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.
1992
Forfattere
Arne Olav Stuanes I. Andersson Nancy B. Dise H. Hultberg O. Janne Kjønaas Per Holm Nygaard U. NyströmSammendrag
Det er ikke registrert sammendrag
Forfattere
Dan AamlidSammendrag
Det er ikke registrert sammendrag
Forfattere
Stein MagnesenSammendrag
The presence of genetic differences attributable to differences in geographic origin has been demonstrated in many temperate zone tree species. The variation between provenances is usually thought of as a result of natural selection. Most strongly affected by selection are characters of great importance to the trees, such as fast growth and resistance to frost. A provenance may be regarded as a climatic type adapted to the climatic conditions at the place of origin. Trees of local provenance will normally be capable of surviving without damage, but introduction of non-local provenances may lead to complete failure. Different climatic types will behave differently according to the climate of the region into which they are introduced. Experiments and field observations have shown that species and provenances transferred to an environment to which they are not adapted, will suffer physiological damage. This in turn leads to inferior growth and weakened trees. Subsequently, injuries and loss of vigour make the trees highly susceptible to pathogens and attacks by insects. Use of poorly adapted provenances may cause, not only reduced vitality and vigour in the trees, but complete destruction of whole stands. The unfortunate choice of provenance may not become apparent till trees are 20-30 years old. There can be mentioned many cases in which promising plantations have become failures at a later stage. In western Norway climatic damage and attacks of the pine needle cast fungus nearly devastated coast plantations of non-coastal Scots pine during the years 1921-23. In the same region climatic damage and disease caused destruction in stands of white spruce and lodgepole pine of interior provenance. In a field trial with Scots pine in eastern Norway nearly all trees of continental European provenance died after 29 growth seasons. In eastern Norway and the Trndelag counties dead and dying trees were observed in planted stands of Norway spruce at age 30-50 years. Investigations showed that the trees in the plantations had a growth-rhythm different from that of the local Norway spruce. An unfortunate growth-rhythm which was out of phase with the climate at the sites, was the most plausible explanation for the damage and mortality found in the plantations. Among forest injuries related to provenance climatic damage is most prominent, and in a northern country like Norway most climatic injuries are attributable to frost. Frost injuries cause reduced height growth and poor wood quality. The extent to which any particular provenance is liable to suffer damage by frost depends on the degree to which its annual growth rhythm synchronizes with the cycle of the seasons. Autumn frost affects forest trees with late and incomplete growth termination. Generally, northern provenances, high altitude provenances and continental provenances stop growing and pass into the hardy winter stage at an earlier date than southern provenances, low altitude provenances and coastal provenances respectively. The variation in resistance to autumn frost is more or less clinal, depending on the tree species. Winter frost damage frequently occurs in late winter when there is a large temperature difference between day and night. However, causal relation is often complicated. Low temperature is decisive, but other factors may be disposing or contributing. A long, mild, wet, dark autumn or a summer extremely deficient in warmth will cause insufficient maturation of tissue, and shoots will not acquire their normal frost hardiness. The predisposed shoots may then be injured by frost during the following winter. For the same reason provenances with late growth cessation and improperly matured shoots will be most liable to injury caused by winter frost. Accordingly, provenance variation in winter frost resistance will be much the same as that in autumn frost resistance. A mild winter period lowers the resistance, and later frost may cause damage. Winter frost stability resistance is the ability to maintain frost hardiness after a period of mild weather. Research indicates that this type of resistance is also under genetic control, i.e. provenance variation does exist. However, winter frost stability resistance does not correspond completely to the seasonal growth rhythm of trees. Spring frost damage is related to the time of flushing, and early flushing populations are most susceptible to frost. In general, southern provenances, low altitude provenances and coastal provenances tend to flush late, but clinal variation in spring frost resistance is hard to establish owing to substantial local variation in most tree species. Differences between species are frequently more significant than those between provenances. Southern provenances commence shoot elongation late in spring. Nevertheless, spring frost has been known to damage southern provenances more severely than those of northerly origin. It seems that populations which mature late in autumn also become more susceptible to spring frosts. On several occasions a significant relationship has been established between spring frost damage and injuries caused by autumn and winter frost. Research indicates that frost damage may also disturb the annual growth rhythm of trees. Drought damage occurs during dry periods in summer or in winter when the frozen ground prevents the trees from replacing their water loss. Constant winds will also cause drought damage. With reference to drought resistance, there are considerable differences between tree species, but provenance variation, e.g. in cuticular transpiration, does not seem to be of great consequence. For Scots pine and lodgepole pine grown in coastal areas, however, there are considerable differences between provenances in their ability to withstand desiccation by wind. Coastal provenances consistently show greater resistance to this type of damage than those of interior origin. For Norway spruce provenance is of great importance regarding stem cracks caused by late summer drought. Trees of continental European provenances are most frequently affected.Diseases caused by pathogenic fungi may seriously damage, or even kill forest trees. From field observations it would appear that many tree species are less resistant to pathogens when grown outside their natural range. Climatic conditions to which the trees are not adapted, may lead to physiological disorders which greatly reduce the capacity of the trees to withstand threats from the major pathogens. As fungi frequently enter through wounds and other injuries, frost is of great importance as a predisposing factor. This has the effect of making frosthardy provenances less prone to infection. On the whole, trees weakened by climatic injuries are apparently more susceptible to pathogens than others. As a result of experiments and field observations it would appear that in some cases resistance to disease is not related to climatic injuries. Attacks by insects may constitute a threat to the growth and vitality of forest trees. However, very little information is available regarding provenance variation in susceptibility to insect attacks. So far investigations suggest that provenance is not of great importance. On the other hand, the physiological condition of the trees will affect the ability of insects to feed and multiply. As weakened trees apparently succumb more easily to invasion pressure than others, it is of great importance to keep the forest healthy and vigorous by using well adapted provenances. Investigations indicate that air pollution may have the effect of making poorly adapted provenances even more susceptible to climatic damage. It is quite obvious that the use of well adapted provenances is a prerequisite for obtaining a healthy and vigorous forest. The occurrence of unexplainable forest injuries may be due to an unfortunate choice of provenance. It is important therefore to check the provenance of injured trees.
Forfattere
Knut Solbraa Svein GrønvoldSammendrag
Selvom resultatene er foreløpige, usikre og mangelfulle, inneholder de viktige elementer. Det ser ut til at det største antallet truete arter finnes innen lavere dyr og planter, og at listen over slike arter fra naboland ikke nødvendigvis passer under norske forhold. Mange av artene lever i skog med mye død ved, med stor tretetthet og på fuktig mark. Slike biotoper er derfor viktige for å bevare et stort artsmangfold og truete arter. Noen arter tåler antagelig ikke hogst og må derfor tas vare på ved vern av mindre områder med skånsom hogst omkring. Andre kan bevares ved forsiktig hogst, som bledningshogst, på passende arealer. Flere arter som i dag ikke er truet vil også ha nytte av tiltak for truete arter. For blant annet hakkespetter vil økt insektproduksjon øke mattilgangen. For svartspett kan mengden av reirtrær begrense bestandstettheten i enkelte områder. Ved å sette igjen store osper og furufrøtrær, sikres ynglemulighetene både for denne spetten og for dyr og fugler som overtar spettens reirhull. Hvitryggspetten har hatt konstant bestandstetthet i undersøkelsesområdet i Hordaland i perioden 1986-91. Arten er klassifisert som truet både i europeisk og norsk naturforvaltning.
Forfattere
Ketil KohmannSammendrag
Etter at godkjennelsen av DDT ble inndratt den 1/1 1989, ble de nye pyretroidene introdusert som alternative midler mot rothalsgnagende insekter. Forsøkene viser at de alternativer som i dag er godkjente sannsynligvis gir bedre vern enn det tidligere brukte DDT. Ved behandling av planter mot rothalsgnagende insekter kan det ved behandling om våren generelt anbefales å bruke ca 2 % Gori 920 eller 4 % Sumicidin 10FW. Ved behandling om høsten før innlegging på kjølelager kan Gori 920 bare brukes dersom det benyttes en rutine med `rothalssprøyting` som dekker mindre enn 50 % av plantens totale lengde. Ved denne rothalsbehandling anbefales 2 % konsentrasjon av preparatet. Total behandling av planten forårsaker forsinket rotvekst om våren, forsinket skuddskyting og redusert toppskuddvekst samtidig som dårlig apikal dominans fører til buskvekst på en stor andel av plantene. Dårlig apikal dominans og buskvekst er påvist i 3 år etter utplanting.Det er ikke godtgjort at man også ved sen høstplanting (med behandling etter midten av september) bør bruke `rothalssprøyting`, men forfatteren regner det for sannsynlig. Ulike andre pyretroider er testet i forbindelse med kjølelagring, og av enkelte midler er det påvist til dels betydelige sviskader av preparat som f.eks. Forse (teflutrin) og oljebasert Karate (cyhalotrin). Sumicidin 10FW kan anvendes både til dypping og rothalssprøyting. En svakt redusert rotaktivitet synes å være tilstede i de første uker etter utplanting uten at dette kan påvises statistisk i feltforsøkene.
Forfattere
Knut Solbraa Svein GrønvoldSammendrag
The goal of this report is to collect and publish knowledge about the Hirkjlen demonstration forest and the area around it. The report will be useful as documentation for visitors to the forest. At the same time the report should be of general interest in showing the different uses and ecology of mountain forests. The report begins with a chapter on Hirkjlens soil conditions. The immigration of important flora and fauna groups is given chronologically. Much of the presentation is connected to human activity, which may have started as early as 6000 years ago. Moose trapping and iron production on a large scale began approximately 2000 years ago. From the end of the migration period (year 500) to year 1000, as well as from the time of the black plague (1349) to the middle of the 1500s there was little activity in the area. Outfarming started around 1690 and lasted almost 270 years. Forest operations in todays scale began around 1710. Tourism began to flourish in the 1870s and there are now three tourist companies with a total of 200 beds at Hirkjlen. Ecological research started in 1931. A large portion of the mountain forest is either not economically harvesteable or has an annual growth under the limit for productive forest (1 m3/ha/year). Climatic and ecological considerations recommend that these forests should not be harvested. These areas are therefore protected from all forestry activities together with 35 ha productive forest. In this way all types of old-growth forest represented in the demonstration area are preserved. The report contains a detailed description of the protected spruce forest on high site index and how the forest structure change as we approach the timber line. The description forms the foundation for evaluation of the maximum acceptable altitude for the harvesting of such forests. Forestry should take into considerations other interests than timber production outside of the protected areas, as well. A forests thematic map shows protected areas and edge zones, as well as restrictions on future operations. Another map shows the location and type of all stand entries for the coming three years. At the demonstration forest the area is presented on information boards both indoors and outdoors. Experiments, demonstrations, natural variations in soil, vegetation, forest types, as well as archeological and cultural findings, view points, lakes, and streams form the basis for five nature paths with a total length of 30 km. All posts are well documented with pamphlets and signs. The total cost of construction and information materials is between 1.5 and 2 million Norwegian crowns. During the summer the area is used daily for teaching school classes of different levels, and for both group and individual excursions. Various research institutions will participate in the future registration of archeological and cultural findings, and of endangered and sensitive species. NISK will be responsible for research upon multiple use possibilities and limitations. In addition to this, NISK is responsible for maintenance and further development of the demonstration area.
Forfattere
Reidar Skaar Halvor WesternSammendrag
Forest truck roads are necessary in order to carry out proper management of a forest area. In the Nordic countries there is now 400.000 km with forest truck roads. Based on a pilot study it was obvious that the conditions of the forest truck roads were not satisfactory from a road maintenance and vehicle transportation point of view.Unsatisfactory standards of bearing capacity, surface course, base course, geometric alignment were observed as major problem areas. Most of these problem areas might be solved by use of better methods and equipment for maintenance and rehabilitation of forest truck roads. Different methods and equipment for measuring the bearing capacity were tested.Use of the falling mass deflectometer (fig. 5) with a falling mass of 14 kg and a drop height of 1 m seems to be an effective method for measuring the bearing strength of forest truck roads. A simple method for analyzing gravel deposits out in the field is developed. This method makes it more relevant to put more emphasis on the quality and composition of the gravel material used for surface and combined surface/base course layers.Mixing on the road of two moraine materials which each has less satisfactory specification band is tried. The mixed material achieved an almost satisfactory specification band. The cost for transport, mixing and levelling on the road amounted to 20 SEK per m3 mixed material. Mixing of two moraine materials in the pit has also been tried. The cost of the mixing operation was 6,20 SEK per m3 mixed material.Research on surface and combined surface/base course layers with stone sizes until 100 mm showed interesting results. Use of such coarse materials give cheaper material and maintenance cost for the road. However, coarse materials might give increased cost for placing and levelling of the materials on the road. Coarse materials with maximum stone size of 70 mm seems to give good overall results on forest truck roads with small and average traffic, that is 0-30 vehicle passes per day.Production of crushed stone materials to be used on forest truck roads has been investigated. Crushing of moraine to 0-60 mm material by use of a mobile crusher showed a production of 53 m3 of crushed material per effective hour. The cost was calculated to 13 FIM per m3 crushed material. When crushing to 0-30 mm the production was reduced to 21 m3 and the cost increased to 24 FIM.Maintenance of fine gravelrich (0-20 mm) surface courses with farm tractor equipment is investigated. This equipment is effective when the task is to remove holes and ruts on the road surface which are not deeper than 3 cm. If the task is to remove deeper holes and ruts a 12-14 ton grader is more efficient. Maintenance of coarse (0-70 mm) surface courses requires a 14-16 ton grader. After the grading the road surface should be compacted with a 5 ton vibrating compactor. Compacting with a vibrating compactor equipped with rings (fig. 19) gave good results on coarse gravel materials.Use of bitumenous materials on forest truck roads has been investigated. On forest truck roads with little traffic spraying of a bitumenous emulsion gave almost maintenance-free road surfaces for until 7 years. On roads with average and greater traffic use of oil gravel can be economically justified especially on the steeper gradients.Trials with open top culverts indicate that these are efficient on 10-16% gradients but only on roads with so minor traffic that grading is very seldom carried out. Rehabilitation for forest truck roads with grader and wheeled front-end loader (shovel) is investigated. This resulted in two improvements of the front-end mounted implements used by the shovel.Forest truck road rehabilitation with farm tractor equipment has also been investigated in the project. This type of equipment is quite effective for light rehabilitation tasks.
Forfattere
Svein SolbergSammendrag
Registrering av skogens kronetetthet og -farge utføres i dag i mange land, og har sin bakgrunn i omfattende skogskader flere steder i verden i seinere år. Som en del av det norske overvåkingsprogrammet har de lokale skogbruksetater siden 1988 utført registreringer på fylkesvise lokale overvåkingsflater. Flatene er subjektivt utvalgt i grupper, hver med fire flater i ulike utviklingstrinn, hovedsakelig i blåbærgranskog. I 1992 er registreringer utført på 746 overvåkingsflater, med totalt 46000 trær. Det har vært en jevn, men ikke dramatisk, nedgang i vitalitet på de fylkesvise lokale overvåkingsflatene i femårs-perioden 1988-92, særlig på Østlandet. Siden i fjor har kronetettheten gått betydelig ned på Vestlandet (nordre del), og Østlandet har hatt nedgang både i kronefarge og kronetetthet. Nedgangen i vitalitet for hele materialet kan delvis ha sammenheng med tørke på Øst- og Sørlandet de siste to somrene, og orkanen på Vestlandet og i Trøndelag ved begynnelsen av året.
Forfattere
Tore SkrøppaSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag