scots pine saplings. Results show increase of expression of thaumatin-like protein (TLP) gene and pinosylvin synthase (PsBBs) gene one day after wounding or artificial inoculation of the saplings. Expression was analysed using the relative absolute quantification method of real-time PCR.
Abstract
We used two datasets of 14C analyses of archived soil samples to study carbon turnover in O horizons from spruce dominated old-growth stands on well-drained podsols in Scandinavia. The main data set was obtained from archived samples from the National Forest Soil Inventory in Sweden and represents a climatic gradient in temperature. Composite samples from 1966, 1972, 1983 and 2000 from four different regions in a latitude gradient ranging from 57 to 67oN were analysed for 14C content. Along this gradient the C stock in the O horizon ranges from 2.1 kg m-2 in the north to 3.7 kg m-2 in the southwest. The other data set contains 14C analyses from 1986, 1987, 1991, 1996 and 2004 from the O horizons in Birkenes, Norway. Mean residence times (MRT) were calculated using a two compartment model, with a litter decomposition compartment using mass loss data from the literature for the three first years of decomposition and a humus decomposition compartment with a fitted constant turnover rate. We hypothesized that the climatic gradient would result in different C turnover in different parts of the country between northern and southern Sweden. The use of archived soil samples was very valuable for constraining the MRT calculations, which showed that there were differences between the regions. Longest MRT was found in the northernmost region (41 years), with decreasing residence times through the middle (36 years) and central Sweden (28 years), then again increasing in the southwestern region (40 years). The size of the soil organic carbon (SOC) pool in the O horizon was mainly related to differences in litter input and to a lesser degree to MRT. Because N deposition leads both to larger litter input and to longer MRT, we suggest that N deposition contributes significantly to the latitudinal SOC gradient in Scandinavia, with approximately twice as much SOC in the O horizon in the south compared to the north. The data from Birkenes was in good agreement with the Swedish dataset with MRT estimated to 34 years.
Authors
Trygve D. Kjellsen Igor A. Yakovlev Carl Gunnar Fossdal Richard StrimbeckAbstract
Siberian spruce (Picea obovata) grows in the coldest forested environments on Earth, with average temperatures in midwinter months below -40 C and record lows below 60 C. Fully acclimated needles of this species survive immersion in liquid nitrogen at -196 C provided they are first cooled to an intermediate temperature of around -30 C. To investigate the role of dehydrins in extreme frost tolerance, we monitored frost tolerance, relative dehydrin concentration, and relative changes in dehydrin transcript levels in P. obovata needles over a full acclimation-deacclimation cycle.
Authors
Peder GjerdrumAbstract
This case study describes reflection, analyses and results obtained from investing in a new saw intake plant with the option to separate pre-sorted logs groups in two sub-sets for increased yield and sawing mini-series of 20-30 logs to maintain high capacity. The new plant was in need of careful trimming and follow-up during a period half a year or more before optimal operation was obtained. Log separation is done based on 3D scaling after debarking. As expected, scaling accuracy was substantially improved. However, scars and damages from the debarker cause some variation in the scaling, and most for 3-dimensional parameters like sweep and taper. Nevertheless, total sawn timber recovery increased by two percent of consumed log volume, equivalent to 2.3 % improvement in the sawmill\"s added value. Sawing two orders simultaneously increased the complexity of planning and sawn timber logistics. Automated sawn timber quality prediction based on observations of barked logs in the 3D scanner has so far not proved successful; one reason for this might be the quality variation within each log. It was concluded that the investment has proven profitable.
Abstract
Coated wooden claddings in building facades are widely used in the Scandinavian countries, and are often preferred to other materials. Wood is facing increasing competition from other materials that are less labor intensive at the construction site and materials with less demand for maintenance thru service life, and makes further development of wooden claddings essential. Growth of discoloring moulds on exposed coated wooden claddings is mainly of aesthetic concern, and is especially disfiguring for light-colored surfaces. Growth of surface fungi often initiates repeated cleaning and shorter maintenance intervals, which in turn increase the total cost of ownership for wooden claddings. Cost and effort of ownership are often important factors considered when choosing a product, and the traditionally good market situation for wooden claddings is therefore threatened. The development of real-time PCR (polymerase chain reaction) and taxon-specific primers has provided new possibilities for specific detection and quantification of fungi in their natural substrates. In qPCR (quantitative real-time PCR), the accumulation of the PCR product is detected for each amplification cycle. An efficient and reproducible sampling and extraction of DNA is required for a high-throughput qPCR based quantification of discoloring fungi. The authors have now adjusted DNA isolation protocols and optimized real-time PCR assays for species specific detection of fungi frequently found on painted surfaces (Aureobasidium pullulans, Alternaria alternata, Cladosporium cladosporides, Ulocladium atrum).
Abstract
The aim of this study is to see if the raw material influences fixation and leachability of wood preservatives. Moving towards more eco-friendly and –concious society, the wood industries must adjust itself to new rules and regulations. Greener solutions in wood protection are being tested and introduced, older systems are being improved, but questions still arise concerning some elements currently used in wood preservation. Preservatives leaching into the nature is a problem, especially agents that consist copper. Studies have been conducted on the raw material`s influence on impregnability and variations in sapwood penetration have been found. This gives reason to believe that the leaching of wood preservatives is also influenced by the raw material. This study tries to set the variation of leachability of Wolmanit CX-8 and Tanalith into a system, evaluating the origin of a tree and the origin of a sample. The study uses Scots pine (Pinus sylvestris) as a raw material. Material was harvested from different stands in Norway and Denmark. Pine`s sapwood was cut into samples in size of 20x20x50mm. The samples were treated with the wood protection agents Wolmanit CX-8 and Tanalith. The variation in leachability within trees, between trees and between different stands was studied. Within this material, it is possible to trace the individual sample to its original position in the stem. Samples were climatized, impregnated with preservatives and leached according to standard EN84. Copper and boron content in water samples was determined by an ICP (Inductively Coupled Plasma) technique. Comparing leaching results with different variables, correlation was found with latitude and vertical position of the sample, indicating that southern stands leach out more preservative. The lowest part of the tree does not fixate preservatives.
Abstract
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Abstract
No abstract has been registered