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
Morten EikenesSammendrag
Det er ikke registrert sammendrag
Forfattere
Terje BirkelandSammendrag
Det er ikke registrert sammendrag
Forfattere
Severin WoxholttSammendrag
Det er ikke registrert sammendrag
Forfattere
Per Otto FlæteSammendrag
Det er ikke registrert sammendrag
Forfattere
Ketil Kohmann Carl Olav HolenSammendrag
Det er ikke registrert sammendrag
Forfattere
Tron EidSammendrag
Det er ikke registrert sammendrag
Forfattere
Arnold Arnoldussen Arne GrønlundSammendrag
EU-kommisjonen har prioritert jordsmonn på linje med luft og vann og har gitt ut en meddelelse med en beskrivelse av en strategi for beskyttelse av jordsmonn. Som et ledd i denne strategien planlagges det et felles europeisk system for jordsmonnovervåking. I denne rapporten er det gitt en oppsummering av meddelelsen fra EU-kommisjonen, med vekt på trusler mot jordsmonn i Europa, relevante forskrifter og direktiver samt krav til en europeisk jordsmonnovervåking. Det er også gitt en kort omtale av jordsmonntilstanden i Norge og de viktigste eksisterende overvåkingsprogrammene som kan bygges videre til en mer fullstendig jordsmonnovervåking.
Forfattere
Vegard GundersenSammendrag
Det er ikke registrert sammendrag
Sammendrag
The rationale for stand growth modelling is often either grounded in a search for improved scientific understanding or in support for management decisions. The ultimate goal under the first task is seen in mechanistic models, i.e. models that represent the stand structure realistically and predict future growth as a function of the current status of the stand. Such mechanistic models tend to be over-parameterized with respect to the data actually available for a given stand. Calibration of these models may lead to non-unique representations and unreliable predictions. Empirical models, the second major line of growth modelling, typically match available data sets as well as do process-based models. They have less degrees of freedom, hence mitigate the problem of non-unique calibration results, but they employ often parameters without physiological or physical meaning. That is why empirical models cannot be extrapolated beyond the existing conditions of observations. Here we argue that this widespread dilemma can be overcome by using interactive models as an alternative approach to mechanistic (algorithmic) models. Interactive models can be used at two levels: a) the interactions among trees of a species or ecosystem and b) the interactions between forest management and a stand structure, e.g. in thinning trials. In such a model data from a range of sources (scientific, administrative, empirical) can be incorporated into consistent growth reconstructions. Interactive selection among such growth reconstructions may be theoretically more powerful than algorithmic automatic selection. We suggest a modelling approach in which this theoretical conjecture can be put to a practical test. To this end growth models need to be equipped with interactive visualization interfaces in order to be utilized as input devices for silvicultural expertise. Interactive models will not affect the difficulties of predicting forest growth, but may be at their best in documenting and disseminating silvicultural competence in forestry.
Forfattere
Peder Gjerdrum Olav Albert HøibøSammendrag
Pine heart- and sapwood can in several respects be considered two different timber products, demonstrating separate wood properties. The efficiency of automated heart- and sapwood separation by analysing temperature images of pine crosscuts has been investigated. A digital, infrared (IR) ThermoVisionfocal plane array camera with 320*240 pixels was employed. IR exposures of the front-end crosscut of 180 pine sawlogs were taken during longitudinal transport on a conveyor, arbitrary crosscut being in front. In each image, one arbitrary diameter was chosen for estimating the heart-wood. The temperature gradient between heart- and sapwood was in the range up to 4oC. An algorithm was established to calculate front-end heartwood diameter as a fraction of log diameter. The correlation between estimated and observed heartwood fraction was r = 0.85. Finally, top end heartwood diameter in mm could be calculated by multiplying top-end diameter, as measured in an ordinary log scanner, with heartwood fraction in front (arbitrary) end. For fresh logs RMSE amounted to 11 mm (front: top end) and 15 mm (front: arbitrary end), respectively. It was concluded that the method might be applicable for an industrial log sorting system and might have a potential to indicate even other wood characteristics. The temperature gradient between heart- and sapwood showed to be a reliable criterion for the accuracy of the model. The temperature gradient might even be used to indicate log freshness.