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.
2001
Authors
Peder GjerdrumAbstract
Fuktforandringer i trelasten etter tørking før den når frem til sin endelige bruk er studert. En dynamisk modell for fuktutvikling i stabilt klima er utviklet og analysert. Temperaturområdet er 3 - 60 gr C, og modellen gjelder for planker av 50 mm gran. Arbeidet inngår i bestrebelene for å finne frem til en mer generell modell for et reelt, vekslende klima.
Authors
E. Mäenpää Oddvar Skre E. Malila R. Partanen Frans-Emil Wielgolaski Kari M. LaineAbstract
Gjennom tre sesongar (1983-85) blei det hausta prøver av bjørk (Betula pubescens) og ulike planteslag i feltskiktet på på seks lokalitetar i bjørkeskog langs ein kyst-innlandsgradient i bjørkeskog i Nord-Skandinavia. Prøvene blei skilt i grupper etter vevstype og analysert for stivelse og løyselege sukker. Analysene viste ein kraftig nedgang i karbohydratinnhaldet gjennom vekstfasen om våren, etterfølgt av ei gradvis oppbygging frå fotosyntesen i nye blad. Deretter var det ein gradvis nedgang, først på grunn av frukt- og frøutvikling, deretter sekundærvekst, og endeleg respirasjonstap gjennom mørkeperioden om vinteren. Denne nedgangen var størt på lågtliggande lokalitetar med lite nedbør.
Authors
H. Saxe M.G.R. Cannell Øystein Johnsen M.G. Ryan G. VourlitisAbstract
No abstract has been registered
Authors
Sondre Skatter R.R. ArcherAbstract
No abstract has been registered
Abstract
Understanding sulfate transport and retention dynamics in forest soils is a prerequisite in predicting SO4 concentration in the soil solution and in lake and stream waters. In this study forest soil samples from the Grdsjn catchment, Sweden, were used to study SO4 transport in soil columns from the upper three soil horizons (E, Bs and BC).The columns were leached using a sequential leaching technique. The input solutions were CaSO4 equilibrated with forest floor material. Leaching behavior of SO4 and concentration in the effluent were measured from columns from individual horizons.SO4 was always retained in the Bs and BC horizons, while the pattern for the E horizon varied. Attempts were also made to model SO4 breakthrough results based on miscible displacement approaches and solute convection-dispersion equation (CDE) in porous media. Several retention mechanisms were incorporated into the CDE in order to account for possible reversible and irreversible SO4 reactions in individual soil layers.The model was not successful in describing the mobility of SO4 in the top (E) horizon. Moreover, a linear equilibrium approach was generally inadequate for describing sulfate mobility in the Bs and BC horizons whereas improved model descriptions were obtained when non-linear equilibrium and kinetic approaches were utilized.We conclude that sulfate retention during transport in this forest soil is most likely controlled by kinetic reactivity of SO4 by reversible and irreversible mechanisms.
Authors
Morten Ingerslev E. Mälkönen Petter Nilsen H.Ö. Nohrstedt H. Óskarsson Karsten Raulund-RasmussenAbstract
Previous research has documented that nitrogen fertilization can lead to a significant tree growth increase in large parts of Scandinavia. Nutrient management of Nordic forests is currently under debate, mainly because environmental values are believed to be unnecessarily endangered by these actions. Nutrient management including fertilization, liming, recycling of wood ash or application of alternative nutrient sources can counteract nutrient deficiencies and imbalances, and be used for compensating the nutrients removed through harvesting. For successful implementation of nutritional management measures, several questions should still be studied. These questions mainly concern diagnosis of the need for applications, nutritional sustainability and treatment effects on the forest ecosystem and the surrounding environment.
Authors
Lars Sandved Dalen M. GriffithAbstract
Adaptation to cold and freezing temperatures is crucial for survival in temperate and boreal areas. Compared with angiosperms, little is known about the mechanisms of freezing tolerance in gymnosperms. Coniferous species such as Norway spruce (Picea abies L. Karst.) have a wide distribution in boreal areas, indicating a strong ability to adapt to lasting periods of cold and freezing temperatures.Freezing-tolerant perennial plants survive subzero temperatures by forming ice in intercellular spaces and the xylem. Certain proteins associated with pathogen attack have been found to exhibit antifreeze activity, i.e. the ability to bind and modify the growth of ice.In order to study the possible role of pathogenesis-related proteins in development of freezing tolerance in Norway spruce, we looked at the accumulation of chitinases during hardening under both artificial and natural conditions.Our findings show that chitinases and other pathogenesis-related proteins, as well as antifreeze activity, are present in needles of Norway spruce, and that they increase in response to shorter daylengths and cold temperature. It is possible that pathogenesis-related proteins accumulated in conifers during cold acclimation could also exhibit antifreeze activity, and thus play an important role during development of freezing tolerance in perennial plants such as the gymnosperm Norway spruce.
Authors
Peder Gjerdrum M. Warensjö M. NylinderAbstract
Log sorting according to dimension and quality is the first important step during conversion from sawlog to sawn timber. Crooked logs should be rejected or sawn to reduced yield. The 3D scanner furnish detailed information about the log geometry.Based on cylindrical co-ordinates four new parameters describing the centroid were evaluated: Maximum Radial Deviation (MRD), Standard deviation of the Sweep Angle (SSA), Distance from Log End to MRD (DLE), and Residual between the Radial deviation and a skew sinusoidal Model (RRM). 56 unbarked spruce logs were sampled, representing six different crook types denoted I, J, C, V, Z and S according to their curvature.Algorithms were established by means of logistic regression models to distinguish between several crook classes. It was concluded that the 3D scanner can be programmed to effectively perform automatic crook detection and classification.
– Natural organic matter in the nordic countries
Rolf D. Vogt, E.T. Gjessing, Dag Olav Andersen, ...
Authors
Rolf D. Vogt E.T. Gjessing Dag Olav Andersen Nicholas Clarke T.C. Gadmar K. Bishop U.S. Lundström Michael StarrAbstract
In the Total Organic Carbon (TOC) intercalibration sub-project a set of 10 synthetic and natural samples as well as non-labile reverse osmosis isolates were sent to 25 laboratories for the analysis of TOC and dissolved Organic Carbon (DOC).The outcome of the statistical treatment of the results from this intercalibration and the information regarding the participants instruments and standard operational procedures is that:Synthetic samples provide apparent better precision than natural samples. This fact, together with the good experience from the use of non-labile Reverse Osmosis (RO) and freeze dried isolates of dissolved organic carbon (DOM) in the intercalibration, lead us to recommend the use of RO isolates as material for the preparation of house standards and for determination of methods merits.The intra laboratory precision (relative standard deviation) varied from 5 to 16%.The fractionation of the DOC by 0.45um membrane filtering causes in some cases a contamination of carbon to the sample.A specific construction in a brand of the TOC analysers give poor results in samples with high TOC concentrations and that are of refractory material. The five selected sampling sites have proven, on the basis of their soil and water chemistry, to be well suited for studying the effect of climate and S-deposition on the characteristics of DOM. 163 water samples from two seasons (fall and spring) and 20 soil samples are collected and analysed.Most water samples are determined for all major charge contributing species, DOM fractions, and several other parameters. The DOM in the surface waters have been isolated both using reverse osmosis and hydrophobic resin (XAD8). The original surface water, reconstructed water by RO isolates as well as the XAD8 fractionated DOM have been characterized by a number of methods ranging from optical properties to pH and metal titration.The RO isolates have been provided to 14 scientific research groups in Europe and North America that are in the process of using their analytical technique to characterize the DOM.The soils have been determined for key explanatory variables as pH, cation exchange capacity and C/N ratio. The main findings from the characterisation of DOM is that:Generally the hydrophobic acid fraction (HPO-A) was the main DOM fractions in all water compartments and sites.Seasonal variation in the DOM fractionation is found to be greater than the variation between the sites and water compartments. The DOM fractionation is therefore not a fingerprint of the site.According to a batch titration experiment the aluminium complexing ability of the HPO-A and hydrophilics (HPI) DOM fractions (fractionated using only the XAD8 resin) was indistinguishable.The HPI fraction has generally a higher site density of weak acids (WA).The reverse osmosis (RO) isolates represent the total DOM in the original sample.NMR spectres of the RO isolates show that the main difference between the sites lie in the amounts of carbohydrates and aromatic compounds.The RO isolates produce reconstructed water with DOM that have similar optical properties.PCA analysis suggest that as the S-deposition is decreasing we should expect relatively more hydrophobic character of the DOM.The spring sample from Svartberget differs from the rest of the samples in that there was a small rainstorm causing a hydrologic episode during the sampling. This led to the lowest pH, highest TOC and organic charge (A-) among the surface water samples. In terms of DOM characteristics this temporal variation in flow regime led to the highest HPO-N DOM fractions, lowest intensity of the NMR spectre and low ash content and lower density of WA then expected. This expresses the importance of temporal variation during hydrologic episodes.
Authors
Carl Gunnar Fossdal Lars Sandved Dalen Jørgen A. Mølmann John Beck JensenAbstract
To find interesting gene products and to study gene expression in the green parts of Norway spruce we have sequenced 1101 cDNA clones based on mRNA isolated from needles. Here we present some preliminary findings describing the frequency of different Expressed Sequence Tags (ESTs), the ratio of similarity to known and unknown sequences present in GenBank and sequences not previously reported from Norway spruce. In addition we have tried to place the ESTs into major categories based on putative function