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.
2011
Abstract
A rapid increase in the frequency of Dutch elm disease (DED), a wilting disease of elm trees caused by bark-beetle vectored fungi, was observed in the early 1990s on several wych elm stands around Oslofjord, southern Norway. To examine the current status of the disease and its impacts on elm population, disease frequency and size distribution of elms were recorded at four locations. Northern parts of Lier, a municipality most affected by DED in Norway 15 years ago, showed in the survey season 4% disease frequency, whereas 13.8% of trees were dead, the dead trees having accumulated over several years in the unmanaged stands. In southern parts of the municipality the mean disease and death percentages were 1.9 and 2.4%. Compatible with their low disease incidence in early 1990s, the other two areas now examined, municipality of Larvik and district of Grenland, showed comparably low frequency of DED. Northern part of Lier showed significantly higher overall density of elm trees per hectare than the other examined areas, and also the small elms below 5 cm in d.b.h. were most frequent in this region. In contrast, the density of large trees was lower in northern Lier than in the other examined areas. These data suggest that regeneration of the tree is not prohibited owing to the disease but that the large trees have been locally reduced in frequency as a result of DED. The superior general density of elm trees in northern Lier, owing to the exceptionally rich soil in the warm southern slopes of the region,> may have contributed to the rapid increase of DED in the area 15 years ago and to the subsequent settlement of the disease outbreak as a chronic stage.
Authors
Holger LangeAbstract
In ecosystem research, data-driven approaches to modeling are of major importance. Models are more often than not shaped by the spatiotemporal structure of the observations: an inverse modeling approach prevails. Here, I investigate the insights obtained from Recurrence Quantification Analysis of observed ecosystem time series. As a typical example of available long-term monitoring data, I choose time series from hydrology and hydrochemistry. Besides providing insights into the nonstationary and nonlinear dynamics of these variables, RQA also enables a detailed and temporally local model-data comparison.
Abstract
No abstract has been registered
Abstract
The Norwegian landscape is changing as a result of forest regeneration within the cultural landscape, and forest expansion has impacts on accessibility, visibility, and landscape aesthetics, thereby affecting the country's tourism industry. This study aimed at identifying the potential areas of forest regeneration and anticipated subsequent landscape effects on different categories of tourist locations in southern Norway. Deforested areas with a potential for forest regeneration were identified from several map sources by GIS-analyses, and 180 tourist locations were randomly selected from the Norwegian national tourism database (Reiselivsbasen), and then buffered by 2 km radius for land cover classes. The findings revealed that approximately 15% of southern Norway has the climatic potential for future forest regeneration, in addition to 5% of cultivated land. Future forest regeneration will affect the landscapes surrounding the tourist locations of rural south Norway, and while the potential is nationwide, it is not uniformly distributed. Two important tourist landscape regions seem especially exposed to forest regeneration: the coastal heath region and the mountain landscapes. Large parts of these areas do not have sufficient numbers of domestic grazing animals necessary to maintain the present character of the landscape.
Abstract
No abstract has been registered
Authors
Tore Filbakk Olav Albert Høibø Janka Dibdiakova Juha NurmiAbstract
To achieve optimal utilisation of logging residues for energy, it is important to know how different handling and storage methods affect fuel properties. The aim of this study was to model how the moisture content and dry matter losses of logging residues develop during storage. Logging residues were collected from five different stands of spruce and pine during different seasons of the year and stored in the same location. The logging residues were stored in covered piles of bundled residues and loose residues. Only minor differences were found in the moisture content profiles between piles of bundles and loose residues. Logging residues located in the centre of both types of piles had considerably lower moisture content than the outer parts. The moisture content significantly affected dry matter loss, with the highest dry matter losses being found in the samples with the least favourable drying conditions. The dry matter losses varied between 1 and 3% per month. Significantly higher dry matter losses were found in the spruce bundles than in the pine bundles. Seasoned logging residues had the lowest dry matter loss, while the logging residues harvested and piled in the autumn had the highest loss.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Tatsiana Espevig Michelle DaCosta Lindsey Hoffman Trygve S. Aamlid Anne Marte Tronsmo Bruce B. Clarke Bingru R. HuangAbstract
Field trials at two locations in Norway previously demonstrated differences in winter survival between two Agrostis species used for turf, velvet bentgrass (VB; A. canina L.) and creeping bentgrass (CB; A. stolonifera L.). The objectives of this study were to compare freezing tolerance and crowncarbohydrate composition of VB and CB. We also compared a direct and two indirect methods of measurements of freezing tolerance. Treatments consisted of: (i) nonacclimated (NA); (ii) acclimation at 2°C for 2 wk (A2); (iii) acclimation at 2°C for 4 wk (A4); and (iv) acclimation at 2°C for 4 wk plussubzero acclimation at –2°C for 2 wk (A4+SZA2). Crowns were harvested for determination of carbohydrates and freezing tolerance. Freezing tolerance (lethal temperature for 50% of the test population [LT50]) was based on whole plant survival (WPS), 2,3,5-triphenyltetrazolium chloride (TTC)reduction, and electrolyte leakage (EL). There were no significant difference in freezing tolerance between VB and CB. The LT50 based on WPS was significantly lower for plants exposed to A2 (–12.7°C), A4 (–14.5°C), and A4+SZA2 (–14.6°C) compared to the NA control treatment (–8.4°C). The concentrations of fructans and sucrose were significantly higher in A2 compared to NA plants of both species, but only fructans continued to increase at A4. The LT50 based on TTC reduction showed better correlation with LT50 based on WPS compared to LT50 values based on EL.
Authors
Wendy Marie Waalen Karen K. Tanino Jorunn Elisabeth Olsen Ragnar Eltun Odd Arne Rognli Lawrence V. GustaAbstract
No abstract has been registered