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.
2004
Authors
Tove M. Østensvik Kaj Bo VeierstedAbstract
No abstract has been registered
Abstract
Sampling the catchment outlet generally is assumed to be a convenient way to infer information about a variety of biogeochemical processes at the catchment scale as it provides a spatial and temporal integral of the predominating catchment output fluxes for a number of chemical compounds of interest.Moreover, the short-term dynamics and long-term trends of the hydrograph and of solute concentrations in the catchment runoff can provide information about the predominating processes at the catchment scale and can be used to refine conceptual and mathematical models.Additional measurements inside the catchment, e.g., of soil solution, groundwater, and stream water at different sites, are used to relate the findings to within-catchment processes and thus to further constrain hypotheses and models.
Authors
Birger VenneslandAbstract
No abstract has been registered
Authors
Stig Lande Morten Eikenes Mats WestinAbstract
No abstract has been registered
Authors
Axel Schmidt K. Witzel Gazmend Zeneli D. Martin J. Bohlmann Paal Krokene Trygve Krekling Ari M. Hietala Carl Gunnar Fossdal Erik Christiansen Jonathan GershenzonAbstract
The study of conifer chemical defense has been dominated by investigations of oleoresin and its components. However, the actual function of resin components in plant defense and their mode of action is still uncertain, and the role of other defense compounds is relatively unexplored.We are studying the biochemical and molecular bases of chemical defenses, including terpenes, phenolics and chitinases, in Norway spruce (Picea abies) to learn more about how the accumulation of defense compounds is regulated, with the long-term goal of manipulating defense levels to test their function.Manipulation can be crudely accomplished by treatment with methyl jasmonate, which often mimics the general increases in defenses seen following herbivore or pathogen attack. Such treatment was shown to increase resistance to a fungal associate of bark beetles.To more conclusively test function, isolated genes of defense biosynthetic pathways are being transformed into Norway spruce to produce plants whose defense profiles are altered more precisely.
Authors
Bernt-Håvard Øyen Petter NilsenAbstract
During the last thirty years the interest for the use of selective cutting in the sub-alpine spruce forests of Norway has increased. However, there have been very few investigations on the post harvesting development after such cuttings. Four plots in irregular Norway spruce (Picea abies (L.) Karsten) dominated forests on semi-fertile sites in Northern Norway have been the subjects of a case study.We performed a reconstruction of the stand development by means of biometric assessments and ring widths measurements of all standing trees. Tree ages, stand structure, growth and recruitment were examined. Even though a hypothetical reverse J-curve for the present diameter distribution was identi- fied, the four plots were even-aged. Growth reactions indicate that most of the present sawtimber trees were established after heavy dimension cuttings in the late 19th century.The recruitment situation is characterized as satisfying in one of four plots. The post harvesting mean volume increment on the plots have been about two thirds of the potential yield estimated from site indices and maximum mean annual increment in regular stands. Managing strategies for irregular spruce forest stands are briefly discussed.
Authors
K.M.J. Taulavuori E.B. Taulavuori Oddvar Skre Jan-Erik Ørnelund Nilsen B. Igeland Kari M. LaineAbstract
The aim was to elucidate the effects of elevated winter temperatures on the dehardening process of mountain birch (Betula pubescens ssp. czerepanovii) ecotypes and to evaluate their susceptibility to frost damage under warming climate conditions. Ecotypes from 60 to 71N latitudes and 20750 m altitudes were grown in northern Norway (70N) and subjected to simulation of the photoperiod in southern Norway (60N) by artificial illumination from September onwards. In November, the seedlings were transported to the south (60N) to overwinter at ambient or 4C above ambient temperatures. Frost hardiness and lipid peroxidation were determined during JanuaryApril. The higher winter temperature accelerated dehardening, and there were significant differences between the ecotypes. Among tree individuals of southern origin, the alpine ecotype exhibited the most rapid rate of dehardening, whereas the oceanic type showed the slowest rate. Lipid peroxidation supported the above findings. Since temperature elevation was unequal for the ecotypes with respect to climatic change, the frost hardiness results were normalized to obtain an equal 4C temperature rise. The risk of frost injury seemed to be lowest in the northernmost ecotypes under a temperature elevation of 4C, obviously due to their adaptation to a wider temperature range.
Authors
Peder Gjerdrum G. Arrighetti Mauro BernabeiAbstract
Resin pocket is a natural property considered one of the main drawbacks of spruce timber, particularly important for appearance and joinery applications. The resins, viscous by nature, might only be solidified at temperatures superior to conventional kiln drying.Induced in the active cambium by traumas of unknown origin, size as well as location of resin pockets are random. Surrounding annual rings appear unaffected, while on the microscopic scale discrepancies in cell structure are easily recognised. Ca. 200 resin pockets per m3 timber have been reported in Scandinavian timber. More resin pockets were experienced in boards sawn from the ca. 16% of logs demonstrating resin pocket in the crosscuts.
Authors
Svein SolbergAbstract
Summer drought, i.e. unusually dry and warm weather, has been a significant stress factor for Norway spruce in southeast Norway during the 14 years of forest monitoring. Dry and warm summers were followed by increases in defoliation, discolouration of foliage, cone formation and mortality. The causal mechanisms are discussed. Most likely, the defoliation resulted from increased needle-fall in the autumn after dry summers.During the monitoring period 19882001, southeast Norway was repeatedly affected by summer drought, in particular, in the early 1990s. The dataset comprised 455 Forest officers plots with annual data on crown condition and mortality. Linear mixed models were used for estimation and hypothesis testing, including a variancecovariance structure for the handling of random effects and temporal autocorrelation.
Abstract
No abstract has been registered