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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

Abstract

Norwegian dairy farmers are facing changes in the economic environment. Prices of products and concentrates are falling, while area and headage payments are increasing. The availability of grasslands has become more abundant. Impact of changes in economic conditions on production systems and profitability are examined. Linear programming models of dairy farms, with grain and beef as alternative enterprises, are designed to analyse the adjustments. Optimal production systems are largely determined by a combination of economic factors associated with the various inputs, outputs and support schemes together with availability of farm resources. The typical Norwegian dairy farm has a small quota compared to other farm resources. Producing a fixed milk quota with moderate yielding cows is then most profitable (1999-conditions). Early cut silage offered ad libitum is most profitable. Changes in the milk price have no effects on production as long as the quota is effective. If all of the land is utilised and grassland is the only possible land use, increased area payments have no production effects. If some grassland is not in use, area payments increase land utilisation as cows are fed less concentrate. If grain is also grown, increased grassland area payments result in more land allocated to grass. Forage and milk production become less intensive. By increasing headage payments, milk yield falls, as it is optimal to have more cows to produce the fixed quota output. This contributes to keep more grassland in production and in a more intensive forage production. Lower concentrate prices lead to increased use of concentrates and higher milk yields.

Abstract

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.

Abstract

Knowledge about the transformation of sapwood into heartwood contributes to the understanding of the nature of pine trees and should be considered prior to the conversion of sawlogs to produce timber of prescribed properties and optimal revenue. In this study, heartwood formation was ascribed to the joint effect of ageing and growth rate. Observations of heart- and sapwood in 1656 trees and sawlogs of Scots pine (Pinus sylvestris L.), sampled throughout Scandinavia, were analysed using mixed models. The most important finding was expressed in the pine heartwood age rule: heartwood age equals the square root of cambial age less three, to the second power. This global formula was valid irrespective of environmental factors and location within the tree, and described 93 per cent of the variance in the sample. Transition rate increases from 0.6 rings a−1 at 50 years to 0.8 rings a−1 at 200 years. The spatial amount of heartwood might be influenced by the silviculture through the annual ring width pattern. For samples missing sapwood, e.g. archaeological wood, the results might be combined with dendrochronology in specimen dating. When the diameter and the heartwood diameter of sawlogs were known, the mean annual ring width could be estimated with a standard deviation of 0.5 mm a−1. The simplicity, consistency and high correlation of the pine heartwood age rule confirms the importance of age as the main factor in heartwood formation.

Abstract

HIBECO-prosjektet har fokusert på naturleg og menneskeleg påverknad på bjørke-økosystemet, og på å utforma ulike skjøtsel-scenarier og skogutvikling for å sikra vidare bærekraftig bruk av bjørkeskogen. Dette er oppnådd ved å ta i bruk ulike faglege disiplinar som kombinerer produktivitet, beiting og sosio-økonomiske forhold. Det var ein markert skilnad mellom proveniensar i frostherdighet og vekst. Insektskader på grunn av Epirrita autumnata var sterkt avhengig av vintertemperatur og av vekstformen hos bjørka. Samanliknande studier viste kraftig reduksjon i lavdekket på Finnmarksvidda sidan 1960-talet, og auke i arealet av Cornus suecica og mose, på grunn av overbeiting av reinsdyr og endra klima. Tradisjonell bruk av bjørk er blitt undersøkt ved ei omfattande spørjeundersøking. Det er blitt utvikla ein dynamisk modell for å få kunnskap om dei langsiktige konsekvensane av endra klima og arealbruk innan seks forsøksområde på 100 x 100 km i Nord-Skandinavia og Island.