Current issue: 54(3)
Under compilation: 54(4)
The paper presents preliminary results of paleobotanical studies on vegetation in Åland, south-west Finland. The investigations concentrated on studying arrival of tree species and stratigraphy of peatlands. According to the studies, some plant fossils found in the peat (Ceratophyllum submersum, Sparagnium neglectum, Najas flexilis) indicate that climate of the region has earlier been warmer than at the present. The present forests in Åland are dominated by coniferous species, but the pollen analysis of the peat indicate that Norway spruce (Picea abies (L.) H. Karst.) became a common species in the region about by the time of Christ’s birth. The species has reached its present distribution in Åland relatively late. The pollen analyses give relatively little information about the arrival of birch (Betula sp.) and Scots pine (Pinus sylvestris L.), but it seems obvious that occurrence of birch reached its culmination just before spruce. During the warm period common alder (Alnus glutinosa (L.) Gaertn.) was the most important species, and also pollen of oak (Quercus robur L.), kinden (Tilia cordata L.) and elm (Ulmus sp.) was relatively common in the peat of some of the studied peatlands. An interesting finding was the pollen of Carpinus betulus in many sites in Åland.
The PDF includes a Finnish and German summary.
For the purpose of defining the area and borders of former Littorina-sea (littorine stage of development of the Baltic) in Finland, the subfossil diatoms are a proof. During the year 1916 there were clay samples collected among the river Pyhäjoki, from the places that are presumably above and below the Littorina sea border. The examination of the samples showed that at six of them there contained no fossils, and four of them had only one kind of them. After this pre-examination 46 samples more were collected from the similar spots than the ones where the diatom fossils were found. This article presents the preliminary results of the project defining the borders of the Littorina-sea. The places of discovery of the diatom fossils are described.
The fossils in Ostrobothnia are rich of diatom flora. The most commonly occurred species were e.g. Epithemia turgida and Gyrosigma attenuatum. The half of the total number of the species are found in only five samples; most species feature only in few samples, if not in only one sample.
The article presents minimum levels of Littorina-sea as preliminary results.
The studies were conducted in 1913-1916 in state forests of Finland as a part of a large survey of peatlands by the Forest Service’s districts in Ostrobothnia in the Western Finland. The area and type of peatlands were estimated based on data of National Land Survey of Finland. In the 36 counties of Ostrobothnia, the total area of peatlands was approximately 1.4 million hectares. 30% of the peatlands are treeless bogs, 45% pine swamps, 5% spruce swamps, 15% areas resembling pine swamps and 5% areas resembling spruce swamps. The article describes in detail different peatland types and their vegetation within these classes. The peatlands were divided into five classes by their suitability for drainage and forestry or agriculture. In addition, the depth of peat, height growth of the peat and formation of peatlands in the area are discussed.
The PDF includes a summary in German.