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.
2005
Authors
S. Craig DeLong Lori D. Daniels Ben H. Heemskerk Ken Olaf StoraunetAbstract
Time since death and time since fall were estimated for hybrid spruce (Picea glauca (Moench) Voss Picea engelmannii Parry ex Engelm.) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) logs to quantify temporal changes in log decay and habitat quality in east-central British Columbia. We sampled 136 logs (72 spruce and 64 fir) for species, size, and morphological attributes and used dendroecological techniques to estimate year of death (n = 97) and fall (n = 122).Time since death and time since fall of spruce and fir were similar in decay classes 1 and 2; fir was older than spruce in more advanced stages of decay. Discriminant analysis based on time since fall correctly classified logs into four decay classes for 67% and 80% of spruce and fir, respectively.Function as wildlife habitat changed significantly as logs decayed. Logs served as elevated runways for approximately 15 years and then increased in value as habitat for invertebrates and insectivores as wood softened and vegetation established. Concealed spaces increased as the wood decomposed but decreased when logs collapsed.We conclude that decay classes represent biologically and statistically significant stages of log decomposition that are relevant to wildlife habitat and therefore provide a useful construct for model development and field interpretation.
Authors
Svein SolbergAbstract
Forest damage will result in two general effects: defoliation and/or discolouration. The two available techniques in remote sensing of forests today, LiDAR and spectroscopy, are promising tools for monitoring these two, respectively. Merging data on foliar mass, estimated by LiDAR, with data on chlorophyll concentrations, estimated by spectroscopy, can provide data on chlorophyll mass pr area unit. Monitoring the temporal changes of this is likely to be a very good measure for variations in forest health.In order to check out the possibilities for this, we are now working on building relationships between foliar mass data and LiDAR data for single spruce trees. In total we have measurements of position and stem diameter on about 2000 trees distributed on 16 plots, where 64 trees are intensively sampled for estimating foliar mass, as well as crown size.We need to parameterize a relationship between the LiDAR data for each of these trees and their foliar mass (or leaf area). If we succeed to build this relationship, we will scale it up to provide foliar mass (or leaf area) estimates for every 10x10 m pixels in two SPOT images of the area.Together with a similar up-scaling of chlorophyll concentrations, based on spectroscopy, we will test the possibility of estimating chlorophyll mass per area from SPOT or other satellites. In addition, we have visually assessed data on crown density for all the trees, being a rough, but valuable data-set for validating the relationship.The work, being in progress now, includes several tasks:a) finding an appropriate canopy surface modelb) segmentation of treesc) estimating crown volume, and evt d) handling of smaller trees standing below (this is a heterogenous canopy layer forest) and e) handling of the relative influence of stem and branches.Additionally, we see some other benefits from using LiDAR together with airborne hyperspectral data and satellite data in general. Firstly, the combination of high resolution LiDAR and hyper-spectral data, is a good basis for separating the signals from ground vegetation and from the tree canopy. Secondly, LiDAR provides both a DTM and a canopy surface model, and they are two alternative surface models for the geo-referencing of other data, and for appropriate handling of effects of shadowing and obstacles from tall trees.
– Working conditions for forest machine operators and contractors in six European countries
Tore Vik
Authors
Tore VikAbstract
No abstract has been registered
Authors
Peder GjerdrumAbstract
Det er stor variasjon i fiberforløp når man betrakter en hel trestamme. Således må den gjengse oppfatning om en regulær tredimensjonal anisotropi i stammen nyanseres. Såvel trevirkets fysiske egenskaper som fiberretningen har betydning når tre skal bearbeides og for egenskapene til den bearbeidede overflate. Denne presentasjonen omtaler varierende fiberretning knyttet til vridd vekst, kvister og overgangssonene rundt kvister, margens svakt slyngende form og uregelmessigheter i årringmønster og stokkens ytre form. Simultane modeller blir komplekse og mye av variasjonen forblir uforklart.
Abstract
Fungi cause serious problems in wood utilization, and environmentally benign wood protection is required as an alternative to traditional chemicals. Chitosan has shown promising antimicrobial properties against several microorganisms. In this study, we present the characterization of and antifungal properties of a commercial chitosan formulation developed for impregnation of wood.A broad range of chemical and mycological methods were used to evaluate the uptake, fixation, and antifungal properties of chitosan for wood preservation. The results show that the higher the uptake of chitosan the lower the relative recovery of chitosan in wood after leaching, and the higher the molecular weight of chitosan the higher the recovery.Chitosan with high molecular weight proved to be more efficient against decay fungi than chitosan with low molecular weight. The fungi tested on chitosan-amended nutrient agar medium were totally inhibited at 1% (w/v) concentration.In decay studies using small wood blocks, 4.8% (w/v) chitosan concentration gave the best protection against brown rot fungi.
Abstract
No abstract has been registered
Authors
Peder Gjerdrum Claudio Pollini Lorenzo ValentiAbstract
Wood is prone to natural decay. Unless properly conserved, sawlog quality will deteriorate due to checks, blue stain, rot wood borers and other causes. Log spraying has proved an efficient method for softwood quality preservation. The method is used both for seasonal storing during spring and summer, and for log preservation, e.g. following storm felling, for periods up to three years. A description of wood quality aspects and environmental impacts as well as practical and technical remedies are given.Most timber quality features will be upheld provided some basic routines are followed. Wood strength seems unaffected. Some discoloration due to tannin diffusion and spots of increased permeability due to bacterial colonies might be experienced. It is suggested that the method might be advantageous for the Italian Alpine forest industry.
Abstract
No abstract has been registered
Authors
Magnus Karlsson Ari M. Hietala Harald Kvaalen Åke Olson Halvor Solheim Jan Stenlid Carl Gunnar FossdalAbstract
No abstract has been registered
Abstract
No abstract has been registered