Publications
NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.
2010
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Helge BerglannAbstract
This article considers the use of a hybrid instrument to regulate .sheries, comparing this instrument with quantity control and linear taxation in regards to economic yields and the risk of resource deple- tion. Hybrid instruments have shown to be central in studies with static models but have hardly ever been explored in the context of dy- namic .sheries. A numerical example concerned with a single-species demersal .shery where the stock estimate is uncertain indicates that a combination of price and quantity control in the form of a strictly convex tax on landings is clearly superior to quantity control. When cost uncertainty is involved, it can also prove more e¢ cient than the price instrument.
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Ingunn ØvsthusAbstract
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Studying the winter survival of forage grasses under a changing climate requires models that can simulate the dynamics of soil conditions at low temperatures. We developed a simple model that simulates depth of snow cover, the lower frost boundary of the soil and the freezing of surface puddles. We calibrated the model against independent data from four locations in Norway, capturing climatic variation from south to north (Arctic) and from coastal to inland areas. We parameterized the model by means of Bayesian calibration, and identified the least important model parameters using the sensitivity analysis method of Morris. Verification of the model suggests that the results are reasonable. Because of the simple model structure, some overestimation occurs in snow and frost depth. Both the calibration and the sensitivity analysis suggested that the snow cover module could be simplified with respect to snowmelt and liquid water content. The soil frost module should be kept unchanged, whereas the surface ice module should be changed when more detailed topographical data become available, such as better estimates of the fraction of the land area where puddles may form.
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