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.
2003
Forfattere
Ragnar EltunSammendrag
Økologiske dyrkingssystem for høgare og meir stabile kornavlingar" er eit 5-årleg strategisk instituttprogram frå Noregs forskingsråd. Programmet er leia av Planteforsk i samarbeid med NLH, NORSØK og Høgskolen i Hedmark. I tillegg deltek forskarar frå Danmark, Finland og Nederland. Kunnskap om moglegheiter for betre avlingsnivå og avlingsstabilitet i økologisk korndyrking utan å redusere på krava til langsiktig bærekraft, i område med begrensa tilgang på organiske gjødselemne, er svært viktig for den framtidige strukturen i økologisk landbruk her i landet. I dette programmet søker ein å løyse denne utfordringa gjennom ei omfattande agroøkologisk analyse i kombinasjon med faktorielle studiar av dei viktigaste flaskehalsane i økologisk korndyrking: dårleg jordstruktur, manglande nitrogenforsyning og fleirårige ugras.
Sammendrag
En kartlegging av insektmiddelbruken i grønnsakdyrkingen og av resistens mot abamectin, cyromazin, cartap, profenofos og cypermetrin hos larver av grønnsakminerflue, Liriomyza sativae, ble gjennomført i dyrkingsområder rundt Hanoi i perioden 2001-2002. Abamectin var det preparatet som ble mest brukt i 2001, fulgt av pyretroider, fosformidler og karbamater. Rundt 50% av dyrkerne sprøytet mindre enn 11 ganger med 8-10 dagers mellomrom i en vekstsesong (3-4 måneder). Resultatene fra resistenskartleggingen tyder på at grønnsakminerflua er resistent mot cypermetrin. Arten ser ut til å være mottakelig for de andre midlene som ble testet, men det er mulig at resistens mot fosformidler er i ferd med å bygge seg opp. Videre forsøk vil bli gjennomført for å undersøke dette.
Sammendrag
Norsk institutt for jord- og skogkartlegging (NIJOS) utførte sommeren 2002 vegetasjonskartlegging av et 357 km² stort område på Ringsakerfjellet. Kartlegginga er utført på oppdrag fra Ringsaker saubeitelag og Ringsaker kvigebeitelag, og er et ledd i prosjektet ”Beitegrunnlag og beitebruk som grunnlag for beitebruksplan for Ringsakerfjellet”. Landbruksetaten i Ringsaker kommune ved Ole Fredrik Dæhli har vært koordinator for prosjektet. Vegetasjonskartlegginga er utført etter NIJOS-instruks for kartlegging i målestokk 1:50 000. Feltarbeidet ble utført i juli og august av Anders Bryn, Johnny Hofsten, Hans Petter Kristoffersen og undertegna. Sammen med vegetasjonskart på digital form er detlaga 2 avleda temakart om beiteforhold for sau og storfe. Kartkonstruksjon er utført av Hans Petter Kristoffersen og kartpresentasjon av Kari Thorvaldsen. Geir Steinheim ved Institutt for husdyrfag ved Norges landbrukshøgskole har lagt til rette data fra Sauekontrollen. Registreringer av beitedyras arealbruk er utført av beitelaga.
Forfattere
Peder GjerdrumSammendrag
The timber industry in Norway is quite fragmented. Several small-scale and a few medium-sized sawmill add up to an annual production of 2.5 mill. m3. Since three decades, most of the timber is kiln dried. Modern kilns and enhanced modelling contribute to improved drying quality and increased drying speed. However, due to harsh competition, fast dried, inferior drying quality timber is continually being offered and accepted for trade in the European area. This might put the overall goodwill for timber at hazard in the long run. Unfortunately, the detection of drying quality properties is quite complex. In this situation, industry and RTD-bodies like the Norwegian Forest Research Institute co-operate to offer competence-building activities. Seminars in wood drying and related topics are offered mainly on a corporate basis, thereby introducing an intimate atmosphere for dealing with these cautious topics. A fixed number of participants meet regularly for two day\"s of intensive work over a period of two or three years. The seminars typically include persons from all levels of the factory organisation, incorporating salesmen, mill operators and maintenance together with kiln operators, sometimes also bringing inn external customers. Work alternate between practical experiments, presentations and training. The activity is continued in working groups between the meetings. All seminars are adequately reported with respect to findings, thereby enhancing the business value of the achievements. The seminars also provide an invaluable basis for research projects and for recruiting fresh candidates. For the institute, this symbiosis with industry helps keeping focus on factors influencing profitability in the timber business.
Populærvitenskapelig – Økologisk epledyrking i Nord-Italia
Gunnhild Jåstad, Dag Røen, Arne Stensvand
Sammendrag
Italia står for 25 % av den totale økologiske matvareproduksjonen i Europa, og omlag 7 % av all matvare produksjon i Italia er i dag økologisk. Både i Trentino og i Sør-Tyrol er 3-4 % av epledyrkinga økologisk. Den største auken i økologisk epleproduksjon har skjedd dei siste 10 åra, og dette skuldast hovudsakleg at marknaden er vorten meir interessert i økologiske produkt. Ein økologisk fruktdyrkar kan i snitt ta ut ein meirpris som ligg 40-45 % høgare pr kg enn ein integrert dyrkar. Det er høve til å gje overgangsstønad til dyrkarar som la om frå konvensjonell til økologisk drift, men ikkje alle provinsar nytta seg av dette. Forsking innan økologisk fruktdyrking er knytt til to forskingsinstitutt i området; Institut Agrario de San Michele all"Adige og Land- und Forstwirtchaftliches Versuchszentrum. Dei viktigaste problemstillingane som det vert arbeidd med i samband med økologisk fruktdyrking ved desse institusjonane er tiltak mot skurv og mjøldogg, tiltak mot viktige skadedyr som epleviklar, raud eplebladlus og ull-lus, tiltak mot ugras i trerekkja, avlingsregulering og sortar. Mot epleskurv hadde ein i Nord-Italia høve til å nytte både kopar og svovelkalk som direkte tiltak i økologisk produksjon. Dei viktigaste tiltaka mot mjøldokk var svovel og svovelkalk. Dei fleste dyrkararane nytta paringsforstyrring ved hjelp av feromoner mot epleviklar. I tillegg nytta dei granulosevius. Neem vart nytta mot raud eplebladlus. Hovudsortane i økologisk epledyrking var mykje godt dei same som i konvensjonell dyrking, men fleire skurvsterke sortar var prøvd introdusert. Dei fleste dyrkararane tynna eple for hand eller ved hjelp av svovelkalk. Ugraset vart i hovudsak fjerna mekanisk.
Sammendrag
The rationale for stand growth modelling is often either grounded in a search for improved scientific understanding or in support for management decisions. The ultimate goal under the first task is seen in mechanistic models, i.e. models that represent the stand structure realistically and predict future growth as a function of the current status of the stand. Such mechanistic models tend to be over-parameterized with respect to the data actually available for a given stand. Calibration of these models may lead to non-unique representations and unreliable predictions. Empirical models, the second major line of growth modelling, typically match available data sets as well as do process-based models. They have less degrees of freedom, hence mitigate the problem of non-unique calibration results, but they employ often parameters without physiological or physical meaning. That is why empirical models cannot be extrapolated beyond the existing conditions of observations. Here we argue that this widespread dilemma can be overcome by using interactive models as an alternative approach to mechanistic (algorithmic) models. Interactive models can be used at two levels: a) the interactions among trees of a species or ecosystem and b) the interactions between forest management and a stand structure, e.g. in thinning trials. In such a model data from a range of sources (scientific, administrative, empirical) can be incorporated into consistent growth reconstructions. Interactive selection among such growth reconstructions may be theoretically more powerful than algorithmic automatic selection. We suggest a modelling approach in which this theoretical conjecture can be put to a practical test. To this end growth models need to be equipped with interactive visualization interfaces in order to be utilized as input devices for silvicultural expertise. Interactive models will not affect the difficulties of predicting forest growth, but may be at their best in documenting and disseminating silvicultural competence in forestry.
Forfattere
Peder GjerdrumSammendrag
Knowledge about the transformation of sapwood into heartwood contributes to the understanding of the nature of pine trees and should be considered prior to the conversion of sawlogs to produce timber of prescribed properties and optimal revenue. In this study, heartwood formation was ascribed to the joint effect of ageing and growth rate. Observations of heart- and sapwood in 1656 trees and sawlogs of Scots pine (Pinus sylvestris L.), sampled throughout Scandinavia, were analysed using mixed models. The most important finding was expressed in the pine heartwood age rule: heartwood age equals the square root of cambial age less three, to the second power. This global formula was valid irrespective of environmental factors and location within the tree, and described 93 per cent of the variance in the sample. Transition rate increases from 0.6 rings a−1 at 50 years to 0.8 rings a−1 at 200 years. The spatial amount of heartwood might be influenced by the silviculture through the annual ring width pattern. For samples missing sapwood, e.g. archaeological wood, the results might be combined with dendrochronology in specimen dating. When the diameter and the heartwood diameter of sawlogs were known, the mean annual ring width could be estimated with a standard deviation of 0.5 mm a−1. The simplicity, consistency and high correlation of the pine heartwood age rule confirms the importance of age as the main factor in heartwood formation.
Forfattere
Petter Nilsen Gunnar AbrahamsenSammendrag
Results from two fertilizer experiments in coniferous forest in south and southeast Norway with applications of nitrogen (N), magnesium (Mg) and phosphorous (P) are presented. A Scots pine stand has been fertilized annually for 9 years and one Norway spruce stand has been fertilized annually for 4 years. The aim of the study has been to investigate to what extent N fertilization in middle-aged stands of Scots pine and Norway spruce stimulates tree growth, and whether Mg and P counteract possible induced nutrient imbalances caused by high N doses. Both stands responded strongly to N addition and application of 30 and 90kgNha-1yr-1 resulted in a relative volume increment of 150 and 250%, respectively, compared to control. The increment effect in the pine experiment ceased after 4 years, but the difference between the two N doses was still significant after 9 years. The application of 1.5kgMgha-1yr-1 had just a slight significant positive effect on volume increment in two of the 9 years in the pine experiment, while no effect of 5.3kgPha-1yr-1 on volume increment was found. Needle nutrient concentrations were mainly affected by the N treatment and concentrations above 30mgg-1 was detected in the pine experiment. The concentration of P, Mg and K was negatively affected by the highest N dose in the spruce experiment, but not in the pine experiment. The imbalanced nutritional status created by N application was partly reduced by the P and Mg addition, but no substantial effect on tree growth has been detected so far. The stands have a large potential for accumulating N in the standing biomass and judged from the effect on nutrient concentrations and growth, Mg might be the next element that could limit tree growth by a continued high N atmospheric input.
Sammendrag
Neozygites floridana is a fungus in the order Entomophthorales that infects and kills the two-spotted spider mite, Tetranychus urticae. N. floridana is the key regulator factor of T. urticae on maize and soybean in the mid-western and south-eastern USA where farmers are encouraged to adapt their fungicide spray programmes to avoid suppressing the fungus (Cross et al. 1999). To our knowledge few systematic studies have been conducted on N. floridana as a mortality factor of T. urticae in strawberry fields. Some preliminary studies have, however, been conducted in Poland which indicate that N. floridana might be important for the regulation of T. urticae in strawberry. A cropping system that enhances the prevalence of N. floridana might therefore be important for the reduction of T. urticae in strawberry. In our studies we therefore aim to clarify the effect of different strawberry growing systems on the infection level of N. floridana. In one study, the occurrence of N. floridana in T. urticae in organic and conventional strawberry fields was studied in the summer 2002 and 2003. Strawberry leaves were collected from two fields, one organic and one conventional, from each of six different locations in Norway (Lier, Follo, Evje, Finnskog, Kise, Toten). Leaf samples were collected at four-weekly intervals. First sampling was conducted in June/July and the second in July/August. Preliminary results show that N. floridana infected and killed T. urticae in all strawberry fields studied. Infections from 0 to 19% were registered, and the highest infection rates were observed late in the season from the second sampling. Our preliminary results do not show any relationship between occurrence of N. floridana and strawberry cropping systems. The fluctuation in the N. floridana infection rate throughout the season might be higher than observed in the first study. A second study on the infection level of N. floridana in a T. urticae population throughout the season 2003 was therefore conducted in a conventional strawberry field in Follo. Our preliminary results show that the highest N. floridana infection level for this field was around 20%.
Forfattere
Francis Nwilene May-Guri Saethre Olusegun OkhidievbieSammendrag
African rice gall midge (AfRGM), Orseolia oryzivora Harris & Gagné (Diptera: Cecidomyiidae), is a serious insect pest of rainfed and irrigated lowland rice in West Africa. Several AfRGM management strategies have been advocated. Of these, host plant resistance and biological control appear as environmentally friendly options, compatible with other non-disruptive pest control methods. Most of the Oryza sativa rice varieties resistant to the closely related Asian gall midge are moderately to highly susceptible to the AfRGM in West Africa. As of today, no O. sativa with high levels of resistance to AfRGM is available. However, high levels of resistance to AfRGM exist among Oryza glaberrima varieties. The difficulty in identifying source material with stable resistance to AfRGM may be due to rice genotypes differing in their reaction to genetically diverse pest populations. Combined effects of AfRGM parasitoids "endoparasitoid Platygaster diplosisae Risbec (Hymenoptera: Platygasteridae) and the solitary ectoparasitoid Aprostocetus procerae Risbec (Hymenoptera: Eulophidae) may result in up to 80% parasitization of AfRGM late in the growing season. Unfortunately, this high level of parasitization does not necessarily mean effective control of AfRGM, but it does show that the parasitoids have potential for the control of AfRGM and, if well manipulated, will provide effective control of AfRGM. Given that considerable progress has been made in identifying sources of resistance to AfRGM, but that levels of resistance are very low, can AfRGM parasitoid activity be interfaced with low levels of resistance for more efficient control of this pest? To optimize the benefits from integrating the breeding for resistance to AfRGM and biological control, four rice varieties showing different levels of resistance were used to determine whether these differences in resistance affected parasitism of P. diplosisae and A. procerae under no-choice conditions. It is desirable that these management options be either complementary or synergistic and not antagonistic, disruptive and complex. Knowledge of such interactions should be explored by plant breeders and chemical ecologists aiming at producing rice varieties possessing appreciable levels of resistance to AfRGM and able to encourage parasitoid activity in rice-based ecosystems.