Current issue: 54(2)
Results on early survival, growth and shoot phenology of hybrid aspen (Populus tremula L. × P. tremuloides Michx.) and poplar clones (P. trichocarpa Torr. & A. Gray, P. balsamifera L., P. maximowiczii A. Henry and their hybrids) in 13 Scandinavian field trials are presented. The trials were established on forest land (7 sites) or former agricultural land (6 sites) within the latitude range of 56° to 65° N and were assessed 3–4 years after establishment. The main aim was to evaluate phenotypic and genetic differences related to early survival, growth and phenology for hybrid aspen and poplar for different site types and latitudes. Growth and survival was generally higher for hybrid aspen than poplar at all sites. The poor performance of poplar compared to hybrid aspen is likely due to climatic maladaptation or high soil acidity. The early growth performance of the species need to be confirmed at a higher age. The genetic variation and genetic control for growth, phenology and survival was in general intermediate to large indicating good possibilities for effective clonal selection. The genetic site x site correlations (rGE) for growth were for hybrid aspen mostly strong, indicating a weak genotype by environment interaction, while rGE were inconsistent for poplars.The result suggests that southern Sweden can be treated as a single test and utilization zone and in northern Sweden the region along the coast may be another zone. It is too early to make any corresponding conclusions for poplar. In addition, the result backs up the current recommendations for utilization of selected hybrid aspen and poplar regeneration material in Sweden.
Stump wood is a possible alternative to fossil fuel. Its harvesting, however, disturbs the ground and this has not yet been quantified at stump level. Such disturbance is likely to be dependent on stump size, type of soil and timing of stump harvesting. Therefore, we measured ground disturbance and root breakage diameter at two Norway spruce sites with sandy glacial till soil. The sites were harvested with a fork type head, 6 and 18 months after clear cutting. Measurements were made within 2 weeks of harvest. No difference was found between the two sites. The mean area of disturbed ground was 6.06 (std 3.14) m2 per stump and increased exponentially with stump size. A regression function modelling the relationship was constructed. Unexpectedly, many fine roots where extracted in the harvest. The arithmetic and basal area weighted mean root breakage diameter was 4.6 (std 2.2) and 29.5 (std 17.9) mm, respectively. There seems to be a limited increase in root breakage diameter with increased stump size. The small root breakage diameter is associated with reduced fuel quality and greater nutrient removal. It appears that much of the ground disturbance is associated with the creation of ruts rather than stump harvest per se. Stump harvesting disturbs a larger percentage of the area of a harvested site than mounding. Postponing stump harvest by one year did not decrease the ground disturbance or increase the root breakage diameter. To achieve less disturbance and larger root breakage diameter, probably new stump harvesting technology is required.
Forest policy can be traced several hundred years back in Sweden. One of the early restrictions was related to iron industry, which was dependent on supply of charcoal. This led in the 17th century to the regulation of the industry in order to fit its capacity to the sustained yield of the forests. Also the early sawmill industry was kept under supervision in the mining districts in order not to compete with the iron industry of the forests resources.
In 1903 the fears of shortage of wood, caused by a few decades of unrestricted use of forests and the rise of pulp and paper industries, resulted in the first forest law (enacted in 1905). The leading principle of the law was that the owner of the forest had to secure reforestation after felling. When previously the regulation had limited the fellings within the sustainable yield of the forests, the new law aimed at promoting the productive capacity of the forests. New felling methods were developed and the new practices were spread to the forest owners with help of education, propaganda and giving advice. One important factor in the success of the forest law was founding of County forestry boards, which are the main agencies to materialize the constructive ideas of the new forest policy.
The First National Forest Survey was conducted in 1923-29, followed by the second in 1938, and third in 1954. A new forest law came into force in 1923, which prohibited the cutting of immature forests in other ways than by thinning. In 1948, new amendments of the law were introduced, which, for instance allowed the forest owner to put part of the income derived from the timber sales into a bank account to be later used in reforestation.
The Silva Fennica issue 61 was published in honour of professor Eino Saari‘s 60th birthday.
Forests and forestry in northern Scandinavia is affected by the climate, as well as economic and demographic questions. In northern Norway the issues of forest management are related to broadleaved forests, in Northern Sweden and Finland, the forests are mainly coniferous. These forests are still mostly primeval forests as the exploitation of the forests have begun slower than in the south. The Finnish forests are mainly owned by the state which makes the challenges of forestry a management problem within the Forest Service. In Sweden, the rational use of forest resources of the north has been lively discussed. Rational management of forests has begun in the southern and central parts of the country, but as the rationalization process reached the northern Sweden, many biological, economic and forest policy problems emerged. This paper outlines the forest resources, forest policy and legislation (so called lappmarkslag, an act that regulate the use of forest in the region) concerning the problems of forest management in northern Sweden.
In Sweden lot of state owned forests or earlier mining districts or districts of ironworks have been afforested during the last decade. The amount of afforested areas sinks from south to north. Afforestation has taken place also in privately owned forests.
The article discusses the common economic questions related to afforestation work and the biological viewpoints related to it. The best cultivation methods are presented for several common forest types, such as herb-rich forest types, moss-grown forests types, swampy forests with heavy raw humus and barren pine forest sites (lichen type).
The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.
The objectives of this study were to record residual stand damage during harvesting operations and evaluate the influence of factors such as distance of the tree from the strip road, machine parts, operational phase, on the occurrence of tree wounds. The machine was a farm tractor equipped with a crane mounted on the front axle and a single grip harvester head. The study was carried out in two stands located in Southeast Sweden. Stand 1 was a 30-year-old Norway spruce (Picea abies (L.) H. Karst.) plantation on an afforested pasture while stand 2 was a 90-year-old mixed stand of Norway spruce, Scots pine (Pinus sylvestris L.), birch (Betula pendula Roth) and aspen (Populus tremula L.).
The mean damage percentage was 6.3% for the first stand and 6.5% for the second stand. Sixty-five percent of the wounds were less than 50 cm2, with 91% of the damage occurring on the stem and 91% of the damage on or below the root collar. Sixty-six percent of the wounds produced by the stem under processing or by the harvesting head while only 10% of the wounds were produced by the tractor wheel. Damaged trees were distributed evenly in the crane reach zone. Significant differences were found between rut depths after one, two, four and six passes of the tractor in stand 1.
Temperature sums required for budburst in various Norway spruce (Picea abies (L.) H. Karst.) provenances were determined, and weather statistics were then used to predict the risk of potentially damaging frosts at 11 locations in Sweden. Frost risk was quantified as the probability of a frost occurring within 100 day-degrees (two weeks) after budburst. The examples provided show that a spruce seedling from central Sweden has to sustain almost twice as many frost occassions as a seedling from Belorussia, when planted in southern and central Sweden. The method presented here can be used for mapping early summer frost risk in Sweden and for supporting provenance transfer guidelines.
The paper gives an introduction of the tree breeding program of Sweden that started in 1936 by the establishment of an association for the tree breeding. In 1967 the Institute of Forest Improvement was founded and it replaced the earlier association. The main species in the programme have been Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), lately also birch (mainly Betula pendula Roth.) and lodgepole pine (Pinus contorta). In addition, limited breeding has been done also with hybrid aspen (Populus tremula x P. tremuloides), oak (Quercus), larch (Larix), black spruce (Picea mariana) and a few other native and exotic species. The dominating initial effort has been to select plustrees in natural stands and use them for production of reforestation material. In addition, a considerable body of tests was built. The paper lists the status of breeding material of the different tree species and introduces the medium and short-term breeding programmes.
Visible frost damage to forest trees in Sweden seldom occurs in winter but is frequent in late spring, summer and early autumn. Frosts are frequent in all seasons in various parts of Sweden, even in the southernmost part (lat. 56°, N) and temperatures may be as low as -10°C even around mid-summer. Ice crystal formation within the tissues, which in most seedlings takes place at around -2°C, causes injury, not the sub-zero temperatures themselves.
The apical meristem, the elongated zone, and the needles of seedlings of Picea abies (L.) H. Karst. in a growing phase were damaged at about -3°C and those of Pinus sylvestris L. at about -6°C. Other species of the genus Pinus were tested and most were found to be damaged at about -6°C, with some variations. Picea species tested were damaged at about -3°C to -4°C.
A method has been designed to compare the response of different species to winter desiccation, which occurs under conditions of (1) low night temperature, (2) very high irradiation and increase in needle temperature during the photoperiod, (3) frozen soil, and (4) low wind speed. There were differences in response to winter desiccation between pine and spruce species. Seedlings of Pinus contorta tolerated these winter desiccation conditions much better than those of P. sylvestris or Picea abies. Picea mariana was the least tolerant of the species tested.
The PDF includes an abstract in Finnish.
To conduct an efficient forest policy, both a normative and a positive theory are necessary. In addition, however, the explicit intertemporal considerations in natural resource economics demand that it is made crystal clear which means are permanent and which are non-permanent. The permanent case is far from easy to solve.
That the theoretical problems have practical relevance is shown by Swedish experience. A practical course of action is to weight possible positive effects from a permanent subsidy against possible deleterious outcomes. It is also desirable to avoid jerkiness in forest policy, which is likely to create uncertainty about the permanence of permanent means.
Law may sometimes be more efficient in creating ”credibility” than economic incentives. Regeneration has been mandatory in Sweden since 1903, and nobody refrains from cutting because he believes that regeneration duty will be abolished in some near future.
The goal of this research was to study the position of forest supervisors, their education, number, pay system, professional organizations and work situations in Nordic countries. The study belonged to a joint Nordic project of the Nordic Research Council on Forest Operations. Participating in the actual work the number of forest supervisors were Denmark (year 1978) 715, Finland (1980) 8,000, Norway (1967) 1,055, and Sweden (1975) 6,400. In Denmark, 87% of the supervisors worked in forestry, in Finland 91%, in Norway 98% and in Sweden 86%.
Forest supervisor education started at the end of the last century. In the 1950s and 1960s the forest supervisors’ education has been renewed in all four countries. Supervisors have a special 1 to 4.5 years’ training, but many have a forest technician’s education, too. In Finland and Sweden forest supervisor education was reformed at the end of the 1970s. Supervisors work in functional as well as in regional organizations. In Nordic countries, supervisors are paid monthly salaries. Salaries are a little higher in private than in public sector companies. In 1981 the start salary in Finland was 3,107 FIM and in Sweden in 1980 about 4,425 FIM. Most supervisors in the Nordic countries belong to some union.
The PDF includes a summary in English.
In the 1980 and 1981, windthrown and felled Scots pine (Pinus sylvestris L.) were examined at 8 localities in Sweden. The number and length of egg galleries as well as the number of exit holes of Tomicus piniperda (L.) and T. minor (Hart.) were recorded on sample sections (30 m in length) distributed at 3 m intervals on the 37 fallen pine stems, which were successfully colonized by the beetles. In addition, 78 uprooted pines were surveyed in 6 localities. Most trees were attacked by T. piniperda, but only a few by T. minor. Successful colonization often resulted in the production of several thousand beetles per tree, the maximum being approximately 1,800. The attack density of T. piniperda seldom exceeded 200 egg galleries/m3 bark area, and the brood production usually remained below 1,000 beetles/m3. Much higher figures were obtained or T. minor. In T. piniperda, the rate of reproduction (i.e. the number of exit holes /egg gallery) decreased rapidly with increasing attack density, whereas T. minor seemed to be less sensitive to intraspecific competition.
The PDF includes a summary in Finnish.
At immediate surroundings of a fiberglass plant in Central Sweden, vegetation shows toxicity symptoms. Soils and birch (Betula pendula Roth) leaves were sampled. The soil was analysed for water soluble and organic bound boron, carbon, nitrogen, and pH. Vegetation was analysed for total boron. Both fractions of boron in the soils increased towards the factory. Organic bound boron increased irregularly because of its strong correlation to carbon content which varied in the area. The C/N ratio increased nearer the industry due to the harmful effect of boron on the decomposition of organic matter. No relation between pH and the distance from the emission source was visible, but B/C ratio was found to increase with increasing pH of the soil. Boron levels in birch leaves were elevated very much close to the factory. The geographical distribution of high levels of boron in birch, corresponded well with high values in soils, and also with the main wind directions. The limit values for visible injury on birch were found to be around 5 ppm of water-soluble boron in soil and around 200 ppm in leaves.
A monitoring program is planned for the terrestrial environment around industries in Sweden, which emit acid compounds and heavy metals. Directions for the County Government Boards are being prepared. The paper deals with the present pollution situation in Sweden, based on recent scientific results, the justifications for local monitoring, and the organizing of the monitoring including the parameters suggested.
Four examples from a case study at an oil power station illustrate reporting of the data and the difficulties in interpreting the results. The examples are the distribution of a lichen indicator, heavy metal content and phosphatase activity in the moor layer, soil respiration and tree growth.
Air pollution injury to vegetation often occurs near a fertilizer factory in Central Sweden. The causing incidence often occurs in the winter and the symptoms appear when metabolism starts in the spring. Deciduous and coniferous trees and bushes were injured in the spring of 1979. Samples of Scots pine (Pinus sylvestris L.) needles were analysed for sulphur, total fluorine and nitrogen content, some of them for nitrate and ammonium. All the compounds showed elevated levels, clearly connected with the degree of exposure of the sampling site. The levels were higher in the spring than later in the growing season, indicating involvement in metabolism or leaching. None of the compounds was significantly in excess, although, elevated to an extent to indicate the cause of injury. Most probably the nitrogen compounds were involved. The problems encountered in tracing the causing pollutant, when injury appeared long after the incidence, might be easier solved with regularly used technical monitoring and bioindicator technique.
The purpose of this paper is to discuss the effect that the various measures by society have on bringing the level of the annual cut by private woodlot owners in line with the forestry policy goal of a long-term sustained yield of wood. The objectives and measures of forest policy in Sweden are described, as well as the central relations which explain the development in the logging policies of the private woodlot owners.
The goal of Swedish forestry policy has long been to safeguard a sustained yield of wood. This demand has successively been tightened, defined and detailed. The principle measure employed by the authorities to obtain the goal has been silvicultural legislation.
The author summarises that of all the means available of influencing the logging policy of private woodlot owners the most effective is silvicultural legislation. However, when viewed in an historical perspective, the legislation has not been able to significantly regulate the level of the annual cut. Nevertheless, at a time when there is a shortage of wood materials the legislation will undoubtedly exert a greater influence. Changes in forest taxation could prove to be an effective means in future of, for example, achieving an increase in the annual cut of private woodlot owners.
The many unsolved questions concerning fertilization makes it difficult to forecast accurately its biological and economic consequences. Some of the problems are discussed in this paper. The most common types of forests in Sweden, Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands on well-drained mineral soil, respond strongly to nitrogenous fertilizers, but the effect of phosphate, potash or lime is small or nil, at least within 5–10 years after application. The response of nitrogen lasts 4–5 years in pine and somewhat more in spruce.
Drained peatlands usually respond to mineral fertilization, but the improvement brought about by a PK application depends, inter alia, on the nitrogen content of the peat. Peatlands with a peat low in nitrogen need NPK fertilization. For deep peatlands, a moderate or high nitrogen content, a single PK application improves growth conditions for a very long time. Experience of fertilizing shallow peatlands and poorly-drained mineral soil is very limited, but it seems easy to get a growth response either with nitrogen alone or with NPK.
The results of fertilization at the time of planting have not, as a rule, been very good in Sweden. An exception is the afforestation of abandoned fields on drained deep peat, where PK fertilizer around the plant seems to be essential for both survival and growth.
The article gives a review on the history of forest management in the Northern countries. The article concludes that in the Northern Countries with their immense supplies of forest and small demand, because of sparse population, there was no hurry for developing the study of forest economics, as was the case in Central Europe. It was only when the modern wood using industry had revolutionized the marketing conditions, that the opportunity was provided for forest economics to develop. The paper introduces the book ’Om skogarnas skötsel in Norden’ (Silviculture in the Northern Countries) written by a Finn C.C. Böcker. That paper was compiled in behalf of a request of the king of Sweden, King Carl XIV Johan, who offered a price to a person who would draw a scheme for organizing forestry in Sweden, where Finland at that time belonged to. The prize was divided by Böcker and a swede, af Ström.
The PDF includes a summary in Finnish and English and the original text in Swedish.