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.
2010
Authors
Tron Eid Andreas Brunner Gunnhild Søgaard Rasmus Astrup Stein Tomter Øyvind Løken Rune EriksenAbstract
Ambitious targets for renewable energy production in Norway draw attention to biomass potent-ials. The objective of this report is to review the state of the art regarding research on estimation methods, the availability and production of tree biomass resources for energy purposes in Norway in order to indentify knowledge gaps and thus facilitate appropriate focus, development and priorities regarding research for the coming years. The review focuses on biomass from pri-mary forest production with emphasis on Norwegian conditions, but also considers international research, especially from the other Nordic countries. Three main subject areas are considered: - biomass estimation - biomass resources and availability - biomass production. The first part of this report comprises an overview of existing biomass equations and associated inventory methods applied for estimating biomass in Norway. The overview includes a description of the Norwegian National Forest Inventory data as a basis for large-scale biomass assessments. The second part of the report comprises an overview of previous Norwegian assessments of biomass as an energy supplier as well as suggestions for improvements in such assessments. Improvement possibilities regarding the impacts of environmentally oriented restrictions, appropriate models for productivity and cost calculations regarding biomass harvesting systems, and implementation of biomass-related features in existing decisions support systems to facilitate analyses, where timber production and biomass production for energy purposes are equally important, are identified. The final part of the review focuses on silvi-cultural options aiming at optimizing the value of total biomass instead of the conventional approach to silviculture where the main focus is timber values.
2009
Abstract
No abstract has been registered
Abstract
Growth of Norway spruce (Picea abies) trees and nitrogen deposition were analysed at about 500 forest plots throughout Norway in six fiveyear periods from 1977 to 2006. Growth was calculated from five repeated calliper measurements of all trees during this period and using treering series from increment cores of a subsample of trees. From the growth data a `relative growth` variable was extracted, being the deviation in % between observed and expected growth rates. The expected growth was estimated from growth models based on site productivity, age and stand density at each plot. The plots were categorized into four age classes. The nitrogen deposition was estimated for each plot for the same five year periods by geographical interpolation of deposition observations at monitoring stations made by the Norwegian Institute for Air Research. Nitrogen deposition from 1977 to 2006 ranged from 1 to 24 kg/ha/yr at the study plots, with about 15 kg/ha/yr in the southernmost region and 3 kg/ha/yr in the northern region of Norway. For the entire 30year period we found a long term relationship between growth and nitrogen deposition, corresponding to a forest growth increase of 0.7% per kg total nitrogen deposition per hectare and year (r2 = 0.13). This is in line with studies carried out on other data sets and for shorter time periods. This apparent fertilizing effect was most pronounced for the youngest forest, while the effect was weak for the oldest forest. The growth increase was observed in the southernmost part of Norway, the region with the highest nitrogen deposition. However, the relationship between nitrogen deposition and growth varied considerably between the time periods. In two of the periods the relationship was slightly negative: these periods corresponded well with summer droughts occurring in the southernmost part of Norway. Drought, as well as other climatic factors, will influence the shortterm variations in forest growth and may obscure the fertilizing effect of nitrogen deposition in some periods. In conclusion, nitrogen deposition has most likely increased growth in Norway spruce in southern Norway. However, our study also shows that inferences from such correlative studies should be drawn with care if the growth period is shorter than 10–15 years because climatic factors produce temporal variations in the relationship between nitrogen deposition and forest growth.
Authors
Richard Fischer Martin Lorenz Michael Köhl Georg Becher Oliver Granke Alexey Bobrinsky Tatyana Braslavskaya Wim de Vries Matthias Dobbertin Philipp Kraft Daniel Laubhann Natalia Lukina Hans Dieter Nagel Gert Jan Reinds Hubert Sterba Svein Solberg Silvia Stofer Walter SeidlingAbstract
No abstract has been registered
2008
Authors
Wim de Vries Svein Solberg Matthias Dobbertin Hubert Sterba Daniel Laubhann Gert Jan Reinds Gert-Jan Nabuurs Per Gundersen Mark A. SuttonAbstract
Nitrogennedfallet i skog virker gjødslende på skog, og fører derfor til økt karbonbinding. Så selv om nitrogennedfallet er en forurensning, så har det den positive effekt at det bidrar til å motvirke klimaendringene. Spørsmålet er hvor stor denne effekten er. Vi har i vårt EU/Forest Focus-prosjekt ”Assessment of the relative importance of nitrogen deposition, climate change and forest management on the sequestration of carbon at intensive monitoring plots in Europe” estimert denne effekten til å være omkring 30 kg ekstra bundet karbon for hver kg nitrogen som blir avsatt i skog...
2007
Authors
Wim de Vries G.W.W. Wamelink Gert Jan Reinds H.J.J. Wieggers J.P. Mol-Dijkstra J. Kros Gert-Jan Nabuurs A. Pussinen Svein Solberg Matthias Dobbertin Daniel Laubhann Hubert Sterba M. van OijenAbstract
No abstract has been registered
Abstract
No abstract has been registered
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
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.