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.
2013
Forfattere
Ivano Brunner Isabella Børja Lise Dalsgaard Gaby Deckmyn Alf Ekblad Douglas L. Godbold Irene Guerra Avalos Martin Lukac Karsten Kalbitz Kaie Kriiska Ivika Ostonen Andrea Schnepf Primož Simončič Elena VanguelovaSammendrag
Det er ikke registrert sammendrag
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Fruit-set involves a series of physiological and morphological changes that are well described for tomato and Arabidopsis, but largely unknown for sweet pepper (Capsicum annuum). The aim of this paper is to investigate whether mechanisms of fruit-set observed in Arabidopsis and tomato are also applicable to C. annuum. To do this, we accurately timed the physiological and morphological changes in a post-pollinated and un-pollinated ovary. A vascular connection between ovule and replum was observed in fertilized ovaries that undergo fruit development, and this connection was absent in unfertilized ovaries that abort. This indicates that vascular connection between ovule and replum is an early indicator for successful fruit development after pollination and fertilization. Evaluation of histological changes in the carpel of a fertilized and unfertilized ovary indicated that increase in cell number and cell diameter both contribute to early fruit growth. Cell division contributes more during early fruit growth while cell expansion contributes more at later stages of fruit growth in C. annuum. The simultaneous occurrence of a peak in auxin concentration and a strong increase in cell diameter in the carpel of seeded fruits suggest that indole-3-acetic acid stimulates a major increase in cell diameter at later stages of fruit growth. The series of physiological and morphological events observed during fruit-set in C. annuum are similar to what has been reported for tomato and Arabidopsis. This indicates that tomato and Arabidopsis are suitable model plants to understand details of fruit-set mechanisms in C. annuum.
Forfattere
Mark J. Ducey Rasmus Astrup Stefan Seifert Hans C. Pretzsch Bruce C. Larson K. David CoatesSammendrag
Terrestrial lidar (TLS) is an emerging technology for deriving forest attributes, including conventional inventory and canopy characterizations. However, little is known about the influence of scanner specifications on derived forest parameters. We compared two TLS systems at two sites in British Columbia. Common scanning benchmarks and identical algorithms were used to obtain estimates of tree diameter, position, and canopy characteristics. Visualization of range images and point clouds showed clear differences, even though both scanners were relatively high-resolution instruments. These translated into quantifiable differences in impulse penetration, characterization of stems and crowns far from the scan location, and gap fraction. Differences between scanners in estimates of effective plant area index were greater than differences between sites. Both scanners provided a detailed digital model of forest structure, and gross structural characterizations (including crown dimensions and position) were relatively robust; but comparison of canopy density metrics may require consideration of scanner attributes.
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Nondetection of trees is a serious problem for the use of terrestrial laser scanning (TLS) in forest inventory applications. The use of multiple coregistered scans can reduce nondetection but may not eliminate it, and it carries substantial field and post-processing costs. We examined and extended previously developed theoretical approaches to modeling nondetection. The results suggested that tree size as well as multiple stand structural characteristics may be factors, but the theoretical models do not lend themselves to empirical estimation. We then used distance sampling techniques to identify detection probabilities and develop adjusted estimates for trees per hectare and basal area in nine forest stands in southern Norway. The results compared favorably with field estimates based on fixed-area plots. The estimated detection probabilities indicate that correction for nondetection is needed unless the search for trees is limited to very small distances from the scanner. Distance sampling appears promising when TLS is used in the context of temporary-plot forest inventories.
Forfattere
Ragnar Johnson Mika Mustonen Tomas Lundmark Annika Nordin Yuri Gerasimov Aksel Granhus Eugene Hendrick Jari Hyninen Vivian Kvist Johannesen Adam Kaliszewski Virginijus Miksis Thomas Nord-Larsen Heino Polley Liana Sadauskiene Pat Snowdon Birger Solberg Erik Sollander Arnor Snorrason Mati Valgepea Sheila Ward Toms ZalitisSammendrag
Forests will play a crucial role in the transformation from an economy based on fossil fuels to one relying on renewable resources. Hence, besides being a source of raw material for the forest industry, in the future, forests are expected to increasingly contribute to the production of energy as well as providing a wide range of environmental and social services. Thus, the objective of the present study is to assess the short-term and long-term potential for increasing sustainable wood supply in the EFINORD countries. Present practices and prospects for intensive forest management have been assessed using information from a questionnaire complemented by compilation and evaluating of national forest inventory (NFI) data and other forest sector relevant information. The study indicates a striking variation in the intensity of utilisation of the wood resources within the EFINORD region. For the region as a whole, there seems to be a substantial unused (biophysical) potential. However, recent NFI data from some countries indicate that annual felling rates can be underestimated. If felling rates are higher than currently recognised then, given the increased demand for wood-based energy, there appears to be a need to discuss strategies for large-scale implementation of more intensive forestry practices to ensure that the availability of wood resources in the future can meet an increasing demand in the EFINORD countries.
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Forfattere
James David Mervyn Speed Erling Meisingset Gunnar Austrheim Alison J. Hester Atle Mysterud Jean-Pierre Tremblay Erling Johan SolbergSammendrag
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
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The mating system ofCapercaillie has been referred to as “exploded lek” because displaying males are spaced farther apart than on classical leks. However, inter-male distances and spacing behavior rarely have been quantified. In 2009–2011, we examined the spatial relationships of males on two leks in southeastern Norway by GPS satellite telemetry. Largely exclusive display territories (median 2 ha) surrounded the mating site, but the males spent most of the time displaying on smaller, well-defined display sites (median 182 m2) within their territories. When on their display sites, neighboring birds were spaced 64–212 m apart; decreasing to a minimum during the time of mating. Occasionally, males made long exploratory excursions (median 243 m) across the territories of neighbors, sometimes interacting with them at close distance (< 10m). During daytime, males resided solitarily in radially extending ranges within 1 km of the lek center, commuting to the lek either in the evening or morning by walking or flying, leaving in the morning mostly by walking. The distance from the lek center to night roosting trees and daytime resting areas decreased during the mating season. With interacting males and a spatial arrangement in-between that of classical leks and dispersed polygyny, the term “exploded lek” seems appropriate for the mating system of Capercaillie.
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Rot fungi are a major problem in the construction sector, and method to study under which moisture and temperature coefficients they grow are therefore of significant interest. Measurements of heat production rate have been made on wood samples with the brown rot fungus Postia placenta at different moisture contents (MCs). The results clearly show the heat production rate (ameasure of respiration rate and fungal activity) is moisture-dependent. For most cases, less heat was produced when the MC was decreased, and more heat was produced when the MC was increased. It was also found that when the MC increased after a dry period, the increase in activity was significantly delayed. However, if the moisture state was then kept constant at a high level, the activity slowly increased, showing that the fungi need time to recover back to the original activity level after drying. Isothermal calorimetry is a measurement technique well suited for the study of the activity of wood-decaying fungi as a function of temperature and moisture content.