Acta Forestalia Fennica vol. 41 | 1935

Healthy, straight, more or less free from branches and slowly tapering stems are good raw material for woodworking industry. The aim of the study was to investigate, from the stand point of forest management, the influence of stand and forest site type on the technical quality of the stems. Sample plots were measured in Norway spruce (Picea abies (L.) H. Karst.) stands in Eastern Finland. Norway spruce growing in a stand with closed crowns developed thin branches and self-pruned, if the stand was dense in the early stages. The decisive time for the stand is, therefore, when it is at seedling stage and young stand. The stems are more branchy if the stand has been planted. The adequate planting density is discussed based on earlier studies. The sufficient density seems to be achieved when the spacing is at maximum two meters. When the stems are branchless up to four meters, thinning of spruce stand does not affect knottiness or stem form. A sparsely stocked, knotty young stand does not produce good-quality timber even if the stand is later dense. Selective thinning from above can be used to improve the quality of the wood.

The PDF includes a summary in German.

• Laitakari, E-mail: el@mm.unknown

The development roots of Norway spruce (Picea abies (L.) H. Karst.) seedlings was studied in sample seedlings grown in different kinds of sites. In the early stage, the seedling roots grow primarily length. The main root is usually long. If the growth of the root is hindered, the tip of the root dies, and the root system growing from the original root collar remains relatively small; in these cases, the secondary root system becomes more important. In unfavourable conditions the root branches can early on replace the main root. The main root of a germling seems to be less able to seek for free growing space than the main and side roots of older seedlings. When the growth of the root is blocked by some kind of obstacle, it does not often hinder the growth of the seedling. The type of soil influences strongly how the root system grows. In good soil and in humus the root system is regular and richly branched, while in clay and coarse sand the root system was small. Spahgnum moss was good substrate for seedlings, Dicranum undulatum moss little less good, while the seedlings grew poorly on Pleurozium Schreberi.

The PDF includes a summary in German.

• Hertz, E-mail: mh@mm.unknown

About 40% forest in Finland are mixed stands that have birch (Betula pubescens and B. verrucosa) as one of the species. The aim of this research was to study the structure of root system of birch and compare it to the other main tree species in Finland.

The root systems were dug out and measured in 28 sample plots in Southern and Central Finland, representing different forest site types. Birch roots correspond 30‒100% of the volume of the stem, the largest root systems being in the sandy soils or peatlands. Also the longest lateral roots can be found at these sites. The size variation of root system of birch is larger than in Scots pine (Pinus sylvestris L.), and the vertical root system is in general smaller in birch. Birch seems to be better than pine able to adapt its root system to the existing conditions. The smallest root systems were found in the good forest site types, but the roots grow in the good sites denser than in the poor sites. The lateral roots of the main tree species in Finland, birch, Scots pine and Norway spruce (Picea abies (L.) H. Karst.) grow in different depths, which decreases the competition between the species. This finding gives support to cultivation of mixed stands.

The PDF includes a summary in English.

• Laitakari, E-mail: el@mm.unknown

The aim of the study was to find out what are the causes of damage in different parts of the trees and the frequency of different kinds of injuries. Sample plots were studied in over 80-year old forests in mineral soil sites and peatlands. All the trees over 1.5 m high were felled in the sample plots and the stem injuries were studied. The structure of the stand and the crown classes were recorded. The proportion of undamaged trees was largest in in dominant and codominant trees and increased towards the better forest site types. The typical injuries are listed for Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L). H. Karst.) and Betula sp. stands. The injuries were divided in inner and outer form defects and injuries, and defined in more detail by the part of the stem and tree species. Defects caused by decay were analyzed separately.

Healing over of injuries was faster in the better sites. Form defects and other injuries were more common in birch stands than in Scots pine and Norway spruce stands. Decay was most common in birch stands. The pine stands were the healthiest, followed by spruce stands. Fire wound were most usual in pine, butt rot for spruce, and crooks and general decay for birch.

The PDF includes a summary in German.

• Tikka, E-mail: pt@mm.unknown