Current issue: 52(3)
Under compilation: 52(4)
Draining of peatlands to improve forest growth started to increase in Finland in the beginning of 1900s. The aim of the study was to find out which kind of peatlands are suitable for draining. The peatlands examined in this study had been drained earlier in 1800s for other purposes, and the original peatland type was deduced afterwards. When the peatland is drained, its vegetation changes gradually towards that of mineral soil sites, depending on the original peatland type. The article includes detailed description of the vegetation on different drained peatland sites. Best represented in the study were different types of pine swamps, which change towards Calluna or Vaccinium forest site type depending on the original peatland type. The Sphangnum species and brushwood disappear gradually and Cladina sp. become common in some drained pine swamp types. Scots pine (Pinus sylvestris L.) regenerates well on most drained pine swamps, and also Betula sp may grow as dominant species. The richer pine swamp types develop to Vaccinium-myrtillus forest site type, which may grow also Norway spruce (Picea abies (L.) H. Karst). Drained treeless bogs change first towards pine swamps. However, trees regenerate poorly on these sites and the growth is low. Flark-bogs develop typically to treeless lichen heaths. Drained spruce swamps develop to forest with grass-herb vegetation or Myrtillus site type.
The PDF includes a summary in German.
The data has been collected from northern Finland between about 64th and 68th north latitudes, excluding the polar tree line areas. The sample plots have been selected to represents greatest variation of the habitats in altitude, rainfall and other site factors. The selected trees were cut, their age, height, and diameter at various heights examined and possible signs of forest fires noticed. The age of the trees was examined also with microscope. The age class distribution of the sample plots was studied. The determination of historical seed years was based on age class distribution of the sample plots.
Grouping of the trees into different age classes was too weak a method to make any conclusions about the periodicity or even less about the frequency of the seed years. There were also noticeable differences in determining the age of the trees between macroscopic and microscopic age examination. There are also differences in the amount of seedlings between different forest types.The growth of pines in northern Finland is very slow particularly in the young ages but the growth increases after they reach 1,3 meters, which may take up to 30 years. The development of the forest has been similar through last centuries