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.
1993
Forfattere
Jan-Ole SkageSammendrag
Det er ikke registrert sammendrag
Forfattere
Torstein LislandSammendrag
Det er ikke registrert sammendrag
Forfattere
Per Kr. Rørstad Birger SolbergSammendrag
Det er ikke registrert sammendrag
Sammendrag
Norwegian forests receive various amounts of air pollutants. Several of them are harmful to trees. The forest health situation is therefore monitored by regular surveys, in accordance with internationally recommended methods. Investigations so far have shown that the deposition of air pollutants is largest in southeastern Norway and in a limited area close to the Russian border, in northeastern Norway.Sulphur and nitrogen compounds are among the main pollutants that may lead to adverse effects. However, their airborne concentrations are not high enough to cause direct injury to trees in Norway, except for northeastern parts being affected by emissions from Russian industries. Indirect injury, by leaching of nutrients from trees and soils, and disturbances of the nutrient balance in various ways, is more likely. Ozone concentrations may reach harmful levels, and may affect vegetation directly, especially in the southern part of Norway.Monitoring is performed in order to reveal whether forest damage occurs from such causes, and if so, where, and whether the amount of damage will change with time. So far the results show that there is no extensive dieback of forests in Norway; the annual death rate of trees is low and appears normal.Based on the international criteria applied, the vitality of the forest appears to be low. Part of the reason for that may be the location of Norwegian forests towards the north, towards mountains, and towards the ocean, where forest growth is limited naturally.However, results indicate that forest conditions in the southern part of the country are affected by air pollution. Most cases of crown discolouration are found in that region, and the number of discoloured (yellow) trees has increased noticeably during the last few years. In the same region crown density has been low, and has been further reduced lately. According to a conservative estimate the average crown density is being reduced by 0.4% (units) annually.Crown density has been shown to be related to tree increment. However, the negative effect of reduced tree vitality is believed to be over-shadowed by the positive effect on growth of nitrogen deposition.Air pollutants are causing various effects in forest ecosystems. It appears that regions in southern Norway receiving large amounts of air pollutants have a high number of acidified lakes containing high concentrations of sulphate and nitrate. In this region the soil is shown to be low in base saturation and leachable phosphate, and high in nitrogen, sulphur and zinc.Those monitored plots showing the highest concentrations of Al and the lowest Ca:Al ratio in their soil water are also located here. The forest in this region receives a more acidic precipitation than elsewhere in Norway, which may contribute to increased leaching from needles. Higher nitrogen deposition is taking place here, causing a heavy cover of epiphytic algae on needles.It is noteworthy that this region contains more low vitality forests (of low crown density and yellowish discolouration) than other regions, and that the negative changes in vitality have been more pronounced than in other regions.More clearly we see that forests in southern, southeastern, and northeastern parts of Norway, next to Russia, are negatively affected. The causal factors may be several, and they may interact in complex processes. The symptoms are not specific, but their regional occurrence seems to indicate a causal relationship with deposition of air pollutants. This indication is now more pronounced than found earlier.
Forfattere
Knut SolbraaSammendrag
Det er ikke registrert sammendrag
Forfattere
Rolf BirkelandSammendrag
Det er ikke registrert sammendrag
Forfattere
Tore FrognerSammendrag
Det er ikke registrert sammendrag
Forfattere
Åge A. NyborgSammendrag
Det er ikke registrert sammendrag
Forfattere
Lennart RasmussenSammendrag
Det er ikke registrert sammendrag
Forfattere
Inge RyenSammendrag
Sommeren 1992 ble 77 stubber av nyhogd gran behandlet med stor barksopp og 77 stubber med urea. 68 stubber forble ubehandlet for kontroll. Hensikten var å finne ut om slik behandling hadde noen effekt i bekjempelsen av rotkjuke under norske forhold. Forsøket ble anlagt medio august i et rent granbestand som ble tynnet. I desember samme år ble det høstet inn skiver fra stubbene. Disse ble oppbevart fuktig ved romtemperatur i en uke, og deretter ble oppveksten av rotkjuke analysert under lupe. 6% av de stor barksopp-behandlede, 5% av de urea-behandlede og 68% av de ubehandlede stubbene fikk oppvekst av rotkjuke. Dette viser at tilførsel av både stor barksopp og urea er effektivt til å bekjempe angrep av luftbårne rotkjukesporer på ferske granstubber.