Current issue: 54(5)
Under compilation: 55(1)
Long-term (47 years) effect of experimental whole tree harvesting (WTH) with a heavy soil scarification on ground cover vegetation was assessed in a dry nutrient-poor Scots pine (Pinus sylvestris L.) stand in Latvia. Neighbouring conventionally managed young (10 years) and mature (119 years) stands of the same type were used for comparison. Higher species richness was observed in the WTH stand compared to conventionally managed young and mature stands (24, 18 and 16 species, respectively), likely due to the profound disturbance. The Shannon diversity index was higher in the young than in the WTH and mature stands (2.36, 1.77 and 1.63, respectively); still, the composition and structure of ground cover vegetation in WTH was more similar to the mature stand. Nevertheless, the occurrence of oligotrophic species in the WTH stand suggested decreased soil nutrient content and potential development of different plant community. Hence, such method might be considered for restoration of oligotrophic stands. Nevertheless, the period of 47 years appeared sufficient for the ground cover vegetation to recover after the WTH.
The Finnish forest industry is undergoing a vast expansion, which has raised questions of forest balance. This paper studies the possibilities to increase the amount available timber by means of forest drainage. About third of the Finnish land area is peatlands. The calculations of the investigation are based on Forestry Board districts. Based on earlier studies, there is estimated to be 3,042,000 ha of true drainable swamps, 973,000 ha of poor swamps, 1,381,000 ha of uplands in need of drainage, and 1,205,000 ha of drained peatlands. Therefore, the area of drainable and drained lands totals 6,6 million ha, and requirement of forest drainage 5,4 million ha. The drainage hardly reaches this extent, however. It can be assumed that part of the poor swamps is uneconomical to drain. In addition, a half of the paludified forest land will probably not be drained. Thus, it can be estimated that the area to be drained in the future is about 5 million ha. It seems possible that this area could be drained within about 50 years with the present draining capacity.
Draining of all objects of forests would increase the annual increment of our forests, in time, by about 10.5 million m3. This would signify an increase of 23% compared to the present growth of the forests. The increase in the growth consists mainly of softwood: 16% is birch, and the remaining 84% almost equally of Scots pine and Norway spruce. The increase of growth is relatively slow. Depending on the rate of the drainage program, the mean increase of growth will be reached in about 25–35 years. The increase in removal indicated by the increase in the mean increment will be reached in only 50–60 years.
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There are contrary opinions on the ability of Scots pine (Pinus sylvestris L.) seedlings to withstand oppression by hold-overs and recover after their felling. The recovery potential of oppressed pine stands in Southern and Northern Finland was studied using two kinds of material, fully recovered Scots pine stands and stands recently released. The volume and volume increment of the stand were measured, and the health of the sample trees was determined.
The study showed that those released pine stands that had been in oppressed state very long (25-60 years) had recovered after clear-cutting. After the release the stands grew at first slowly, but after recovery at about the same rate as natural normal stands of a similar height. The smaller, younger, and less stunted the seedlings were when they were released, and the better the site, the faster was the recovery. At the base of released pine stands various defects was detected. When the trees were released, the defects decrease their technical value. A heavy partial cutting had generally a disadvantageous effect on the stand. Recovering seedlings were found clearly to hinder the development of younger seedlings nearby. This inhibition seemed to be a result of the rapid spread of the root system of released pine trees.
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This investigation concerns the felling volumes in Finland in 1935-1945 as regards future fellings. The statistics are divided in two time periods: 1935-1939, when there was an upward trend in the trade cycle, and 1940-1945, when the trade was disturbed by the Second World War. Fellings of household timber and for sales are presented separately.
Removal was annually in average 38.1 million cubic meters (cbm) without bark in 1935-1939, and 29.8 million cbm in 1940-1945. According to the statistics, felling volumes decreased by about one quarter after the period of 1935-1945. Reduction was largest in private and company forests, but smaller in the state forests. The increment balance for the 1935-1945 shows an excess of growth that gives an accumulated yield of 24.4 million cbm.
In private forests the cut is about half as large as the growth of the standing stock due to the poor silvicultural condition of the forests. Private forests account for about ¾ of the total forest area in Finland. In the state lands the cut is 130% of the growth. The report introduces also rental cut, a method developed by the writer, which defines the volume to be cut aiming at the same time to optimise the future increase of the yield. The principle is to preserve the young and vigorous stands, while cutting stands that have low growth.
According to the statistics, the felling volume of private forests has followed the variations in demand. It seems likely that in the coming years the fellings will not be kept within the limits calculated by the rental cut. Consequently, the reserve formed during the war will be utilized. To meet the demand of wood, forest management must be improved and preference should be given to regeneration fellings. Improving transportation systems, such as roads, would give access to forest resources that are now difficult to harvest.
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The Economic Council asked Heikinheimo, Holopainen and Kuusela to prepare a report on the development of Finland’s forest resources up to the beginning of the next century. The expansion of forest industry beyond the level foreseen in earlier forecasts, the large-scale removal and neglect of the basic improvements required have weakened the condition of the wood production to such an extent that extensive measures are needed to ensure the continuity of the supply of wood. The results of the calculations are formed in three separately analysed alternatives.
Alternative I: Realisation of the Teho programme and the removal corresponding to it. The development of the growing stock according to the programme would only permit a cut amounting to an annual drain of ca. 51 million m3 up to the year 2000. After that it would be possible gradually to increase the removal. This drain would not itself to utilise fully the already existing production capacity of the industry.
Alternative II: Consequences of the predicted removal if the Teho programme is realised as such. The wood utilization forecast based on the premises given to the team show that the annual drain will grow in 1964–1975 from 52 to 58 million m3, and thereafter by 0.5% annually. This would lead to over-cutting, and exhaust the present growing stock by the turn of the century. If annual total drain of ca. 58 million m3 would after 1975 be sufficient, exhaustion of the growing stock would be postponed for 4–5 years.
Alternative III. Teho programme expanded in conformity with the removal forecast. A new programme is proposed, which includes, among others, large scale fertilization of fully grown firm forest land at about the rate of 100,000 ha/year, intensified artificial regeneration, assurance of the supply of planting stock and seed, increase of forest drainage from the present 155,000 to 250,000 ha/year by 1970, site preparation of the cutting areas for artificial regeneration, increase of tending or seeding stands to 300,000 ha/year, replacement of fuelwood by other fuels, increase of wood import and new forest roads.