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.
2012
Authors
Therese With BergeAbstract
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Authors
Anders Skonhoft Vebjørn Veiberg Asle Årthun Gauteplass Jon Olaf Olaussen Erling Meisingset Atle MysterudAbstract
This paper presents a bioeconomic analysis of a red deer population within a Norwegian institutional context. This population is managed by a well-defined manager, typically consisting of many landowners operating in a cooperative manner, with the goal of maximizing the present-value hunting related income while taking browsing and grazing damages into account. The red deer population is structured in five categories of animals (calves, female and male yearlings, adult females and adult males). It is shown that differences in the per-animal meat values and survival rates (‘biological discounted’ values) are instrumental in determining the optimal harvest composition. Fertility plays no direct role. It is argued that this is a general result working in stage-structured models with harvest values. In the numerical illustration it is shown that the optimal harvest pattern stays quite stable under various parameter changes. It is revealed which parameters and harvest restrictions that is most important. We also show that the current harvest pattern involves too much yearling harvest compared with the economically efficient level.
Authors
Johannes DeelstraAbstract
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Janka Dibdiakova Kjell VadlaAbstract
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Authors
Jonathan Edward Colman Diress Tsegaye Alemu Christian Pedersen Ruben Eidesen Herbjørg Arntsen Øystein Holand Alex Mann Eigil Reimers Stein Ragnar MoeAbstract
Interspecific interaction among sympatric ungulates is important in management and conservation. We investigated behavioral interference between sympatric wild or semidomestic reindeer (Rangifer tarandus tarandus) and sheep (Ovis aries) in two field studies and one enclosure experiment. For free-ranging wild and semidomestic reindeer, interference between the two species increased with decreasing distances, occurring only at less than 200 m and 30 m, for wild and semidomestic reindeer, respectively, and neither species consistently dominated the other. In a controlled, duplicated experiment we tested interference and confrontations at the feeding patch level among semidomestic reindeer and sheep within 40 × 50 m enclosures. When new reindeer or sheep were introduced into enclosures already occupied by reindeer, new reindeer resulted in significantly more interference and confrontations among individuals compared to new sheep; i.e., intraspecific interference was more prevalent than interspecific interference at equal densities. For all study areas, confrontations decreased with time after “first encounter,” indicating cohabituation. A sympatric use of pastures was not visually disruptive for recorded grazing behavior for either species.
Authors
Christian Brischke Christian Welzbacher Antje Gellerich Susanne Bollmus Katharina Plaschkies Wolfram Scheiding Gry Alfredsen Joris Van Acker Imke De WindtAbstract
Die Dauerhaftigkeit von Holz gegenber Basidiomyceten wird in Europa nach CEN/TS 15083-1 (2005) bestimmt. Die bisherigen Erfahrungen mit diesem Standard sind sehr heterogen, und Ergebnisse frherer Ringversuche teilweise nicht oder nur unvollstndig verffentlicht. Insbesondere die Notwendigkeit einer natrlichen Vorbewitterung der Prfkrper, u.a. mit dem Ziel einer Detoxifizierung des Materials, wird kontrovers diskutiert. Fnf europische Forschungseinrichtungen haben sich deshalb zu einem neuen Ringversuch zusammengeschlossen, in dem die Dauerhaftigkeit gegen holzzerstrende Pilze von fnf Holzarten mit und ohne Auswaschbeanspruchung bzw. 6-monatiger natrlicher Vorbewitterung gegen Coniophora puteana und Trametes versicolor geprft wurden. Es ergaben sich Unterschiede in der Dauerhaftigkeitsklassifizierung zwischen den Prfinstituten (bis zu vier Klassen) sowie in Abhngigkeit von der Vorbeanspruchung und den statistischen Auswertungsgren. Die natrliche Vorbewitterung der Prfkrper hatte teilweise eine Angleichung der Dauerhaftigkeitsklassifizierung zwischen den Prfinstituten zur Folge. In allen Fllen wurde eine Homogenisierung der Dauerhaftigkeitseinschtzung durch Vorbewitterung jedoch nicht erreicht. Generelle Aussagen zum Einfluss der Vorbeanspruchung auf die Klassifizierung der Dauerhaftigkeiten lieen sich somit nicht ableiten, weshalb diese weder zwingend zu empfehlen noch abzulehnen ist.
Authors
Habtamu AlemAbstract
No abstract has been registered
Authors
Inger MartinussenAbstract
No abstract has been registered