Merete Myromslien
Driftsleder
(+47) 901 62 770
merete.myromslien@nibio.no
Sted
Fureneset
Besøksadresse
Furenesvegen 210, 6967 Hellevik i Fjaler
Forfattere
Ali Hosseini Hans-Christian Teien Till Seehusen Merete Myromslien Marit Nandrup Pettersen Justin Brown Brit Salbu Deborah Helen OughtonSammendrag
A series of 131I tracer experiments have been conducted at two research stations in Norway, one coastal and one inland to study radioiodine transfer and dynamics in boreal, agricultural ecosystems. The hypothesis tested was that site specific and climatological factors, along with growth stage, would influence foliar uptake of 131I by grass and its subsequent loss. Results showed that the interception fraction varied widely, ranging from 0.007 to 0.83 over all experiments, and showing a strong positive correlation with biomass and stage of growth. The experimental results were compared to various models currently used to predict interception fractions and weathering loss. Results provided by interception models varied in the range of 0.5–2 times of the observed values. Regarding weathering loss, it was demonstrated that double exponential models provided a better fit with the experimental results than single exponential models. Normalising the data activity per unit area to remove bio-dilution effects, and assuming a constant single loss rate gave weathering half-times of 22.8 ± 38.3 and 10.2 ± 8.2 days for the inland and coastal site, respectively. Whilst stable iodine concentrations in grass and soil were significantly higher (by approximately a factor of 5 and 7 times for grass and soil respectively) at the coastal compared to the inland site, it was not possible to deconvolute the influence of this factor on the temporal behaviour of 131I. Nonetheless, stable iodine data allowed us to establish an upper bound on the soil to plant transfer of radioiodine via root uptake and to establish that the pathway was of minor importance in defining 131I activity concentrations in grass compared to direct contamination via interception. Climatological factors (precipitation, wind-speed and temperature) appeared to affect the dynamics of 131I in the system, however the decomposition of these collective influences into specific contributions from each factor remains unresolved and requires further study. The newly acquired data on the interception and weathering of radioiodine in boreal, agricultural ecosystems and the reparametrized models developed from this, substantially improve the toolbox available for Norwegian emergency preparedness in the event of a nuclear accident.
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Sammendrag
Increasing abundance of Juncus effusus (soft rush) and Juncus conglomeratus (compact rush) in pastures and meadows in western Norway has caused reductions in forage yield and quality in recent decades. Understanding plant development and regrowth following cutting is essential in devising cost-effective means to control rushes. In a field experiment in western Norway, we investigated development of above- and below-ground fractions of rush from seedlings to three-year-old plants, including the impact on vigour of disturbing growth by different cutting frequencies during the period 2009–2012. Each year, the plants were exposed to one or two annual cuts or left untreated and five destructive samplings were performed from March to early December. Juncus effusus showed significantly more vigorous growth than Juncus conglomeratus in the last two years of the study period. The above-ground:below-ground biomass ratio of both species increased mainly in spring and early summer and was reduced in late summer and autumn. Removal of aerial shoots also reduced the below-ground fraction of both species. One annual cut in July effectively reduced biomass production in both species by 30–82%, which was only a slightly smaller reduction than with two annual cuts, in June and August. Mechanical control measures such as cutting can thus effectively reduce rush vigour when performed late in the growing season.
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Forfattere
Samson Øpstad Odd-Jarle Øvreås Merete Myromslien Stein Harald Hjeltnes Svein Arne Vågane Liv ØstremSammendrag
I denne rapporten er det gjeve ei vurdering av kva framskriving av klimaendringane med auka nedbør og temperatur kan få å seia for landbruket på Vestlandet. Det er lagt hovudvekt på å omtala situasjonen for grovfôrdyrking då det saman med grovfôrbasert husdyrhald er tyngde-punktet i vestnorsk landbruk. Betring av dreneringstilstand er viktig då meir nedbør og moderne jordbruksdrift set større krav til dreneringstilstanden.Dreneringstilstand verkar sterkt inn på arealproduktiviteten.Ved-likehald av jordkapitalen har vore for lite vektlagt over tid, og det er eit etterslep som må takast att. Overvintring av engvokstrar er vist til både som viktig utfordring i dag sett i samanheng med klima og driftsmåte, og at det er ei utfordring å skaffa klimatilpassa plantemateriale framover. Gjødslingspraksis må både ut frå agronomiske- og miljømessige grunnar leggjast opp slik at ein unngår spreiing av husdyrgjødsel seint i veksetida, for å auka N- og P-utnyttinga og redusera tap til vatn og luft. Dette vil innebera at ein del må utvida lagerkapasiteten for husdyrgjødsel. Frukt og bærproduksjon er svært klimaavhengig. Auka frekvens av vind vert vurdert som utfordrande, ikkje minst økonomisk. Meir nedbør er utfordrande m.o.t. meir sjukdom og bakteriosar. Sterk vind, kombinert med vassmetta jord, fører til meir vindfall i skog. Dette er økonomisk, fagleg og i ressurssamanheng utfordrande for ei ung næring. Auka nedbørsmengde og nedbørintensitet er tilhøve som gjer at fare for flaum og skred må vurderast grundigare i ulike samanhengar, noko som vedkjem landbruket m.o.t. dimensjonering av drenering, avlaup, stikkrenner og sikring mot graving og erosjon. Verksemd som skogsvegbygging må ta meir omsyn til auka vassføring, og med fare for erosjon, flaum og skred. Det å dimensjonera for auka vassføring og førebyggja mot flaum og skred, gjeld og for andre samfunnssektorar.