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.
2008
Abstract
The treatability of Scots pine (Pinus sylvestris) sapwood is ranked in the European standard EN 350-2 as class 1 (easy to treat), although huge differences in sapwood penetration exist. To obtain full sapwood penetration, process parameters have to be adjusted to the material most difficult to treat. It is therefore of importance to understand the factors that are responsible for penetration differences. Scots pine sapwood was investigated for anatomical differences influencing the ratio of filling (RoF) when treated with the wood modifying agent furfuryl alcohol. The database for the study was samples from two test series including Scots pine from Norway and Denmark. Within these experimental series each sample can be reassigned to its original position in the stem. The RoF for each sample was evaluated, and the variation in treatability within trees, between trees and between different stands was studied...
Abstract
No abstract has been registered
2007
Authors
Peder GjerdrumAbstract
Predicting sawn timber yield continues to be a challenging task, influenced by several stochastic processes. In this paper, a simulation model for main yield and sideboards in softwood sawing is presented. Predicting sawn timber yield usually involves either straight and notional mathematics, or empiric figures, both with inherent drawbacks. Most geometric models fail to take into consideration random variation: in log position when entering the saw, no log being perfectly straight, smooth and circular, sawing accuracy, etc., and therefore systematically overestimate the yield, in particular the sideboards...
Abstract
Host tree terpenes can influence attraction of conifer-infesting bark beetles to their aggregation pheromones, and both synergistic and inhibitory effects have been reported. We tested a gradient of ratios of (–)-α-pinene, the predominant monoterpene in Norway spruce, to the pheromone of Ips typographus, a major pest of Norway spruce. Attraction of I. typographus increased as the release rate of (–)-α-pinene increased. The two highest (–)-α-pinene : pheromone ratios (526 : 1 and 2595 : 1) attracted twice as many I. typographus as pheromone alone, whereas low to intermediate ratios (56 : 1, 274 : 1) did not differ from pheromone alone. Our results are in agreement with a proposed model, which suggests that bark beetles display unique response profiles to host terpenes depending on the physiological condition of the host trees that they typically colonize. Ips typographus, which is an aggressive species capable of colonizing and killing healthy trees, showed an increased attraction to monoterpene : pheromone ratios, and this may be high enough to inhibit attraction of less aggressive beetle species typically colonizing dead, dying or stressed trees. Attraction of associates of I. typographus was also modified by (–)-α-pinene. Ips duplicatus, a competitor of I. typographus, showed increased attraction to the pheromone of I. typographus across all concentrations of (–)-α-pinene.
Authors
Patrik Flisberg Bertil Lidén Mikael RönnqvistAbstract
In this paper, we consider an operational routing problem to decide the daily routes of logging trucks in forestry. The industrial problem is difficult and includes aspects such as pickup and delivery with split pickups, multiple products, time windows, several time periods, multiple depots, driver changes and a heterogeneous truck fleet. In addition, the problem size is large and the solution time limited. We describe a two-phase solution approach which transforms the problem into a vehicle routing problem with time windows. In the first phase, we solve an LP problem in order to find a destination of flow from supply points to demand points. Based on this solution, we create transport nodes each of which defines the origin(s) and destination for a full truckload. In phase two, we make use of a standard tabu search method to combine these transport nodes, which can be considered to be customers in vehicle routing problems, into actual routes. The standard tabu search method is extended to consider some new features. The solution approach is implemented as part of a newly developed decision support system and we report on tests made on a set of industrial cases from major forest companies in Sweden.
Abstract
River floods may cause considerable damage. Water management strategies intend tomoderate or mitigate the severe effects of extreme discharge events. In this context,techniques for the detection and attribution of changes is of crucial importance. Extremeflood events seem to occur more frequently in recent decades in central Europe.It is anticipated that climate change and weather regime shifts may contribute to this...
Authors
Svein Ole BorgenAbstract
No abstract has been registered
Authors
Arnstein Staverløkk May-Guri Sæthre Eline HågvarAbstract
No abstract has been registered
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
Anna Arneberg Per Holm Nygaard Odd Egil Stabbetorp Bjarni D. Sigurdsson Edda Sigurdis OddsdóttirAbstract
The aim of this study was to investigate variation in decomposition and vegetation due to afforestation. The ICEWOODS sites containing stands of different tree species and age in the western (Skorradalur) and eastern (Hallormsstaður) parts of Iceland were investigated during the summer of 2004. These stands were compared with treeless pastures. The planted stands represent chronosequences, i.e., different age classes within each tree species were studied. Decomposition was studied by a cotton strip assay. Cotton strip decomposition increased with incubation time and decreased with soil depth. The tree species can be ranked according to increasing decomposition in the following series: lodgepole pine < Sitka spruce< Siberian larch < mountain birch. In general, decomposition decreased with increasing age of the stands...