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.
2013
Authors
Karl Henrik Haugholt Matthieu Jean P Lacolle Marion O'Farrell Atle Honne Kari Anne Hestnes Bakke Aina Lundon RussenesAbstract
A low-cost Fourier transform infrared (FTIR) instrument was developed where the traditional He–Ne reference laser was replaced by a low-cost linear encoder. An RMS sampling error of less than 20 nm was achieved by oversampling both the interferogram and the encoder signal and then resampling the interferogram using a correction table for the encoder. A gas calibration model was developed for the system, which was chosen to have a stroke length of 21 mm and, thereby, a resolution of 0.4 cm −1 after apodization. The instrument was mounted on a vehicle and employed in an agricultural field test for measuring soil emissions, in particular nitrous oxide (N 2 O ). The concentration of N 2 O was measured with a root mean squared error of 6 ppb. The results compared well with lab-based gas chromatography measurements.
Authors
James David Mervyn Speed Erling Meisingset Gunnar Austrheim Alison J. Hester Atle Mysterud Jean-Pierre Tremblay Erling Johan SolbergAbstract
Browsing by cervids plays a key role in structuring forest ecosystems and dynamics. Many boreal forest systems are managed for timber resources, and at the same time the wild cervid populations are also harvested. Thus, the determination of sustainable densities of cervids for the purpose of forest and game management is challenging. In this study we report on a red deer (Cervus elaphus) exclosure experiment in the mature forests of Western Norway. Ten pairs of exclosures and browsed plots were initiated in 2008. The rate of browsing and height growth of marked individuals was recorded annually, and the total densities of all tree species assessed over the following 4 y. We found that height growth of rowan (Sorbus aucuparia) saplings (1 m tall), the most numerous tree species at the site, was prevented when 20% of the shoots were browsed. Outside of the exclosures, net height growth of rowan saplings tended to be positive when trees were below 40 cm in height, but growth was constrained in rowan saplings over this height. The density of rowan also increased in both treatments, showing that recruitment was occurring, but the increase was greater where browsed than in the exclosure. The increase in density of rowan, combined with the curtailment of height growth in the presence of red deer, serves to create a carpet of short stature rowan saplings. This has parallels with the browsing lawn concept, but it seems to occur in interaction with snow depth; individuals protruding above the snow layer are likely to be browsed during the winter, whilst smaller individuals are protected during this season, when browsing is at its peak. Keywords: browsing lawns, Cervidae, Cervus elaphus, herbivory, snow depth, sustainable management. Résumé : Le broutement par les cervidés joue un rôle clé dans la composition, la structure et la dynamique des écosystèmes forestiers. De nombreux systèmes forestiers boréaux sont gérés à la fois pour la production de ressources ligneuses et la chasse sportive des cervidés. Un enjeu majeur réside dans la détermination d’une densité de cervidés permettant une exploitation durable de ces ressources. Dans cette étude, nous rapportons une expérience d’exclusion du cerf élaphe (Cervus elaphus) dans les forêts matures de l’ouest de la Norvège basée sur 10 paires d’exclos et de parcelles accessibles au broutement établies en 2008. Nous avons mesuré annuellement durant 4 ans le taux de broutement et de croissance verticale de semis et de gaulis marqués et estimé les densités totales de toutes les espèces d'arbres. Hors des exclos, la croissance des gaules (1 m de haut) de sorbier des oiseleurs (Sorbus aucuparia), l’espèce ligneuse la plus abondante sur le site, était compromise lorsque 20 % des pousses étaient broutées. Nous avons observé une tendance positive dans la croissance des gaules de moins de 40 cm alors qu’elle était compromise au-delà de ce seuil. La densité de sorbiers a également augmenté à l’intérieur et à l’extérieur des exclos révélant un recrutement positif, toutefois l'augmentation de la densité était plus marquée dans les parcelles soumises au broutement. L'augmentation de la densité de sorbiers, combinée à la réduction de la croissance en hauteur, en présence du cerf élaphe génère une strate dense de sorbiers de petite stature. Cette situation présente des similitudes avec le concept de haie de pâturage (browsing lawn), mais pourrait être liée à l’épaisseur de neige au sol. En effet, les arbustes qui dépassent la couche nivale sont plus susceptibles d’être broutés que les plus petits qui sont protégés en hiver lorsque la consommation d’espèces ligneuses est maximale. Mots-clés : cervidés, Cervus elaphus, épaisseur de neige, exploitation durable, haie de pâturage, herbivorie
Authors
Ghislain Tchoromi Tepa-Yotto Trond Hofsvang May SæthreAbstract
No abstract has been registered
Authors
May Sæthre Ghislain Tchoromi Tepa-Yotto Trond HofsvangAbstract
No abstract has been registered
Authors
Susanne Friis Pedersen Marte Meland Celine ReboursAbstract
No abstract has been registered
Authors
Susanne Friis Pedersen Marte Meland Celine ReboursAbstract
No abstract has been registered
Authors
Ricardo HolgadoAbstract
No abstract has been registered
Authors
Tore SkrøppaAbstract
No abstract has been registered
Authors
Atle WibeAbstract
No abstract has been registered
Authors
Mekjell Meland Eva Birken Clive KaiserAbstract
Crop load adjustments in European plum trees (Prunus domestica L.) require thinning either by hand (mechanical) or chemical means to achieve marketable size, fruit quality and to overcome alternate bearing. Efficient tools for crop load management are highly desirable, since only a few chemical thinners are registered and hand thinning is labor intensive and costly. Gibberellic acid (GA3) was tested as a novel approach to regulate the crop load of the plum cultivar ‛Opal’ at Ullensvang, western Norway. The objective was to reduce flower bud induction in the “off-year” thus adjusting crop load the subsequent year. In 2008, an “off-year”, GA3 was applied to 9 year-old ‘Opal’ trees as a high volume spray to the point of run-off at 50 ppm or 100 ppm at either 5 weeks after full bloom or 10 weeks after full bloom, or on both dates and compared with untreated control trees. Trees were unthinned the first year but then thinned to commercial standard the following year. In the year of application, total yield was recorded and fruit quality evaluated. Return bloom, fruit set, yield and fruit quality were assessed the subsequent year. In general, there were no significant differences in crop load of all treated trees compared to untreated trees in the year of application (non-target crop) however, fruit weight increased slightly on those trees when GA3 was applied 5 weeks after full bloom compared to all other treatments and untreated trees. The following year (target crop) fruit set was significantly reduced for all GA3 treatments. The most effective application time was 5 weeks after full bloom. Before thinning, initial fruit set was greatest on untreated trees as well as on those trees treated with GA3 10 weeks after full bloom. Fruit weight and fruit colour were significantly better on trees with the least fruit set. GA3 applications had no effect on fruit firmness. It is concluded that GA3 is an effective tool for inhibiting flower bud induction in an “off-year” thus enabling crop load management the subsequent “on-year”.