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
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
Det er ikke registrert sammendrag
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
Forfattere
Tone GroeggenSammendrag
Forest Officers’ Monitoring Plots. Vitality survey 1999 In 1999 totally 648 plots were assessed comprising 42088 trees (Table 2). The plots are organised in clusters of four plots subjectively chosen in different cutting classes; III (young), IV (intermediate), V (old forest) and one in declining forest. For Norway spruce a reduction in crown density of 0,7% was observed last year. The largest reduction was observed for young stands (1,4%) (Fig. 2). As usual, crown density in the western part of the country was high (Fig. 3). In mid Norway the greatest reduction was observed in old stands whereas in eastern Norway the reduction was greatest in young stands (Table 3). For Scots pine the reduction in 1999 was 1,8%, and it was particularly high in young stands (3,7%). Only in old stands a small increase in crown density was observed. As in the case of Norway spruce the greatest reduction in crown density was observed in eastern Norway. In the western part of the country an increase in crown density was observed (Table 3). For Norway spruce the number of green trees in 1999 were reduced by 1,9%, a decrease which was consistent in all stands (Fig. 4, Table 4). For Scots pine the number of green trees increased in all stands but old stands. For Norway spruce the amount of cones was generally low in 1999 (Fig. 6 and 7). For some parts of northern Norway, the largest amount of cones was observed ever since establishment in 1988. The mortality rate was 0,2%. Infection of needle rust (Chrysomyxa abietis) in mid and northern Norway was less abundant in 1999 than in 1998 and 1997. There were a number of attacks of the fungus in eastern Norway. In 1999 results from Forest officers plots are not consistent with results from Level 1 plots. There was an increase in crown density and less discolouration of trees in level 1 plots. The monitoring of forest tree vitality is motivated by the concern for negative effects due to air pollution, and hence deserves to be given priority.
Forfattere
Svein SolbergSammendrag
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
Forfattere
B.J. Stocks M.E. Alexander B.M. Wotton R.A. LanovilleSammendrag
Det er ikke registrert sammendrag