The aim of the ongoing change to environmental forms of energy is to reduce the use of fossil fuels and increase the use of domestic renewable forms of energy. So far, biofuels from forestry has mainly consisted of branches, tops, bark and firewood, but if use of bioenergy is to expand, "new" fuels are required. Stumps on forest clear-cuts are a resource that has been almost untapped so far in the context of biofuels. Nevertheless, more than 20% of the biomass of conifers is left in the stumps. In the forestry industry there is now a clear interest in using stumps, but since there are large gaps in knowledge, it is difficult to judge whether it is environmentally acceptable to harvest stumps on a large scale. The National Board of Forestry is therefore demanding that an environmental analysis should first be made, i.e. a general evaluation of the advantages and risks of a large scale extraction of stumps.
Lack of knowledge
The judgment is that there is a lack of knowledge at all stages - from the logistics of stump extraction to the effects on watercourses, biodiversity, forest production and carbon and nitrogen cycling. The Swedish Energy Agency (STEM) has therefore made a large investment in broad based research by several groups at SLU Uppsala which together receive MSEK 21 up to 2010. The forestry industry has also contributed MSEK 2. And the SLU faculty for natural resources and agricultural sciences has now decided to add MSEK 15 to create the joint research programme Stump harvesting and environmental effects. More than 20 researchers are participating in the programme, but collaboration will also take place with SLU Umeå, Forestry Research Institute of Sweden, Metla in Finland, IVL in Göteborg and National Swedish Forest Survey. Bringing the individual projects together in a joint research programme is expected to yield clear synergistic effects.
The aim of the studies is to draw up recommendations as to which stumps and environments should be left out of an environmentally sound stump harvest and how disruption of soil can best be prevented. This work necessitates concrete collaboration across institutional and disciplinary boundaries. It is hoped that a new programme will add new insights to present knowledge and will also form a more coherent picture of the benefits and risks of stump extraction.
Four action areas
Research is broken down into four areas:
- Fuel quality and environmental effects of stumps in a system perspective
- Effects on insect pests in the forest
- Effects on biodiversity
- Carbon and nutrient cycling and water quality.