Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
2003
Forfattere
Live S. Vestgarden O. Janne KjønaasSammendrag
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.
Forfattere
Tor MykingSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Torjus BolkesjøSammendrag
Det er ikke registrert sammendrag
Forfattere
Erlend Ystrøm Haartveit J. Chaseling Per Otto FlæteSammendrag
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.
Sammendrag
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.
Forfattere
Kristen FretheimSammendrag
Det er ikke registrert sammendrag
Forfattere
Peder GjerdrumSammendrag
Mens norske sagbruk tidligere stort sett klarte å holde følge med de svenske og finske i størrelse, er situasjonen sterkt forandret i løpet av de seneste ti årene, skriver forsker Peder Gjerdrum i denne rapporten fra et studieopphold i Nord-Italia. Øst-Europa er åpnet for handel med tømmer og trelast. Brukene rundt Østersjøen er nå stort sett fem ganger større enn våre. Blant annet på grunnlag av det han har sett i Nord-Italia, mener forfatteren at vårt fremtidige fortrinn kan vise seg å bli den gode balanse mellom egen produksjon og forbruk.
Forfattere
Per Otto FlæteSammendrag
Det er ikke registrert sammendrag
Forfattere
Morten NittebergSammendrag
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.