by Tommy Milburn & Stephen Bessant
After studying British forestry for a year myself and with Stephen (an Environmental Science student at Newcastle University) focusing his final year dissertation on forestry, we were both very interested in visiting Sweden.
Sweden is a country with a very high percentage forest cover at 27.1 million hectares, it also has high timber productivity. In 2002 the total production of sawn timber was 16.6 million metres cubed. During our trip we concentrated mostly on harvesting and wrote the following report:
We met with a Swedish forester from the Skogsvardsstyrelsen (S.V.O) called Mikael Hedin, who talked us through Swedish forestry methods and showed us various different forest stands.
The first was a large stand of pine. Clear felling of Pine trees (Pinus sylvestris) takes place at around 80- 120 years. The Forest owner can expect to receive between 300 and 320Kr/m3 for timber. Highest quality timber may be sold for 400Kr/m3 with no signs of old branches that have been lost from the tree. The best quality timber comes from the first length that is cut from the base of trunk.
Highest quality trees grow on medium quality soils; if the soil is of high quality the tree will grow too fast and will not lose its bottom branches, trees will not grow properly on nutrient poor soils. (Spruce trees are best grown on higher quality soils.)
No clear felling of trees can take place in Sweden if they are less than 70 years old. When trees are felled ‘mother trees’ are left standing to encourage natural regeneration. These trees are identified prior to felling and are ideally left at 10m spacing. This means that even in an area that has been clear felled, there will still be 100 trees left standing in one hectare.
Mother trees need to have a large green biomass at the crown. It is important that they are not the tallest trees in the stand as they will be susceptible to strong wind, but also not be the smallest. If the mother trees are spaced more than 10m apart, regeneration will be sparse. Also, if trees are spaced too far apart grass will colonise as sunlight penetrates the ground layer. If this occurs the problem is difficult to rectify as regeneration will not occur. Natural regeneration is used more in Sweden than Britain as it has a lower wind throw classification and the mother trees are much more likely to stay up until their 7-8 year growth target.
Natural regeneration has the advantage over hand planting as it allows for a greater number of trees to grow. It is cheaper, but trees take longer to establish. When trees are planted at 2m intervals (as standard) there are 2,500 trees/ha. Natural regeneration produces 10,000-20,000 trees/ha.
The Swedish Forest Act states that once an area has been clear felled, regeneration must occur within 10 years if left to regenerate naturally (5 years if new trees are hand planted). Once an area has been clear felled the soil must be disturbed to provide the optimum seed bed for falling seeds. P. sylvestris naturally regenerates after disturbance from fire.
Regeneration may be visible after 2 years. The mother trees protect regrowth and help regulate environmental conditions such as air and soil temperature. It is important however that the mother trees are felled 7- 8 years after clear felling when the young trees are around 5 years old because the mother trees will begin to out-compete saplings for resources, in particular, light. It is also important that the mother trees are felled at this age as regrowth may be damaged by the harvester if allowed to grow taller. It also benefits the regrowth if the mother trees are felled in periods of snow cover as this provides further protection. Mother trees are generally sold at 450Kr m3. (13kr = 1 pound Sterling)
A management technique adapted to the growing of P. sylvestris is that of Cleaning. Birch (Betula pendula) will rapidly colonise areas of new Pine forest. If allowed to grow B. pendula will compete with P. sylvestris soil nutrients (Mg, P and K) and other resources such as water and sunlight. The consequence of this is reduced growth of P. sylvestris and inferior timber.
Cleaning is carried out using large petrol strimmers and contractors charge around 3,000Kr ha to clear forest. Cleaning should occur when P. sylvestris is 5-6 years old and at 10-12 years. No profit is made from B. pendula but the practice pays for itself in years to come by encouraging increased growth of P. sylvestris.
The forest is thinned between 35-40 years old and again at 50-55 years.Thinning is carried out using harvesters and forwarders, the machines used are generally smaller than those used for Clear Felling and can get among the trees without causing damage. Any damage caused to the trees results in a lower price when felled. The trees that are selected for thinning are those growing at an inferior rate to others and those that will result in reduced growth of healthier trees by competing for resources. Trees that are to be thinned are selected visually by the harvester operator.
First thinning is worth 60Kr/m3 and second thinning is worth 120Kr/m3.
Forest is clear felled at 80-120 years. Trees are sold for 300-320Kr/m3. When the trees are felled they are cut into lengths ranging from 3.4m-5.5m in 0.3m increments, as specified by the buyer. All timber with a diameter >0.05m under bark is used.
The process of surveying forest in Sweden
Forest ownership in Central Sweden is 50% family forest while the other 50% is owned by companies, the State or other public owners (see booklet for breakdown).
Family forest is passed down generations as inheritance in Sweden and is divided up between sons and daughters. The size of family forest varies, but commonly ranges from 5ha to 300ha.
Skogsvardsstyrelsen (the regional forestry board), a government funded company, creates additional income is by surveying private owned forest and informing the owner what price he should ask for his timber. Private owners expect to receive 350Kr- 360Kr/m3. Good quality Pine (as at the site we visited) will be sold for 420Kr/m3.
Six weeks notice must be given to the regional forestry board before any felling occurs. This allows an inventory of the site to be compiled. If any species of ecological importance are discovered measures will be taken to safeguard their survival.
A map of the forest to be surveyed is printed off from the Skogsvardsstyrelsen database and shows boundaries of ownership and other features including rivers, lakes, roads and power lines. Important habitats such as bogs and streams are protected. It is important that trees are not felled on wetland areas as it is difficult for trees to re-establish.
Once on site, the boundary of ownership is located and marked accurately. A tolerance of 1m is accepted, but a tolerance of 0.5m is preferred. GPS is not sufficient to locate boundaries of ownership, as it is only accurate to 5m.
Boundary lines are defined by the Lantmateriet and can only be altered by paying a large fee. In the forest, boundaries are defined by locating piles of stones (put in place by the Lantmateriet) at the corners of each plot. The trees located at the division of two plots are marked with an axe. These are sometimes difficult to locate as the marks may be up to 70 years old.
Boundaries are also defined by using a mirror compass. Once a definite mark has been located (i.e. a pile of stones) by using compass lines from the site map, a straight line can be worked out. Tape is hung from the trees at the boundary of the site so that the plot is clearly defined.
Once the site is clearly marked, the survey is carried out. An inventory of the site is made and any Flora or Fauna of ecological importance is noted. Important habitats such as Sphagnum bogs and watercourses are also recorded.
If the site is of great ecological importance, or if any Red List species are found, the Skogsvardsstyrelsen have the power to halt all forestry operations. Red List species include the White-backed woodpecker (Dendrocopos leucotos), the Brown trout (Salmo trutta) and Crane’s Bill (Geranium bohemicum). Forest owners are compensated for their losses and the area designated a nature reserve, but the private owner still remains the owner of the forest.
If the site contains an area of historical, or cultural importance, timber operations will again be halted. In the region we visited charcoal hearths which are commonly found.
Thanks to Mikael and Bjorn Hedin for making us feel welcome in Sweden and guiding us around the forest stands, and to all those at Woodland Heritage for making our trip possible. The whole week was fascinating and will help us greatly throughout the remainder of our courses and in future employment.