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.
2015
Sammendrag
Remotely sensed data from airborne laser scanning (ALS) and interferometric synthetic aperture radar (InSAR) can greatly improve the precision of estimates of forest resource parameters such as mean biomass and biomass change per unit area. Field plots are typically used to construct models that relate the variable of interest to explanatory variables derived from the remotely sensed data. The models may then be used in combination with the field plots to provide estimates for a geographical area of interest with corresponding estimates of precision using model-assisted estimators. Previous studies have shown that field plot sizes found suitable for pure field surveys may be sub-optimal for use in combination with remotely sensed data. Plot boundary effects, co-registration problems, and misalignment problems favor larger plots because the relative impact of these effects on the models of relationships may decline by increasing plot size. In a case study in a small boreal forest area in southeastern Norway (852.6 ha) a probability sample of 145 field plots was measured twice over an 11 year period (1998/1999 and 2010). For each plot, field measurements were recorded for two plot sizes (200 m2 and 300/400 m2). Corresponding multitemporal ALS (1999 and 2010) and InSAR data (2000 and 2011) were also available. Biomass for each of the two measurement dates as well as biomass change were modeled for all plot sizes separately using explanatory variables from the ALS and InSAR data, respectively. Biomass change was estimated using model-assisted estimators. Separate estimates were obtained for different methods for estimation of change, like the indirect method (difference between predictions of biomass for each of the two measurement dates) and the direct method (direct prediction of change). Relative efficiency (RE) was calculated by dividing the variance obtained for a pure field-based change estimate by the variance of a corresponding estimate using the model-assisted approach. For ALS, the RE values ranged between 7.5 and 15.0, indicating that approximately 7.5–15.0 as many field plots would be required for a pure field-based estimate to provide the same precision as an ALS-assisted estimate. For InSAR, RE ranged between 1.8 and 2.5. The direct estimation method showed greater REs than the indirect method for both remote sensing technologies. There was clearly a trend of improved RE of the model-assisted estimates by increasing plot size. For ALS and the direct estimation method RE increased from 9.8 for 200 m2 plots to 15.0 for 400 m2 plots. Similar trends of increasing RE with plot size were observed for InSAR. ALS showed on average 3.2–6.0 times greater RE values than InSAR. Because remote sensing can contribute to improved precision of estimates, sample plot size is a prominent design issue in future sample surveys which should be considered with due attention to the great benefits that can be achieved when using remote sensing if the plot size reflects the specific challenges arising from use of remote sensing in the estimation. That is especially the case in the tropics where field resources may be scarce and inaccessibility and poor infrastructure hamper field work.
Sammendrag
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Forfattere
Svein SolbergSammendrag
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Forfattere
Inger HansenSammendrag
This literature review documents behavioural differences in organic and conventional sheep and goats in Norway. Increased indoor space results in increased lying time, more synchronized lying behaviour, less displacements and higher milk yield in sheep, and increased lying time and lower frequency of agonistic behaviour in goats. Sheep and goats spend 45-50 % of their time outdoors when given access to an outdoor yard during winter. Under normal thermal conditions, fully fleeced sheep do not need solid floors of welfare reasons in Norway. Neither do dairy goats in insulated buildings. The significance of different milk feeding strategies in goat kids is poorly documented, but studies on lambs and calves show that suckling increases the growth rate, gives better social competence and more exploratory behaviour. Thus, the organic regulations in Norwegian sheep and goat production have some positive impact on behavioural indicators of sheep and goat welfare, especially during winter housing.
Forfattere
Inger HansenSammendrag
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Sammendrag
Nesten to millioner søyer og lam blir sluppet på utmarksbeite i Norge hvert år. Rundt 125 000 av disse kommer ikke tilbake om høsten. Mortalitet grunnet predasjon av fredet rovvilt er økende i mange områder, og miljøforvaltningen betaler årlig ca. 75 millioner kroner i erstatning for rovviltdrepte sauer (www.rovbase.no). Tap av sau kan også skyldes ulykker og sjukdom, og sammenhengene mellom tapsårsaker er komplekse....
Forfattere
Tore SkrøppaSammendrag
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Sammendrag
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Tore SkrøppaSammendrag
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Tore SkrøppaSammendrag
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