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
Ståle Størdal Gudbrand Lien J. Brian HardakerAbstract
This paper presents empirical insight into part-time and full-time property owners’ perceptions of risk and risk management strategies. In addition, the relationships between forest owners with varying degree of off-property work and property and forest owner characteristics, risk perceptions, risk management strategies and harvesting behaviour are examined. The data originate from a questionnaire responded to by forest owners in eastern Norway which were merged with 9 years of logging data. Timber price variability and institutional risks were perceived as primary sources of risk. Use of advisers from the forest owners’ association, buying personal insurance and off-property work were perceived as the most important ways to handle risk. The results show that off-property work affects to a lesser degree what forest owners perceived as important risk sources, but that risk perceptions affect to a stronger degree the ways in which risk was dealt with. The chosen risk management strategies influenced the forest owner's harvesting behaviour to some extent, but more research on the issue is needed to clarify the relationship. There was a positive relationship between owners with off-property activities and their performance as timber suppliers. Several measures, such as improved rural education, revision of some of the arrangements that regulate property mergers and support measures for increased on-property diversification may increase annual timber harvesting and reduce variability in harvesting level.
Authors
Guro Ådnegard Skarstad Svein Ole BorgenAbstract
No abstract has been registered
Authors
Leif Jarle AsheimAbstract
No abstract has been registered
Authors
Guro Ådnegard Skarstad Svein Ole BorgenAbstract
No abstract has been registered
Authors
Lene Frost Andersen Trine Husøy Svein Olav Kolset Henrik Jakobsen Jan Alexander Mona-Lise Binderup Knut Helkås Dahl Erik Dybing Wenche Kristin Farstad Livar Frøyland Ragnhild Halvorsen Margaretha Haugen Kåre Julshamn Georg Kapperud Hilde Kruse Øyvind Lie Anne-Katrine Lundebye Helle Margrete Meltzer Judith Ann Narvhus Kristine Naterstad Ingolf Nes Bjørn Næss Jan Erik Paulsen Tore Sanner Janneche Utne Skåre Inger-Lise Steffensen Leif Sundheim Åshild KrogdahlAbstract
No abstract has been registered
Abstract
Model simulations show that an increased frequency in storms and drought periods may result in more frequent and shorter outbreaks of bark beetles. Warmer summers can result in two bark beetle generations per summer instead of one, giving bark beetles the opportunity to attack forests twice in a single year.
Authors
Arne Oddvar Skjelvåg Ole Einar Tveito Inge BjørdalAbstract
An example is given from a pilot project on a coherent application of soil and weather data to produce crop security estimates of barley. GIS was used to interpolate daily weather elements from a network of weather stations to individually mapped soil type units, oil average less than 1 ha, of arable land. Other model tools are: a soil moisture model to estimate soil drying from the day of snow thaw until sowing date, temperature Run functions to estimate daily advance in phenological development to emergence, heading, and yellow ripeness, and thereafter, a grain moisture model for logging of combine harvesting days, taking also daily precipitation into account. The outcome is probability estimates of getting at least a given number of combining options within a given calendar day.
Abstract
Forest health monitoring may be done with remote sensing. Satellite based SAR is one promising technology as it works day and night and with cloud cover, and because it is sensitive to 3D properties. We here apply an interferometry based XDEM approach, where we assumed that an increasing defoliation would cause an increasing X band penetration downwards into the canopy layer, and that the penetration depth is a function of the amount of leaf area index (LAI) penetrated. We had at hand data for a 4 km2 forest area, having an SRTM X and C band SAR data set from 2000; a discrete-return laser scanning data set from 2003; and ground based measurements of some hundred trees and a forest stand map from 2003. We initially adjusted the XDEM and CDEM using elevation data from some agricultural fields nearby the forest using an official, Norwegian DTM data base having a 25mx25m spatial resolution. All further analyses were carried out on a 10mx10m grid. With the laser data we obtained a DTM and a canopy surface model (CSM), where the latter was set to the 75 percentile of the DZ data in each grid cell. The X band penetrated about six m downwards into the canopy layer, which means that for all grid cells having a forest canopy lower than six m, the XDEM was around zero. With an increasing DSM from six m upwards, the DSM could be approximated by the linear function DSM = 6 + 0.91*XDEM, having a RMSE of 4.0 m. The laser data provided the possibility to estimate LAI in every grid cell and at any height in that cell. For every grid cell, an LAI value was estimated for the forest canopy being above the XDEM height, using the method of Solberg et al (2006), where LAI = C * ln(N/Nb), where LAI is effective LAI above a given height; C is a constant calibrated from ground based measurements with the value 2.0, N is the total number of laser pulses; and Nb is the number of laser pulses below the given height. The median LAIaboveX value was 1.42, and 25-75 percentile values being 0.86-2.15. Also, in order to have a more homogeneous data set we redid the analyses using only spruce dominated stands, and excluding all grid cells at stand borders. The latter was set as grid cells that had neighbour grid cells in a neighbour stand. This had however, only a minor influence on the results.
Abstract
The objective was to evaluate whether Lowry-impregnation of Scots pine with FA100-mix, instead of the FA40-mix, would lead to similar or slightly higher WPGs and to investigate any potential changes in penetration pattern. The results indicate that the penetration was better, also penetrating the outer zone of the heartwood. Furthermore, it was possible to reduce the WPG-levels for pine down to 50-70% (corresponding to PFA retentions of 260- 315 kg/m³) from 120% (approx. 550 kg/m³) with full-cell impregnation using FA100-mix. Using the Lowry process with FA100-mix would probably be a possible treating schedule for products aimed for use in ground contact. The reduced content of hygroscopic salts in the furfurylated wood product would also further reduce hygroscopisity compared with FA-40 mix. However, more trials are needed in order to optimize penetration while still keeping the final WPG low.
Abstract
Furfurylated wood (wood modified by furfuryl alcohol) has over the last years gained marked shares from both tropical wood and conventional preservative treated wood and this has, in turn, generated several research projects concerning process development. The impregnation of spruce is well known from literature to be a difficult task. Furthermore, the sapwood of Scandinavian grown Scots pine is also known to be difficult to fully impregnate from time to time. The primary objective of the study was to evaluate whether the Oscillating Pressure Method (OPM) could be used to impregnate green and dry Norway spruce wood (Picea abies) with a Furfuryl alcohol (FA) - mixture. The secondary objective of the study was to evaluate if OPM could improve the penetration of FA in Scots pine (Pinus sylvestris) as compared to conventional full cell (Bethell) treatment. Impregnation tests were carried out on boards and planks as well as 300 mm and 500 mm clear wood samples. Samples were removed for MC measurement and the initial weight of the test samples was determined. Four different impregnation schemes were tested. The results indicate that Norway spruce can be impregnated by the OPM method to produce a protective shell of treated wood around a core of untreated wood. The penetration in Spruce showed great variation between different boards and between different parts of the individual boards. This is in part expected, but can also be caused by uncontrolled pre drying of the test material which was stacked uncovered after sawing. For Scots pine, the OPM improved the penetration of both sapwood and, to some extent, the outer heartwood.