Publikasjoner
NIBIOs ansatte publiserer flere hundre vitenskapelige artikler og forskningsrapporter hvert år. Her finner du referanser og lenker til publikasjoner og andre forsknings- og formidlingsaktiviteter. Samlingen oppdateres løpende med både nytt og historisk materiale. For mer informasjon om NIBIOs publikasjoner, besøk NIBIOs bibliotek.
1991
Forfattere
Oddvar SkreSammendrag
There was a strong accumulation of non-structural carbohydrates in the root and stem tissue, particularly at low temperatures and short daylengths. This was most obvious in the arctic birch population. The highest nitrogen and phosphorus accumulation was, on the other hand, found in leaves at high temperatures and moderate daylengths. As a result the C/N ratio between the total non-structural carbohydrate and total nitrogen content decreased with increasing temperature. The ecological significance of these results were discussed.
Forfattere
Bjørn LangerudSammendrag
Det er ikke registrert sammendrag
Forfattere
Knut SolbraaSammendrag
This is the first of five annual reports from the research program Forest ecology and multiple use, in which the universities in Trondheim, Bergen, Oslo and s, the Norwegian Institute for Nature Research and the Norwegian Forest Research Institute participate. To date, 12 projects have been started, covering bird species, invertebrates, cryptogames, methods of forest regeneration, timber production and quality in uneven-aged stands, timber extraction methods, and public use of forests, as well as economic consequences of various silvicultural methods and usages of forest land. The programme period is five years, with an estimated total input of resources between 30 and 40 million NOK. In accordance with the conditions set by the government departments of Environment and Agriculture, the highest priority is given to research dealing with conservation of animal and plant species threatened by modern forestry. The content of this report is summarized in the following eight points. 1. Despite a 75% reduction in input of resources compared to an initial evaluation of the needs, it was possible to establish an integrated research programme, covering important gaps in knowledge of ecologically better forestry practices in Norway. At least the projects dealing with invertebrates and cryptogames should be continued after the period in order to work out lists of threatened species, describe their living area requirements, and examine their distribution in Norway. 2. In Norway today, there are likely neither large areas of virgin forest nor areas of coniferous forest which have been in climax stage throughout several tree generations. This may limit the number of strongly specialized species. 3. Probably only a small number of higher animal and plant species are threatened by forestry in Norway. A large number of invertebrates and cryptogames may be vulnerable, however. Most of these are directly or indirectly dependent on a continuous supply of dying or dead trees, high air humidity and protection against heavy wind and sun radiation. Therefore, they may survive only in old and dense forest stands, often on high-productivity sites. 4. By pointing out threatened species or groups of species and describing their living area requirements, the programme may provide a basis for a better choice between alternative treatments in silviculture and also secure a great diversity of less specialized species. 5. Many of the species in question should be maintainable during commercial forestry. In order to secure the genetic variation and spread of specialized species, smaller areas should be preserved, as a supplement to the larger state-owned areas. 6. Norwegian forestry is now at the end of a 40 to 50-year period of partly exaggerated perfectionism and intensive utilization of the timber production potential. This is now shifting to more extensive silvicultural methods and a widespread interest in multiple use. 7. Descriptions of alternatives to clear-cutting and planting and cost-benefit analyses given by the programme may also contribute to ecologically better forestry in Norway. Evaluation of non-commercial benefits, such as the preservation of species, is necessary for a complete cost-benefit analysis. 8. Forest planning on both district and property levels is an important tool in multiple use which makes claims both to the field work and to the plan utilization in practical forestry.
Forfattere
Erik ChristiansenSammendrag
Det er ikke registrert sammendrag
Forfattere
Carl Gunnar FossdalSammendrag
Det er ikke registrert sammendrag
Forfattere
Anders Göransson Toril Drabløs EldhusetSammendrag
The effects of aluminium concentrations between 0.2 and 30 mM at pH 3.8 0.2 on small plants of Norway spruce [(Picea abies (L.) Karst], Scots pine (Pinus sylvestris L.), and Scots pine infected with the ectomycorrhizal fungus Suillus bovinus (L. ex Fr.) O. Kuntze were investigated. The plants were grown at maximum relative growth rate (RG % day1) with free access but very low external concentrations of nutrients. Steady-state conditions with respect to relative growth rate (RG) and internal nutrient concentrations were achieved before addition of aluminium, which was added as AlCl3 and/or Al(NO3)3. There were reductions in rg at aluminium concentrations of 0.3 mM in spruce, 6 mM in pine and 10 mM in ectomycorrhizal pine, i. e. at aluminium concentrations considerably higher than those normally occurring in the top layer of the mineral soil where most fine roots are found. Nutrient uptake rate per unit root growth rate was calculated for different nutrient elements. The uptake rate of calcium and magnesium was reduced at aluminium concentrations of 0.2 mM (spruce), 1 mM (pine) and 3 mM (ectomycorrhizal pine), without influencing Rg. The results question the validity of the hypothesis of aluminium toxicity to forest tree species at low external concentrations.
Forfattere
Oddvar SkreSammendrag
Seedlings of four populations from the two mentioned species were grown for 6 weeks in varying temperature, light and daylength. In accordance with earlier studies there was a strong latitudinal effect on the critical daylengths for growth. There was also a weaker, but significant effect due to altitude. Large differences were also found in growth pattern and compensation mechanisms. Fast-growing lowland populations reacted to low light levels and high temperatures by increasing their shoot/root ratios and the temperature optimum for shoot elongation. In mountain birch from Kevo, northern Finland, plants reacted to increasing temperatures by increasing their net assimilation rates. The shoot/root ratios and leaf area ratios were highest at the early stages of growth while maximum net assimilation occurred later. This illustrates the high priority in birch for leaf growth. In all populations except the northern population the plants grew better in alternating day and night temperatures than at the corresponding constant temperature.
Forfattere
Per Holm Nygaard Gunnar AbrahamsenSammendrag
A study on the effects of eight years application of artificial acid rain on the vegetation and soil in an old Scots pine forest is described. Artificial rain of pH 2.5 and 3.0 caused severe damage to mosses, especially Pleurozium schreberi and Dicranum polysetum. The presence of Melampyrum pratense decreased drastically in plots treated with rain of pH 2.5 and 3.0. In Vaccinium myrtillus reduced leaf production was found in plots treated with rain of pH 2.5. A considerable decrease in base saturation had taken place in plots treated with pH 2.5 and pH 3.0 rain. Exchangeable calcium and magnesium in particular had been reduced, and the content of mangnesium in tissue of Vaccinium myrtillus appeared also to be reduced in plots treated with water of pH 2.5. The study demonstrates the need for better methods in evaluating vegetation responses in field studies. The use of visual cover recording should be supplemented by frequency analysis and harvesting methods to get better estimates of changes in vegetation structure.
Forfattere
Oddvar SkreSammendrag
Support is given for the dark respiration as a limiting factor for growth at low temperatures. The existence of a so-called alternative respiration that is not linked to the growth process, supports this hypothesis, because of its possible function as a stabilizing factor (overflow function). Physiological mechanisms influencing plant survival in a cold environment and tree-line forming processes are discussed.
Forfattere
Gunnar Ogner Magne Opem Gabriele Remedios Gro Sjøtveit Britt SørlieSammendrag
Det er ikke registrert sammendrag