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.
2017
Abstract
No abstract has been registered
Academic – A study of variance estimation methods for systematic spatial sampling
Geir-Harald Strand
Authors
Geir-Harald StrandAbstract
An undesirable property of systematic spatial sampling is that there is no known method allowing unbiased estimation of the uncertainty of statistical estimates from these surveys. A number of alternative variance estimation methods have been tested and reported by various authors. Studies comparing these estimators are inconclusive, partly because the studies compare different sets of estimators. In this paper, three estimators recommended in recent studies are compared using a single test dataset with known properties. The first estimator compared in this study (ST4) is based on post-stratification of the data. The second estimator (V08) is using a predetermined correction factor calculated from the spatial autocorrelation. The third estimator (MB) is a model based prediction calculated using values from the semivariogram. MB and ST4 were both found to be fairly accurate, while V08 consistently underestimated the variance in this study. V08 relies on the assumption that the autocorrelation structure in the dataset can be described using a particular exponential function. The most likely explanation of the weak result for V08 is that this assumption is violated by the empirical data used in the experiment. A better correction factor can be calculated, but the safe approach is to use MB or ST4.
Authors
Geir-Harald StrandAbstract
No abstract has been registered
Authors
Nicholas Clarke Wenche Dramstad Wendy Fjellstad Jørn-Frode Nordbakken Hilde Karine Wam Tonje Økland Holger LangeAbstract
No abstract has been registered
Authors
Anto Raja Dominic Ole Martin Eklo Marianne Stenrød Eivind Solbakken Roar Lågbu P Horney D Daehmlow Jörn StrassemeyerAbstract
No abstract has been registered
Authors
Anto Raja Dominic Ole Martin Eklo Marianne Stenrød Eivind Solbakken Roar Lågbu P Horney D Daehmlow Jörn StrassemeyerAbstract
No abstract has been registered
Abstract
Mountain tourism depends intensively on the quality of the landscape. In recent years, the Norwegian Trekking Association has focused on local food products at their staffed lodges and it uses the slogan “eat the view.” Such a strategy raises the focus on the agricultural use of the land and the quality of the products. Several Norwegian studies were carried out to investigate the quality of different mountain products and connections with vegetation types and grazing behavior. The results show that milk and meat products from animals grazing on alpine rangelands have improved quality compared to “normal” products. A healthier fatty acid composition and a higher content of secondary plant metabolites were characteristic of mountain products. Furthermore, grazing is of the utmost importance for the maintenance of open mountain landscapes and the biodiversity that is dependent on such landscapes. Maintaining traditional grazing systems also secures the preservation of traditional ecological knowledge about utilizing natural resources. Mountain tourism experiences could be improved and enhanced by documenting and telling the unique story of these complex connections between mountain landscapes, biodiversity, agricultural traditions, and local food products.
Authors
Synnøve Rivedal Samson Øpstad Sverre Heggset Sissel Hansen Trond Børresen Torbjørn Haukås Johannes Deelstra Peter DörschAbstract
No abstract has been registered
Authors
Synnøve Rivedal Samson Øpstad Sverre Heggset Trond Børresen Torbjørn Haukås Sissel Hansen Peter Dörsch Johannes DeelstraAbstract
No abstract has been registered
Abstract
No abstract has been registered