The effects of different forest management methods on timber quality in pine plantations
Urban Nilsson (project leader)
Summary of results with list of publications from SLU.
Email: Urban.nilsson@ess.slu.se
Thinning determines quality in the long run
In forestry, a long time elapses between a measure and the economic result. There may be a wait of 20-40 years from planting a stand until the first income is received in the form of net thinning results, and 60-100 years before the net income from final felling is received by the forest owner – all this makes it difficult to visualise the economic consequences of different management options.
The cheapest option is therefore often chosen. But it is not certain that it is best in every instance to look only at costs. It may be economically advantageous to incur a cost today if it can produce a larger revenue within a foreseeable future. It is, for example, easy to visualise that the distance between seedlings can have completely different outcomes on future timber quality depending on thinning programmes.
In this project, an investigation was made of different management options on long term production. Studies were made of the effect of the intensity of regeneration work in the form of number of seedlings and the significance of gaps in pine plantations, and the impact of the thinning programme on future timber quality through measurable variables on the logs, such as ring width and knot size. The strength and shape stability of timber that had been sawn and harvested from stands treated with different thinning programmes were also studied. The results show that timber which had been sawn near the heartwood had a strength and shape stability clearly inferior to that of timber sawn further out from the heartwood. It is therefore an advantage to produce the largest possible logs. Perhaps the most important aspect in choosing as thinning programme is the growth and final dimension of the individual tree.
Edge effects in fragmented forests: estimation of long term ecological effects
Per-Anders Esseen (project leader)
Summary of results with list of publications from Umeå University
Email: per-anders.esseen@emg.umu.se
Forest fragmentation is a process that occurs all over the world and is a serious threat to biodiversity. It results in loss of natural forests, smaller patches of forest, increased isolation and a larger number of forest edges. New research shows that many of the effects of forest fragmentation are due to forest edges.
The project focused on sharp forest edges since these have large effects on biodiversity. The overriding objective was to estimate the ecological effects of forest edges on landscape level. In order to estimate how this diversity is affected it is necessary to combine edge, forest and ambient variables that regulate the impact on biodiversity.
Natural forest landscape in the boreal areas of Scandinavia
Lars Östlund (project leader)
Summary of results with list of publications from SLU.
Email: Lars.Ostlund@svek.slu.se
The myth of the virgin forest
Some of the last virgin pine forests in Europe are situated in the north of Scandinavia. They are in areas that have never been developed for agriculture or silviculture and are therefore considered to be largely unaffected by humans. These forests are very old, with large quantities of dead wood, and there are few signs of forest fires. But although these forests have not been exploited, they have been used by humans for thousands of years for hunting, fishing and gathering plants, but these have been regarded to be insignificant forms of disturbance and have often been ignored in ecological studies of forest structure and biodiversity.
For many of the forests that had been given the epithet "virgin forest" and have been used as reference in ecological studies and preservation work, there is a complete lack of a historical analysis of development and use by humans. That a virgin forest should be completely unaffected by humans is a great simplification. Forest areas ought not to be indiscriminately designated virgin forests just because they are today difficult to get into or are remote. The results of this study are in good agreement with the increasing number of indications from other parts of the world, in particular temperate and tropical forests, which have also shown that pre-industrial forest utilisation may have a comprehensive impact on the ecosystem.
To sum up, major forest areas without the impact of utilisation are very rare. For several reasons, the preservation value of these areas is very high. Apart from the fact that these forests have high biological values and are important reference areas for ecological research, they are also part of a unique cultural landscape.
Risk assessment of the use of microorganisms for biological control of pathogenic fungi
Jan Stenlid (project leader)
Summary of results with list of publications from SLU.
Email: Jan.Stenlid@mykopat.slu.se
This project is in two parts: a risk assessment and monitoring of a genetically modified microorganism (GMM) in the field, and an analysis of how a fungus used for biological control spreads into the ambient environment. Measurement of the gene flow to indigenous populations of the same species and investigation whether this treatment affects the flora of non-target organisms in their ecological niche are important parts of this analysis. The risk that the target organism for the biological control will deveop resistance was assessed in laboratory experiments.
Functional diversity of ectomycorrhizal fungi in mineral soils
Anna Rosling (project leader)
Summary of results with list of publications from SLU.
Email: Anna.Rosling@mykopat.slu.se
Mycorrhizal fungi are key organisms in nutrient and energy flows in forest soil. But in spite of the fact that forest soil largely consists of mineral soil, the role of fungi is almost completely unresearched. Earlier studies have shown that up to one half of all mycorrhizal fungi occur only on roots in mineral soils. In principle, this can double the already high fungal biodiversity that is known from organic soil strata. It is only when we understand the activity of mycorrhizal fungi in the entire soil profile that we can understand their importance for the forest ecosystem. The supply of nutrients and thus the conditions for growth of the fungi vary in the soil. The distribution of one species is determined by its ability to utilise the nutrient resources in the soil, in interaction with other organisms such as fungi, bacteria and small soil animals.
The project makes a thorough investigation of the relationship between the abundance of species and local environments. A study of the specific capability of species to take up nutrients will result in clarification of whether differences in function are the basis for the great species richness of fungi. Species-specific functions that create and maintain biodiversity are of great fundamental scientific and general interest. The results are therefore published as both scientific and popular scientific articles.
Responsible for this page: Birgitta Bruzelius