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.
2012
Authors
Peder Gjerdrum Birger EikenesAbstract
Density is one of the most basic quality traits, influential for wood processing and most applications. The aim of this paper has been to present a mathematical model for dry density variation along spruce stems. 85 mature spruce trees were sampled from afforestation plantations at the west coast region of Norway. 20 mm wide cubes of clear wood were extracted from the pith outwards in north and south directions at 10 equidistant heights along the trunk. Green and dry weight and volume were recorded. In this way, the 85 stems yielded 523 disks and a total of 6019 valid observation sets. A mathematically expressed model for density variation is presented. Overall R2 = 0.64, of which between stem variation s = 35 kg/m3 accounts for two thirds. The model standard error is 32 kg/m3; however, the model fails to identify the most extreme density values. The most important results are the quantitative, mathematical form of the model, and the identification of a general density minimum at a certain distance from the pith.
Abstract
No abstract has been registered
Authors
Daniel RasseAbstract
No abstract has been registered
Authors
Hanne Gro Wallin Gunnar EnganAbstract
An overall societal aim is to ensure a sustainable use and management of agricultural landscapes. This requires continuous delivery of reliable and up-to-date information to decision-makers. To be able to deliver this information, a monitoring program for agricultural landscapes was initiated in Norway 13 years ago. The program documents and reports on land use / land cover changes from data captured through interpretation of true colour aerial photos using stereo instruments. The monitoring programme is based on a sample of 1000 squares of 1 x 1 km and the entire sample of squares is photographed over a five-year period. Each square is then mapped repeatedly every fifth year to record changes. Aerial photo interpretation is based on a custom classification system which is built up hierarchically, with three levels. The first level comprises seven land type classes: Agricultural land, Bare ground, Semi-natural open vegetation, Unforested wetland vegetation, Forest, Urban areas and Water. These land classes are further divided into 24 land types at level two, and approximately 100 land types at level 3. In addition to land type units we map both line elements like stone fences and point elements like buildings and solitary threes. By use of indicators that describe status and change focusing on themes of particular policy interest, we can report on whether policy aims are being fulfilled or not. Four indicator themes have been in focus hitherto: landscape spatial structure, biological diversity, cultural heritage and accessibility. Our data is stored in databases and most of the data quality check/structure process and analyses are now being made in open source software like PostGIS and PostSQL. To assess the accuracy of the photo-interpretation, ground truthing is carried out on 10 % of the squares. The results of this operation document the benefits of having access to photos of the same area from two different years. The program is designed first and foremost to provide reliable statistics at a national level but the aim is also to report at regional levels – for example for counties or for agricultural landscape regions. The national coverage and application of standardized methods enable frequent updating. This method is cost effective and enables us to quantify changes in landscape qualities as well as adapting the programme to take account of e.g. new findings on relevant indicators.
Abstract
No abstract has been registered
Authors
Flavio Paoletti Antonio Raffo Kristian Thorup-Kristensen Randi Seljåsen Torfinn Torp Nicolaas Busscher Angelica Ploeger Johannes KahlAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
The combined effects of light, soil fertility, and ontogenetic changes on plant growth rates are poorly understood, yet these three factors play fundamental roles in structuring plant communities. We sought to determine how lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia), interior spruce (Picea glauca engelmanii (Moench) Voss), and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) sapling growth responds to the combination of light, soil fertility, and ontogeny and how these three dominant conifer species in sub-boreal forests of British Columbia differ in their responses.Using maximum likelihood methods, we found that 0.204 m tall sapling growth rates changed during ontogeny and were limited by both light and soil resources. The strongest differences among species growth rates were due to tree size, with smaller differences due to soil fertility, and there were no differences among species in the shape of their growth responses to light. Rank order in growth rates for small saplings (pine spruce fir) inversely corresponded to classic shade-tolerance ratings, thus supporting the carbon balance theory. Interior spruce height growth rates increased relative to lodgepole pine with increasing soil fertility, clearly matching the landscape-scale increase in canopy dominance of interior spruce over lodgepole pine with increasing soil fertility.
Abstract
No abstract has been registered
Authors
HJ Van der Fels-Klerx Sonja Klemsdal V Hietaniemi M. Lindblad E Ioannou-Kakouri ED Van AsseltAbstract
This study aimed to investigate mycotoxin contamination of cereal grain commodities for feed and food production in North Western Europe during the last two decades, including trends over time and co-occurrence between toxins, and to assess possible effects of climate on the presence of mycotoxins. For these aims, analytical results related to mycotoxin contamination of cereal grain commodities, collected in the course of national monitoring programmes in Finland, Sweden, Norway and the Netherlands during a 20-year period, were gathered. Historical observational weather data, including daily relative humidity, rainfall and temperature, were obtained from each of these four countries. In total 6382 records, referring to individual sample results for mycotoxin concentrations (one or more toxins) in cereal grains were available. Most records referred to wheat, barley, maize and oats. The most frequently analysed mycotoxins were deoxynivalenol, 3-acetyl-deoxynivalenol, nivalenol, T-2 toxin, HT-2 toxin and zearalenone. Deoxynivalenol had the highest overall incidence of 46%, and was mainly found in wheat, maize and oats. Mycotoxins that showed co-occurrence were: deoxynivalenol and 3-acetyl-deoxynivalenol in oats; deoxynivalenol and zearalenone in maize and wheat; and T-2 toxin and HT-2 toxin in oats. The presence of both deoxynivalenol and zearalenone in wheat increased with higher temperatures, relative humidity and rainfall during cultivation, but the presence of nivalenol was negatively associated with most of these climatic factors. The same holds for both nivalenol and deoxynivalenol in oats. This implies that climatic conditions that are conducive for one toxin may have a decreasing effect on the other. The presence of HT-2 toxin in oats showed a slight decreasing trends over time, but significant trends for other toxins showed an increasing presence during the last two decades. It is therefore useful to continue monitoring of mycotoxins. Obtained results can be used for development of predictive models for presence of mycotoxins in cereal grains.