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
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
Abstract
No abstract has been registered
Authors
Ketil KohmannAbstract
Side effects of the permethrin formulations Gori 920 and Gori 920 L, the fenvalerate formulation Sumicidin 10 FW and the emulsifier of the Gori formulations have been studied in seedlings of Norway spruce. Whole plant treatment with the Gori formulations in early autumn resulted in a 5 - 10 C poorer frost tolerance (TDI) later in the autumn. Moreover, this treatment increased mortality by 30 % within two years of testing in field trials. A basal part treatment with the Gori formulations and whole plant treatment with Sumicidin 10FW containing 10 % fenvalerate, gave on the other hand no negative effects during two years of field testing. Late autumn treatment with Gori 920 and Gori 920 L. followed by cold storage for six months revealed poorer frost tolerance (3-4 C) in the spring than the control. These treatments also reduced leader shoot growth in the first year, and increased the frequency of plants lacking a dominant leader after two years by 20-40 %. The detrimental agent in Gori 920 L was found to be the emulsifier, ethoxylated nonylphenol, alone and in combination with the dispersal agent, the linseed oil. The linseed oil gave no significant additional negative effect on frost resistance and growth after the cold storage during the winter. The investigation demonstrates the necessity of testing for possible side effects before practical use of any commercial pesticide formulation. The experiments were conducted in Norway at the nursery of Buskerud Forestry Society and at The Norwegian Forest Research Institute at s
Authors
Rune Halvorsen Økland Knut Rydgren Tonje ØklandAbstract
No abstract has been registered
Authors
Per Holm Nygaard Torbjørn ØdegaardAbstract
Vegetation data were collected in 1931, 1961 and 1991 from permanent plots in a boreo-nemoral forest 20 km north of Oslo in southern Norway. Major changes were found in the vegetation composition during 60 years. The main changes were a reduction in the frequency and frequency of joint occurrence of species like Calluna vulgaris, Vaccinium uliginosum, Trientalis europaea, Maianthemum bifolium, Melampyrum pratense, Cornus suecica, Andromeda polifolia, Eriophorum vaginatum, Vaccinium oxycoccus, Pleurozium schreberi, Hylocomium splendens, Ptilium crista-castrensis, Dicranum fuscescens and Ptilidium ciliare. The observed changes were interpreted as induced by internal processes e.g., a long-term change from paludified forest to mesic forest. In particular the growth of Picea abies seems in particular to be a main driving force. The dominance of Picea abies and Vaccinium myrtillus appears to have made the conditions more unfavourable to other species. A doubling of the living stem biomass of P.abies during the last 67 years shows that this old-growth forest has not reached a steady state. Species like Deschampsia flexuosa and Molinia caerulea did not increase in frequency as has been demonstrated in response to nitrogen deposition elsewhere in northern Europe. The results of this study indicate that protection from logging has promoted the reduction of species in the field layer and bottom layer. This study questions if monitoring of forest vegetation should be restricted to protected forests as is the practice in Scandinavia today. We recommend that areas with some kind of selective cutting are also used for monitoring of forest vegetation
Abstract
No abstract has been registered
Authors
Tore SkrøppaAbstract
No abstract has been registered