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.
1999
Abstract
No abstract has been registered
Abstract
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.
Abstract
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.
Abstract
No abstract has been registered
Authors
Isabella BørjaAbstract
Practical handbook for identification of diseases and disorders in european forest nurseries. Many colour photos and illustrations.
Authors
Kari Anne Sølvernes Øystein Johnsen Lars Sandved Dalen Gunnar OgnerAbstract
No abstract has been registered
Authors
Svein SolbergAbstract
Relationships within stands between growth and crown condition are presented. The data set contained about 25000 trees on 500 plots. Growth of single trees was determined by diameter measurements in 1991 and 1996. Diameter increments were recalculated to relative values in two steps; firstly relative to their stem diameter, and secondly relative to reference values for trees in the same plot, having no defoliation or no discoloration. These relative increment values, or growth indices, were distributed on a scale common for all plots, rendering them influenced neither by site and stand properties, nor by social status of each tree. The correlation between crown condition and growth, although of moderate strength, did validate crown condition assessments as a meaningful, but rough measure of forest health or vigour. The relationships were concave, and considerable growth depressions were already found at slight levels of defoliation and discoloration. Growth approached zero as defoliation and discoloration increased towards 100%. These relationships applied for all plots, regardless of their site productivity, development stage or regeneration method
Authors
B.J. Stocks M.E. Alexander B.M. Wotton R.A. LanovilleAbstract
No abstract has been registered
Authors
Atle Hindar Erik Norgaard Petter Nilsen R. Høgberget Richard Frederic WrightAbstract
No abstract has been registered
Authors
M. Kurm Ü. TammAbstract
No abstract has been registered