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.
1999
Forfattere
Rune Halvorsen Økland Knut Rydgren Tonje ØklandSammendrag
Det er ikke registrert sammendrag
Sammendrag
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Forfattere
Arnt Kristian Gjertsen Svein Ola MoumSammendrag
The paper describes an operational method for automatic map generalisation. Operational methods are often pragmatic in nature and only works well in special cases. General methods need to be founded on solid knowledge based on understanding of the map generalisation process as performed by expert cartographers. Today, much research in the area is concentrated on knowledge-based systems, and the research is directed on formalising generalisation knowledge. NIJOS has developed a pragmatic map generalisation method to generalise land-type maps from working scale 1:5000 to a working scale in the range 1:100.000–1:300.000. The method involves both attribute and geometric generalisation. The former was simple to implement in a database query language; the latter was more complex. A method based on deviding classes into separate thematic layers followed by a series of expansion and shrinkage operations was developed. The separate layers were later combined in a predefined and prioritised order. Important control factors were minimum area and minimum width. Both the size and the display time were greatly reduced. The method was successful in removing small areas, however, it was not 100% successful in removing narrow bridges and gaps.
Forfattere
Svein Solberg Knut Breivik Nicholas Clarke Tone Groeggen Ingvald Røsberg Kjetil Tørseth Dan Aamlid Wenche AasSammendrag
Det er ikke registrert sammendrag
Sammendrag
The area along the Norwegian-Russian border is threatened by air pollution from emission sources on the Kola Peninsula. A permanent network of 78 systematically chosen monitoring sites has been established in eastern Finnmark, Norway. Species abundance data from the ground vegetation have been recorded from 1320 systematically chosen permanent plots inside 66 of these sites, using frequency in subplots and visual estimates of percentage cover. Environmental variables were obtained for the whole site. Multivariate data analysis has been used to describe the variation in the species composition and to study its relation to environmental variables and pollution impact. The analyses show that much of the variation in the species composition, based on average species abundance at the sites, is well explained by different soil and climatic conditions. However, estimated SO2 deposition, Ni, and Cu in the soil, and Ni in Cladina tissue have also been found to be statistically significantly correlated with the variation in the species data, but they explain only a minor part of the variation. The pollution impact over several years may have lead to a reduced lichen cover in the bottom-layer vegetation. Further development in an either negative or positive direction can be detected by re-investigations of the monitoring sites.
Sammendrag
This study aims to evaluate the quality of crown density data, based on independent, pairwise tree assessments. The data originates from monitoring of forest health (crown condition) in Norway; 250 plots, comprising 12 000 individual trees of Norway spruc e, have been reassessed by a single observer during 1990-95. Of the trees, 2300 were controlled more than twice, providing the possibility of evaluating the quality of assessed temporal changes of crown density. True errors (standard deviation) are estima ted to be about 10% for single trees and 5% for plot means, while the real standard deviation of the differences were slightly higher. The errors of the temporal changes of crown density were of similar magnitude. Systematic differences in crown density w ere found between sites and plot types, partly resulting from observer bias. However, the results suggest that observer bias is really the result of each observer\"s personal style in assessment.
Sammendrag
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Del av bok/rapport – Damaging agents in European forest nurseries. Practical handbook
Isabella Børja
Forfattere
Isabella BørjaSammendrag
Practical handbook for identification of diseases and disorders in european forest nurseries. Many colour photos and illustrations.
Sammendrag
The Norwegian Monitoring Programme for Forest Damage has now been running for more than 10 years. Its main objective has been to monitor forest condition in relation to air pollution. Surveys of forests are performed on plots in a nation-wide representative grid network (Level 1 in the UN/ECE ICP Forests system), in a network of local county-wise plots, and in a network of intensively monitored plots (Level 2 in the UN/ECE ICP Forests system). Vitality indicators have shown a declining trend as reported earlier, expressed as reduced crown density and more of discoloured trees, particularly in spruce forests. However, results from last year have shown a slight improvement in tree crown condition. Tree mortality in excess of normal is not recorded. Forest condition generally depends upon soil, tree age, climate, pests and diseases, and other natural impact. The observed decreased crown density since 1989 is likely caused by a harsh climate, poor soil conditions and forest diseases. Air pollution loads, add to and interact with these factors. Most likely initiating factors are needed to produce visual symptoms. Summer drought is possibly such a factor of relevance to Norway. The actual effect of the air pollution component is therefore difficult to estimate; however, its importance is not excluded. In future, possible effects of a changed global climate should also be considered. Considering these results it is reasonable to presume that most Norwegian forest ecosystems generally are still in a satisfactory condition.
Forfattere
Kari Anne Sølvernes Øystein Johnsen Lars Sandved Dalen Gunnar OgnerSammendrag
Det er ikke registrert sammendrag