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
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.
Authors
Cecil C. Konijnendijk Anders Busse Nielsen Jasper Schipperijn Yngve Rosenblad Heldur Sander Mikk Sarv Kirsi Mäkinen Liisa Tyrväinen Janis Donis Vegard Gundersen Ulrika Åkerlund Roland GustavssonAbstract
A review of research and research needs in urban forestry was carried out in Denmark, Estonia, Finland, Latvia, Norway and Sweden during 2005. A questionnaire addressing post-2000 and ongoing research was sent to 146 researchers and generated 76 completed questionnaires. Universities were found to lead urban forestry research, while municipalities headed funding organisations in terms of number of projects funded. Planning, ecological and management aspects were the most common research themes, but socially oriented research also played an important role. The research needs questionnaire was sent to 192 key research actors (assignors, users and researchers), resulting in 63 completed needs assessments. The research themes of ‘urban forest management\", ‘social and cultural values\" and ‘urban forest and green planning\" were prioritised for future research. Comparison of ongoing research and research needs showed discrepancies, as ongoing research does not always cover the same themes identified as primary research needs. Priorities for future research as identified by the research community respective those assigning and using research also differed. Economic assessment of benefits, for example, scored much higher as a need among researchers than other respondents. In terms of present weaknesses in the research ‘infrastructure\", research actors emphasised lack of funding, fragmentation of research and insufficient critical mass. The region\"s urban forestry research can be enhanced and made more meaningful by strengthening national and international networking within the research community, across disciplines, as well as between researchers and those commissioning and using research.
Authors
Kristoffer Segerholm Roger Rowell Pia Larsson-Brelid Magnus Wålinder Mats Westin Gry AlfredsenAbstract
No abstract has been registered
Authors
Svein Solberg Lars Eklundh Arnt Kristian Gjertsen Tomas Johansson Steve Joyce Holger Lange Erik Næsset Håkan Olsson Yong Pang Anne SolbergAbstract
The REMFOR project evaluates remote sensing data and methods for monitoring forest health using variation in leaf area index (LAI) as a primary measure of defoliation. A large-scale pine sawfly outbreak in Norway serves as a test case. An LAI map of the study area was derived from airborne LIDAR measurements before and after the insect attack to serve as ground truth for satellite image analysis. The method predicts LAI from laser penetration rates through the canopy layer in accordance with the Beer- Lambert law calibrated with point measurements of LAI with LICOR LAI-2000. Comparing two cloud-free SPOT scenes from September 2004 and September 2005 shows obvious visual patterns of defoliation in pine forests from the 2005 outbreak. Preliminary analysis shows that the insect defoliation caused an increase in middle-infrared (SPOT band4) reflectance and a decrease in SPOT NDVI, and both these responses may be used as a reasonable predictor of LAI loss as derived from laser scanning. MODIS NDVI data were gathered for the area over the period 2000-2006, and the Timesat algorithm is used to smooth the seasonal variation. The insect attack is evident from the smoothed NDVI data both as a reduction in the summer mean value, and as an alteration of the seasonal profile during the larvae feeding period in June and July. REMFOR also encompasses a range of other remote sensing data types, including GLAS LIDAR, SAR and hyperspectral data from both airborne and satellite platforms (e.g. Hyspex and Hyperion). Landsat TM is used to generate a tree species map.
Abstract
No abstract has been registered
Abstract
In the context of an ongoing project on REMote sensing of FORest health (REM-FOR), we analyze airborne high-resolution hyperspectral images of a pine-dominated region in southeast Norway heavily attacked by the Pine sawfly Neodiprion sertifer, leading to severe defoliation. Leaf Area Index (LAI) is used as a proxy of the crown density, and comparing LAI maps from before and after the attack lead to indicators for damage extent. We discuss the application of the Forest Reflectance Model (FRT) of Kuusk and Nilson, which was designed for the application to (managed) Northern European Forests, to model the spectral response from the canopy. It is based on conventional forest inventory data, species-dependent parametrized crown shapes, canopy LAI, needle clumping index, and needle optical properties. Here, however, we run the model in an inverse mode, by iteratively minimizing the discrepancy between measured and simulated reflectances, and predicting the LAI, keeping known parameters of the model fixed. The LAI values are then compared to those obtained with either ground-based Licor LAI2000 measurements, or with airborne laser-scanning. Some preliminary results of this modelling concept for the case study are discussed.
Authors
Isabelle Schülli-Maurer Daniela Sauer Karl Stahr Ragnhild Sperstad Rolf SørensenAbstract
We investigated the development of Albeluvisols and Podzols with time in southern Norway. The Vestfold region at the western shore of the Oslofjord was chosen because it is characterized by continuous glacio-isostatic uplift for the last 12,000 years. Due to the permanent elevation process, no distinct marine terraces have been built, and the age of the sediments continuously increases with distance from the modern coastline. Albeluvisol development was assessed in a soil chronosequence on loamy marine sediments with ages ranging from approximately 1,800 to 10,200 years. The most obvious change during soil development was that after 4,500 - 5,000 years light tongues intruded from the E horizon into the B horizon, and became more pronounced with time. The combined thickness of the A and E-horizons was constant at 40 ± 3 cm in 9 of the 12 profiles and did not change with age. The organic matter content of the A-horizons, the fine silt to coarse silt ratio of the Btg horizons and the Feo/Fed ratio all decreased with soil age, whereas the thickness of the organic surface horizon and B horizon, as well as the Fed/Fet ratio all increased. Podzol development was investigated in a chronosequence on sandy beach sediments, the ages of the soils ranging from 2,400 to 8,500 years. All soil properties investigated - the organic matter content of the B horizons, clay content, Feo, Alo, Sio, Feo/Fed and Fed/Fet - tend to increase with advancing podzolization, and are strongly correlated with soil age. Topsoil pH values decrease with age. The characteristic Bh and Bs horizons had developed after approximately 4,000 years.