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1991

Sammendrag

This is the first of five annual reports from the research program Forest ecology and multiple use, in which the universities in Trondheim, Bergen, Oslo and s, the Norwegian Institute for Nature Research and the Norwegian Forest Research Institute participate. To date, 12 projects have been started, covering bird species, invertebrates, cryptogames, methods of forest regeneration, timber production and quality in uneven-aged stands, timber extraction methods, and public use of forests, as well as economic consequences of various silvicultural methods and usages of forest land. The programme period is five years, with an estimated total input of resources between 30 and 40 million NOK. In accordance with the conditions set by the government departments of Environment and Agriculture, the highest priority is given to research dealing with conservation of animal and plant species threatened by modern forestry. The content of this report is summarized in the following eight points. 1. Despite a 75% reduction in input of resources compared to an initial evaluation of the needs, it was possible to establish an integrated research programme, covering important gaps in knowledge of ecologically better forestry practices in Norway. At least the projects dealing with invertebrates and cryptogames should be continued after the period in order to work out lists of threatened species, describe their living area requirements, and examine their distribution in Norway. 2. In Norway today, there are likely neither large areas of virgin forest nor areas of coniferous forest which have been in climax stage throughout several tree generations. This may limit the number of strongly specialized species. 3. Probably only a small number of higher animal and plant species are threatened by forestry in Norway. A large number of invertebrates and cryptogames may be vulnerable, however. Most of these are directly or indirectly dependent on a continuous supply of dying or dead trees, high air humidity and protection against heavy wind and sun radiation. Therefore, they may survive only in old and dense forest stands, often on high-productivity sites. 4. By pointing out threatened species or groups of species and describing their living area requirements, the programme may provide a basis for a better choice between alternative treatments in silviculture and also secure a great diversity of less specialized species. 5. Many of the species in question should be maintainable during commercial forestry. In order to secure the genetic variation and spread of specialized species, smaller areas should be preserved, as a supplement to the larger state-owned areas. 6. Norwegian forestry is now at the end of a 40 to 50-year period of partly exaggerated perfectionism and intensive utilization of the timber production potential. This is now shifting to more extensive silvicultural methods and a widespread interest in multiple use. 7. Descriptions of alternatives to clear-cutting and planting and cost-benefit analyses given by the programme may also contribute to ecologically better forestry in Norway. Evaluation of non-commercial benefits, such as the preservation of species, is necessary for a complete cost-benefit analysis. 8. Forest planning on both district and property levels is an important tool in multiple use which makes claims both to the field work and to the plan utilization in practical forestry.

Sammendrag

Large differences were found in survival stratey among species and ecotypes. The maple and elm populations and the two southern birch populations all responded to high temperatures by rapid leaf expansion as a possible compensation for increased respiration loss, and themaple and birch also by increasing their stem elongation rates, thereby competing more efficiently for available light. In the northern subalpine birch population, however, the seedlings developed leaves with high net assimilation rates instead of increasing their leaf areas and stem elongation rates. In this population abiotic climatic factors rather than competition therefor seem to be the most important adaptive force.