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
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.
Sammendrag
Nitrate leaching is often low from grasslands, primarily due to the long period of N uptake compared to arable crops. In the present paper we explore the combined effects of N input regime, soil type and climatic conditions through a combination of field lysimeter studies and simulation modelling of temporary grassland. A lysimeter consisting of eight 10´4´1 m individually drained cells was constructed in SW Norway, a region with a cool and wet marine climate. Six cells were filled with silty sand and two cells with coarse sand. The lysimeters were cropped first with barley for two years, followed by five years of grassland. Treatments included various combinations of N input (fertilizer, manure or both), and the results were analyzed by means of two coupled dynamic simulation models (CoupModel: a heat- and water transport model, SOILN_NO: a soil nitrogen model). The models were further used to assess a scenario with a more continental climate (somewhat cooler and dryer). All treatments resulted in a net export of N, with N amounts removed by harvest ranging between 121 and 139% of that applied. Measured N yield from the treatment receiving manure only was almost as high as that from the treatment receiving fertilizer only, even though it received on average about 80 kg ha-1 less inorganic N for which possible explanations are discussed. Nitrogen losses through leaching were in the range of 5-23% of the N input, and soil type had a greater effect than source of N input. The inorganic N fraction of the leachate was 71-82% of the total N, and 98% of this was nitrate. The models gave reasonable simulation of N yields as well as of the timing and magnitude of nitrate leaching from the different treatments. They also clearly illustrated the importance of plant uptake of N in early spring and late autumn, in order to reduce the risk of nitrate leaching. The scenario using weather data from a cooler and dryer region showed a large decline in plant uptake of N outside the main cropping season, but simulated nitrate leaching was nevertheless significantly lower. With this scenario, precipitation was only 50% of that at the actual experimental site, and the lower temperatures during autumn and winter reduced net mineralization of soil organic N significantly. Thus, the reduction in precipitation and net mineralization of soil organic N apparently more than outweighed the effects of shorter growing season in the continental climate sc.
Sammendrag
I forbindelse med implementeringen av EUs nye vanndirektiv, er det behov for å lage rutiner og prosedyrer for enhetlig forvaltning, systematisk kartlegging og gjennomføring av tiltak innenfor et nedbørsfelt. Gjevingvassdraget i Tvedestrand kommune er et av tre norske vassdrag som er med på et internasjonalt pilotprosjekt hvor dette skal testes ut. Det er derfor behov for å kartlegge forurensningstilførslene til vassdraget. Avløp fra spredt bebyggelse er en av hovedkildene til forurensning av vassdraget. Ved hjelp av modellen GIS i avløp har kommunen registert alle avløpsanlegg i spredt bebyggelse. Data fra feltregistrering er lagt inn i GIS-modellen, og utslipp av fosfor, nitrogen og organisk stoff er beregnet for 57 anlegg. Det er også registrert data om privat vannforsyning. Utslippsmengder og miljøbelastning er deretter beregnet for hver resipient. Årlig gir dette en samlet tilførsel fra spredt avløp til Gjevingvassdraget på ca 41 kg fosfor, 313 kg nitrogen og 427 kg organisk stoff.Det er også beregnet miljøindeks for anleggene. Høy miljøbelastning tilsvarer høy indeksverdi. Beregningen viser at 44 % av anleggene har høy eller meget høy miljøindeks. Resultatene er lagret i en GIS-database, som er et godt grunnlag for videre oppfølging av anlegg, analyse av alternative tiltak samt produksjon av kart og rapporter.