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.
2010
Authors
Hans Haavardsholm Blom Louise LindblomAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Seminatural grasslands and their species and populations are declining rapidly throughout Europe, bringing about a need for successful vegetation recreation methods. To maintain biodiversity and ecological services of seminatural grasslands, we need more nowledge on the relative performance of different recreation methods. In a replicated experiment in western Norway, we evaluated two hay transfer methods (hard or light raking of local hay), sowing of local seeds and natural regeneration for recreating seminatural grassland in a road verge. We compared treated trial plots with their respective donor plots (where hay and seeds were harvested) for three successive years by evaluating vegetation cover, species richness and species transfer rates, and vegetation dynamics analysed by Bray–Curtis compositional dissimilarity (BC) and GNMDS (Global NonMetric Multidimensional Scaling) ordination. Vegetation cover at the trial site exceeded that of donor sites in three years. Transfer rates of common species were high for seed sowing and both hay transfer procedures. Species composition in trial plots for all three treatments became significantly more similar to donor plots, but was still relatively dissimilar after three years. Natural regeneration showed a different temporal pattern and also had a higher successional rate. The species composition of the other treatments followed the same trajectory toward the donor sites as revealed by GNMDS. We found relatively small differences between the two hay transfer methods and seed sowing. Transfer of local hay therefore appears to be a successful method of establishing local species when recreating seminatural grasslands, and is generally cheaper than using commercial local seed mixtures.
Abstract
This study focused on a suite of vascular plant species (six herbs and two grasses) common to traditionally managed, species-rich grasslands in Western Norway. We assessed the suitability of two species transfer methods (seed sowing and soil seed bank) for restoration of species-rich grassland on a newly established road verge. We compared the species\" frequencies one and three years after they were sown on a naked, newly created road verge with their frequencies in aboveground vegetation and soil seed banks of comparable, local grasslands. Species frequencies in the aboveground vegetation differed significantly from those in the seed banks. Moreover, the frequencies in the seed banks differed from those recorded one year after sowing, and the frequencies in the aboveground vegetation differed from those recorded three years after sowing. Avenula pubescens and Knautia arvensis, found in more than 25% of the aboveground grassland plots, did not germinate from any of the seed bank samples. Festuca rubra, Galium verum, Pimpinella saxifraga and Silene vulgaris were more frequent in the aboveground plots than in the seed bank samples. Pimpinella saxifraga, Galium verum and Lychnis viscaria emerged quite well both from sown seeds and from the seed bank. Avenula pubescens was frequent in the aboveground vegetation, but did not germinate from sown seeds. Six species established well from seeds, and most increased in frequency in the sown plots from the first to the third year. No species was found in the sown plots only, but three years after sowing, three species were more frequent in the sown plots than in the aboveground vegetation of donor grassland plots. Our fine-scale, point-to-point study demonstrates that different restoration methods produce widely differing species composition even when the donor material is identical. We propose that different substrates and a combination of establishment methods (sowing and hay transfer) are needed as supplements to seed banks to re-establish species-rich grassland.
Authors
Kjell Andreassen Birger Solberg Øyvind JacobsenAbstract
Four forest management systems, clear cutting, mountain forest selective cutting (50-90 % of volume removed), group system and single tree selection system (20-50 % of volume removed) were compared in two Norway spruce mountain forest stands. The sites are located 650 m.a.s.l., which is about 100 meter below the alpine tree line in this region. The background for this experiment was that the forest owner wanted to examine alternatives to clear cutting with silvicultural methods where some trees were left in the stand to protect regenerating against frost, to maintain biodiversity, and for recreational reasons in such areas close to the tree line. In twenty 400 m2 systematically sampled plots we assessed or measured vegetation type, regeneration, diameter of all trees > 2.5 dbh, tree heights, annual growth from increment cores, tree quality, old stumps and windthrows. In addition, time studies of the four harvesting methods were performed close to each other in the area. The following mean values were estimated in the two stands before cutting: Area 7 hectares, volume 170 m3/ha, mean diameter 23 cm, mean height 18 m, stems 550/ha, seedlings 150/ha, productivity 3 m3/ha/yr. The diameter distribution of the two stands was almost similar to a reverse J-shaped curve, but a larger amount of trees in some medium and large diameter classes were observed. However, most of the 230 m3 harvested trees were medium and large sized. Annual increment indicated growth reactions 3 years after harvesting. The operational costs were estimated according to time studies of the harvesting and extraction of 580 trees. Analyses of net present value, where bare land value and all future revenues and expenses were estimated and discounted backwards to the harvesting year, indicates less profitability for group selection and selection system than clear cutting and mountain forest selective cutting.
Abstract
Modification of wood with furfuryl alcohol or furfuryl alcohol prepolymer leads to a wood product with increased decay resistance, hardness and dimensional stability. In normal application, i.e. under Use Class 3 conditions, furfurylated wood can be regarded as non-toxic. This has earlier been demonstrated by toxic hazard tests on water leachates using relevant leaching procedures, e.g. the OECD Guideline 313 or the Dutch shower test procedure. These leachates showed slight to no toxicity towards standard aquatic test organisms. However, when using forced leaching procedures with limited amount of water such as the EN 84 procedure, slight to moderate toxicity to the same test organisms was observed, depending on furfurylation process. Furthermore, earlier studies have shown that leachates from wood treated with furfuryl alcohol pre-polymers have higher toxicity to Vibrio fischeri (luminescent marine bacterium) than leachates from wood treated with furfuryl alcohol monomers and that this probably is attributed to differences in leaching of chemical compounds. The ambition of the present study, was to investigate which chemical compounds in the leachates causes toxicity to the aquatic organisms V. fischeri and Daphnia magna (water flea). In this study five different wood species, both hardwoods and softwoods, treated with three different furfurylation processes, were leached according to two different leaching methods. The study shows that this difference in toxicity of leachates towards V. fischeri most likely cannot be attributed to maleic acid, furan, furfural, furfuryl alcohol or 2-furoic acid. However, the difference in toxicity might be caused by the substance 2,5-furandimethanol. Leachates from furfurylated wood still need to be investigated further in order to identify the chemical differences between wood furfurylated with furfuryl alcohol monomers and furfuryl alcohol prepolymer causing differences in toxicity to different organisms.
Authors
Peder Gjerdrum Bjarne HamarAbstract
Commercial timber sawing is always done in trade-off between yield and capacity, between cost of raw material and of production. Accurate knowledge of the dimensions for every single log is needed for successful breakdown. Traditionally, mills sawing to customers\" order, i.e. timber lots of given dimension and quality, start the breakdown process by scaling and sorting unbarked logs. However, accuracy can be greatly improved if scaled after barking. Scaling barked logs to adapt sawing pattern to each log inevitably slows down production speed, and also produces a variety of sawn boards besides the ordered one. The goal of the project described in this paper was to optimise the yield while maintaining high capacity and sawing to order. A modern, medium-sized sawmill producing ca. 60 000 m3 spruce timber annually was about to renew the sawlog intake. A two-stage log scaling/sorting and sawing twin mini-series was concluded. The first stage is the traditional sorting of unbarked logs. In the new intake, when the order is to be produced, logs are debarked before a second scaling with a 3D scanner based on laser beams reflected from the smooth and bright log surface. Logs are directed to either of two log decks, or buffers, each of ca. 25 logs, and sawn in twin mini-series alternating between the two. Sorting criteria might be purely diameter, log length, quality prediction generated from log geometry, or a combination. The sawn timber yield was increased by up to 3 000 m3 annually, corresponding to the contribution margin improved by 3 mill. NOK or more. Production speed is increased by ca. 4%, but producing two orders simultaneously increases planning complexity, requiring additional training for involved personnel. It can be concluded that the chosen set-up: Two-stage log sorting with accurate scaling in the final sorting and sawing twin orders in alternating twin mini-series, has proved successful with respect to sawn timber recovery and production capacity.
Abstract
Measurements of heat production rate have been made on wood samples with the brown rot fungus Postia placenta at different moisture contents. The results clearly indicate that the heat production rate (a measure of respiration rate and activity) is moisture dependent. When the moisture content is decreased, less heat is produced, and when the moisture content is increased, more heat is produced. Isothermal calorimetry seems to be a measurement technique well suited to the study of rot fungal activity as a function of temperature and moisture content.
Authors
Peder GjerdrumAbstract
A number of presentations were given at the GlueLam Study Tour in Trøndelag arranged by The Norwegian Forest and Landscape Institute April 2010 within the Developing the Scots Pine Resource project. The editor wishes to express his gratitude to all those who contributed to the outcome of the study tour: To the host businesses, to the participants and those giving presentations, and to Northern Periphery Program for contributing to the funding. The presentations listed in this report has been collected, trimmed and otherwise slightly modified by the editor. However, the content as well as the layout have been the choice and responsibility of each author. The report is intended for publication in electronic format on the project\"s web page and distribution to the participants. However, the report is public and free to use for anybody, provided a proper citation is given.
Abstract
Plants use an array of responses to pathogenic infection. Understanding of the underlying defence mechanisms may lead to new strategies for reducing the damage. Our objective here was to study histological and cytological responses in Norway spruce of different ages (from seedlings to mature trees) to infection with several pathogenic organisms (Pythium dimorphum, Ceratocystis polonica and Heterobasidion annosum) and compared them to effects of mechanical wounding. To visualize the reaction on infection/wounding we used different histological staining techniques followed by laser confocal microscopy and TEM. Primary roots of Norway spruce seedlings were infected with P. dimorphum, while mature trees (about 30 years old) were infected with C. polonica, H. annosum and wounded. In seedling roots the hyphae of P. dimorphum penetrated the tissue rapidly and colonized the root within 24 hours. In the infected tissue the lignin concentration doubled within 6 days compared to non infected roots. General response to infection by C. polonica and H. annosum in mature trees was the production of lignosuberised wound periderm, accumulation of polyphenolic aggregates in living parenchyma cells in the phloem and development of traumatic resin ducts in the xylem. Upon wounding, we observed a similar, but less intense response. In conclusion, although we tested fungi belonging to different taxonomical and ecological groups, the responses were similar, differing in intensity and timing of the defence response mainly. The response seems to be similar but dependent on the degree of susceptibility in the individual trees and clones.