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.
1999
Authors
M. AlvetegAbstract
No abstract has been registered
Authors
Peder GjerdrumAbstract
In pine, heart- and sapwood can in some respect be considered two different timber species, with divergent wood properties. The knowledge of their occurrence has thus been a task for wood scientists ever since the fundamental work of Pilz (1907) a century ago. Close to 1800 observations from all over Scandinavia are analysed. Conclusion is that the physiological conversion from sap- to heartwood in the living tree is under the sole control of time, i.e. years past since activity in the apical. Other factors (height in tree, tree or stand characteristics) seem to be without influence The prediction of heartwood amount in individual trees in a stand of known age is thus attainable. Accordingly, the estimation of age in a log cross-cut, and thus of mean annual ring width, is also feasible, once diameter and heartwood ratio is known. Experiments using IR photography indicate the potential of using such equipment in heartwood detection.
Authors
J. MikolaAbstract
No abstract has been registered
Authors
Severin WoxholttAbstract
No abstract has been registered
Authors
Jan Mulder E. Matzner J.F. Gallardo Edward TippingAbstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Erik Christiansen Bohumil KuceraAbstract
Kvaelommer fins i mange bartreslekter; de skaper problemer for treforedlingsindustrien, og man vet ikke hvordan de oppstår. De er vanlige i Sørøst-Norge hvor skogen ofte angripes av granbarkbillen, men ikke på Vestlandet hvor billen ikke finnes. Det kunne derfor tenkes at de oppstår som følge av billeangrep. Dette ble undersøkt i et materiale fra Ås i Akershus.Våren 1987 ble et dusin grantrær angrepet av granbarkbillen etter at det var satt feromondispensere på dem, men billene var for få til å erobre trærne. Angrepspunktene på stammen ble merket av, og flere år senere ble trærne felt og undersøkt. Resultatet viste at billeangrepet etterlater tydelige spor i veden hos trær som overlever, men disse er helt forskjellige fra kvaelommene, som derfor må ha en annen årsak.
Authors
V.I. Kharuk S.G. Shiyatov M.M. Naurzbaev E.V. FedotovaAbstract
No abstract has been registered
Abstract
DOC concentrations in soil water in podzols decreased from median values of 37 and 39 mg/l in the F and H layers, respectively, to about 6 mg/l in the B horizon. The decrease was most pronounced in the mineral soil. An increase in concentrations was found in the surface soils in late summer and autumn, apparently due in large part to increased production, which took place in both the canopy and the forest floor, although evaporative concentration of soil water could also have been partially responsible. In the B horizon, increased concentrations of DOC could be observed in the autumn, although these increases were much lower than for the surface horizons. A correlation was found between the surface soil DOC concentrations and the mean surface soil temperature 1 to 2 months previously, which could be due to the buffering effect of sorption processes. However, the increase in the net amount leached could not be clearly attributed to increased temperature. In the autumn, concentrations did not decline immediately when temperature decreased, which may be due to leaching of previously adsorbed organic matter. During the autumn, concentrations of DOC in streams increased in periods of high discharge due to increased input of high-DOC surface soil water. At the same time, DOC concentrations in surface soil water largely decreased, presumably as DOC was washed out. An increase in DOC was not seen in periods of high discharge in the early spring. The highest concentrations of TOC (both with and without flux-weighting) at the weir were also found in the autumn). Correlation of TOC in streamwater with temperature was poor but, for the winter months, often significant. A positive correlation in the winter was probably associated with higher fluxes due to temperature-induced snowmelt. DON, which is the dominant form of dissolved nitrogen at all depths in the podzols at Birkenes, also decreased sharply in concentration in the mineral soil. However, there was an increase in the concentration of DON relative to DOC. The C/N ratio thus decreased downwards in the soil, indicating a possible preferential adsorption of N-poor DOC. Much of the DON in throughfall appeared to be of low molecular weight. This was not the case for DON in soil water.
Authors
Tore SkrøppaAbstract
No abstract has been registered