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
Helmer BelboAbstract
The theoretical potential for increased efficiency in early thinning by using accumulating harvester heads was investigated through simulation. Thinning was performed in corridors perpendicular to the strip road in 75 artificially generated stands with varying average tree size and density. The work pattern and work time in the crane work for five sizes of heads, with grapple diameters in the range of 10 to 50 cm, was estimated by the simulation model. The efficiency increased rapidly when the grapple diameter increased from two to four times the average diameter in the harvested stand, reducing the work time per tree by 15 to 50 percent compared to the single tree handling harvester head. Further increases in grapple dimension also increased the efficiency, but not at the same rate. In real work, the efficiency increase by an accumulating harvester head will probably be slightly lower due to less optimal harvesting conditions, operator skills and other non-productive work tasks that are not affected by work method.
Abstract
The species composition of wood-inhabiting fungi (polypores and corticoids) was investigated on 1138 spruce logs and 992 pine logs in 90 managed and 34 natural or near-natural spruce and pine forests in SE Norway. Altogether, the study included 290 species of wood-inhabiting fungi. Comparisons of logs with similar properties (standardized tree species, decay class, dimension class) in natural and managed forests showed a significant reduction in species number per log in managed spruce forests, but not in managed pine forests. The species number per log in managed spruce forests was 10–55% lower than on logs from natural spruce forests. The reduction was strongest on logs of large dimensions. A comparison of 200–400 spruce logs from natural and managed forests showed a 25% reduction in species richness corresponding to a conservative loss of ca. 40 species on a regional scale. A closer inspection revealed that species confined to medium and very decayed spruce logs were disfavored in managed forests, whereas species on early decay classes and decay generalists were unaffected. Similarly, species preferring large spruce logs were disfavored in managed forests. Forest management had strongest impact on low-frequent species in the spruce forests (more than 50% reduction), whereas common species were modestly affected. Corticoid fungi were more adversely affected than polypore fungi. These results indicate that wood-decaying fungi in pine forests are more adapted to forest disturbances than spruce-associated species. Management measures securing a continuous supply of dead wood are more important in spruce forests than in pine forests.
Authors
Robin Engler Christophe E. Randin Wilfred Thuiller Stefan Dullinger Niklaus E Zimmermann Miguel B. Araujo Peter B. Pearman Gwenaëlle Le Lay Christian Piedallu Cécile H. Albert Philippe Choler Georghe Coldea Xavier De Lamo Thomas Dirnböck Jean-Claude Gegout Daniel Gómez-García John-Arvid Grytnes Einar Heegaard Fride Høistad Schei David Nogues-Bravo Signe Normand Mihai Puscas Maria Teresa Sebastia Angela Stanisci Jean-Philippe Theurillat Mandar R. Trivedi Pascal Vittoz Antoine GuisanAbstract
Continental-scale assessments of 21st century global impacts of climate change on biodiversity have forecasted range contractions for many species. These coarse resolution studies are, however, of limited relevance for projecting risks to biodiversity in mountain systems, where pronounced microclimatic variation could allow species to persist locally, and are ill-suited for assessment of species-specific threat in particular regions. Here, we assess the impacts of climate change on 2632 plant species across all major European mountain ranges, using high-resolution (ca. 100 m) species samples and data expressing four future climate scenarios. Projected habitat loss is greater for species distributed at higher elevations; depending on the climate scenario, we find 36–55% of alpine species, 31–51% of subalpine species and 19–46% of montane species lose more than 80% of their suitable habitat by 2070–2100. While our high-resolution analyses consistently indicate marked levels of threat to cold-adapted mountain florae across Europe, they also reveal unequal distribution of this threat across the various mountain ranges. Impacts on florae from regions projected to undergo increased warming accompanied by decreased precipitation, such as the Pyrenees and the Eastern Austrian Alps, will likely be greater than on florae in regions where the increase in temperature is less pronounced and rainfall increases concomitantly, such as in the Norwegian Scandes and the Scottish Highlands. This suggests that change in precipitation, not only warming, plays an important role in determining the potential impacts of climate change on vegetation.
Authors
Fride Høistad ScheiAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
Aims Beech (Fagus sylvatica L.) is an important species in natural and managed forests in Europe. This drought-sensitive species dominates even-aged stands as well more natural stands composed of a mixture of tree species, age and size classes. This study evaluates the extent that heterogeneity in spacing and tree diameter affect the seasonal availability and use of water. Methods Two stands were evaluated: 1) a heterogeneous forest remnant (NAT) with trees up to ca. 300 years old, a mean top height of 28.4 m, and a total of 733 stems ha-1 with stem diameters averaging 18 cm and 2) an even-aged 80-year old stand (MAN), with a height of 25 m, and a total of 283 stems ha-1 with diameters averaging 38 cm. Stem sap flow, Js (g m-2 s-1), was continuously measured in 12 (MAN) and 13 (NAT) trees using 20 mm long heat dissipation sensors. Individual tree measures of sap flow were correlated using non-linear statistical methods with air vapour pressure deficit (D, hPa) and global radiation (Rg, J m-2 day-1), along with contraints imposed by reductions in soil water content (SWC). Soil water content was measured as volumetric % using time domain reflectometry. Important findings The daily integrated Js (Js-sum) for trees growing in the evenly spaced MAN stand and trees in canopy and closed forest positions in NAT stand decreased as the availability of soil moisture was reduced. In the heterogeneous NAT stand, SWC in a recently formed canopy gap remained high throughout the vegetation period. Based on regression models, the predicted relative decrease in Js-sum for dry relative to moist soil water conditions in the closed forest (at mean daily D = 10 hPa) was 7-11% for trees near the gap and 39-42% for trees in the closed forest. In MAN the reduction in Js-sum was 29% in dry relative to moist conditions. Js-sum in the outer 20 mm of the xylem in NAT was lower than that in MAN and the rate of decline in Js with xylem depth was less in NAT than in MAN. In MAN, Js-sum in deep and outer xylem was negatively affected at low soil moisture availability; in NAT this was the case for only the outer xylem indicating that deep roots could be important in supplying water at times of low soil moisture in the upper soil.
Abstract
No abstract has been registered
Abstract
The aim of this study was to use energy-dispersive X-ray spectroscopy (EDX) to localize chitosan in the cell wall of chitosan-impregnated Scots pine. It was of interest to investigate the concentration of chitosan in wood to gain further knowledge and understanding of the distribution of chitosan in the wooden matrix. After deacetylation, chitosan was re-acetylated with chloroacetic anhydride to achieve a covalent bonding of chloride to the chitosan polymer. Chloride-labelled chitosan was measured by EDX using a scanning electron microscope and described as chloride intensity. Analysis of free chloride anions was performed by dialysis and inductively coupled plasma atomic emission spectroscopy. There was a significant correlation between the molecular weight of chitosan and the intensity of covalentbonded chloride to the chitosan polymer. High molecular weight chitosan showed a better interaction with the cell wall structure than low molecular chitosan.
Abstract
In Norway log buildings are normally produced from logs canted on two sides. The canted faces are prone to crack formation during drying. This can cause some disadvantages, e.g. the cracks can trap water from rainfall, because the canted faces form the wall surfaces in the log buildings.
Abstract
The objective of the study was to assess the influence of wood properties on copper leaching from wood treated with preservatives. Scots pine (Pinus sylvestris L.) trees were harvested from two different stands in Norway and one in Denmark. Sapwood was cut to samples (20 x 20 x 50 mm) in as many layers as the radial size allowed. Within this material, it is possible to trace the individual sample to its original position in the stem. Approximately half of the samples were treated with Wolmanit CX-8 and half with Tanalith. All samples were conditioned, impregnated with preservatives and leached according to EN84. Copper and boron content in water samples was determined by an ICP (Inductively Coupled Plasma) technique. The variation in leachability within trees, between trees and between different stands was studied. Statistical analyses showed that trees from the south are more prone to leaching and that samples from the lowest part of the tree fixate less preservative than those from the upper parts. In addition, drying method of the sample had an influence and differences were also noted between products used in the study.