Articles containing the keyword 'uudistuminen'

The objective of this investigation was to study the influence of stand density of white birch (Betula pubescens Ehrl.) on the minimum temperatures in the stand during the growing season, and the actual minimum temperatures of the leading shoot of Norway spruce (Picea abies (L.) H. Karst.) seedlings growing in the open. The 40-year-old uniform white birch stand was situated in 142 m above the sea level in Southern Finland. The stand was treated with thinnings of three different densities in 1961.

Air temperature was recorded in four sample plots at heights of 0.1 m, 0.5 m, 1.0 m, 2 m and 4 m. In the stand of moderate density, temperatures were measured at heights of 6.0 m, and in the stand of full density at 6.0 m, 8.0 m and 10.0 m.

The temperature differences between stands of various densities proved to be rather small. Especially the thinnest stand differed very little from the open area. The soil surface has in all cases been warm compared with the higher air layers indicating meadow-fog-type by Geier (1965). On cloudy or windy weather all the temperature profiles in the various stands resembled each other. The difference between the air temperature and temperature of the spruce shoot was greatest at midnight and decreased steadily thereafter.

The problem in using shelter stands for spruce regeneration areas is that optimum shelter stand density is difficult to define. Already a thin shelter stand causes drawbacks to the young seedlings, but in order to be effective enough against early frosts, the shelter stand should be comparatively dense.

The PDF includes a summary in English.

• Leikola, E-mail: ml@mm.unknown
• Pylkkö, E-mail: pp@mm.unknown

In 1933, forest fire caused by locomotive sparkle burned about 600 hectares of forest in a forest district named Vehkatallinmaa, in Central Finland. In 1934–36, the burned area was reforested, using different sowing and planting methods. At the same time, areas with poor runoff were drained. The results from reforestation throughout the area have been good. Also, natural regeneration of coniferous trees, especially Scots pine (Pinus sylvestris L.) has occurred. Even deciduous trees, especially birch (Betula sp.), have regenerated naturally in the area. The forests are an evidence of the adaptability of broadcast sowing on snow crust as a method of reproduction.

The PDF includes a summary in English.

• Kolehmainen, E-mail: vk@mm.unknown

The most common way to artificially regenerate cutting areas in Northern Finland has been sowing, which has, however, often given poor results. The aim of the study was to assess the success rate of sowing and study the causes of poor regeneration.

An inventory was made of 28 areas on Empetrum-Myrtillus and Hylocomnium-Myrtillus type sites sown with Scots pine (Pinus sylvestris L.) seeds in 1948-1950. In addition, to study the effect of substrata, a sowing experiment was established. According to the inventory, regeneration failed completely in 8 and partially in 6 of the 28 sown areas. Factors that explained the poor regeneration included unfavourable weather conditions in 1948-1952, insufficient clearing of sowing spot especially when the humus layer was thick, and insect damage by Otiorynchus dubius weevil.

The article includes a summary in English.

• Sirén, E-mail: gs@mm.unknown

Distribution of European white elm (Ulmus laevis Pallas) is on its northernmost border in Pyhäjärvi and Kokemäenjoki area. This survey describes distribution of European white elm in the flooded shores of the central lake of Pyhäjärvi and Kokemäenjoki river water system.

Both Ulmus laevis and U. montana (now U. Glabra Hudson) can be found in the area, but most of the elms qrowing in thea area are U. laevis. U. laevis occurs around the lake in two separate areas, almost entirely in flooded shores of the lake. Regeneration of elm from seeds was limited on a narrow belt on the higher part of the flooded shore. Consequently, U. laevis can be found as zones around the lake, created by the changes in water level of the lake. The trees are judged to be native for the area.

The article includes an abstract in German.

• Saarnijoki, E-mail: ss@mm.unknown

Finland has a long tradition of grazing cattle in the forests and common land. There are also reports of degradation of forests by grazing already in 1600th century. The aim of the survey was to study which positive and negative effects grazing has in forests.

The study concludes that grazing has caused considerable economic losses through damages to forests. In addition, woodland pastures cannot give the yields required in modern animal husbandry. The quality of woodland pastures have decreased after the woodlands used in slash and burn culture have become wooded.

Grazing has also some positive effects to forests. It increases the diversity of vegetation in the woodland pastures and spreads species to new areas. This is supported by the lists of species found in different woodland pastures. Cattle destroy large grasses like Calamagrostis, which may avail growth of tree seedlings in the pastures. Grazing can also prepare the site for tree seedlings. On the other hand, prolonged grazing destroys tree seedlings and prevents regeneration.

The article includes a German summary.

• Lampimäki, E-mail: tl@mm.unknown

Silva Fennica issue 46 includes presentations held in professional development courses, arranged for foresters working in public administration in 1937. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service. 

This presentation describes forest regeneration on poor forest sites.

• Laitakari, E-mail: el@mm.unknown

Norway spruce (Picea abies (L.) H. Karst.) is rarely the dominant species on dry mineral soil sites in Northern Finland. These sites are, in general, too poor and dry for spruce, and suit better for Scots pine (Pinus sylvestris L.). According to the study, the natural regeneration of spruce is in Northern Finland poor. In the sample plots, cones could be found in 35% of spruce trees in the stands in natural state and 46% in the harvested stands. Compared to the spruce areas in Northern Finland, or fresh mineral soil sites in Southern Finland, cone and seed production of Norway spruce was in dry mineral soil sites very low due to scarcity of seed trees and their low cone number. There were few spruce seedlings in the sample plots, but according to the observations, spruce is able to regenerate on lichen and heath covered sites. The seedling growth was, however, poor on dry sites. Spruce seedlings were often found near fallen trees and stumps. The growing trees prevent growth of seedlings of all species. Norway spruce seems, however, to be able to spread also to the poor sites. The success depends on the vegetation and dryness of the site. For instance, spruce can spread to dry mineral soil sites from seed trees of nearby peatlands.

The PDF includes a summary in German.

• Tikka, E-mail: pt@mm.unknown

This paper aims at studying regeneration of Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) by sowing and natural regeneration of birch (Betula sp.) in Western Finland.

Germination of spruce and pine seeds may be prevented by dryness and temperatures below the optimum for germination. In natural conditions, when temperature and moisture is insufficient for germination, the type of seedbed generally has en effect on germination result. Trenching of the seeding spots showed that root competition during the early stage of regeneration was not of decissive importance. It seemed to, however, improve the preservation of the seedlings later. It is common that it can take long before the seeds germinate, and during that time the number of viable seeds decrease strongly.

Also, the seedling stock quickly began to decrease in number after germination, especially during the first growing season and the following winter. The decrease was larger in intact vegetation than on mineral soil or in the humus layer. The emerging seedlings were destroyed by drought very easily, but their tolerance to drought improved later on.

The PDF includes a summary in English.

• Yli-Vakkuri, E-mail: py@mm.unknown

Natural regeneration of Scots pine (Pinus sylvestris L.) by leaving a seed tree stand on a cutting area has long been the most popular regeneration method in Finland. Results of the method have, however, been unsatisfactory. The aim of the investigation was to study the basic problems of natural regeneration of Scots pine. Regeneration success was studied in 144 sample plots in pine stands at different stages of regeneration in Southern Finland. In addition, the data included information of 42 previously investigated areas.

According to the results, Scots pine can be successfully regenerated naturally on sandy and gravelly soils in Southern Finland. Preparing the ground surface by breaking or burning considerably facilitates the establishment of a seedling stand. The number of seedlings was considerably lower in the ground vegetation than in the mineral soil. Considering growth of the seedlings, root competition of the mother trees was heavy in dense stands, but insignificant in thin stands. The stand density did not affect germination of the seeds. In regeneration areas proper, where the density of mother trees usually is under 50 per hectare, there was in average 4,700 seedlings per hectare in Calluna type forests and 5,200 in Vaccinium type forests.

The PDF includes a summary in English.

• Lehto, E-mail: jl@mm.unknown

Root systems of a Scots pine (Pinus sylvestris L.) stands of seed trees on a Vaccinium sites in Southern Finland were studied by taking soil samples around the seed trees. The results show that root system of an old Scots pine spreads relatively evenly around the tree up to at least 10 meters from the stem. The densest part of the root system is near the stem, which part is often acentric. This is probably due to root competition in the early stages of growth of the tree.

Root systems of the seed trees affect stocking of the site with seedlings and the growth of the seedlings. The root competition can cause, for instance, uneven grouping of the seedlings. It seems that the largest trees of a stand have the most even root system. It is therefore recommended to choose the strongest trees of the stand as seed trees, to ensure even distribution of seedlings.

The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.

The PDF includes a summary in German.

• Kalela, E-mail: ek@mm.unknown

Pine swamps are easily regenerated by natural regeneration of Scots pine (Pinus sylvestris L.). Usually seeding felling is used, but also strip system or clear cutting and regeneration along stand edge has been suggested. This article discusses the regeneration by clear cutting and sparing the existing undergrowth. The article focuses on pine swamps to be drained and the ones in natural state.

Pine swamps in natural state usually have plenty of trees of smaller diameter classes, that can be trusted to form the future tree generation after the felling. This shortens the rotation by 20-30 years. The undergrowth has been shown to recover quickly. The method suits for regeneration of drained peatlands but could fit also for regeneration of pine swamps in natural state.

The seedlings in the pine swamps are mainly 1-5 years old, and the stock is changing. It seems that larger trees produce a wider selection of age groups, but the seedlings survive longer under smaller mother trees. Part of the younger generations of seedlings seem to be destroyed when the peatland is drained. Further studies are needed to investigate how the draining and felling are to be performed to spare the young seedlings.

The Acta Forestalia Fennica issue 61 was published in honour of professor Eino Saari’s 60th birthday.

The PDF includes a summary in German.

• Heikurainen, E-mail: lh@mm.unknown

Norway spruce (Picea abies (L.) Karst.) invading sites is common in Finland. The species tends to establish itself as undergrowth, and takes over when it gets space to grow. To determine whether the undergrowth is suitable as the new generation requires knowledge on the biology of spruce undergrowth. One of the issues is determining the age of the stunted trees. In this investigation, 100 undergrown spruce trees, their crown and their root systems were studied. A method was developed to determine the age of the trees.

The root system of all trees in Vaccinium sites and of stunted trees in Myrtillius sites were superficial. The root systems of older spruces were purely of adventitious origin. The longer the period of stunting growth, the younger is the root system. In addition to acropetal and general adventitious ramification there is often adventitious branching of the roots of pathological causes. Mortality among the long roots is frequent.

A stunted tree has not the same ability as a viable tree to make use of already existing branches for building assimilating surface. When comparing trees with equally large assimilating surface, a stunted tree had greater sum of roots compared to a viable tree. The root system of a stunted undergrown spruce was very superficial compared with the other trees.

The PDF includes a summary in English.

• Sirén, E-mail: gs@mm.unknown

The aim of the investigation was to study natural regeneration of Norway spruce (Picea abies (L.) Karst.) in drained peatlands and frost injuries in seedlings, and to compare microclimates of the regeneration areas. The experiments included peatlands in Satakunta in Western Finland. Restocking of the areas with seedlings and their survival was followed in 1935-40 at sample plots that were mainly 1 are large.

Susceptibility to freezing was shown to be dependent on the stage of development of the shoots. Shoots that have just begun to grow contain little water, and withstand better freezing temperatures than shoots in later stages of growth. Damages to the seedlings were observed when the temperatures decreased to -2.8–-4.3 °C. The most severe damage to a seedling was caused by the death of the leading shoot by spring frost.

Norway spruce regenerates easily on moist peatlands, but peatlands with dry surface tend to have little or no seedlings. The species regenerated better in marshy sites than correspondingly fertile mineral soil sites. However, it needs shelter to avoid frost damage. On clear cut spruce swamp the undergrowth spruce seedlings that were left in the site got severe frost damage. If the site had birch (Betula sp.) coppice or undergrowth, spruce seedlings survived in their shelter depending on the height and density of the birch trees. To be effective, the protective forest should have relatively even crown cover. Young spruce seedlings could grow well even under relatively dense birch stand.

The PDF includes a summary in German.

• Multamäki, E-mail: sm@mm.unknown

Birches’ (Betula sp.) ability to grow sprouts is low. The stump grows root collar and stump shoots, but the stump shoots are not proper stump shoots that will grow from the space between wood and bark. The buds are situated very low in the base, even under the ground. In this study, no actual root shoots could be found. Also the bushy alpine birches seem to be formed from stump and root collar shoots.

In Southern Finland silver birch (Betula pendula Roth) is more common than downy birch (Betula pubescens Ehrh.) in dry upland forest sites, while downy birch is common in fresh mineral soil forests and peatlands. In Northern Finland downy birch is the dominant birch species. Of the two species downy birch has markedly better capacity to form stump and root collar shoots both in Northern and Southern Finland. In general, birches grow sprouts much more strongly in Northern Finland.

Growth of the shoots is fastest during the first year after the felling of the parent tree and slows down gradually. The stump shoots may get separated from the stump when the stump decays, and the decay may also spread to the shoots. It is common that the shoots have no own roots, and die along with the stump. The shoots may have own root system or use roots of the parent tree that have stayed alive, in the latter case decay spreads almost always from the stump to the shoot. Whether the tree was felled with axe or saw had no effect on sprouting, probably because the sprouting buds are situated in the base of the tree. The larger stumps had usually fewer sprouts than smaller stumps. The fertility of the site seemed to have little effect on sprouting, but more moist sites formed more sprouts.

Forest regeneration using sprouts may be possible in peatlands for firewood production. on mineral soil sites birch does not suit for coppicing. The proportion of trees originating from sprouts decreases strongly by the time. Consequently, in Southern Finland sprouts have little effect on regeneration of birch. In Northern Finland sprouting is the most important way of regeneration.

The PDF includes a summary in German.

• Mikola, E-mail: pm@mm.unknown

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 8^th or 10^th 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.

• Sarvas, E-mail: rs@mm.unknown

The aim of the study was to determine the effect of grazing of the cutting areas to the ground vegetation and regeneration of spruce. The cutting areas could be divided into two kinds of areas based on the vegetation. Hillocks were drier and poorer than other parts of the cutting areas. Their vegetation did suffer less from grazing than the other parts of the cutting areas. The shade-loving plant species decreased, but as the poorer sites have less edible plants, cattle caused less damage than in the better sites. The even spaces between the hillocks had both positive and negative changes. Cattle transport seeds, tile and fertilize the soil, promote paludification, and decrease competition by the primary species like large grasses. This is beneficial to new species. Grazing is directed to large grass species like Calamagrostis. Those species that cattle reject, become more abundant. Stamping damages especially shallow rooted species and perennial species, like Norway spruce (Picea abies (L.) H. Karst.). Larger tree seedlings may get injuries in the stem.

The PDF includes a summary in German.

• Hertz, E-mail: mh@mm.unknown

The northern range of small leaved lime (Tilia cordata Mill.) in Finland has remained the same since the end of 1800s, but according to the studies of subfossiles of lime found in peatlands, the northern limit has once been higher than at the present. The northernmost natural specimens of the species in Reisjärvi do not produce seed, and are therefore probably a relict. The article includes a review on the distribution of the species in Finland and its capacity to regenerate. The natural regeneration of lime in Finland is at present very rare. The species has lost its ability to sexual reproduction, but reproduces readily vegetatively.

The PDF includes a summary in German.

• Hertz, E-mail: mh@mm.unknown

The frequency of years when Scots pine (Pinus sylvestris L.) produces cones and seeds affects its reproduction in the north. The study area covered most of the pine lands in Northern Finland. Scots pine seems to be able to produce cones relatively often in the north. The amount of seeds produced in one year was, however, not sufficient to produce a dense seedling stand. Thus, the natural pine stands contain usually trees in different ages-classes, which have germinated in different years. The cone production is highest in 150-170 years old trees. Pine also needs warm summers to produce viable seeds. Brush fires avail the growth of seedlings, because they clear of ground vegetation that hinders germination of seeds. The seedlings need also moisture to survive; good regeneration years have often had rainy summers.

The PDF includes a summary in German.

• Lassila, E-mail: il@mm.unknown

The fifth part of the six-article series about protection forest in Northern Finland outlines sustainable forest management practices for the Scots pine (Pinus sylvestris L.) forests in the pine timber line area. The author stresses the need to secure the seed production and regeneration capacity of the forests, and the growth and protection of seedlings. At the same time, the local communities’ need for timber has to be taken into account when considering the means to protect the pine forests. The main principle is not to cut more trees than has been regenerated during the time period between good seed years. The article outlines good forest management practices for the timber line area.

The article is divided in six parts. A German summary is in a separate PDF.

• Renvall, E-mail: ar@mm.unknown

This fourth part of the six-article series about protection forest in the Northern Finland is a proposal for organizing reindeer grazing to enable scots pine (Pinus sylvestris L.) regeneration near the timber line. Protection forests in the Northern Finland cover third of the natural pastures of reindeer in the area. In these areas reindeer grazing can harm the young pine seedlings. The proposal suggests temporary restrictions in grazing in the coniferous forests. Also, in the northernmost parts of Lapland the pine timberline area would be used only as winter pastures. Regional limits should be set for the number of reindeer. Also the ownership of reindeer herds and herding coopearatives included problematic issues that should be solved.

The article is divided in six parts. A German summary is in a separate PDF.

• Renvall, E-mail: ar@mm.unknown

The second part of the six-article series about protection forest in Northern Finland outlines the principles of protecting Scots pine (Pinus sylvestris L.) timber line. The protected areas should include at least all of the viable pine stands and those birch (Betula sp.) lands that are necessary to safeguard fuel wood supply in the pine forest zone. Outside the actual pine forest zone also those birch stands that are near populated regions should be protected to secure sustainable fuel wood supply. Third, south and down of the pine forest zone should be protected pine forest stands and adjacent open fell areas where forests are especially vulnerable. A new protection forest commission should be established to execute the protection forest legislation.

The article is divided in six parts. The parts II and III of the article series are included in the same PDF. A German summary is in a separate PDF.

• Renvall, E-mail: ar@mm.unknown

The success of natural regeneration of Scots pine (Pinus sylvestris L.) is dependent on the amount and quality of seeds produced in each year. While seed production of Scots pine in Northern Finland is well known, there is little information about frequency of good seed years in Southern and Central Finland. The success of regeneration of Scots pine was studied by defining from the growth rings of felled sample trees in which year they started to grow. The aim was to choose sample trees so that they would form a continual series from seedlings to 100 years old trees. In the material there was too little sample trees from certain years. However, within the period of 1827-1910 it could be identified 13 good regeneration years of pine in Southern Finland. According to the study, pine has regenerated very well every 6th year and at least moderately well every 4th year. When compared to the previous studies made in Northern Finland, part of the good regeneration years seems to be same both in Northern and Southern Finland. Regeneration of Scots pine is affected also by the type and condition of the site.

The PDF includes a summary in German.

• Ilvessalo, E-mail: li@mm.unknown

The present study is a part of larger project into the size and age of certain forest plants. This study seeks to confirm the size-age relationship of Lycopodium clavatum L. and L. annotium L. stands, and the time of sporal regeneration. The stand dimensions were plotted against the size of bracken (Pteridium aquilinum (L.) Kuhn) and ground pine (Lycopodium complanatum L.) stands growing on the same site, and against the age of the timber and the time of fire on the site.

The method based on parallel measurements carried out in burned forests has proved to be suitable for establishing the rate of spreading of stands and their age. The three club-moss species proved to be much alike in their sporal regeneration. They, as well as bracken, regenerate under the condition created by fire. The largest detached patches are often clones. Both Lycopodium clavatum and L. annotium survive fire poorly. Thus, the maximum size of the clones is usually connected with the last forest fire. Pieces of the shoots may survive the fires.

Sporal regeneration of these species also occur without the aid of fire. As also variation in the annual growth of the shoots can be considerable, the stand size of these species is not as good indicator of the date of fire as with Pteridium aquilinum and L. complanatum. The winding appearance of the shoots increases the error in determination of stand age by the stand size further.

The results emphasize the importance of taking into account the time and spread of the plants in the traditional vegetation analysis. A central question is: what is an individual.

The PDF includes a summary in English.

• Oinonen, E-mail: eo@mm.unknown