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.
2007
Forfattere
L. Kirwan A. Lüscher J. A. Finn M. T. Sebastiá R. P. Collins C. Porqueddu A. Helgadottir O. H. Baadshaug C. Brophy C. Coran S. Dalmannsdóttir I. Delgado A. Elgersma M. Fothergill B. E. Frankow-Lindberg P. Golinski P. Grieu A. M. Gustavsson M. Höglind O. Huguenin-Elie C. Iliadis M. Jørgensen Z. Kadziuliene T. Karyotis T. Lunnan M. Malengier S. Maltoni V. Meyer D. Nyfeler P. Nykanen-Kurki J. Parente H. J. Smit U. Thumm J. ConnollySammendrag
Summary 1 Ecological and agronomic research suggests that increased crop diversity in species poor intensive systems may improve their provision of ecosystem services. Such general predictions can have critical importance for worldwide food production and agricultural practice but are largely untested at higher levels of diversity. 2 We propose new methodology for the design and analysis of experiments to quantify diversity-function relationships. Our methodology can quantify the relative strength of inter-specific interactions that contribute to a functional response, and can disentangle the separate contributions of species richness and relative abundance. 3 Applying our methodology to data from a common experiment at 28 European sites, we show that the above-ground biomass of four-species mixtures (two legumes and two grasses) in intensive grassland systems was consistently greater than that expected from monoculture performance, even at high productivity levels. The magnitude of this effect generally resulted in transgressive overyielding. 4 A combined analysis of first-year results across sites showed that the additional performance of mixtures was driven by the number and strength of pairwise inter-specific interactions and the evenness of the community. In general, all pairwise interactions contributed equally to the additional performance of mixtures; the grass-grass and legume-legume interactions were as strong as those between grasses and legumes. 5 The combined analysis across geographical and temporal scales in our study provides a generality of interpretation of our results that would not have been possible from individual site analyses or experimentation at a single site. 6 Our four-species agricultural grassland communities have proved a simple yet relevant model system for experimentation and development of methodology in diversity-function research. Our study establishes that principles derived from biodiversity research in extensive, semi-natural grassland systems are applicable in intensively managed grasslands with agricultural plant species.
Sammendrag
To obtain information that might help in the use of Neozygites floridana (Zygomycetes: Entomopthorales) in biological control of Tetranychus urticae (Acari: Tetranychidae), in strawberries and cucumbers we have tried to answer the following questions in a series of studies*): 1) When, and at what infection levels does N. floridana occur in T. urticae populations in field grown strawberries? 2) How does N. floridana survive harsh climatic conditions (i.e winter) in Norway? 3) Where do N. floridana infected T. urticae move and sporulate on a plant? 4) How do commonly used pesticides in strawberries affect N. floridana and T. urticae? 5) How can N. floridana be inoculated in augmentative microbial control of T. urticae? Results show that N. floridana infected and killed T. urticae in 12 out of 12 Norwegian strawberry fields studied. Infection levels up to 90% were observed, and the highest levels were observed late in the season. The infection levels throughout a season varied considerably. N. floridana was observed to over-winter as hyphal bodies in hibernating T. urticae females throughout the winter. Cadavers with resting spores were found from October to the end of January. Cadavers then probably disintegrated, and resting spores were left on leaves, soil, etc. In a bioassay where a Norwegian N. floridana isolate was tested for numbers and distance of spores thrown at three different temperatures (13o, 18o, 23o C), results show that the highest numbers of spores (1886 and 1733 per cadaver) were thrown at 13o and 18o compared to 23o C (1302 per cadaver). Spores were thrown at the same distance (up to about 6 mm) at all three temperatures when cadavers were placed with dorsal side facing up. Cadavers placed with dorsal side down (hanging) threw equal numbers of spores up (on the underside of the leaf in nature) and down (on the leaf below). The effects of pesticides used in strawberries on the N. floridana infection level were studied to evaluate factors that might be important for conservation biological control. The pesticides tested were three fungicides; Euparen (tolylfluanid), Teldor (fenhexamid), Switch (cyprodinil +fludioxonil) and one acaricide/ insecticide: Mesurol (methiocarb). The experiment indicated that all three fungicides affect N. floridana negatively but that Euparen might be the least harmful. Mesurol did not affect N. floridana. Our attempt to inoculate N. floridana artificially in a strawberry field has not yet been successful, but we now work on promising methods for inoculation of N. floridana in T. urticae populations in greenhouse cucumbers. More detailed results from the studies referred to in this abstract will soon be published elsewhere.
Sammendrag
To obtain information that might help in the use of Neozygites floridana (Zygomycetes: Entomopthorales) in biological control of Tetranychus urticae (Acari: Tetranychidae), in strawberries and cucumbers we have tried to answer the following questions in a series of studies*): 1) When, and at what infection levels does N. floridana occur in T. urticae populations in field grown strawberries? 2) How does N. floridana survive harsh climatic conditions (i.e winter) in Norway? 3) Where do N. floridana infected T. urticae move and sporulate on a plant? 4) How do commonly used pesticides in strawberries affect N. floridana and T. urticae? 5) How can N. floridana be inoculated in augmentative microbial control of T. urticae? Results show that N. floridana infected and killed T. urticae in 12 out of 12 Norwegian strawberry fields studied. Infection levels up to 90% were observed, and the highest levels were observed late in the season. The infection levels throughout a season varied considerably. N. floridana was observed to over-winter as hyphal bodies in hibernating T. urticae females throughout the winter. Cadavers with resting spores were found from October to the end of January. Cadavers then probably disintegrated, and resting spores were left on leaves, soil, etc. In a bioassay where a Norwegian N. floridana isolate was tested for numbers and distance of spores thrown at three different temperatures (13o, 18o, 23o C), results show that the highest numbers of spores (1886 and 1733 per cadaver) were thrown at 13o and 18o compared to 23o C (1302 per cadaver). Spores were thrown at the same distance (up to about 6 mm) at all three temperatures when cadavers were placed with dorsal side facing up. Cadavers placed with dorsal side down (hanging) threw equal numbers of spores up (on the underside of the leaf in nature) and down (on the leaf below). The effects of pesticides used in strawberries on the N. floridana infection level were studied to evaluate factors that might be important for conservation biological control. The pesticides tested were three fungicides; Euparen (tolylfluanid), Teldor (fenhexamid), Switch (cyprodinil +fludioxonil) and one acaricide/ insecticide: Mesurol (methiocarb). The experiment indicated that all three fungicides affect N. floridana negatively but that Euparen might be the least harmful. Mesurol did not affect N. floridana. Our attempt to inoculate N. floridana artificially in a strawberry field has not yet been successful, but we now work on promising methods for inoculation of N. floridana in T. urticae populations in greenhouse cucumbers. More detailed results from the studies referred to in this abstract will soon be published elsewhere.
Forfattere
Marie Alexis Daniel Rasse C. Rumpel G. Bardoux N. Péchot P. Schmalzer B.G. Drake A. MariottiSammendrag
Fire profoundly modifies the terrestrial C cycle of about 40% of the Earth"s land surface. The immediate effect of fire is that of a net loss of C as CO2 gas and soot particles to the atmosphere. Nevertheless, a proportion of the ecosystem biomass is converted into charcoal, which contains highly recalcitrant molecular structures that contribute to long-term C storage. The present study aimed to assess simultaneously losses to the atmosphere and charcoal production rates of C and N compounds as a result of prescription fire in a Florida scrub-oak ecosystem. Pre-fire and post-fire charred and unburned organic matter stocks were determined for vegetation leaves and stems, litter and soil in 20 sub-plots installed in a 30-ha area that was subjected to prescribed fire. Concentrations of C and N were determined, and fluxes among pools and to the atmosphere were derived from these measurements. Soil C and N stocks were unchanged by the fire. Post-fire standing dead biomass contained 30% and 12% of pre-fire vegetation C and N stocks, respectively. In litter, post-fire stocks contained 64% and 83% of pre-fire C and N stocks, respectively. Most of the difference in relative losses between vegetation and litter could be attributed to substantial litter fall of charred and unburned leaves during the fire event. Indeed, an estimated 21% of pre-fire vegetation leaf C was found in the post-fire litter, while the remaining 79% was lost to the atmosphere. About 3/4 of the fire-induced leaf litter fall was in the form of unburned tissue and the remainder was charcoal, which amounted to 5% of pre-fire leaf C stocks. Charcoal production ranged between 4% and 6% of the fireaffected biomass, i.e. the sum of charcoal production and atmospheric losses. This value is below the range of literature values for the transformation of plant tissue into stable soil organic matter through humification processes, which suggests that fire generates a smaller quantity of stable organic C than humification processes over decades and potentially centuries.
Forfattere
Kjell Mangerud Lars Olav BrandsæterSammendrag
Our objective in an ongoing study is to improving weed harrowing in organic cereal production as well as implementing weed harrowing as an alternative for herbicides in conventional farming. The study includes experiments on three locations during three years. The experiments have included different types of spring tine weed harrows used with different aggressiveness (by differing tine working depths and speeds), cereal developmental stages, soil types (locations) and conditions as well as competition levels (natural variation in severity of weed infestation during three years on three locations). Cereal yield and quality, number and dry matter weight (biomass) of weed and soil water content, soil share strength and soil penetration resistance are recorded. Pre-emergence harrowing, or harrowing at early 1-leaf stage reduced in general weed number and biomass compared to untreated control. The mean weed reduction over locations and years was about 40%, but this reduction was not always significant different to control plots. In general pre-emergence harrowing or at early 1-leaf stage increased the yield compared to untreated, but harrowing at that stage has also under certain circumstances given small yield reductions as well. The combination of pre-emergence harrowing and harrowing at 3-4 leaf stage gave a significant reduction of weed number and biomass compared to untreated control. In general, harrowing twice gave increased cereal yield, but the differences were only significant at one of the locations. The potential benefit of a second harrowing at the 3-4 leaf stage depends on the weed situation, number and biomass, as well as the compatibility of the cereal. Furthermore, our results indicate that the different types of harrows and tines will not do a proper job on all soil types. On light soils all of them have given satisfying results. A normal tine (7 mm bent Einböck or a 10 mm long straight CMN) is not rigid enough on soil types that build a crust after rain. An 8 mm bend Einböck tine, however, broke down the crust and gave increased cereal emergence on such soils. On the other hand it is important not to adjust this tine to aggressive when there is no crust. Other trial show that in stony soils a straight tine will pick up less stones compared with a bent one, stones witch can damage the combine harvester. Our result from one of the location (medium light soil with stones) indicate no difference in yield, reductions in weed number or biomass pr m² with a straight tine compared width a bent one.
Forfattere
Bernt Johansen Stein Rune Karlsen Christian UhligSammendrag
Oppsummering og konklusjon Denne rapporten har vist vegetasjons- og beiteklartlegging basert på Spot 5 satellittdata og feltstudier. Den har i tillegg gitt en vurdering av jorderosjon. Vegetasjonskartet presentert har 26 kartlagte enheter, derav 17 med vegetasjonsinnhold. Kartet viser at impedimentstyper av forvitringsmateriale og morenemateriale med berg, stein og grus i dagen dominerer. Inkluderer vi de sparsomt vegeterte enhetene her dekker de til sammen over halvparten (51,5 %) av arealet innen Hammerfest kommune på Kvaløya. Den andre store enheten er ulike utgaver av fjellkreklingheier som dekker 35,0 % av arealet. Fukt- og grasheier dekker 6,8 % av arealet, mens skog og myrtyper utgjør hver bare omkring 1 % av arealet. Reinbeite i barmarksperioden preger vegetasjonen på Kvaløya sterkt, både med hensyn til art sammensetning, dekning og vekstform. Mest påfallende er det på den sparsomme utbredelsen av vierkratt og bjørkeskog. Reinbeite gir ett åpent, og etter manges mening ett naturskjønt landskap, som er lett å ferdes i. Skogspotensialet er derfor stort i de vindbeskytta områdene under et par hundre meter. Dette er typisk for flere sommerbeiteområder på finnmarkskysten, men få steder er det så iøynefallende som på Kvaløya. Beitekvalitetet er vurdert ut fra artsinnhold i vegetasjonstypene og fra produksjon målet med vegetasjonsindeksen NDVI. I tillegg er kart som viser start og slutt på grønnbeitene presentert. Ut fra dette har vi gitt vegetasjonstypene beiteverdi fra 0 til 10 og laget et beitekart. Beitekartet illusterer tydelig at spesielt de indre deler har liten verdi som sommerbeite for rein, mens gode sommerbeiter finner vi rundt Hammerfest by, I Storvikvannet-Middagsfjellet området, i Torskefjorddalen og dels i området Straumnestet-Molstrandneset. I mange tilfeller har beiting av vegetasjonen ført til jorderosjon, spesiell på opprinnelig lav- og moserik vegetasjon, samt dvergbjørk-krekling dominerte vegetasjonstyper på eksponerte lokaliteter. Men også lokale forekomster med mer næringsrike vegetasjonstyper er tydelig degradert og utsatt for jorderosjon. Det antas at reinens påvirkning på vegetasjon og jordmonn var størst for ca. 15-20 år siden ved høyest antall rein på beite, og at den siden har betydelig minket. Reduksjon av reinflokken, men også økt utnyttelse av de forholdsvis gode beite i Hammerfest by har nok minket beitepresset på store deler av Kvaløya, så at naturlig plantesuksesjon ved flere lokaliteter har sinket eller stoppet jorderosjonen. Hvilken konkrete konsekvenser dette medfører er avhengig av mange forskjellige faktorer og vanskelig å forutsi. Dermed er det anbefalt å følge den framtidlige utviklingen av jorderosjon på Kvaløya med nye registreringer i årene som kommer.
Forfattere
Elena A. Kasatkina Oleg I. Shumilov Paul E. Aspholm Natalia V. LukinaSammendrag
Among some of the mysteries of the Tunguska meteorite event, is the cause of the accelerated tree growth after 1908 in the catastrophe area (about 2000-2500 km^2). The main explanation of accelerated growth of old trees, was a result of decrease of competition level due to falling of considerable part of neighbour trees. We analyzed all available tree ring records (more than 100) including our own ones collected in the Taymir Region of Northern Siberia (72N; 105E) at a distance of about 1500 km to the North from the Tunguska catastrophe epicentre (61N; 102E). It was found that there were a considerable increase of tree ring growth in 1908 over a vast area of Siberia (60N-75N; 80E-110E) that at much more vast area (10^3 times more) than had been earlier considered. The similar effect was detected after the Chulym bolide explosion in 1984 (57.7N; 85.1E). Of course, the Chulym forest response area was some smaller taking into account incomparable powers of Tunguska and Chulym events). It is obvious that the interpretation mentioned above, of tree growth observed too far from epicentre, could hardly be accepted. A more likely hypothesis is that the growth of the trees became stimulated by the matter from comet that where spread over a large territory of Eurasia. It is generally believed that meteorites and comets delivered large amounts of simple organic composites to the early Earth. Another hypothesis is connected to NO produced during the event analyzed. For example, in time the Tunguska event the comet (probably fragment of the comet Enke) tail started to influence the Earth atmosphere several days before the fall of the meteorite causing optical anomalies observed mainly westwards from the place of TO explosion (Western Siberia, European Russia, Northern Europe). We discuss as well the role of "small signals" in simulation of biological object response. The work was supported by a grant from the Russian Foundation for Basic Research (grant N 05-04-97528), by the Program "Biodiversity and dynamics of gene pool" of the Russian Academy and by the Regional Scientific Program of the Murmansk region.
Forfattere
Leif Sundheim May Bente Brurberg Trond Hofsvang Christer Magnusson Trond Rafoss Brita Toppe Anne Marte Tronsmo Bjørn ØklandSammendrag
This Pest Risk Assessment (PRA) of the fire blight bacterium Erwinia amylovora was initiated by a review or revision of a policy by the Norwegian Food Safety Authority. Fire blight was detected in Norway for the first time in 1986. The focus of infection was in and around the city of Stavanger in Rogaland county on the south west coast of the country. Mainly Cotoneaster bullatus and C. salicifolius were attacked. The disease was contained and finally eradicated from the area in 1992. However, in 2000 fire blight re-emerged, in the same county, on the island Karmøy, separated from the first outbreak by 25 km open sea. A new containment and eradication programme was started. Nevertheless the disease continued to spread to the north, mainly due to the movement of beehives contaminated with E. amylovora, from areas with diseased plants to areas free from fire blight with warm and humid weather conditions, favorable for the development of the disease. Fire blight has been detected in private gardens, around public buildings, in recreation grounds, along roads, and in rural areas in the coastal areas of the counties of Rogaland, Hordaland and Sogn og Fjordane. It has not been detected in nurseries, in fruit-growing areas, or in other parts of the country. The main hosts are still C. bullatus and C. salicifolius and some other Cotoneaster spp. Occasionally diseased Sorbus aria, Pyrachanta and apple and pear have been detected. Recently a very limited outbreak on C. bullatus and C. salicifolius was detected in the city of Kristiansand in Vest-Agder county. The endangered area, where presence of fire blight will result in economically important loss is the commercial fruit growing areas of Norway. If E. amylovora is introduced into the main fruit growing districts, it is expected that the damage and losses to commercial fruit production and nurseries will be minor, under the current phytosanitary regime in Norway. Relaxation of the regulations in force for fighting fire blight in Norway will increase the expected damage and losses to commercial fruit production and nurseries to a moderate level. Importation of fruit trees and fruit tree propagation material from countries where fire blight is established is not expected to increase the risk of fire blight in Norway significantly, given that appropriate phytosanitary requirements and quarantine are followed.
Sammendrag
To stabilize organic cereal production systems it is necessary to control Canadian thistle (Cirsium arvense) and other perennial weed species. The aim of the two presented experiments (I and II) has been to evaluate the effects of mechanical treatment in spring combined with competition from a one season cover crop. In both experiments we used the same mixture of cover crops; phacelia (Phacelia tanacetifolia Benth.), common vetch (Vicia sativa L.), red clover (Trifolium pratense L.) and Italian ryegrass (Lolium multiflorum Lam.). The first experiment (I) was arranged in a complete factorial split-plot design. In this experiment different root burial depths and root lengths of C. arvense simulated different mechanical treatments. Use of cover crop was the single factor that most effectively reduced the gain of biomass of C. arvense. At the final harvest combined treatment of deep root burial (15 cm), short root length (5 cm) and cover crop reduced number of new shoots of C. arvense by 95% and root biomass by 97% compared to shallow burial and no cover crop. At minimum regenerative capacity of C. arvense the number of leaves were 2 to 6 for the treatment with cover crop and 4 to 8 for the treatment without cover crop. In the second experiment (II), which had a complete factorial design, ± ploughing in autumn was combined with different fallow strategies in spring before sowing the cover crop. The disc harrowing during the fallow period was performed either 2x when fallow lasted for 3 weeks, or 4x when fallow lasted for 6 weeks. Additionally, all combinations of ± ploughing in autumn and length of the fallow period were combined with ± ploughing before sowing the cover crop (all together 8 treatments). In two additional subplots shallow ploughing preceded the autumn ploughing treatment (± ploughing). Preliminary results from experiment II confirms in general the conclusions from experiment I. Combining soil tillage and competition from a fast growing cover crop have potential for retarding perennial weeds. The classical approach for controlling couch grass (Elymus repens) was confirmed in this experiment, the longer soil tillage period the better weed control, and the soil tillage period should be proceeded by a deep ploughing. Ploughing in the autumn gave no additional effect on couch grass. Best control of Canadian thistle was obtained when only shallow ploughing was performed in the autumn, followed by a 6 week soil tillage period (3 weeks was not tested here) in spring and early summer and completed by ploughing before sowing the green manure cover crop. In conclusion, the experiments showed that intensive soil tillage combined with competition from a cover crop gave promising results for weed control. Due to the positive effect of moderate tillage operations attention to factors as nutrient supply, soil structure and energy use may still be ensured while a satisfying weed control is obtained.
Forfattere
Ragnar Eltun Lars Olav Brandsæter Anne-Kristin LøesSammendrag
Belgvekster som kløver er viktige i økologisk landbruk fordi disse plantene samler nitrogen fra lufta, som kan bli til næring for seinere plantevekst. Kornet treskes vanligvis i slutten av august, og etterpå kan det være opp til to måneder da det fortsatt kan vokse planter på jordet. Dette kan vi utnytte ved å så inn kløver sammen med kornplantene om våren. Etter tresking vil kløverplantene vokse seg store, og samle nitrogen som kan komme neste års plantevekst til gode. Slik kløverdyrking kaller vi underkultur. Underkultur i korn kan også være et gras, og da kan den også samle opp nitrogen som er til overs i jorda om høsten. I tillegg kan underkulturvekster redusere veksten til både ett- og flerårige ugras. Gjennom fem år har vi undersøkt om det kan samles nok nitrogen til kornet og om ugraset kan holdes under kontroll ved å ha kløver underkultur i kornet hvert år eller dyrke en grønngjødslingseng hvert fjerde år. Vi hadde forsøk på to ulike steder på Østlandet, Kise i Hedmark og Apelsvoll i Oppland. I gjennomsnitt økte kornavlingen med 30% ved gjentatt bruk av kløver som underkultur. Forsøkene viste imidlertid at det ble fjernet mer nitrogen med kornet enn kløveren klarte å binde fra lufta. Dette gjaldt både ved bruk av kløver som underkultur hvert år, og når en brukte en ettårig eng som grønngjødsel hvert fjerde år. Over tid vil dermed en driftsform som baserer seg bare på grønngjødsling tære på humusinnholdet i jorda. Derfor trengs det tilførsel av andre nitrogenkilder enn kløver i økologisk korndyrking under norske forhold. Slike kilder kan være husdyrgjødsel, rest etter våtkompostering av organisk avfall eller humanurin. Det er imidlertid en utfordring å ta i bruk slike nitrogenkilder i praksis, og foreløpig er ikke andre nitrogenkilder enn belgvekster og husdyrgjødsel godkjent i reglene for økologisk landbruk. Bruk av kløver underkultur hadde liten effekt på frøugraset, men en reduserende effekt på enkelte flerårige ugrasarter som åkerdylle. I økologisk korndyrking vil det i de fleste tilfeller være nødvendig å ugrasharve for å holde kontroll med frøugraset. Det kan imidlertid være vanskelig å få til effektiv ugrasharving ved bruk av underkultur. Det må således arbeides videre for å finne ut hvordan man kan få til en god kombinasjon av kløver underkultur og ugrasharving, slik at man både kan tilføre nitrogen til systemet og kontrollere ugraset. Mer kunnskap om de flerårige ugrasartene sin voksemåte, og hvordan de kan bekjempes ved en kombinasjon av konkurranse med kulturplantene og jordarbeiding blir også viktig for å oppnå tilfredsstillende og stabile økologiske kornavlinger.