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.
2011
Sammendrag
In spring and autumn 2011, we carried out a baiting program for Phytophthora spp. in urban streams and lakes in Rogaland and Hordaland counties in western Norway, and in a stream in a beech forest in Vestfold county in southeastern Norway. We used rhododendron leaves from the cultivar ‘Cunningham White’ as bait. Prior to baiting, all leaves were surface sterilized with 70% ethanol and placed in perforated bags (2-3 leaves per bag), each with a styrofoam floater to keep the bait near the surface. The bags were anchored to the shore and left in the water for 6-8 days. All locations were recorded with a field mapping GPS-device, and thus all mapping tasks could be finalized in the field. At many locations the leaves had dark and/or water soaked spots when removed from the water. Small sections from the leading edges were dissected and plated on Phytophthora-selective media (PARP and/or PARPH). One interesting finding was P. ramorum in a river in Rogaland county, but we also isolated a number of other Phytophthora spp. that are currently being identified. The results will be presented at the meeting.
Forfattere
Atle HaugeSammendrag
I rapporten er det laget skisser av 3 anlegg med bekkevoller/sedimentasjonsdammer for å bedre oppsamlingen av partikler og fosfor i åkerkanten på hellende grønnsaksarealer. Ideen er at det i nedbørepisoder dannes midlertidige dammer slik at eroderte partikler fra landbruksarealet sedimenterer. Slike midlertidige dammer vil være bedre enn bare en ugjødslet randsone, fordi partiklene får bedre tid til å sedimentere. Anleggene skal anlegges som pilotanlegg, og det foreslås å registrere effekten ved måling av sedimentene på sedimentasjonsplater. Dette er billige tiltak, og kan vise seg å være svært kostnadseffektive.
Forfattere
Kjersti Holt HanssenSammendrag
The pine weevil (Hylobius abietis) is an important pest to conifer seedlings in large parts of Europe. To get an objective measure of the extent of damages related to pine weevils in South-Eastern Norway, a survey was implemented in the autumn of 2010 in nine counties. Altogether, 155 stands regenerated by planting in 2009 or 2010 were examined. The percentage of seedlings killed from pine weevil attacks varied between 0 and 63 % in the surveyed fields. On average, 7 % of the seedlings were killed by pine weevils, while 23 % had bark wounds. In addition, 3 % of the seedlings were killed by other causes. Few of the registered field variables were correlated to the degree of damage, but there was a tendency towards higher mortality at the largest clear cuts, in hilly areas, and for dry soil types. The present survey shows that in unscarified stands in SE Norway pine weevils are the most important cause of seedling mortality. A total seedling mortality of at least 10% should be expected the first two years.
Forfattere
Christer MagnussonSammendrag
In the Nordic countries the total forest area is 67 million hectars, with conifers covering 38 milllion hectars. The Nordic standing crop of conifer wood is about 5 million m3, with an almost equal share of pine (Pinus sylvestris) and spruce (Picea abies). Because of this large and precious forest resource, the recent spread of pinewood nematode (PWN) Bursaphelenchus xylophilus in Europe is of great concern to Nordic countries. The expression of pine wilt disease requires summer temperatures higher than normal for Scandinavia. However, in the area of the recent outbreak in Galicia in Spain, temperatures seem modest, with mean values for July and August at or just above 20oC. Climate change may push the Nordic area into warmer conditions. Available models suggest that damage to Nordic forests is expected to be small in a 50 years perspective. Long-term models are scarce, but in view of pine tree production cycles of up to 120 years, mortality may occur more frequently within one or a few forest generations. Since PWN may exist in trees free of wilt symptoms its distribution in Europe becomes unclear. Monitoring of the pest in Nordic forests requires sampling of cutting waste with signs of activity from vector insect in the genus Monochamus. In the Nordic area more than 9000 samples have so far been analyzed from risk areas and risk commodities. A recent simulation PWN spread in Norwegian forests indicates that 14 years may elapse before detection by the present level of 400 samples annually. We are convinced that large sampling volumes and strict import regulations are vital strategies for keeping the Nordic area free from PWN.
Forfattere
Nina SvartedalSammendrag
Det er ikke registrert sammendrag
Sammendrag
Det er ikke registrert sammendrag
Forfattere
Ricardo Holgado Christer MagnussonSammendrag
A major challenge facing agricultural scientists today is the need to secure food for an increasing world population. The World Bank in 2008 estimated a population increase of 35% by 2050. Reducing yield losses caused by pathogens of agricultural crops is one measure that can contribute to increased food production. Plant-parasitic nematodes are often important constraints on crop production; they can cause extensive damage and substantial yield losses. Nematode attack can also predispose plants to attack by other pathogens either through mechanical damage or on a genetic basis. These interactions between nematodes and other pathogens in disease complexes increase yield losses. The degree of damage can also be dependent on host plant and age. In addition, environmental and climatic conditions influence the nematode density. Damage that results from nematode attack affect not only the feeding cell, but reduces also the capacity of the root system, to take up nutrients and water. The decreasing availability of agrochemicals makes the situation complicated as the use of nematicides has been the principal tool for nematode management over the past decades. Nematode management strategies are targeted at preventing nematode multiplication and hence protect the crop from damage. In absence of nematicides the growing of resistant varieties is the most cost-effective and successful means of management. Combined with knowledge of the biology life-cycle, and the effects of cultural practices like crop rotation, organic amendment, growing resistant cultivars may minimize the effect of plant parasitic nematodes. To meet these challenges interdisciplinary research is needed.
Forfattere
Ellen Merethe MagnusSammendrag
Det er ikke registrert sammendrag
Forfattere
Ylva-li Blanck Juan Gowda Linda-Maria Mårtensson Jakob Sandberg Ann-Mari FranssonSammendrag
The aim of this study was to ascertain whether there is a relationship between plant species richness and plant-available N, P and water in an environment subject to little anthropogenic disturbance. To accomplish this we studied the vegetation in matorral shrub-lands in northern Patagonia, Argentina. Due to the variation in slope, precipitation and aspect between the sites water status was determined using the 12C/13C fraction, δ13C, to investigate whether this was a confounding factor. The numbers of herb, shrub, liana and tree species were determined at 20 sites along an estimated precipitation gradient. Leaf P and N content and the δ13C of Berberis buxifolia were determined, as well as the soil P and N content at the different sites. A negative correlation was found between species richness and Berberis buxifolia foliar P concentration (52% of the species richness variation was accounted for), and a positive correlation was found between plant species richness and Berberis buxifolia foliar N: P ratios (54% of the species richness variation was accounted for). The relationship between species richness and foliar P was seen when all layers of vegetation were included (trees, lianas, shrubs and herbs). Foliar N showed no correlation with species richness, while soil extractable NH4 showed a weak positive correlation with the number of shrub layer species (lianas, shrubs and trees). The species richness of the shrub layer increased with decreasing values of δ13C. Low soil P availability thus affects local species richness in the matorral shrub-lands of Patagonia in Argentina although the growth of vegetation in the area has been shown to be limited by N. We suggest that low P levels increase plant species richness because low soil P concentration is associated with a high P partitioning and high potential for niche separation.
Forfattere
Geir Kjølberg Knudsen Tasin MarcoSammendrag
Det er ikke registrert sammendrag