Current issue: 57(2)
Under compilation: 57(3)
Silva Fennica issue 52 includes presentations held in professional development courses, arranged for foresters working in public administration in 1938. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.
This presentation describes different methods of assessing tree growth.
The article is a review on methods used in Central Europe and in Finland to construct growth and yield tables, and on their defects and advantages. One of the main defects of growth and yield tables prepared previously in Central Europe is that the site quality classes for different tree species have been formed independently and using different principles. Thus, the yields of different tree species on a similar site can’t be compared. In addition, the quality classes of this kind of growth and yield tables and growth series are artificial.
The Society of Forestry in Finland (now Finnish Society of Forest Sciences) started to prepare new yield tables for the most important tree species in Finland in 1916. The new yield tables aimed to improve the yield tables made in Central Europe in two aspects. Firstly, the quality of the site of each sample plot was assessed on the spot and independently from the standing crop. Thus the sample plots of each site class in setting up the growth series can be treated as independent groups. Consequently, the quality classes are be the same for all tree species. Secondly, mathematical-statistical methods were used to determine which of the stands that belong to the same quality class belong also to the same growth series.
The PDF includes a summary in Finnish.
One of the difficulties in constructing growth and yield tables has been to determine which of the sample plots growing the same tree species and belonging to the same forest site type, with reference to the quality of stands, have to be included in the same growth series.
New growth and yield tables for the most important tree species were constructed in Finland in 1916–1919, using new principles that aim at avoiding some of the common weaknesses. There were two main differences to the earlier work. First, the site quality class (forest site type) was determined for each sample plot when the sample plot was measured, independently of the stand occupying the site. In this way it was possible to treat the sample plots of each site as an independent group from the beginning, and so that the quality classes were the same for all the tree species. Second, mathematic-statistical methods were used to deduct the so-called stem frequency distribution series, when studying which of the sample plots of the same quality class belong to the same growth series. They represent the average number of stems of the different diameter classes. A more detailed description of the method used to create the growth and yield tables is published in Acta Forestalia Fennica no. 15.
In the PDF is included a summary in Finnish.
New growth and yield tables were prepared for Southern Finland. To finalize the tables, it had to be determined whether the forest site types developed by Cajanus could be used in mensurational research.
Comparative study was performed in 1916-1919 to study the growth of the trees in different forest site types. Total of 467 sample sites were measured in Southern and Central Finland. All the forest site types were found to have a distinctive vegetation typical to the site. It can be concluded that the ground vegetation can be used to determine the forest site type. The growth of trees was different in different forest site types, yet similar within each site type. The forest site types are uniform, natural and easy to determine, and can thus be used to classify the forest stands and used in mensurational research and a basis to growth and yield tables.
The PDF includes a summary in German.