Skogsstatistisk årsbok 2003.pdf - Skogsstyrelsen

SUMMARY3 Forest and forest landThe total land area of Sweden is approximately 41.0 million hectares, out of which:• 22.6 million hectares are forest land,• 4.6 million hectares are mires,• 1.0 million hectares are rock surface,• 3.4 million hectares ares high mountains and subalpine coniferous woodland,• 3.5 million hectares are arable land and pasture land.Information on land use classes (see summarydefinitions) and for units of measurements (seesymbols and abbreviations).Forest resource data relating to area, growingstock, and growth are presented in this chapter.Estimates are usually current five years averages(1997–2001) and the information is based on theSwedish National Forest Inventory data (NFI).Historical development of growing stock, speciescomposition and ownership distribution isavailable (figures 3.2, 3.3 and 3.4).• Forest land covers 55 per cent of the total landarea (table 3.1). This percentage has variedbetween 55.5 and 58.1 since the first NationalForest Inventory 1923–1929. In recent yearsthe forest land area has decreased due to theestablishment of many and to some extent largenature reserves. These area are included in theland use class Nature reserves and land undermilitary supervision.• Age class distribution (table 3.2) is characterizedby a general lack of medium-aged forest and acorresponding surplus of forest older than 100years. Normal rotation ages are (approximately)130 years in Norra Norrland, 120 years inSödra Norrland, 100 years in Svealand and 90years in Götaland. (Regional map of Swedenfigure 1.1.)• Table 3.3 shows the distribution of forest landinto maturity classes. The category mature forfinal felling indicates that the selected standsmeet the legal requirements for final felling atthe time of the inventory. The category ageingforests not mature for final felling comprisesstands that are above thinning age but do notmeet standards for final felling. A general observationis that historically the share of forest inthinning age has been large, but is successivelydecreasing.• Site productivity and site indices are shown intables 3.4a–b. Site productivity expresses thecapability of a site to produce wood. It ismeasured as mean production in m 3 sk (stemvolume from stump to tip of the tree, incl. bark)per year and hectare during a specified rotationperiod in an ideal forest.• Table 3.4b shows the forest land area distributioninto site productivity classes according tothe University of Forestry system (SHS system).A first step in the SHS system is the classificationof forests into site index classes for a specifiedspecies. The mean site quality on forest land was5.3 m 3 sk per hectare and year. Table 3.4a indicatesthe upper height of a forest 100 years old.• The growing stock of the entire country,including dead and wind thrown trees, isestimated to be 3 billion m 3 sk of which 95 percent grows on forest land (tables 3.5, 3.6 and3.7). The distribution by tree species was Norwayspruce 42 per cent, Scots pine 39 per cent, birch11 per cent and other broad-leave species 5 percent. The growing stock has increased steadilysince the 1920’s from a level of 1,760 millionm 3 sk (figure 3.1). The increase has beenparticularly high in southern Sweden and fortrees with a diameter above 25 cm. The standingvolume per hectare of forest land was 127m 3 sk per ha.• Annual growth is shown in table 3.8. Annualgrowth during the 1920’s was around 60 millionm 3 sk/year. The current annual growth isaround 100 million m 3 sk per year.299