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.
2011
Sammendrag
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Sammendrag
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Forfattere
Kjell Andreassen Bernt-Håvard ØyenSammendrag
Fourteen Nordic increment functions have been validated by use of with a test data set from long-term research plots in Norway of even-aged, pure stands of Scots pine, Birch and Norway spruce. In selected functions from Denmark, Finland, Norway and Sweden measures of site productivity, mean tree size and various stand characteristics are represented. Different models display both strengths and weaknesses in their predicting ability. Some measures of precision and bias have been calculated and the functions are ranked due to their performance. Basal area increment models for spruce and pine from Sweden, and a Finish volume increment model for birch has the best fit to the Norwegian test data. Some of the growth models developed outside Norway estimate the growth with about the same accuracy as the models frequently used and developed in Norway. The results indicate that forest conditions and traditional even-aged forest management practice in the Nordic countries seem to have small influence on the relative growth of even-aged stands. By careful recalibration of existing functions from other Nordic countries with data from Norway, a reasonable accuracy could be achieved in Norwegian forest with a reduction of the bias.
Forfattere
Vibeke Stærkebye Nørstebø Ulf Johansen Hanne Marie Gabriel Bruce Talbot Jan-Erik Ørnelund NilsenSammendrag
Hovedmålet med prosjektet er å utarbeide en prioritert investeringsplan for utbygging av tømmerkaier langs norskekysten, slik at forholdene legges til rette for en rasjonell tømmertransport fra skog til industri. Vi har benyttet matematisk programmering til å identifisere det optimale antall, størrelse og lokalisering av tømmerkaier - i dag og over en tidshorisont på 20 år. Modellen er tilpasset slik at den tar hensyn til dagens og fremtidens avvirkningsvolum, infrastruktur, kostnader og tariffer, og for øvrig andre målbare faktorer som påvirker samlede transportkostnader. Ved hjelp av modellen har vi identifisert en skissemessig plan for lokalisering, dimensjonering, og utbygging av tømmerkaier langs norskekysten, samt en følsomhetsanalyse for viktige drivere. Den viser at investeringskostnad for kaier, kundenes lokalisering og tilhørende etterspørsel, og kostnad for lastebiltransporten og endret veikvalitet / bruksklasse (foruten totalt avvirkningsvolum) har størst effekt på resultatet og totalkostnaden. Prosjektet har også vurdert andre miljø- og samfunnsgevinster av en slik utbygging langs kysten. Flere kaier (for samme mengde avvirket tømmer), og tilhørende redusert antall kilometer tømmertransport med lastebil ser ut til å være gunstig med tanke på miljøutslipp. Det er også potensial for å utvikle modellen til å analysere flere ting enn hva som ligger inne per i dag. Et aspekt som bør inkluderes er profittmaksimering (overskudd) og verdikjedeoptimering.
Forfattere
Bruce Talbot Morten NittebergSammendrag
In the coastal region of Norway, large volumes of relatively inaccessible plantation timber are maturing for harvest. The economic feasibility of accessing much of this timber has limited the level of harvesting activity considerably. Harvesting planners are faced with the classic dilemma of finding the appropriate level of investment in infrastructure, as against inoptimal transportation. In this paper, we present results from a simple deterministic simulation carried out to illustrate the efficiency frontiers of three transport methods, one of which requires a substantial investment in road upgrading. Results depend on assumptions made, but clearly show that in these conditions, upgrading roads for truck+trailer transport should be evaluated on a cases by case basis. Forest road length and condition, public road distance to conversion site, and investment level all play important roles in the decision structure. In the coastal regions, road upgrades would generally need to be justified by benefits other than timber harvesting alone.
Sammendrag
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2010
Sammendrag
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Sammendrag
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Sammendrag
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Forfattere
Helmer BelboSammendrag
In this study, the efficiency of a small multi-tree felling head, mounted on a farm tractor with a timber trailer was studied, when harvesting small trees for energy in thinnings. Both separate loading and direct loading of the felled trees was studied. Time studies were carried out in a mixed stand of Norway spruce (Picea abies (L.) Karst) and birch (Betula pubescens Ehrh.). The time consumption of the work elements in the different work methods was formulated by regression analysis, where the independent variables were tree size and degree of accumulation. The average size of the harvested trees was 0.035 m3. The time consumption for the harvesting and loading were similar for the two studied methods, 20 minutes per m3 at a tree size of 0.035 m3, but the two methods showed different characteristics for different tree sizes and level of accumulation. The direct loading method had the highest productivity when more than 0.1 m3 were collected in the felling cycle, whereas the separate loading method had the highest productivity when less than 0.05 m3 were collected in the felling cycle. The total effective time consumption for harvesting and forwarding the biomass 300 meters to roadside landing was 27 minutes per m3. The efficiency of the initial felling and collecting of the small trees was the main challenge. Both the harvesting technique and harvesting technology needs further development to provide a feasible production chain for woodfuel from energy thinning.