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
A. PliuraAbstract
No abstract has been registered
Authors
Tor MykingAbstract
Winter dormancy reduces or inhibits totally the growth ability of buds. Dormancy release and budburst in Scandinavian Betula pendula Roth. and B. pubescens Ehrh. ecotypes were studied in controlled environments. There was a gradual decline in the heat-sum requirement for budburst with increasing chilling time. Two main clines in time of dormancy release appeared in ecotypes of different geographic origin, a latitudinal cline and a coastal-inland cline in which the duration of dormancy increased southwards and towards the coast. In addition, dormancy was later alleviated in high-altitude than in lowland B. pubescens ecotypes. In late autumn, after 44 chilling days, time to budburst at 15C was less in plants chilled at 0C than in plants chilled at 10C, indicating that 0C was most effective for dormancy release. In January, after 105 chilling days, however, dormancy release was completed, and budburst was earliest in plants chilled at 10C. At this stage there were no detectable differences in effectiveness between fluctuating and corresponding constant temperatures (6 to 21C) in promoting growth and budburst in B. pubescens. Long photoperiods significantly reduced time to budburst in partly dormant buds, but had no effect when dormancy was fully released
Authors
Oddvar SkreAbstract
The biomass in four dominant field layer species was followed during six years after a fire in a pine forest in Sveio, western Norway. The overall biomass in the different species was estimated from the biomass per shoot, the shoot densities in pure stands of the investigated species and the percentage cover at medium burned sites. Corresponding measurements were made at control plots outside the burned area.The method was checked by comparing with ordinary area based sampling technique, and a general good agreement was found. The Vaccinium species and calluna were the dominant species at the control plot.Three years after the fire the total overall biomass at the burned site was already higher than at the control site, due to improved light and nutrient conditions. A strong increase in the overall biomass of Calluna vulgaris and deschampsia flexuosa was found in burned areas, and a slower regrowth of Vaccinium myrtillus and V. vitis-idaea.However, in the future the biomass is expected to decrease, and the species composition will probably change as nutrients are leached out of the soil and pine and deciduous trees (Betula pubescens and Salix caprea) are regerating from seeds and roots, leading to increased competition in the field and shrub layer.
Authors
Albert WinsentsAbstract
Describes results of a comparison of logging with running skylines on low bearing capacity terrain and typical skyline terrain in Norway. Study addresses technical issues of the same growing concern to minimize logging impact on sensitive terrain. Study also describes use of running skylines over special intermediate supports. Future research needs for mobile tailholds and supports, plus mechanized harvesting opportunities are suggested.
Abstract
No abstract has been registered
Authors
Jorunn Elisabeth OlsenAbstract
No abstract has been registered
Authors
V. Koski Jouni Partanen H. Hänninen Egbert BeukerAbstract
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
Kari Anne Sølvernes Gunnar OgnerAbstract
The impact of climate change on a mini forest ecosystem was studied for three years in an open-top chamber (OTC) experiment with an outside control plot. Clones of Silver birch (Betula pendula Roth.) and Norway spruce (Picea abies (L.) Karst) were grown in monolithic lysimeters containing undisturbed profiles of podsolic forest soil. The original understory was also present.The soil temperature was increased with 2-3 C. The atmospheric CO2 concentration in the OTCs was ambient (380mol mol-1 CO2), approximately 500 and 700 mol mol-1 CO2. The leachates from the lysimeters was collected, and the solute concentration was analysed monthly.Increased soil temperature increased the mineralisation of soil organic matter, and large amounts of nitrate, dissolved organic nitrogen (DON) and aluminium were released. In the leachates from the 500 mol mol-1 CO2 birch lysimeters, high concentrations of Al were recorded during the second and third growth seasons.The high concentrations of Al were correlated with high concentration of total organic carbon (TOC) and increased pH. Large amounts of Al was organically bound in these leachates. The origin of the organic ligands could have been products of the birch roots, e.g. root exudates.
Authors
Harald Kvaalen M. AppelgrenAbstract
We studied how light from different light sources influences germination and postgerninative growth of plants from somatic embryos and seeds of Norway spruce (Picea abies [L.] Karst).Somatic embryos of three spruce genotypes and seeds were subjected to light from commercially available light sources: Philips TLD Blue 18W/18 (BL), Osram Fluora (FL), Philips Cool White TL 50W/33 (CW), Osram Warm White 18W/30 (WW), Philips Yellow 36W/16 (YE) and Philips TLD Red 36W/15 (RE), 18 h a day, with a photon flux (PAR) at 30 mu mol m(-2) s(-1). After 6 weeks the germination frequencies of the somatic embryo-derived plantlets were 50% under BL and 98% under RE. The corresponding mean root lengths were 6.7 and 15.4 mm. In somatic embryo-derived plantlets cultured under BL, FL, CW and WW, both roots and hypocotyls turned brown, presumably due to production of phenolic substances. Browning was less severe in somatic embryo-derived plantlets cultured under RE and YE. Under RE, the epicotyl elongated in 37% of the plantlets after 6 weeks, compared with 70% under the other light sources. Seed germination and postgerminative seedling growth was modestly influenced by light from these light sources. RE and WW initially delayed germination as compared with BL, FL and CW, but after 2 weeks, more than 90% of the seeds had germinated under all light sources. In conclusion, germination and postgerminative growth of somatic embryos of spruce is sensitive to differences in light quality, whereas seed germination and seedling growth is not.