Skogsskötsel för att minimera stormfällning över järnväg
The society of today is dependent of secure transports and deliveries of electrical power. Interruptions in different activities because of fallen trees cost a great deal of money in form of reparations and claimed damages for transport companies and electrical suppliers. Fallen trees along some railway sections are a severe problem. For instance, to repair the damages of the storm of week 5 year 2002, costed 2 800 000 SEK for the line region of Hässleholm. Today, the Banverket railroad company has no norms in general for how close to the railway the forest is allowed to grow. Private forest owners manage the forest that is situated most close to the railway without any influences from Banverket. In some sections though, are security felling carried out approximately every tenth year, when the unstable trees most close
to the railway are removed. The work was carried out as a case study of the 55-kilometre Emmaboda-Karlskrona section. The criterion for the selected section was that it was supposed to be situated within the line region of Hässleholm and also be severely affected by wind throws. The aim of the study was to examine how big part of the section that would be regarded as a high-risk area of wind throws. Another motive was to study what the forest looked like from a viewpoint of the risk of wind throws. The result of the studied section will be the basis of a long term silvicultural suggestion to bring about more stable border zones most close to the railway, without silviculture of too high intense and expense.On the 14-kilometre section between Emmaboda and the border of Blekinge County, 30 percents of the forest consisted of risky stands. The reason for the great amount of high risk stands was that the forest mainly consisted of old spruce forest and that many landowners did not pay any real attention to the risk of wind throws in their silvicultural activities in the forest that borders the railway.
If the share of risky stands is to be decreased, more consideration must be taken to closely situated stands. Late thinning in higher border zones ought to be avoided and final felling should instead be carried out earlier.
The silviculture method, suggested to reach more stable edges of the stands, is about
managing a 25-metre broad zone of broadleaved trees between the railway and the other
stand. There is need for neither soil scarification nor planting within the border zone, since it is almost always naturally regenerated. A sparse regeneration is enough, since trees with high stability, not quality, is the target. The trees need a lot of space from an early age to be able to develop a robust root system and a coarse stem. It is therefore important with heavy and early thinnings.
If the suggested silviculture is implemented will the borders of the forest be approaching the ideal state in about 50 years. The scenario also shows that the problem with wind throws is not solvable during a too short period of time. The goal must be in the term of long-range. There may also be problems from an organisational viewpoint, due to the high number of landowners that are influenced and the long distance of the section that is affected. There will be a minor economical loss for the private landowners due to the small area that is touched
upon, and a small cost for Banverket as well. Out of one kilometre of railway is the impact only on 3 ha, since 15 metres on each side of the track shall be managed as a broadleavedOn the 14-kilometre section between Emmaboda and the border of Blekinge County, 30 percents of the forest consisted of risky stands. The reason for the great amount of high risk stands was that the forest mainly consisted of old spruce forest and that many landowners did not pay any real attention to the risk of wind throws in their silvicultural activities in the forest that borders the railway.
If the share of risky stands is to be decreased, more consideration must be taken to closely situated stands. Late thinning in higher border zones ought to be avoided and final felling should instead be carried out earlier.
The silviculture method, suggested to reach more stable edges of the stands, is about
managing a 25-metre broad zone of broadleaved trees between the railway and the other
stand. There is need for neither soil scarification nor planting within the border zone, since it is almost always naturally regenerated. A sparse regeneration is enough, since trees with high stability, not quality, is the target. The trees need a lot of space from an early age to be able to develop a robust root system and a coarse stem. It is therefore important with heavy and early thinnings.
If the suggested silviculture is implemented will the borders of the forest be approaching the ideal state in about 50 years. The scenario also shows that the problem with wind throws is not solvable during a too short period of time. The goal must be in the term of long-range.
There may also be problems from an organisational viewpoint, due to the high number of
landowners that are influenced and the long distance of the section that is affected. There will be a minor economical loss for the private landowners due to the small area that is touched upon, and a small cost for Banverket as well. Out of one kilometre of railway is the impact only on 3 ha, since 15 metres on each side of the track shall be managed as a broadleavedfringe. The 10 metres most close to the railway are never to comprise any bigger trees. The estimated total loss in soil expatiation value will in this study be approximately 27 000 SEK per kilometre railway.