Forest Resources of Southernmost Finland, 1986-1988

1993

111 S.

zahlr. Lit. Ang.

Bandaufführung

2628

37310

The paper presents the results of the 8th National Forest Inventory (NFI8) in Finland for Ahvenanmaa and the nine southernmost Forestry Board Districts based on the material collected in 1986-88. The combined area is referred to as Southernmost Finland. Results have been calculated for this area both for NFI8 and for the previous inventory (NFI7) carried out in 1977-79, as far as the data collection in successive inventories has made it posible. A totally new topic in the present inventory is the follow-up of cuttings, silvicultural measures, ground preparations and draining activities accomplished during the previous 10-year period. At the same time the classification of recommended measures has been diversified. Recommended, likewise accomplished cuttings have been observed by cutting treatments. Information concerning the need of cuttings has been expanded by a variable indicating the immediate, urgent need of cuttings. Volume and increment estimates are given for birch separately from other deciduous species. Previously all deciduous species have been mainly described as one group. Seedling stands have been subdivided by the number of seedlings and the classification of mix tree species, the undergrowth and the overstorey has been diversified. Observation of drainage activities has been elaborated by separating forestry drainages undertaken to improve forest growth from other drainages and by recording forestry drainages carried out on too barren mires. Mires, where the peat layer is thinner than 30cm, form their own group. Geologically these thin-peated areas have not at all been considered as mires. The foolow-up of land class area changes, presentation of forest and forestry land areas by ownership groups and tabulation of areas, where forestry use is strictly restricted, form the new land-use information calculated from the inventory data by Forestry Board Districts. The inventory results in Southernmost Finland indicate, that the forest has become more dense, large-dimensioned and older. The volume and increment of the growing stock has increased during the time between the latest inventories by 13%. The corresponding mean volume estimates on forest land are 116 and 130 m3/ha. The proportional volume of trees having a diameter of at least 35cm has enlargened from 9 to 12%. The area of thinning stands has risen at the expense of seedling stands and regeneration areas. The area of stands older than 100 years has increased by more than 35%.