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.
2000
Abstract
No abstract has been registered
Abstract
Nitrogen is among the most important plant nutrients, and the effects on forest trees of changes in the concentrations and fluxes of both inorganic and organic nitrogen need to be known. In Norway, much of the nitrogen present in natural waters is organic (Mulder et al., 2000), therefore this fraction can not be neglected. Work using glycine has shown that forest plants can take up some forms of organic nitrogen directly, without preliminary mineralisation (Nsholm et al., 1998).Amino acids and amino sugars appear to be the most important organic sources of nitrogen for plants, including Norway spruce (Picea abies (L.) Karst.) (Johnsson et al., 1999). Organic nitrogen occurs in different forms. In soils, the most important are heterocyclic compounds and amino acids (35 % and 40 % respectively, Schulten and Schnitzer, 1998). In soil waters, amino sugars may also be important (Michalzik and Matzner, 1999).At present, organic nitrogen is normally determined as the difference between total nitrogen and the sum of nitrogen in nitrate and ammonium. This is not entirely satisfactory, as there will be a certain amount of uncertainty in each of the three determinations required. The total uncertainty involved in the determination of organic nitrogen may then be quite large compared to the actual concentration, especially when most nitrogen is present as inorganic nitrogen.A method for the direct determination of organic nitrogen is therefore desirable. Because organic nitrogen generally has a higher molecular weight than inorganic nitrogen, it might be possible to separate organic from inorganic nitrogen using size fractionation methods. In 1998, we worked on the setting up of methods for the determination of amino acids and amino sugars in soil waters, and on the direct determination of organic nitrogen using equilibrium dialysis.
Authors
Tor Arvid Breland Ragnar EltunAbstract
No abstract has been registered
Authors
Dag Fjeld Leif Egil Hem Tom Roar EikebrokkAbstract
This study examines the role of forest operations strategies in sector development for Norway's fjord region. The paper starts with an examination of forest owner attitudes and perceptions in relation to their harvesting behaviour, use of contractor harvesting and road net extension. The influence of forest owner decisions, contractor mechanisation and road net extension standards on operational efficiency is examined in a simple deterministic model of the regional wood chain. Average wood procurement costs are calculated for increasing sector capacity. Direct and indirect harvesting costs are also followed throughout this development.
Authors
Lars Sandved Dalen Carl Gunnar Fossdal Inger Margrethe Heldal Nina Elisabeth Nagy Praveen Sharma Geir Østreng Anders Lönneborg Øystein JohnsenAbstract
Plants are sessile and have to adjust to the prevailing environmental conditions of their surroundings. This has led to a development of a great plasticity in gene regulation, morphogenesis, and metabolism. Adaptation and defence strategies involve the activation of genes encoding proteins important in the acclimation or defence towards the different stressors.Some of the molecular responses to biotic and abiotic stress factors such as pathogenic fungi or drought are specific, but it has also been shown that similar genes are acitvated by several stressors.At the Norwegian Forest Research Institute we are currently developing a diagnostic tool using the induction pattern of several selected genes from Norway spruce to use as a fingerprint for different types of biotic and abiotic stress. The ultimate goal of this project is to be able to identify unique mRNA expression patterns specific for different stressors such as heat, cold, drought, pathogens etc.In order to study the induction pattern expressed under biotic and abiotic stress, Norway spruce seedlings grown on glass beads in a phytotron we have treated with drought, a root pathogenic fungi (Rhizoctonia sp.), and a combination of drought and the root fungal pathogen.Physiological measurements of height, weight, ion leakage, gas exchange, and chlorophyll fluorescence are taken troughout the experiment. In addition, we have used light and electron microscopy, and immunolocalization to study structural cell and tissue changes. The results so far show great variance in the expression patterns between treatments and over time.
Authors
Eirik Romstad Arild Vatn Per Kristian Rørstad Viil SøylandAbstract
Multifunctionality is a systems oriented concept. It addresses the fact that in addition to the provision of private goods like food and fiber, agriculture also provides a set of public goods. The most central public good elements are: - Landscape values: biodiversity, cultural heritage, amenity value of the landscape, recreation/access, scientific/educational value. - Food related aspects: food security, food safety and food quality. - Rural activity: rural settlement and economic activity. Moreover, agricultural production results in negative external effects, like nutrient runoff, erosion, and pollution from pesticide and herbicide use. These aspects also need to be considered when designing policies and determining the extent and type of agriculture. The linkages between agricultural production and public good attributes imply that the costs of providing the public goods may vary. Polices directed at changing the amount of some public goods provided by agriculture will therefore influence domestic commodity production, and thereby als
Authors
Tor J. JohansenAbstract
No abstract has been registered
Abstract
The effect of six cropping systems (rotations of either mainly arable or mainly forage crops) on the soil N content was evaluated using mass balances of total N, and the usefulness of such N balances to predict N runoff (total N losses via drainage and surface water) was investigated. All the arable cropping systems resulted in a net reduction in the calculated soil N pool, and the reduction increased with decreasing N input. Only the forage system with the highest N input maintained the initial soil N content. Mass N balances were found to be a useful tool for predicting N runoff, as up to 87% of the variation in N runoff could be explained.
Authors
Gudbrand LienAbstract
No abstract has been registered
Abstract
No abstract has been registered