After critically reviewing earlier studies on soil properties and their influence on forest growth and yield, it seems that defining the forest yield could be possible by means of soil properties. To be able to do so, the site needs to be defined and delineated in some other way. It is also necessary to decide the right soil properties to study for the purpose.
For the classification of forest sites the results of soil analyses need to be compared with growth and yield data from the site. To further the practice of classification of forest sites by means of soil studies, four aspects need to be taken into account:
1) the site needs to be delineated beforehand according its vegetation, preferable with Cajander’s forest type classification
2) the experiments about soil needs to be done for as many properties as possible
3) the studied sites need to be as representative as possible in their class
4) there are as many samples for one site as possible studied
The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.
The article contains tree lectures given in the meeting of the Geographical Society in Finland on February 25th 1921. The titles of the lectures are I Forest types in general, II Forest types as a basis for new growth and yield tables in Finland, and III Other research on forest types.
The first lecture is a follow-up of the Cajander’s 1909 published article on forest types. It deepens the theory on forest types. The classification into forest types represents primarily different plant communities of ground cover. The types are named after the characteristic plant species, indicator plants, however, many other species appear in different abundance.
The second lecture represents the research proceedings of mensuration of forest stands of different types to compile yield tables for pine. The forest types differ from each other distinctly on their growing preconditions, but inside one class the variation of the growing conditions is so small, that the classification can be used for yield tables, determining the basis of taxation and for classification of forest based on height over age.
The third lecture is a summary of other studies about forest type classification. They confirm the results presented in earlier lectures.