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
Roman Gebauer Daniel Volařík Josef Urban Isabella Børja Nina Elisabeth Nagy Toril Eldhuset Paal KrokeneAbstract
Conifer needles are extraordinarily variable and much of this diversity is linked to the water transport capacity of the xylem and to xylem conduit properties. However, we still know little about how anatomical characteristics influence the hydraulic efficiency of needle xylem in different parts of the crown. In this study we evaluated needle function and anatomy in Norway spruce families exposed to different light conditions. We measured tracheid and needle characteristics of sun-exposed and shaded current-year needles in two experimental plots: a control plot and a thinned plot with 50% reduction in stand density. Sun-exposed needles had a larger tracheid lumen area than shaded needles, and this was caused by a larger maximum tracheid lumen diameter, while the minimum lumen diameter was less plastic. Sun-exposed needles had also higher theoretical hydraulic conductivity than shaded needles. Thinning leads to increased radiation to the lower branches, and presumably exposes the upper branches to stronger water stress than before thinning. Thinning affected several needle parameters both in sun-exposed and shaded needles; tracheid lumens were more circular and minimum tracheid lumen diameter was larger in the thinned plot, whereas maximum tracheid lumen diameter was less plastic on both plots. This study demonstrates that needle xylem structure in Norway spruce is clearly influenced by the light gradient within the tree crown.
Abstract
No abstract has been registered
Authors
Annika Höjer Steffen Adler Stig Purup Hansen-Møller Jens Martinsson Kjell Håvard Steinshamn Anne-Maj GustavssonAbstract
Phytoestrogens are hormone-like substances in plants that can substantially influence human health (positively or negatively), and when fed to dairy cows are transferred to their milk. The aim of this study was to investigate effects of varying the botanical composition and regrowth interval of legume-grass silage on silage and phytoestrogen intake and milk phytoestrogen concentrations. In one experiment, 15 Swedish Red dairy cows were fed two- or three-cut red clover-grass silage (designated R2 and R3, respectively), or two-cut birdsfoot trefoil-grass silage (B2). In a second experiment, 16 Norwegian Red dairy cows were fed short-term ley silage with red clover (S3) or long-term ley silage with white clover (L3), and the effects of supplementation with α-tocopherol were also tested. There were high concentrations of formononetin and biochanin A in all silage mixtures with red clover (R2, R3, and S3). The milk concentration of equol was highest on diet R2 (1,494 μg/kg milk). Due to metabolism of biochanin A, genistein and prunetin, their concentrations in milk and the apparent recovery were low. Coumestrol was only detected in silage mixtures S3 and L3, and its milk concentration was low. Concentrations of secoisolariciresinol and matairesinol were higher in silage mixtures B2 and L3, those with legume species other than red clover and the highest grass proportions. B2 also resulted in higher enterolactone concentration than the other diets (226 μg/kg milk). Lengthening the regrowth interval increased the intake of secoisolariciresinol and decreased recovery of lignans. Feeding long-term ley silage resulted in higher lignan milk concentrations, but lower isoflavone milk concentrations than feeding short-term ley silage. The apparent recovery of all phytoestrogens except prunetin was highest on B2, indicating that condensed tannins (present in the birdsfoot trefoil) affect rumen metabolism. There was no effect of α-tocopherol supplementation on milk concentrations of any of the measured phytoestrogens. There were variations in milk concentrations of phytoestrogens, especially of equol, among cows, which could not be explained by variations in diet composition or phytoestrogen intake. The results show that milk phytoestrogen concentration is strongly influenced by silage botanical composition and management, but questions regarding phytoestrogen metabolism remain to be answered.
Authors
Nicholas ClarkeAbstract
This report aims to summarise briefly the findings in the scientific literature concerning the effect of both stem-only and whole-tree harvesting on soil carbon stocks. Although the findings reported by previous authors vary, it is possible to draw some general conclusions about the effect of harvesting on soil carbon, and on whether whole-tree harvesting has a greater effect than stem-only harvesting. In general it appears that the organic C content in the soil’s organic layer is reduced after stem-only harvesting, sometimes by as much as 50%. This reduction has been explained in several ways. After a period of maybe 20 years, the carbon content of the organic layer starts to increase again. In the mineral soil a reduction is not always apparent and the C content can even increase, probably because of the incorporation of residues into the soil. Some studies have shown that this increase is short-lived, while others have found a longer-term increase. Unsurprisingly, thinning appears to affect the soil carbon content much less than clear-cutting; the effect tends to be proportional to the thinning intensity. The soil carbon content appears to be higher after selection cutting than after clear-cutting. Studies comparing effects of whole-tree harvest with those of stem-only harvest have tended to show smaller carbon contents in the mineral soil after whole-tree harvest than after stem-only harvest, although once again results vary greatly. There are many factors affecting soil C content and thus accounting for the observed differences, including temperature, moisture content, and harvesting type. Variation in the results obtained may depend on site-specific factors such as site nutrient status, especially with regard to the most common limiting nutrient nitrogen, which will affect growth in the next rotation. Making sure there are enough nutrients available, if necessary by compensatory fertilisation, will improve carbon sequestration in both trees and soil.
Authors
Nicholas ClarkeAbstract
This report presents preliminary results from investigations on changes in soil water chemistry after stem-only and whole-tree harvesting at a site in eastern Norway, with emphasis on major nutrients, pH and dissolved organic carbon. For stem-only harvesting (SOH) and whole-tree harvesting where slash had been piled (WTH pile), concentrations of nitrate, calcium, magnesium, and potassium peaked in the second year after harvesting and again, but lower, in the third. Ammonium concentrations peaked in the year after harvesting. There was slight acidification after harvesting. No increased concentrations of dissolved organic carbon were observed. In general, trends were similar between SOH and WTH piles, compared to where slash had been removed to form the piles. Peaks in concentrations were higher for WTH piles compared to SOH. The results agree well with results from other field measurements reported in the scientific literature.
Authors
Randi Seljåsen Per Lea Torfinn Torp Hugh Riley Erling Berentsen Mette Thomsen Gunnar BengtssonAbstract
No abstract has been registered
Abstract
Various oils can be used to lower the equilibrium moisture content and increase the service life of Scots pine wood products. The aim of this study was to investigate effects of the lateral wood zone on the brown rot resistance of untreated and linseed oil-impregnated Scots pine wood in a laboratory test (EN 113). Significant differences were found in the mean mass losses of treated and untreated specimens taken from three lateral heartwood zones, but not between specimens taken from sapwood. The treatment had no significant effect on sapwood, although it seems to have some positive effect on the durability of heartwood, apparently due to interactive effects with the high extractives contents of heartwood.
Abstract
No abstract has been registered
Authors
Lone Ross Gobakken Geir Isak VestølAbstract
Wooden claddings are common in faades in Norway, and Norway spruce (Picea abies) is the most frequently used species. The cladding is a major part of the facade, and it has visual requirements that may define the aesthetic service life. The visual changes that occur during weathering can be colour changes, abrasion or wear, blistering, flaking, and even cracks in the wood or coating, but more often growth of mould and blue stain fungi are the main challenge.A field test with synchronous monitoring of relative humidity, air temperature, material temperature and wood moisture content in Norway spruce claddings has been established in southern Norway as part of the ClimateLife project. Visual evaluation of blue stain and mould growth according to EN 927-3 was performed, and evaluation data after 10 months exposure is presented.The objectives were to study the effect of 1) environment, 2) cardinal direction and 3) colour of the cladding on growth of blue stain and mould fungi, and further study the variation in relative humidity, air temperature in front of a surface and the material temperature due to change in 1) environment, 2) cardinal direction and 3) colour of the cladding.After 10 months exposure, the red coating system had lowest mould ratings and the uncoated claddings had the highest. Claddings facing south tend to have higher mould ratings than those facing north. No difference was found between shaded and open environment.The relative humidity was higher in front of the claddings exposed in a shaded environment compared to an open environment, and in an open environment the relative humidity was lower against south than north. The temperature in front of the red coloured claddings was highest. Except for the red-coated claddings, the air temperature was higher than the material temperature.
Abstract
No abstract has been registered