Acta Forestalia Fennica vol. 44 | 1936

The stem form influences the value and volume of the stem. Sample trees in homogenous mixed stand of Scots pine (Pinus sylvestris L.) and Betula sp. were measured to define the stem form of the trees, and to develop research methods. The height of butt swelling and the turning point of taper curve varies greatly. In Scots pine and Betula sp. it was typically between the 2/10 and 3/10 height of the tree. Consequently, the theoretical normal curves describing stem form, where the turning point of taper curve is situated under the breast height diameter, are not entirely generally applicable. There was a correlation between the base curve and the form of actual taper curve of the stem. The form of the top of the stem depends on the structure and dimensions of the crown. The most reliable measuring point to define taper curve would be a diameter that is above butt swelling, near the turning point of the taper curve. Length of the crown can be used to deduce the form of the top of the stem. According to the study, the volume tables could be based on diameter on breast height, slenderness of the stem (D_0,25h:h) and length of the crown. Age of the tree and position in the stand influence stem form, but the forest site type seemed not to have clear effect on the stem form.

The PDF includes a summary in German.

• Lappi-Seppälä, E-mail: ml@mm.unknown

Ground vegetation can be used to determine the fertility of the peatlands. This information is needed when deciding if a peatland is suitable for drainage. The spruce and pine swamp types of Finland have been well established. The aim of the study was to develop further the peatland type classification for treeless bogs in Finland, presented in earlier studies. The treeless bogs consist of diversity of small patches of different vegetation that blend into complexes. Consequently, classification that is based on defining bog complexes makes it easier to determine a peatland type for a larger peatland area. A system describing peatland complexes for treeless bogs is presented with detailed description of the vegetation. The study identifies nine different peatland complex types for treeless bogs.

The PDF includes a summary in German.

• Paasio, E-mail: ip@mm.unknown

Shifting cultivation, practiced earlier in Finland, was beneficial for grey alder (Alnus incana (L.) Moench). It can produce seeds early and the early growth of the seedlings is fast. Areas where shifting cultivation was intensive, the areas next to the fields were pure alder stands, next circle was Betula sp. dominated, beyond that could be found Scots pine (Pinus sylvestris L.), and finally Norway spruce (Picea abies (L.) H. Karst.). When shifting cultivation ended, Norway spruce became more common. Many young mixed stands had Norway spruce undergrowth and alder overgrowth. The aim of the study was to find out how the stands develop to spruce dominated stands, and how they should be managed.

The density of spruce undergrowth affects the further development of both spruce and alder. The number of alder stems decreases the faster the denser the spruce undergrowth is. Alder overgrowth slow down the early diameter and height growth of spruce compared to pure stands. Also the diameter and height growth of alder remains smaller in mixed stands. The basal area of spruce develops slowly in the beginning, increases significantly by the age of 30, and surpasses the growth of pure spruce stands in Oxalis-Myrtillus site type. Thus, Norway spruce do not suffer from growing in the undergrowth. In the first years, fast growing alder seedlings limits growth of ground vegetation and protects spruce seedlings from frost.  Later thinning or removal of alder benefits spruce growth. The density of spruce undergrowth decides how much alder can be leaved in the stand. If the spruce undergrowth is thin, more alder can be left in the stand.

The PDF includes a summary in German.

• Kalela, E-mail: ek@mm.unknown

Earlier studies show that different kind of biological processes occur in the soil of different forest types. These differences may be due differences in microbiology of those soils. This article studies these differences.

Soil samples from five different forest types were collected from the Ruotsinkylä research forest in three different seasons: in January, March and September.

The amount of bacteria in the samples is at the lowest in March and highest in September.   During the winter more anaerobic bacteria were found. The amount of denitrifying bacteria is higher in the soil than amount of nitrifying bacteria.

The results indicate that the species composition of soil varies between the forest types in the same manner than the vegetation composition above the soil. However, this study is only a preliminary and more knowledge is needed about the discipline before practical implications can be drawn.

The PDF contains a summary in Finnish.  

• Svinhufvud, E-mail: vs@mm.unknown