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.
2003
Authors
Øystein Johnsen Carl Gunnar Fossdal Rüdiger Baumann Jørgen A. Mølmann Ola Gram Dæhlen David Clapham Tore SkrøppaAbstract
No abstract has been registered
Authors
Petter Nilsen Gunnar AbrahamsenAbstract
Results from two fertilizer experiments in coniferous forest in south and southeast Norway with applications of nitrogen (N), magnesium (Mg) and phosphorous (P) are presented. A Scots pine stand has been fertilized annually for 9 years and one Norway spruce stand has been fertilized annually for 4 years. The aim of the study has been to investigate to what extent N fertilization in middle-aged stands of Scots pine and Norway spruce stimulates tree growth, and whether Mg and P counteract possible induced nutrient imbalances caused by high N doses. Both stands responded strongly to N addition and application of 30 and 90kgNha-1yr-1 resulted in a relative volume increment of 150 and 250%, respectively, compared to control. The increment effect in the pine experiment ceased after 4 years, but the difference between the two N doses was still significant after 9 years. The application of 1.5kgMgha-1yr-1 had just a slight significant positive effect on volume increment in two of the 9 years in the pine experiment, while no effect of 5.3kgPha-1yr-1 on volume increment was found. Needle nutrient concentrations were mainly affected by the N treatment and concentrations above 30mgg-1 was detected in the pine experiment. The concentration of P, Mg and K was negatively affected by the highest N dose in the spruce experiment, but not in the pine experiment. The imbalanced nutritional status created by N application was partly reduced by the P and Mg addition, but no substantial effect on tree growth has been detected so far. The stands have a large potential for accumulating N in the standing biomass and judged from the effect on nutrient concentrations and growth, Mg might be the next element that could limit tree growth by a continued high N atmospheric input.
Authors
Live S. Vestgarden O. Janne KjønaasAbstract
The objective of this study was to quantify the net potential N mineralisation and nitrification rates in mineral soils of two coniferous forest soils subjected to different N additions. One study site was located at Åmli (Pinus sylvestris L. forest), southern Norway and another at Gårdsjön (Picea abies forest), southwestern Sweden. Mineral soil was collected from 14 to 19 and 24 to 29 cm depth in May at Gårdsjön and in May, July, September and November at Åmli. The soil was incubated in the dark at 15 °C for 2 months in the laboratory, and the NH4+ and NO3- content were compared relative to pre-incubated values. The initial contents of NO3- and NH4+ in the soil at the two sites were of about the same magnitude, but the potential net N mineralisation, ammonification and nitrification rates differed significantly. At Gårdsjön, the net N mineralistion ranged from 6 to 29 mg N kg-1 per 2 months, whereas a net N immobilisation generally occurred at Åmli. Additions of 0–50 kg N ha-1 per year had no effect on the transformation rates at the two sites. Applications of large single doses of 90 kg N ha-1 per year during the last 8 years have significantly increased the net nitrification rate in the soil at Åmli. However, a net N mineralisation was only observed in the soil 1 month after the N addition. At low N input levels, site-specific factors, such as the content of organic matter, clay, and moisture, seemed to a large degree to determine the transformation rates. Large spatial variability both within catchments and between catchments at Gårdsjön may have obscured the effects of small N inputs.
Authors
Erlend Ystrøm Haartveit J. Chaseling Per Otto FlæteAbstract
The use of PLS as a tool for developing reliable models for predicting wood quality is demonstrated with two case studies, one involving Norwegian spruce as manufactured lumber, and the other involving decay resistance of Scots pine wood. It is concluded that a PLS model involving eight simple measurements taken on the trees standing in the forest and on their unprocessed logs, can be used to predict the bending stiffness and bending strength of subsequent manufactured lumber.This approach can be used to provide a non-destructive way of predicting wood strength before processing, thus enabling more efficient use of raw materials. The use of different levels of segmental cross validation, with units being tree, forest stand, growing environment or country, did not change the predictive outcome of the models.More complicated models involving additional variables and their interactions did not provide an improved prediction. In the second case study, all but one of the wood samples were successfully classified into their correct class of heartwood or sapwood using PLS dummy regression models based on 926 wavelength variables in the NIR and visual regions.Models including the visual region as well as the NIR region proved to be superior even when there was no observable colour difference between the two wood types. Satisfactory models were obtained for predicting the resistance to decay of heartwood by using PLS on the non-destructive NIR data. As for the classification models, better predictions were achieved when the visual region of the spectra was included.
Abstract
A multiplex real-time PCR assay was developed to monitor the dynamics of the Picea abies-Heterobasidion annosum pathosystem. Tissue cultures and 32-year-old trees with low or high resistance to this pathogen were used as the host material. Probes and primers were based on a laccase gene for the pathogen and a polyubiquitin gene for the host.The real-time PCR procedure was compared to an ergosterol-based quantification method in a tissue culture experiment, and there was a strong correlation product moment correlation coefficient, 0.908) between the data sets. The multiplex real-time PCR procedure had higher resolution and sensitivity during the early stages of colonization and also could be used to monitor the host.In the tissue culture experiment, host DNA was degraded more rapidly in the clone with low resistance than in the clone with high resistance. In the field experiment, the lesions elicited were not strictly proportional to the area colonized by the pathogen.Fungal colonization was more restricted and localized in the lesion in the clone with high resistance, hereas in the clone with low resistance, the fungus could be detected until the visible end of the lesion. Thus, the real-time PCR assay gives better resolution than does the traditionally used lesion length measurement when screening host clones for resistance.
Authors
Morten NittebergAbstract
The Norwegian Forest Research Institute (Skogforsk) is conducting a study of mechanised harvesting in cable operations.The activity of cable crane systems is heavily reduced the last years in Norway. There are different reasons for this:Low price on wood High direct logging cost Relative low technical development Hard to recruit workers General scepticism to logging in steep terrain, due to environmental influences The positive environmental effect by use of cable crane systems is not well known, and is overshadowed by the negative publicity. Use of cable crane systems may among other things contribute to reduce technical encroachment in the terrain, road building, and wheeled terrain transport.When the harvesting operation in steep terrain is mechanised the safety will increase and the working load will be easier. We hope this will have a positive effect on recruiting workers to this kind of work.The use of harvester inn logging operation will probably also increase the productivity of the cable crane system, and will hopefully give better economy for steep terrain harvesting. A harvester (Menzi Muck A71) is developed in Switzerland for use in steep and difficult terrain. The harvester is based on a Menzi Muck excavator. The machine is mainly build for operations in steep terrain up to 60 %, but with a safety winch it may operate in steepness up to 100%.The Menzi Muck harvester is now working together with a Owren 400 cable crane system in steep terrain (30 70 % steepness), and Skogforsk will during the project period study the productivity and the operating cost of the cable crane system in cooperation with Menzi Muck harvester, and compare the result with ordinary manual felling. This will be done time study and operational statistics.The project started up 1 July 2002, so at this moment we do not have much data, but within March 2003 we will have data enough to present some results.
Authors
Halvor SolheimAbstract
No abstract has been registered
Authors
Arne Sandnes Toril Drabløs EldhusetAbstract
With small seedlings and dilute nutrient solutions, the use of glass beads as growth medium alters pH, conductivity and elemental composition of the solution to an extent that may affect the glass beads\" suitability as growth medium in plant cultivation experiments.
Authors
Staffan JacobsonAbstract
No abstract has been registered
Authors
Risto Seppälä Thomas RimmlerAbstract
No abstract has been registered