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.
2013
Abstract
Retention of selected trees in clear-felling areas has become an important conservation measure in managed forests. Trees with large size or high age are usually preferred as retention trees. In this paper we investigated whether a single large or several small trees should be left in clear-felling areas to serve as life boats and future habitat for epiphytic species. The focal species were 25 Lobarion epiphytic lichens hosted by aspen (Populus tremula). We analyzed the relationships between: (1) proportion of trees colonized and tree size, (2) number of lichen thalli (lichen bodies) and aspen area, and (3) number of lichen species and aspen area, for 38 forest sites. Mixed effect models and rarefaction analyzes showed that large and small host trees had the same proportion of trees colonized, the same number of thalli, and the same species richness for the same area of aspen bark. This indicates that larger aspens do not have qualities, beyond size, that make them more suitable for Lobarion lichens than smaller sized aspen trees. None of the species, not even the red-listed, showed any tendencies of being dependent on larger aspens, and our results therefore did not support a strategy of retaining only large and old trees for conservation of epiphytic Lobarion lichens. Additionally, young aspens have a longer expected persistence than old aspens. However, old retention trees might be important for other species groups. We therefore recommend a conservational strategy of retaining a mixed selection of small/young and large/old aspens.
Editors
Helmer BelboAbstract
Skilled, motivated and well-informed contractors today form the backbone of a professional, cost-effective, and environmentally friendly forest sector in the Nordic countries. This understanding forms the playground for policy makers, forestry certification bodies, forestry education, business standards and research in forest operations. The aim of this workshop is to provide a special forum for researchers, practitioners and other interested parties to get together in exchanging information, experiences and outlooks in the field of contractor forestry. The fundamental goal and our prime hope is that events like this will bring the Nordic-Baltic forest sector further in improving local and global competitiveness. These proceedings are a collection of abstracts that represent a range of issues being faced, and the status of research within the field of contractor forestry in participating countries. Contractor forestry is a term that includes both operating skills and business management acumen of forestry contractors, but also the formulation of the special environment in which they operate, not least the conditions set and information passed on by landowners, forest management companies, other supply chain actors, and the markets themselves. As such, it represents the whole spectrum of ‘service provision’ in the forestry sector – both the process of placing the work tasks on the market, successfully winning the contract, and carrying out the work in both an economically and environmentally sustainable way that promotes the long-term existence of professional contracting outfits. Not only is the Nordic forestry sector fully dependent on contractor forestry, but the region plays an important role in determining international trends in forest operations and the world closely watches developments and emulates many of them, as the CTL method continues to expand into new markets. This places special impetus on the importance of the research work being done in this field. We wish to thank the OSCAR coordinating committee for their constructive input, as well as all those who participated or contributed to making the seminar a success. We also would like to thank the Nordic Forest Research Cooperation Committee (SNS) for the financial support of the OSCAR2 network, and the Forestry Extension Institute at Honne who provided an exceptionally suitable environment and hosting for the workshop participants.
Authors
Jutta Kapfer Harry John Betteley Birks Vivian Astrup Felde Kari Klanderud Tone Constance Martinessen Louise C. Ross Fride Høistad Schei Risto Virtanen John Arvid GrytnesAbstract
Background: Studies quantifying and comparing the variation and degree of compositional stability of vegetation and what determines this stability are needed to better understand the effects of the projected climate change. Aims: We quantified long-term vegetation changes in different habitats in northern Europe by exploring changes in species co-occurrences and their links to diversity and productivity gradients. Methods: We re-sampled vegetation in 16 arctic, mountain, and mire sites 20 to 90 years after first inventories. A site-specific change in species assemblages (stability) was quantified using species co-occurrences. We tested if the observed changes were significantly greater than would be expected by chance using a randomisation test. Relationships between patterns in vegetation stability and time between surveys, numbers of plots, or species diversity and proxies for productivity were tested using regression analysis. Results: At most sites, changes in species co-occurrences of vascular plants and bryophytes were greater than expected by chance. Observed changes were not found to be related to gradients in productivity or diversity. Conclusions: Changes in species co-occurrences are not strongly linked to diversity or productivity gradients in vegetation, suggesting that other gradients or site-specific factors (e.g. land-use, species interactions) might be more important in controlling recent compositional shifts in vegetation in northern Europe.
2012
Authors
Fride Høistad ScheiAbstract
No abstract has been registered
Abstract
No abstract has been registered
Abstract
No abstract has been registered
Authors
Kjell Andreassen Bernt-Håvard ØyenAbstract
Growth conditions in Fennoscandia are characterized by relatively short growth seasons and cold winters, from 130 growth days (T 5C) in the far north high mountains to more than 200 in south Sweden and Norway. Growth models from different regions predict different forest growth.In this study, we compare some models commonly applied in forest growth prognosis in pure even aged stands of Norway spruce, Scots pine and birch in Finland, Sweden and Norway. The objectives is to identify behavioural properties, accuracy and bias in selected Nordic growth models using a wide-ranging test data set from permanent research plots in Norway.Present tentative conclusions about the accuracy of growth outside the geographical range of the original base materials. With four different response variables in the tested models we emphasized relative deviations rather than absolute values as most suitable for comparisons. The models were compared by statistical tests, a visual inspection of the smoothed curve of the relative deviations in different stand properties and ranked due to their performance.We observed site index, stand density and mean tree size as the three main components in the models. For Norway spruce a basal area increment model from Sweden had the lowest standard deviation with 23 %. The mean R2 between residuals and stand characteristics from this model was also low (1.3 %), which indicates that variables are well included in the model. For Scots pine and birch, Finnish percent volume growth models showed the best fit to the Norwegian test data, with a R2 between residuals and stand characteristics of 2.8 and 6.7 %, respectively. Several of the models from Sweden and Finland predict the growth as well as stand models frequently in use in Norway.
Abstract
No abstract has been registered
Abstract
No abstract has been registered
2011
Authors
Helmer BelboAbstract
The theoretical potential for increased efficiency in early thinning by using accumulating harvester heads was investigated through simulation. Thinning was performed in corridors perpendicular to the strip road in 75 artificially generated stands with varying average tree size and density. The work pattern and work time in the crane work for five sizes of heads, with grapple diameters in the range of 10 to 50 cm, was estimated by the simulation model. The efficiency increased rapidly when the grapple diameter increased from two to four times the average diameter in the harvested stand, reducing the work time per tree by 15 to 50 percent compared to the single tree handling harvester head. Further increases in grapple dimension also increased the efficiency, but not at the same rate. In real work, the efficiency increase by an accumulating harvester head will probably be slightly lower due to less optimal harvesting conditions, operator skills and other non-productive work tasks that are not affected by work method.