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.
2008
Forfattere
S. Craig DeLong Glenn D. Sutherland Lori D. Daniels Ben H. Heemskerk Ken Olaf StoraunetSammendrag
Patterns of tree mortality, rates and type of tree and snag fall, and relationships between snag characteristics and potential wildlife habitat value were estimated for hybrid spruce (Picea glauca (Moench) Voss x engelmannii Parry ex Engelm.) and subalpine fir (Abies lasiocarpa (Hook.) Nutt.) in eastcentral British Columbia in order to provide important parameters for deadwood modelling. We sampled 172 snags (52 spruce and 120 fir) for species, size, morphological, and habitat attributes, and used dendroecological techniques on a subsample of these (n = 158) to estimate year of death. Input of snags appeared to occur at a nearly constant rate in these stands. Estimated annual tree fall, including live trees and snags, was 5.3% for hybrid spruce and 6.1% for subalpine fir and stem breakage was more frequent than uprooting. Long-term annual snag fall rates were 4.6% for hybrid spruce and 2.9% for subalpine fir. Discriminant analysis based on time since death correctly classified snags into three decay classes for 85% and 72% of spruce and fir, respectively. Snags that potentially could provide important functions for wildlife habitat were more prevalent in fresh and intermediate classes for hybrid spruce and in intermediate and old classes for subalpine fir. The results provide valuable parameters for further development of deadwood models, which are an important tool for development of best practices for deadwood management.
Forfattere
Daniel Kwaku A. Asante Anne-Katrine Ree Rosnes Anna Holefors Ragnhild Nestestog Stein E. Lid Jørgen A. Mølmann Jorunn Elisabeth Olsen Øystein Johnsen Olavi Junttila Carl Gunnar FossdalSammendrag
Studies have implicated the involvement of the phytochrome light receptors in adaptation of trees to light climate, but the molecular basis of this in gymnosperms is less understood. The promoter regions of plant genes are modular and contain a number of cis-acting elements, each of which may contribute to one or more aspects of a complex expression profile. As a step towards characterization of Norway spruce phytochromes at the transcript level, we isolated fragments (between 700-1500 bp upstream of their putative ATG translational start) of phytochrome N, O and P promoters...
Forfattere
Peder GjerdrumSammendrag
Pine (Pinus sylvestris) heartwood and pine sapwood can, in several respects, be considered two different timber products. Sapwood demonstrates open structures that easily adsorb moisture and is vulnerable to bio-chemical disintegration, but also more easily painted, glued or impregnated. Heartwood, on the other hand, is less disposed to moisture fluctuations, hence, more dimensionally stable, and durable. Heartwood content is closely related to cambial age and to the progress of annual ring width. It is also the nature of pine is to grow timber of quite varying quality along the stem. Resins are more abundant near the base, and the knottiness is shifting, following certain patterns from the base upwards. Several of those traits can be identified prior to breakdown, applying specific wood technology knowledge, recent research and standard log scanner equipment. Even with this potential for producing more homogeneous board quality by including heartwood in the breakdown decision basis, one should not forget the practical implications for the sawmill. The cost of keeping separate heartwood quality classes and the risk of mistakes might easily exceed the price gain.
Sammendrag
Aerial dispersal of inoculum is critical to the spread of many plant diseases; including potato late blight (Phytophthora infestans (Pi)), lettuce downy mildew (Bremia lactucae (Bl)) and cucurbit downy mildew (Pseudoperonospora cubensis (Pc)). In addition to relative humidity and temperature, spore survival during aerial dispersal is affected by solar irradiation (SI), in particular during long-distance transport at higher altitudes. We evaluated the potential survival of spores in air by placing detached spores of Pi, Bl and Pc on filter paper in either direct sun or shade at time intervals from 0.5 to 3 h (Pi and Bl), or up to 42 hours (Pc). Thereafter, the filter papers were placed in moist chambers for 15 min prior to incubation on pea agar (Pi) or water agar (Bl and Pc) for 24 h, before the viable spores were enumerated. Spores were considered viable if they exhibited a germ tube or released zoospores. Preliminary results show that no spores of Pi, Bl and Pc germinated after 1, 3 and 30 h exposure to direct sun, with critical SI doses near 700, 2000 and 8500 Wm-2, respectively. In shade, no Pi spores germinated after 3 h, while spores of Bl and Pc were still viable after 3 and 42 h, respectively. In Norway, the potential for long distance distribution of Pi is restricted, but more likely for Bl and Pc. Further experiments will be conducted to find the maximum survival time for spores of these pathogens under Norwegian climatic conditions.
Forfattere
L. Riccioni A. Inman H.A. Magnus M. Valvassori A. Porta-Puglia Piero Conca G. Di Giambattista K Hughes M. Coates R. Bowyer C. Sansford Jafar Razzaghian A. Prince G.L. PetersonSammendrag
Representative European wheat cultivars were tested under quarantine containment for their susceptibility to Tilletia indica, the cause of Karnal bunt of wheat. Fifteen winter and 15 spring wheat (Triticum aestivum) and 11 durum wheat (Triticum durum) cultivars were inoculated by boot injection just prior to ear emergence to test their physiological susceptibility. Selected cultivars were then re-tested by spray inoculation after ear emergence to determine their morphological susceptibility, which is a better predictor of field susceptibility. At maturity, the ears and seeds were assessed for incidence and severity of disease. For the physiological susceptibility tests, 13/15 winter wheat cultivars were infected and the percentage of infected seeds ranged from 1 to 32%. For spring cultivars, 13/15 cultivars were infected and the percentage of infected seeds ranged from 1 to 48%. For the durum cultivars, 9/11 were infected and the percentage of infected seeds ranged from 2 to 95%. Across all cultivars, 35/41 were infected. Based on historical Karnal bunt susceptibility categories using coefficients of infection, one cultivar was classed as highly susceptible, three as susceptible, 11 as moderately susceptible, 20 as resistant and only six as highly resistant. The spray-inoculation morphological susceptibility tests broadly confirmed the physiological susceptibility results, although lower levels of infection were observed. Overall, the range of susceptibility was similar to that found in cultivars grown in Karnal bunt affected countries. The results demonstrate that European wheat cultivars are susceptible to T. indica and thus could potentially support the establishment of T. indica if introduced into Europe.
Sammendrag
Aerial dispersal of inoculum is critical to the spread of many plant diseases; including potato late blight (Phytophthora infestans (Pi)), lettuce downy mildew (Bremia lactucae (Bl)) and cucurbit downy mildew (Pseudoperonospora cubensis (Pc)). In addition to relative humidity and temperature, spore survival during aerial dispersal is affected by solar irradiation (SI), in particular during long-distance transport at higher altitudes. We evaluated the potential survival of spores in air by placing detached spores of Pi, Bl and Pc on filter paper in either direct sun or shade at time intervals from 0.5 to 3 h (Pi and Bl), or up to 42 hours (Pc). Thereafter, the filter papers were placed in moist chambers for 15 min prior to incubation on pea agar (Pi) or water agar (Bl and Pc) for 24 h, before the viable spores were enumerated. Spores were considered viable if they exhibited a germ tube or released zoospores. Preliminary results show that no spores of Pi, Bl and Pc germinated after 1, 3 and 30 h exposure to direct sun, with critical SI doses near 700, 2000 and 8500 Wm-2, respectively. In shade, no Pi spores germinated after 3 h, while spores of Bl and Pc were still viable after 3 and 42 h, respectively. In Norway, the potential for long distance distribution of Pi is restricted, but more likely for Bl and Pc. Further experiments will be conducted to find the maximum survival time for spores of these pathogens under Norwegian climatic conditions.
Forfattere
Hugh RileySammendrag
Yield results for the last decade are presented from eight long-term trials (started 1977-1991) on loam and clay loams in southeast Norway. Autumn ploughing has been compared with reduced (ploughless) tillage and/or direct drilling. In most cases, spring cereals were grown. Perennial weeds have been sprayed with herbicides when necessary. Fungicides were not used in the trials. In most trials straw residues were chopped and spread. On loam soils, the effects of tillage on yields were mostly similar to those obtained in earlier years. In Trial 1, on loam, mean grain yield was, with spring harrowing only, 95% of that with annual autumn ploughing. It was 96% when harrowing was performed in autumn as well as in spring and 97% when the soil was ploughed every third year. In Trial 2, on loam, positive crop rotation effects were found both with and without ploughing. Reduced tillage, with spring harrowing only, gave 5% lower grain yield than autumn ploughing in this trial also. In Trial 3, on loam, the tillage system did not affect yields of cereals grown in rotation with potatoes, but reduced tillage gave 12% lower potato yield than annual ploughing. In this trial, little difference was found between tillage systems in crop responses to N fertilizer. In Trial 4, on loam, reduced tillage on large-scale (0.7 ha) plots gave 11% lower grain yields than annual ploughing, possibly partly due to shallower sowing depth. In trials on loam soil, the percentage yields obtained without ploughing, relative to those with ploughing, correlated positively with the amount of rainfall in May and with mean air temperature in August. On clay soils. somewhat poorer results have been obtained with reduced tillage in recent years than in previous periods. In Trial 5, on clay loam, the mean grain yield with spring harrowing only, was, over the last ten years, 87% of that obtained with annual autumn ploughing, whereas it was 94% for the whole period since 1991. The inclusion of autumn harrowing increased these figures to 94% and 98%, respectively. Grain protein was lowest with spring harrowing only. Over the last six years, when a treatment with spring ploughing was introduced, this gave 5% lower yield than autumn ploughing. Yields without ploughing, relative to those with ploughing, were negatively correlated with summer rainfall in this trial. In Trial 6, on clay loam, direct drilling has since 1998, as in previous years, given ca. 10% lower yield than autumn ploughing. Autumn harrowing gave 4% lower yield in winter wheat and 6% higher yield in spring oats, than autumn ploughing, whilst yields of spring turnip rape were not affected by tillage. In Trial 7, on clay loam, six alternative straw treatments were compared under various ploughless tillage regimes. Relative to straw removal, retaining large residue amounts depressed yields hardly at all when harrowing was performed in both autumn and spring, but it reduced them by 7% with spring harrowing only and by 13% with direct drilling. The latter system gave on average 18% lower yields than the system with both autumn and spring harrowing. The yield reduction with spring harrowing was 7%. In Trial 8, on silt loam, both direct drilling and spring harrowing of unploughed soil have since 1998 given 6% lower yield than autumn ploughing, whereas both autumn and spring harrowing has given 6% higher yield than ploughing. In this trial, under drier conditions during 1991-1997, unploughed treatments gave up to 11% higher yield than autumn ploughing. Straw retention was beneficial on unploughed treatments during that period, but has had little effect recently.
Forfattere
Mats Høglind Ann NorderhaugSammendrag
I denne rapporten prøver vi å belyse hvilke økologiske konsekvenser klimaendringene kan få for stølslandskapet i Valdres og det biologiske mangfoldet som er knyttet til de gamle slåtte- og beitemarkene der. Som utgangspunkt brukes nedskalerte scenarioer for daglig temperatur og nedbør som er tilgjengelig for nedlasting fra internett, samt kunnskap og modeller som er utviklet i Bioforsks strategiske instituttprogram WINSUR (2004-2008) om klimaeffekter på dyrket eng. Klimascenarioene viser at det vil bli store klimaforandringer både på "gårdsnivå" og i stølslandskapet i Valdres. Beregninger er gjort for en gård på 525 m høyde og en støl på 890 m høyde. Vekstsesongen vil bli lengre og klimaindeksberegninger for vinterstressfaktorer for flerårige fôrvekster i fulldyrka eng indikerer at overvintringen vil bli minst like god som i dag. Produksjonen vil derved øke både på gårds- og seternivå og man vil kunne øke antallet slåtter til tre. Beregningene, som er gjort for dyrka eng, kan delvis overføres til semi-naturlig beiteog slåttemark (naturbeite og natureng), men fordi de er ugjødsla vil produksjonsøkningen ofte bli mindre og økningen blir i stor grad påvirket av endringer i næringsforsyningen som følge av klimaendringene. Disse endringene vil variere fra sted til sted og er vanskelige å beregne uten omfattende studier. Vår kunnskap om hvilke effekter klimaforandringene vil få for de semi naturlige grasmarkene er fortsatt begrenset, men vi vet at konkurransen mellom artene vil forandres. Det er likevel stor sannsynlighet for at disse grasmarkene kan bevares der de finnes i dag og kanskje også spre seg oppover, hvis beiteog slåttedriften opprettholdes og justeres i forhold til klimaendringene. Tørrere somre vil kunne gi en negativ effekt på den seminaturlige engvegetasjonen, i hvert fall på tørkesvak jord, noe som ytterligere kan forsterkes av for sterkt beitetrykk. Det vil derfor bli ekstra viktig å opprettholde et "optimalt" beitetrykk. De semi naturlige grasmarkene i seterlandskapet representerer en stor beiteressurs og en "in situ"-bevaring av arter og genressurser som kan få stor betydning i en verden der matproduksjonen på forskjellig måte trues av klimaendringene. Menneskelig aktivitet kan både forsterke og motvirke effektene av klimaendringene på de semi-naturlige slåtte- og beitemarkene. Stølslandskapet truesi dag av gjengroing på grunn av mindre eller opphør av stølsdrift og denne trusselen vil forsterkes av klimaforandringene. Også oppdyrking vil utgjøre en økende trussel for det biologiske mangfoldet som er knyttet til disse grasmarkene når klimaet forandres, men en gjennomtenkt forvaltning av viktige stølsområder basert på tradisjonelle driftsformer, vil kunne motvirke en negativ utvikling.
Sammendrag
Recent in situ 13C studies suggest that lignin is not stabilised in soil in its polymerised form. However, the fate of its transformation products remains unknown. The objective of the present research was to provide the first comprehensive picture of the fate of lignin-derived C across its transformations processes: (1) C remaining as undecomposed lignin molecules, (2) C in newly formed humic substances, i.e. no longer identifiable as lignin-polymer C, (3) C in microbial biomass, (4) C mineralised as CO2, and (5) dissolved organic C. To achieve this objective, we designed an incubation experiment with 13C-labelled lignin where both elementary and molecular techniques were applied. Lignin was isolated from 13C labelled maize plants (13C-MMEL) and incubated in an agricultural soil for 44 weeks. Carbon mineralisation and stable isotope composition of the released CO2 were monitored throughout the incubation. Microbial utilisation of 13C-MMEL was measured seven times during the experiment. The turnover rate of the lignin polymer was assessed by 13C analysis of CuO oxidation products of soil lignin molecules. After 44 incubation weeks, 6.0% of initial 13C-MMEL carbon was mineralised, 0.8% was contained in the microbial biomass, and 0.1% was contained in dissolved organic C form. The compound-specific 13C data suggest that the remaining 93% were overwhelmingly in the form of untransformed lignin polymer. However, limited transformation into other humic substances potentially occurred, but could not be quantified because the yield of the CuO oxidation method proved somewhat variable with incubation time. The initial bacterial growth yield efficiency for MMEL was 31% and rapidly decreased to plateau of 8%. A two-pool first-order kinetics model suggested that the vast majority (97%) of MMEL lignin had a turnover time of about 25 years, which is similar to field-estimated turnover times for soil-extractable lignin but much longer than estimated turnover times for fresh plant-residue lignin. We conclude that natural lignin structures isolated from plants are rather unreactive in soil, either due to the lack of easily available organic matter for co-metabolism or due to enhanced adsorption properties. The data also suggest that fairly undecomposed lignin structures are the main reservoir of lignin-derived C in soils.
Forfattere
Haithem Bahri Daniel Rasse Cornelia Rumpel Marie-France Dignac Gerard Bardoux Andre MariottiSammendrag
Recent in situ 13C studies suggest that lignin is not stabilised in soil in its polymerized form. However, the fate of its transformation products remains unknown. The objective of the present research was to provide the first comprehensive picture of the fate of lignin-derived C across its transformations processes: 1) C remaining as undecomposed lignin molecules, 2) C in newly formed humic substances, i.e. no longer identifiable as lignin-polymer C 3) C in microbial biomass, 4) C mineralised as CO2, and 5) dissolved organic C. To achieve this objective, we designed an incubation experiment with 13C-labelled lignin where both elementary and molecular techniques were applied. Lignin was isolated from 13C labelled maize plants (13C-MMEL) and incubated in an agricultural soil for 44 weeks. Carbon mineralisation and stable isotope composition of the released CO2 were monitored throughout the incubation. Microbial utilisation of 13C-MMEL was measured seven times during the experiment. The turnover rate of the lignin polymer was assessed by 13C analysis of CuO oxidation products of soil lignin molecules. After 44 incubation weeks, 6.0% of initial 13C-MMEL carbon was mineralized, 0.8% was contained in the microbial biomass, and 0.1% was contained in dissolved organic C form. The compound-specific 13C data suggest that the remaining 93% were overwhelmingly in the form of untransformed lignin polymer. However, limited transformation into other humic substances potentially occurred, but could not be quantified because the yield of the CuO oxidation method proved somewhat variable with incubation time. The initial bacterial growth yield efficiency for MMEL was 31% and rapidly decreased to plateau of 8%. A two-pool first-order kinetics model suggested that the vast majority (97%) of MMEL lignin had a turnover time of about 25 years, which is similar to field-estimated turnover times for soil-extractable lignin but much longer than estimated turnover times for fresh plant-residue lignin. We conclude that natural lignin structures isolated from plants are rather unreactive in soil, either due to the lack of easily available organic matter for co-metabolism or due to enhanced adsorption properties. The data also suggest that fairly undecomposed lignin structures are the main reservoir of lignin-derived C in soils.