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
Authors
Rimvis Vasiliauskas Audrius Menkis Roger D. Finlay Jan StenlidAbstract
Fungi of roots of declining pine and spruce seedlings were assessed by pure culture isolations and direct sequencing. The isolation from 1440 roots of 480 seedlings (240 per each tree species) yielded 1110 isolates which, based on mycelial morphology and ITS rDNA sequences, were found to represent 87 distinct taxa.
Authors
Rune Halvorsen Økland Harald Bratli Wenche E. Dramstad A. Edvardsen Gunnar Engan Wendy Fjellstad Einar Heegaard Oddvar Pedersen Heidi SolstadAbstract
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.
Abstract
In a preliminary experiment terminal stem cuttings (4 – 5 cm) were collected in the spring (May) from a wild population of lingonberry near Holt Research Center, Tromsø, Norway. The cuttings were rooted in peat mixed with 30% perlite with and without auxin treatment (Seradix 1 or Seradix 2: 3-indol-butyric-acid). The effect of dipping in a fungicide (Rovral) was also tested. With the best treatment, control without auxin and fungicide, as much as 66% of the cuttings rooted. Both dipping in Seradix and in the fungicide reduced rooting of the cuttings. To test the seasonal variations in rooting of lingonberry cuttings, terminal cuttings were harvested regularly every month in more than one year. The results indicate that a relatively short cold period is needed to induce bud break and shoot growth. Cuttings harvested during spring and summer rooted poorly compared to cuttings harvested in late autumn and during winter. The best rooting was obtained using cuttings harvested in September and November.
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Authors
Svein Solberg Erik Næsset Ole Martin BollandsåsAbstract
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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).
Authors
Bed Mani Dahal Bishal K. Sitaula Roshan M. Bajracharya K. Atreya Alhaji JengAbstract
No abstract has been registered
Authors
Helge Lundekvam Lillian Øygarden Trond Børresen Arnold Arnoldussen John Boardman Jean PoesenAbstract
Soil erosion in Norway Abstract Soil erosion in Norway mainly occurs in autumn and winter period. High soil losses may occur by heavy snowmelt and/or rainfall in combination with frozen and not covered soil. Dominating erosion processes are sheet and rill erosion, deeper rilling caused by concentrated surface runoff, gullying and erosion in connection with tile drains. Research on tillage systems have been ongoing since the mid- seventies and the systems have been ranked according to their relative erosion risk. Soil losses are documented both in plot, field and at catchment scale and also in the National Agricultural Environmental Monitoring Programme (JOVA). The data have been used for the development of the Norwegian erosion risk model ERONOR and in several governmental actions involving subsidies and new regulations based on soil erosion risk maps using an USLE ?equation adapted to Norwegian conditions. Subsidies are given for tillage practice with low erosion risk, catch crops, grass covered waterways, buffer zones and sedimentation ponds. Soil losses (annual mean values) have been 0.1- 4.36 t ha-1 in plot studies, 0.028 ? 5.2 t ha-1 in field scale studies and 0.1- 3.5 t ha-1 in catchment studies. Soil losses by extreme gullying have exceeded 100 t ha-1.