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
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
No abstract has been registered
Abstract
No abstract has been registered
Abstract
There is a great demand for involving rapid, non destructive and less time consuming methods for quick control and prediction of soil quality, environmental monitoring, and other precision measurements in agriculture. Near infrared reflectance spectroscopy (NIRS) is considered as an appropriate alternative method to conventional analytical methods for large scale measurements. The objective of this study was to investigate the possibilities of NIRS for prediction of some chemical properties of soil samples. A total of 97 samples from Stara Zagora, Kazanlak and Gurkovo region taken from the 0-40 cm layer were collected. Soil types were Luvisols, Vertisols, Fluvisols and Rankers. The samples were analyzed for total phosphorus by spectrometric determination of phosphorus soluble in sodium hydrogen carbonate solution, total nitrogen by Kjeldahl method, pH (H O)-potentiometrically and electrical conductivity (EC). 2 The spectral data of all air dried samples were measured using an Perkin Elmer Spectrum One NTS, FT-NIR Spectrometer, within the range from 700 to 2500 nm. Partial Least Squares (PLS) regression was used to built models to determine soil chemical parameters from the NIR spectra. Two-third of the samples were used as a calibration set and the remaining samples as independent validation test set. The best model was obtained for total nitrogen with a coefficient of determination r=0,91, standard error of calibration SEP=336 mg/kg, and the ratio of the standard variation of the reference data to the SEP, indicating the performance of the calibration, of RPD=2,3. The accuracy of prediction was poor for electrical conductivity. The results obtained clearly indicated that NIRS had the potential to predict some soil components rapidly and without sample preparation.
Authors
Lone Ross Gobakken Olav Albert HøibøAbstract
Mould growth on exterior coated cladding façades is an undesirable element and will often shorten the aesthetical service life. Mould growth on painted surfaces is influenced by type and concentration of film fungicides, the paint formulation and the wood substrate itself, and wooden cladding may experience exponential fungal deterioration caused by variation in the climatic factors, often within a small limited area. The objective of this study was to gain knowledge about which factors influence surface mould growth on coated and uncoated wooden cladding in an outdoor environment, with a special attention to modified wood substrates. The data are based on evaluation of mould growth coverage on outdoors exposed wood panels consisting of different combinations of wood substrates and surface finishes. Panels were exposed on three locations; Bogesund (Sweden), Birkenes and Sørkedalen (Norway). The panels were monitored up to 4.5 years. The analysis showed that coating typology and exposure time both had highly significant influences on mould growth. Furthermore, wood substrate, temperature and relative humidity had a significant influence on mould growth, but comparatively less than coating typology and exposure time. Siberian larch heartwood, copper-organic preserved Scots pine and Scots pine heartwood performed best among the wood substrates. Heartwood as wood type was less susceptible to mould growth than a mix of sapwood and heartwood wood and pure sapwood. Acetylated Scots pine as wood substrate and Aspen as wood species had lower resistance to mould growth than the other wood substrates and wood species, respectively. The physical surface structure of a paint film also influences the mould growth. A hard model paint was significantly more susceptible than the other model paints. A soft model paint performed best, with the least mould growth coverage. Aureobasidium pullulans (deBary) Arnaud was the dominating fungal species on all the wood substrates.
Authors
Marte Haave Annette Bernhard Finn K. Jellestad Einar Heegaard Trond Brattelid Anne-Katrine LundebyeAbstract
Background: Polychlorinated biphenyls (PCBs) are widespread in the environment, human food and breast milk. Seafood is known to contain nutrients beneficial for the normal development and function of the brain, but also contaminants such as PCBs which are neurotoxic. Exposure to non-coplanar PCBs during brain development can disrupt spontaneous behaviour in mice and lead to hyperactive behaviour. Humans are chronically exposed to the highest relative levels of organochlorines in early childhood during brain development, though usually at doses which do not give clinical symptoms of toxicity. This study aimed to elucidate the developmental and behavioural effects of 2,2’,4,4’,5,5’ hexachlorobiphenyl (PCB153) in mice, mimicking human exposure during gestation and lactation. Methods: Environmentally relevant doses of PCB153 were added to the experimental diets. Feed concentrations were approximately 0.5, 6.5, and 1500 μg PCB153/kg feed, representing a realistic and a worst case scenario of frequent consumption of contaminated fish. The study also investigated the effects of maternal nutrition, i.e. a standard rodent diet versus a high inclusion of salmon. Mice pups were examined for physical- and reflex development, sensorimotor function and spontaneous behaviour from five days after birth until weaning. A selection of pups were followed until 16 weeks of age and tested for open field behaviour and the acoustic startle response (ASR) with prepulse inhibition (PPI). Blood thyroid hormones and liver enzymes, blood lipids and PCB153 content in fat were examined at 16 weeks. Statistical analyses modelled the three way interactions of diet, PCB exposure and litter size on behaviour, using generalized linear models (GLM) and linear mixed effect models (LME). The litter was used as a random variable. Non-parametric tests were used for pair wise comparisons of biochemical analyses. Results: Litter size consistently influenced pup development and behaviour. Few lasting PCB153 related changes were observed, but results indicated effects on synchronization of physical development. Perinatal PCB153 exposure appeared to reduce habituation and cause aggression in males, though not statistically significant. Conclusions: Litter size and maternal diet influenced physical development and function more than PCB153 in perinatally exposed mouse pups and supports the developmental importance of maternal care and the social environment.