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.
2007
Authors
Arnt Kristian GjertsenAbstract
A multi-source forest inventory (MSFI) method has been developed for use in the Norwegian National Forest Inventory (NFI). The method is based on a k-nearest neighbour rule and uses field plots from the NFI, land cover maps, and satellite image data from Landsat Thematic Mapper. The inventory method is used to produce maps of selected forest variables and to estimate the selected forest variables for large areas such as municipalities. In this study, focus has been on the qualitative variables ‘dominating species group\" and ‘development class\" because these variables are of central interest to forest managers. A mid-summer Landsat 5 TM scene was used as image data, and all NFI plots inside the scene were used as a reference dataset. The relationship between the spectral bands and the forest variables was analysed, and it was found that the levels of association were low. A leave-one-out method based on the reference dataset was used to estimate the pixel-level accuracies. They were found to be relatively low with 63% agreement for species groups. An independent control survey was available for a municipality and estimates from the MSFI were compared to it. The levels of error were quite high. It was concluded that the large area estimates were biased by the reference dataset.
Authors
Ketil Kohmann Øystein JohnsenAbstract
The object of this study was to obtain Norway spruce seedlings with buds set, ready for summer planting from the 1st of July. With an early long night treatment we prevented flushing of the newly formed terminal buds, ceased height growth, but slightly reduced hardiness in buds and needles. Nevertheless, a sufficient hardiness level in the autumn was acquired at a Norwegian nursery at 59°46’ N, with plants of the local provenance given a long night treatment (14 hours) for 13 days from the 25th of June. The similar treatment at a nursery at 64°30’N did not give the same result; all treatments led to a second flush with resumed growth of the local provenance. A trial with seed lots from several provenances was therefore performed at this nursery, and a significant correlation between the critical night length of the seed lot, and their ability to produce non-flushing buds, was found; the longer the critical night length of the seed lot, the less non-flushing buds. Responses at the northern nursery are probably due to the non existing dark period after termination of the treatment, and a too short treatment period to attain bud dormancy. An early and successful long-night treatment will, in addition, produce shorter seedlings with a larger root collar diameter.
Authors
Erlend Nybakk Terje Birkeland Knut FinstadAbstract
This study is based on a certain case with the largest Norwegian Forest Association (Viken Skog BA) as timber seller and Haselstad Bruk AS buyer of saw logs. The objective of the study is to adopt a more effective, accurate and market-oriented timber production system in the south-east of Norway using bucking-to-demand. A bucking simulator called OptApt is further developed with the addition of a function for near-optimal bucking-to-demand, to evaluate this bucking regime in relation to the traditional bucking-to-value approach used under Norwegian conditions, which means large variations in forests when it comes to dimensions and quality between, but also within, regions and stands. ....
Authors
Erlend Nybakk Eric N. HansenAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Elena Iordanova Vanguelova Yasuhiro Hirano Toril Drabløs Eldhuset Lidia Sas-Paszt Mark R. Bakker Ülle Püttsepp Ivano Brunner Krista Lõhmus Douglas Lawrence GodboldAbstract
No abstract has been registered
Authors
Torstein KvammeAbstract
No abstract has been registered
Abstract
The effectiveness against soft rotting micro fungi and other soil inhabiting micro-organisms was tested according to ENV 807 using different treated Scots pine sapwood and beech wood samples. The treatments differed in basic material, solvent, depolymerization agent, viscosity and post treatment. The chitosan treated Scots pine samples showed improved performance against soft rot, whereas a large amount of untreated pines sapwood samples failed during the test. The different chitosan treatments showed only slight differences in performance during the test.Further results of ongoing field tests should give more information about the life performance of the treated samples.
Abstract
No abstract has been registered
Abstract
Studies of defense mechanisms in Norway spruce Picea abies against the spruce bark beetle Ips typographus show that inducible defenses are triggered by unsuccessful beetle attacks. Moreover, spruce trees can be vaccinated against bark beetle attacks through stem bark inoculation with Ceratocystis polonica, an aggressive fungal associate of Ips typographus. Artificial inoculation with certain other fungi has a similar effect, making treated trees a tougher mach for attacking beetles. A similar enhancement of resistance can be achieved by stem surface treatment with methyl jasmonate. Enhanced resistance is associated with the formation of traumatic resin ducts, and mobilization of phenolic substances in living parenchyma cells. The phenolics appear to mix with the traumatic resin. Similar mechanisms are operating in other conifers. We hypothesize that unsuccessful beetle attacks produce a vaccination effect in the trees, enhancing their resistance to later attack. Adding the effect of induced resistance as a model factor shows an immediate effect on the population dynamics of Ips typographus.