Current issue: 54(5)
Under compilation: 55(1)
This paper deals with two machines designed for abrading seed wings, and their influence on the germinative capacity of seed of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.). Both machines are commonly used in Finland.
The results of the study indicate that the act of abrading may cause slight or even serious injuries to the seed. Slight injuries of about 3% are probably not easily avoided if mechanical abrading is resorted to. It must be noted, however, that even this reduction in germinative capacity causes significant yearly loss. If the reduction in germinative capacity is greater, which seems to be possible, it is advisable to test the mechanism of the machine and its method of abrading. As the clearance of the machines can affect the extent of injuries, all machines should be tested. If possible, a continual operation control should be arranged. It could, at the same time, to supply material for improving the abrading method and equipment.
The PDF includes a summary in English.
Natural regeneration has been common in Northern Finland, where forest fires have been usual, and the large areas make artificial regeneration expensive. The regeneration, and for instance tree species composition and density of the stand, cannot been controlled. In Northern Finland there is little demand for Betula sp. which is often abundant in the burnt areas. The unburned forests are generally Scots pine (Pinus sylvestris L.) or Norway spruce (Picea abies (L.) H. Karst.) dominated mixed forests with single Betula sp. trees.
The fire destroys birch for the most part in the Vaccinium site type, but the surviving trees produce enough seeds to regenerate the areas. The largest trees of Scots pine usually survive the fires. Pine has good seed years in the north only every 8th or 10th year. Spruce is totally destroyed in the forest fire and the seedlings grow poorly as primary species. The seedling stands are usually dominated by Scots pine and birch, but birch seedlings grow in batches, and do not hinder growth of pine. The drier Calluna site type stands are dominated by Scots pine. Birch seedlings may be abundant in the beginning, but most of them do not survive. Abundant emergent pine trees prevent the growth of seedlings especially in the dry site types, and they should be thinned to guarantee regeneration. Sowing results are better few years after the fire. The birch seedling should be removed from the seedling stands.
The PDF includes a summary in German.
Broadcast sowing on snow was relatively new method in the beginning of the 20th century in Finland, and the experiences of regeneration were diverse. The aim of the survey was to study the success rate of regeneration in the oldest and largest areas regenerated with this sowing method in Tuomarniemi district. Scots pine (Pinus sylvestris L.) was the most common tree species, but also Norway spruce (Picea abies (L.) H. Karst.) and European larch (Larix decidua Mill.) were used in broadcast sowing on snow.
According to the study, the success of broadcast sowing on snow was as good as patch sowing and sowing in furrows in the sites typical for Tuomarniemi. The regeneration areas were often drained peatlands or paludified lands. When sowing is done using Norway spruce seeds, site preparation either by broadcast burning or scalping with hoe is recommended. Mixed sowing with pine and spruce seldom succeeded due to the differences in site requirements of the species and growth of seedlings. Sowing of Scots pine succeeded well on the drained peatlands. Sowing should be done some years after draining to let the peat dry and sink. Site preparation is needed in sites growing Polytrichum-moss. Broadcast burned areas larger than 10 hectares seemed to regenerate poorer than sites in average, possibly due to dryness of the sites. Trials with European larch were successful, and the growth of the seedlings acceptable despite the sites being relatively poor for the species.
The PDF includes a summary in German.