Current issue: 52(3)
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 paper studies the relationship of settlements to the forest types and forest soil. The observations have been done and data collected in southern Finland, around lakes Päijänne and Saimaa during summer 1917. Because of the shortcomings in the data, the results in the paper can be seen only as indicative.
The settlements have spread out firstly to areas of grove alike soils and herb-rich forests. The human settlements are still on these days concentrated on those areas. When more land is needed for agricultural purposes, the more fertile areas were introduced first. With forest type classification this means moving from herb-rich Oxalis-Myrtillus-type to Pyrola-type and to some extent Myrtillus-type. The more barren types are used as fields only very seldom. The differences in the fertility of the soils affects strongly the welfare and development of the people and the communes.
The study shows that when considering the soil and vegetation, preconditions for agriculture are very different in different part of Finland. Also the climate and the geographical characters vary. To win more agricultural land, the fertile peatlands should be considered.
The paper deals with the ground vegetation of the barren coniferous forests of Åland Islands and seeks to describe its special vegetation characters with general features. The study is based on data collected during summers from 1918-1922 on Åland Islands. Work presents the forest types of Åland Islands classified according Cajander (1909) with their typical species.
The Ålandian coniferous forests seem to have a low number of species. This is because they are mostly old and closed, and have been developing for a long time without human induced disturbances from outside. Some changes have occurred due to forest fires. There is very few traces of non-native species in the forests. If some are found, they have not been able to regenerate or distribute widely.
The article describes the Ålandian vegetation of most typical habitats with greatest detail. The primary goal of the paper is to find out which deciduous species are native in the Åland Islands and hence can be seen as indicator plants for the living conditions. In addition to determining the native species of the Åland Islands, the study seeks to determine the human influence to the vegetation systems: which species are original, which have been introduced by agricultural activities, and how has the human activity influenced the abundance of the species.The number of species varies from 44.1% to 79% of the total number of deciduous species. There is a close relation between the size of the area available for species and the number of species found. Because of that, there is a need to consider the abundance of the species alongside their diversity when studying the formation of vegetation systems or their habitats.