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
Large differences were found in survival stratey among species and ecotypes. The maple and elm populations and the two southern birch populations all responded to high temperatures by rapid leaf expansion as a possible compensation for increased respiration loss, and themaple and birch also by increasing their stem elongation rates, thereby competing more efficiently for available light. In the northern subalpine birch population, however, the seedlings developed leaves with high net assimilation rates instead of increasing their leaf areas and stem elongation rates. In this population abiotic climatic factors rather than competition therefor seem to be the most important adaptive force.
Forfattere
Tron EidSammendrag
This work deals with some effects erroneous measurements might have for the inventory results, the forecasts and the priorities of treatments in forest stands. The following variables are evaluated; site quality, total age, tariff number, number of trees/ha, basal area, mean height, conditions for logging and hauling, hauling distance and timber quality. The consequences of errors are considered by means of sensitivity analysis for 14 different stands (Table 2). Some considerations on how and why erroneous measurements appear, are done in chapter 2.3.Incorrect site quality or total age influences the total production, partly because the increment changes and partly because the treatments change. Fig. 1 shows an example of how a 20% incorrect site quality during a period of 35 years makes the volume change by 7-9%. The increment and the volume also change if the total age is incorrectly estimated (10%). The volumes change by 1% and 9% depending on the number of years in the time period between the \"inventory\" and the final fellings (Table 5).Incorrect site quality or total age might also influence the treatments of a stand, e.g. changed rotations age because the value increment has changed. An incorrect site quality might also insert \"incorrect\" regeneration methods. This is most likely in stands of medium site quality. An example shows that the net present value decreases about 30% if planting is selected instead of natural regeneration because the decision-maker believe that the site quality is F17, instead of F14.Incorrectly estimated basal area or mean height directly influence the volume. 10% biased basal area means that the volume changes 10% (Table 9 and 10). Approximately the same bias for the volume appears with 10% error for the mean height (Table 11 and 13). There is, however, quite big differences between these two variables with respect to other consequences.A biased basal area has small (Table 9) or none (Table 10) effects on the prices and costs/m3 because the size of the \"mean tree\" is little or not effected. A biased mean height has larger effects because the size of the \"mean tree\" changes. Cases where the net revenue/ha increases by 30-40%, if the mean height is 10% too high, is quite likely (Table 11 and 13).Incorrect tariff number or number of trees/ha do not influence the volume. The changes of the net revenues/ha are accordingly quite small (Table 7 and 8). This is particularly the situation for Norway spruce where both prices and costs/m3 increase if the tariff number or the number of trees/ha are positively biased.The change for Scots pine is larger because the prices/m3 decrease while the costs/m3 increase. For the costs/m3, errors have similar effects for Norway spruce and Scots pine, i.e. a positively biased tariff number or number of trees/ha increase the costs/m3, while a positively biased basal area or mean height decrease them.For the prices/m3, however, there is an opposite effect for tariff number, number of trees/ha and basal area, i.e. if incorrect measurements for one of these variables make the mean diameter increase, the prices decrease for spruce while they increase for pine (Fig. 2). A positively biased mean height makes the prices higher for both tree species in the considered stands.Two procedures to decide the volume/ha, the \"mean tree\" and the number of trees/ha are described in chapter 2.3.3. (see Table 1). The selected procedure is irrelevant for the volume, because this volume in both cases are based on the basal area and the mean height. The differences between the procedures appear when the \"mean tree\" is decided; the effects of errors are different because the number of trees/ha is measured in \"the number of trees procedure\", while the tariff number is measured in \"the tariff number procedure\".With a 10% biased tariff number in a spruce stand, the mean diameter change about 10% and the number of trees/ha change about 15%. There are more significant changes for pine, i.e. examples where the mean diameter changes more than 30% (Table 6). With a 10% biased number of trees/ha, the mean diameter changes about 5% for both tree species. The big changes of the variables describing the \"mean tree\" of \"the tariff number procedure\", make the changes for prices and costs/m3, and accordingly also the net revenue/ha, larger than the changes of \"the number of trees procedure\" (Table 7 and 8).An incorrect basal area has a small effect on the \"mean tree\" in both procedures (Table 9 and 10). For an incorrectly estimated mean height, however, the consequences are severe for \"the tariff number procedure\". This is accordingly also the situation for the prices and costs/m3, and the net revenue/ha (Table 11 and 13). Effects of erroneous measurements in cutting class II (age class, i.e. young stands) are considered for the variables regulated number of trees/ha and site quality.If these variables are biased, the volume increment change, accordingly also the volume of the final fellings. With a positive bias of 30% for the regulated number of trees/ha, there are examples where the volume of the final felling is more than 15% too high (Fig. 3). If the site quality is one 3-meter class too high or low, the volume of the final felling might have a bias of 30% (Table 14).The changes of the costs/m3 and net revenues/m3 are quite small if the conditions for logging and hauling are incorrectly classified (Table 15). The changes are larger if the timber quality is incorrectly classified. A 10% bias for the share of pulpwood, means that the net revenue/m3 changes 5.5% and 15.6% for spruce and pine stands respectively (Table 16). The large change for pine is due to the big difference between the price/m3 for pulpwood and sawtimber.
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
Jarle BerganSammendrag
Picea abies does not grow naturally north of the Polar circle in Norway (except for some sporadic occurrences in Finnmark). From 1973 to 1985 20 field tests were carried out at different vegetation types and altitudes in Nordland and Troms. The main objective of the investigation was to study survival, height growth and injuries to northern provenances of Norway spruce grown under various soil and climatic conditions. The climatic conditions at the experimental areas represent different kinds of heat and frost climate. According to Kielland-Lund (1981), the vegetation types represented in the investigation are: 13. ass.: Eu-Piceetum abietis a) Subass.: myrtilletosum b) Subass.: dryopteridetosum c) Subass.: athyrietosum 14. ass.: Melico nutantis-Piceetum abietis b) Subass.: typicum c) Subass.: aconitetosum The provenance codes are made up of a letter indicating the seed collection zone, and a number indicating the altitude (1=0-149 m a.s.l, 2= 150-249 m a.s.l. etc.). Fig. 1 shows the seed collection zones together with the geographical position of the field experiments. Particulars of plots and provenances are given in Tables 1 and 2. P2-Rana is used as standard provenance. The test fields are divided in two groups: 8 main fields including the 15 provenances shown in Table 2. 12 other fields includes a selection of the fifteen provenances listed in Table 2. In addition, three Finnish provenances are included in some of the experiments (see Chap. 2). The main results are given in Tables 59, 60 and 93. Provenances of Region 1 have in average for the eight main fields about 10% bigger heights than provenances from the regions 2, 3 and 4 (Table 60). As regards mean heights, P1 and P2 from Rana have turned out to be ranked among the best provenances at every experimental field, which is not always the case for P1-Drevja and P 1-Hemnes. At frosty sites and by unfavourable growth conditions at high altitudes, the results indicate that P2 from Rana is to be preferred to P1-Rana. At high levels not far from the timberline, P1 and P2 from Rana seem to be as well adapted to unfavourable local climatic conditions as local provenances in the southern part of Nordland (O4 and O5). At localities exposed to frost in the bottom of the valleys in Troms, the results show that provenances from high altitudes in the most southern part of Nordland (O4 and O5) are not to be preferred to P2-Rana. On the other hand, P3-Rana has achieved relatively good height growth and high survival at sites with unfavourable growth climate.At such areas, production of birch has to be considered instead of planting spruce. The height growth and survival of the three Finnish provenances have been good. However, there seems no reason to prefer theese provenances to P1 or P2 from Rana. At areas outside the natural bounderies of the provenances, Q1, Q2 and R1 has reached the relatively best heights and survival percentages at sites of favourable growth climate, preferentially in the outer districts of Nordland and Troms. The same can be said about O1-Vefsn and O1-Grane. The mean survival percentage of the plots varies between 80 to 90% for the different provenances (Tables 59, 60 and 93). The survival of the plants depends more on injuries by voles, vegetation pressure etc. rather than distinctions of provenances. Late summer frost is the most usual injuries by frost in North-Norway. All frost injuries specified in the tables are such injuries.
Forfattere
Ivar SamsetSammendrag
Rundt Islands nord- og vestkyster ligger det betydelige mengder drivtømmer. Det er mest furu og lerk, men også en del gran, edelgran, bjørk og osp. Det er tildels store tømmerdimensjoner, men også en del som er istykkerslått av isgang og bølgeslag mot strendene. Drivtømmeret på Jan Mayen ligner det vi fant på Island. Det er sannsynlig at tømmeret stammer fra Sibirs nordkyst. Det er revet løs av flom, isgang og storm, bl.a. fra områdene ved elvene, Ob, Jenisei og Lena. Derfra tar de nordøstlige overflatestrømmene tømmeret med til det når hovedstrømmer fra Beringstredet. Isen bringer tømmeret over Polhavet til havområdene mellom Spitsbergen og Grønland. Derfra bringer overflatestrømmene og nordveststormene det videre til Jan Mayens og Islands kyster. Bøndene foredler tømmeret i små sagbruk på gårdene. Lengst i nord er gårdene fraflyttet, slik at tømmerressursene samler seg opp.
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
Harald Eikeland Knut Rumohr BlingsmoSammendrag
I årene 1962 til 1966 anla Det norske Skogforsøksvesen fire proveniensforsøk med gran i Ringsaker kommune, Hedmark fylke. Formålet med forsøkene var å få produksjonstall for bestand av ulike provenienser. Det ble prøvd fire utenlandske provenienser, to østerrikske og to tyske, sammen med ni norske. De norske proveniensene strakte seg fra kyststrøkene på Sørlandet til midtre Trøndelag, og representerte et spenn på 6 breddegrader. Produksjonstallene fra oppmålingen av forsøkene i 1985-87 viste generelt små forskjeller mellom proveniensene. Mellom proveniensene med lavest og høyest produksjon var forskjellen omlag 10 prosent for diameter og 20 prosent for volum. Proveniensene varierte mye fra forsøk til forsøk, men jevnt over var de utenlandske proveniensene blant de høyest produserende, mens den nordligste av de norske, Trøndelag midtre, lå lavest. Den proveniensen som representerte den stedegne, lå hele tiden blant de med høyest produksjon. For et av forsøkene ble det foretatt toppskuddmålinger for 6-års perioden 1966-72. Det var svært god sammenheng mellom målingene av høydevekst for disse årene, og produksjonstallene fra 1985. Forklaringsprosentene lå mellom 70 og 80 prosent. Denne høye forklaringsprosenten var betinget av at en representativ andel av trærne ble høydemålt. De 1000 høyeste trær pr. ha gav best forklaring. Skader som gankvist, stammesprekk, krok og kløft ble registert på forsøkene. Gankvist var den vanligste skaden, og fantes hos omtrent 20 prosent av trærne. Stammesprekk fantes hos om lag 1 prosent av trærne. Det var små forskjeller mellom de ulike proveniensene. Årringbredden hos alle provenienser hadde det meste av tiden siden trærne nådde brysthøyde ligget over 4 mm. På grunnlag av disse forsøkene ble det konkludert med at hvis ikke lokalklimaet er ugunstig, er det lite grunnlag for å gi sentraleuropeiske provenienser noen særbehandling i takst- eller prognosesammenheng. Det tas forbehold om dette også gjelder for østeuropeiske provenienser og for foredlet materiale.
Forfattere
Halvor SolheimSammendrag
During an outbreak in the 1970\"s, millions of Norway spruce trees were killed by the spruce bark beetle Ips typographus. At that time, little was known about the associated fungi and their role in the tree-killing process. Studies were started to elucidate ecological aspects of fungi associated with I. typographus, with special emphasis on the fungal invasion process.I. typographus has no mycangium and caries a variety of fungal spores, externally in pits on the pronota and elytra and internally within the digestive tract. Spores are also transmitted by phoretic mites. Most species belong to Ophiostomataceae and confusions within some important species have been put right. The fungal flora aseetle, but with some variations. Four species proved to be common in Norway, but Ophiostoma polonicum was more frequent in epidemic areas man in endemic areas . The frequency of this species is thus suspected to increase during epidemics. Studies during epidemic conditions revealed that the fungi invaded the sapwood of infested Norway spruce trees in an obvious succession, with O. polonicum in the leading edge of fungal penetration until heartwood was reached. The species found to be most commonly transmitted by I. typographus were shown to be first in the succession.The temperature is important for the rate of fungal invasion and the development of visible blue-stain, which occurred close to the leading edge of fungal penetration. The fungal colonization of sapwood leads to a gradual decrease in the moisture content, followed by desiccation symptoms in the foliage of infested trees. The tree trunks soon reached a moisture level not favourable for decaying Hymenomycetes, except near the base of the trees.The primary invader O. polonicum appeared to be pathogenic to Norway spruce trees when mass inoculated, while the secondary invaders were not at the given load of infection doses. However, the inoculation doses are of importance for the success of inoculated fungi. Judging from the large reaction zones in the phloem made by same secondary invaders, they may play an important role in the tree killing process in areas with low frequencies of O. polonicum. O. polonicum can kill other species of spruce used in European forestry and Douglas fir, so the fact that conifers other than Norway spruce rather rarely are attacked by I. typographus seems not to depend on the absence of a pathogenic fungus to overwhelm the trees.The fungi associated with I. typographus are sensitive to the lesion resin produced by Norway spruce trees in response to the fungal invasion. The potential of O. polonicum to be a primary invader seems to be linked to its rapid growth rate and ability to grow for a prolonged period under oxygen-deficient conditions. In conclusion, it seems that the interrelationship between Norway spruce, I. typographus and associated fungi is similar to other interrelationships. One of the associated fungi, O. polonicum, appeared lo play a key role in overwhelming infested trees due its abilily to grow for a prolonged period in wood with low oxygen pressure.
Forfattere
Jon DietrichsonSammendrag
Gran av mellomeuropeiske provenienser fra Syd-vest Tyskland og Østerrike plantet på Syd-Østlandet har på uheldige steder fått frostskader, stammesprekker og meget gankvist. Plantearbeidet foregikk i stor skala fra 1960-79, og har ført til at tre- fire prosent av granskogarealet, for eksempel i Østfold, er beregnet å være bestokket med slike provenienser. Senere, i den mest forplantningsdyktige alderen, vil andelen av trær med mellomeuropeisk opprinnelse kunne utgjøre ca 10-20 %. For genspredningen er det uheldig at det innførte materialet overensstemmer ganske godt med den stedegne granas blomstringstid. Videre er det uheldig at det samme ofte kan være tilfelle for blomstringsmengdene. Vindbestøvende skogstrær viser størst genspredning. Gran rangerer imidlertid lavt i forhold til furu (Fig. 1).Beregninger er gjennomført for befruktningsandeler utenfra på 50 % eller 30 % i alle bestand (Fig. 2 og 3 ). I tillegg til de rene krysningene innen bestandene av mellomeuropeisk opprinnelse vil det oppstå provenienskrysninger. Halvparten av disse vil komme fra mellomeuropeiske mødre og den andre halvparten fra de norske. Fordi genspredning ved frø er over meget kortere avstander enn ved pollen, vil den første type av provenienshybrider hovedsakelig vise seg i eller like i nærheten av bestand av mellomeuropeisk opprinnelse. Den andre halvparten vil bli spredd utover i skogene. Frekvensene for de sistnevnte vil etter beregningene bli lave (4.5 - 8 %). I de tilfellene hvor provenienshybridene er dårlig tilpasset til klimaet ventes de å bli borte på grunn av naturlig seleksjon eller ved avstandsregulering. For å redusere eventuelle negative effekter av genspredningen er det anbefalt å utelate tynning av bestand som er spesielt dårlige. Videre kan omløpstida senkes. Naturlig gjenvekst i og omkring bestandene er anbefalt fjernet for å bli erstattet med kjent godt plantemateriale. I alle tilfelle vil de innførte proveniensene øke den arvelige variasjonen i skogene.
Forfattere
Anders Göransson Toril Drabløs EldhusetSammendrag
Det er ikke registrert sammendrag