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.
2008
Abstract
The difficulty in subculturing biotrophic fungi complicates etiological studies related to the associated plant diseases. By employing internal transcribed spacer rDNA-targeted quantitative real-time polymerase chain reaction, we now show that the heteroecious rust Thekopsora areolata, commonly associated in natural conditions to sapling shoots and cones of Norway spruce and leaves of wild bird cherry, frequently infects nurserygrown seedlings of the conifer. A spatial sampling scheme was used to investigate seedlings and saplings of Norway spruce showing phloem necrosis: the highest concentration of DNA of T. areolata was recorded in the area with necrotic phloem. The separate analysis of bark and wood tissues suggested that the initial spread of the rust to healthy tissues neighboring the infection site takes place in the bark. A Phomopsis species found to coexist with T. areolata in several seedlings showed very high DNA levels in the upper part of the lesion, and even in the visually healthy proximal tissues above the lesions, which indicates that the ascomycete, most probably a secondary invader following primary infection by T. areolata, has a latent stage during early host colonization. We hypothesize that this hemibiotrophic mode of infection contributes to the successful coexistence of Phomopsis with a biotrophic rust.
Authors
Anders BrynAbstract
The forest limits of south-east Norway have expanded to higher altitudes. Two main processes are believed to cause these changes; re-growth after abandonment of human utilisation and recent climate changes. This article aim at separating the effects of these two processes on the upper forest limits and recent forest expansion. The results show that raised forest limits and forest range expansion often attributed to recent climate change is rather the product of re-growth, a process that was climatically retarded from 1959 to 1995. From 1995 to 2006, the data indicate a preliminary effect of climate change escalating the re-growth and probably pushing the future forest limits to higher altitudes.
Authors
David Bredström Patrik Flisberg Linda Rud Mikael Rönnqvist Mikael RönnqvistAbstract
This is a manual for the Refinery Optimization Platform ROP which is a flexible platform for studying refinery production planning. The user can model the overall refining process in a multiperiodic setting, with linear and nonlinear representation of the refinery processes. All input and output is communicated via Excel sheet, where the user can define a general refining process together with required output reports. ROP enables the user to study the planning problem by experimenting with alternative modeling approaches and restrictions. A case study with input data and results is presented.
Authors
David Bredström Patrik Flisberg Mikael Rönnqvist Mikael RönnqvistAbstract
In this paper we present a general model and solution approach for refinery process planning. The model is nonlinear and has a flexible description to account for different configurations at a refinery. The solution approach is based on solving the nonlinear model directly with a commercial solver. Since the model is highly nonlinear we apply a special procedure to find a good starting solution. We test standard commercial nonlinear solvers on a set of standard test examples.
Authors
Peder GjerdrumAbstract
No abstract has been registered
Authors
Øyvind Nordli Frans-Emil Wielgolaski Anne Kjersti Bakken Stein Harald Hjeltnes Finn Måge Anders Sivle Oddvar SkreAbstract
Data series for bud burst, beginning of flowering and petal fall for 20 species of deciduous trees and conifers at four sites in different regions of southern Norway have been analysed and related to temperature series. On average, the spring phenophases occurred 7 days earlier during the period 1971–2005. The most significant linear trends were observed for the earliest phases. The trends in this period were compared with trends in other periods, the longest one starting in 1927. Those starting in cold decades and ending in 2005 were in most instances statistically significant, whereas hardly any significant trend appeared for series starting in warm decades. This fact showed that the results of trend studies are very sensitive to the choice of starting year. There were significant decadal variations in 40% of the series. The dates of occurrence of the phenophases, varying from the first days of May to the first days of June, correlated with seasonal temperature series, in most cases strongest to mean temperatures for the seasons March–May and April–May. The North Atlantic Oscillation Index (NAOI) for January and February appeared to have some predictive power for the date of occurrence of the recorded phases. The basis for this may be that the oscillations described by the index are of importance for the fulfilment of physiological chilling requirements needed to break bud dormancy. The same genotypes of the trees were grown in region West Norway and in Central Norwegian region; during the period 1965– 2005 the trends towards earlier bud burst were more pronounced and steeper at the western site.
Abstract
No abstract has been registered
Authors
Audun KorsæthAbstract
No abstract has been registered
Authors
Clemens Reimann Belinda Flem Arnold Arnoldussen Peter Englmaier Tor Erik Finne Friedrich Koller Øystein NordgulenAbstract
Le Roux et al. consider the approach that led to the above article as trend-setting. However, according to Le Roux et al. the data are unfortunately ‘‘inappropriately interpreted”. It is appreciated that le Roux et al. took the effort to study the original data and attempted a re-interpretation along the lines of an impressive list of publications which they claim have been ignored by Reimann et al. (2008). Here the achievements and shortcomings of their alternative interpretation will be discussed in view of the facts substantiating the conclusions of the original article......
Authors
Clemens Reimann Belinda Flem Arnold Arnoldussen Peter Englmaier Tor Erik Finne Øystein NordgulenAbstract
The recent article entitled ‘‘The biosphere: A homogenizer of Pb-isotope signals` has attracted considerable interest from other researchers in this area. According to the critical comments by Bindler and Shotyk, the authors have supposedly neglected a substantial body of the literature and especially the reported temporal changes in Pb-isotope ratios in a variety of sample materials. They conclude that the urban transect is not appropriate for defining natural variation, and state that a substantial body of research indicates a limited uptake of Pb in plants.......