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.
2006
Sammendrag
This study is based on data from the Level I and from forest Officers plots. We combined three sets of data on growth, deposition and soil chemistry, totally 204 plots in south-eastern and mid-Norway. As response variable we used observed growth in % of estimated growth calculated from standard Norwegian growth models. In this way we filtered out the influence of site and stand properties as this were included in the model.The dependent deposition variable used was the N deposition from the national air and precipitation monitoring program. The dependent soil chemistry variables were N, C/N ratio, base saturation, pH, Al, and Ca/Al ratio. Soil chemistry variables should reflect the properties that most likely are influenced by S and N deposition, and that could influence the trees in the hypothesised ways.We used analyses of covariance as statistical method. Growth was positively correlated to nitrogen deposition and to soil nitrogen, and negatively correlated to the C/N ratio in the soil. Also, nitrogen deposition was positively correlated to soil nitrogen and negatively to soil C/N.It was concluded that N deposition probably has increased N availability and thereby growth in southernmost Norway with an order of magnitude around 25%. There were no relationships between growth and the soil acidification variables pH, base saturation, Al concentration or Ca/Al-ratio, and we concluded that no evidence for negative effects of soil acidification on forest growth was found.
Sammendrag
In this study, we present a new method for single tree segmentation and characterization from a canopy surface model (CSM), and its corresponding point cloud, based on airborne laser scanning. The method comprises new algorithms for controlling the shape of crown segments, and for residual adjustment of the canopy surface model (CSM). We present a new criterion that measures the success of locating trees, and demonstrate how this criterion can be used for optimizing the degree of CSM smoothing. From the adjusted CSM segments, we derived tree height and crown diameter, and based on all first laser pulse measurements within the segments we derived crown-base height. The method was applied and validated in a Norway spruce dominated forest reserve having a heterogeneous structure. The number of trees automatically detected varied with social status of the trees, from 93 percent of the dominant trees to 19 percent of the suppressed trees. The RMSE values for tree height, crown diameter, and crown-base height were around 1.2 m, 1.1 m, and 3.5 m, respectively. The method overestimated crown diameter (0.8 m) and crown base height (3.0 m).
Forfattere
Jenny Fäldt Halvor Solheim Bo Långström Anna-Karin Borg-KarlsonSammendrag
To identify chemical resistant markers induced by fungal or mechanical injury, young trees of Scots pine (Pinus sylvestris) were subjected to inoculations of blue stain fungi associated with the pine shoot beetles Tomicus piniperda and T. minor. Among the 20 trees selected for chemical analyses, 16 were divided into four groups: one as control and three were pretreated by wounding only, or by inoculation with either the blue stain fungus Leptographium wingfieldii or Ophiostoma canum.Four wk after pretreatment, all 16 pretreated trees were mass-inoculated with L. wingfieldii. The absolute and relative amounts, as well as the enantiomeric compositions of monoterpene hydrocarbons in the phloem, were determined via a small sample of the phloem before and after the pretreatment and mass inoculation, by using two-dimensional gas chromatography (2D GC) and GC-mass spectrometry (MS).After mass inoculation, the absolute amounts of most of the monoterpenes decreased in the phloem sampled 20 cm from the fungal infection, and were higher in the phloem sampled within the infected reaction zone.The relative amounts of both ()--pinene and ()-limonene increased in phloem samples taken 20 cm above the fungal inoculation in the preinoculated trees compared with phloem sampled from the remaining four control trees. The enantiomeric compositions of -pinene and limonene changed, after fungal growth, at defined distances from the inoculation site: the proportion of the ()-enantiomers was highest in the phloem sampled 20 cm from the fungal inoculation.Four wk after pretreatment, monoterpene production in the phloem at the site of inoculation was more enhanced by L. wingfieldii than by O. canum. However, the different virulence levels of the fungi did not affect the enantiomeric composition of the monoterpenes. The biosynthesis of monoterpene enantiomers is discussed in relation to induced pathogen resistance.
Sammendrag
No abstract has been registered
Forfattere
Harald Bratli Erik Framstad Jogeir N. Stokland Odd Egil StabbetorpSammendrag
No abstract has been registered
Forfattere
Risto Kasanen Jarkko Hantula Timo Kurkela Martti Vuorinen Antti Komualinen Johanna Haapala Henna Penttinen Egbert BeukerSammendrag
No abstract has been registered
Forfattere
Michael M. Müller Kari KorhonenSammendrag
No abstract has been registered
Forfattere
Rune Halvorsen Økland Harald Bratli Wenche E. Dramstad A. Edvardsen Gunnar Engan Wendy Fjellstad Einar Heegaard Oddvar Pedersen Heidi SolstadSammendrag
Knowledge of variation in vascular plant species richness and species composition in modern agricultural landscapes is important for appropriate biodiversity management. From species lists for 2201 land-type patches in 16 1-km2 plots five data sets differing in sampling-unit size from patch to plot were prepared.Variation in each data set was partitioned into seven sources: patch geometry, patch type, geographic location, plot affiliation, habitat diversity, ecological factors, and land-use intensity.Patch species richness was highly predictable (75% of variance explained) by patch area, within-patch heterogeneity and patch type. Plot species richness was, however, not predictable by any explanatory variable, most likely because all studied landscapes contained all main patch types ploughed land, woodland, grassland and other open land and hence had a large core of common species.Patch species composition was explained by variation along major environmental complex gradients but appeared nested to lower degrees in modern than in traditional agricultural landscapes because species-poor parts of the landscape do not contain well-defined subsets of the species pool of species-rich parts.Variation in species composition was scale dependent because the relative importance of specific complex gradients changed with increasing sampling-unit size, and because the amount of randomness in data sets decreased with increasing sampling-unit size. Our results indicate that broad landscape structural changes will have consequences for landscape-scale species richness that are hard or impossible to predict by simple surrogate variables.
Forfattere
Jolanda Roux Halvor Solheim Gilbert Kamgan Nkuekam Michael J. WingfieldSammendrag
No abstract has been registered
Sammendrag
We examined growth responses of Norway spruce using tree-ring series from increment cores and monthly climate variables over the period 19001998. The 1398 cores were selected from 588 plots scattered all over Norway. We correlated tree-ring indices with temperature, precipitation, Palmer drought severity index and length of the growing season.The weather in June had the largest influence on ring widths. However, two different, and almost opposite, response types were found: Tree growth was restricted by June precipitation in the lowlands in southeastern Norway, but by the June temperature in other regions and at high altitudes.In order to define the shift between these two main response types, we correlated response functions with various 30-year mean climatic variables, including humidity and aridity indices. The 30-year mean June temperature was the variable most clearly showing this shift in response, with a threshold at 1213C. At sites with normal temperature below this threshold, spruce responded positively to unusually warm and dry June months, and vice versa.