Articles containing the keyword 'tree species'

Distribution, biodiversity and reforestation dynamics of the platyphyllous forests in the Northwest European Russia were investigated. Data assembled from 21 landscape regions (250–350 km² each) show special features of small-leaved lime (Tilia cordata Mill., Norway maple (Acer platanoides L.), mountain elm (Ulmus glabra Mill.) and English oak (Qurecus robur L.) reforestation during the last two decades. New tendencies were found for the taiga areas with natural Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) vegetation. Natural platyphyllous reforestation in cut spruce areas poses as supposed a special question for forest management policy in the relationship to global climate changes. Feasible unsustainability of the common types of succession (Norway spruce - European birch (Betula pendula Roth); Norway spruce - European aspen (Populus tremula L.)) is discussed. Biodiversity of herbs, shrubs and tree species of platyphyllous forests is high and complex and is situated in 4–15 old-growth relics in each landscape region. Low-level genotype heterogeneity of nemoral flora species of such isolated populations is presumed. Special biodiversity conservation regulations are proposed.

• Chtchoukine, E-mail: ac@mm.unknown

The effect of species mixture was studied in a mixed stand of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) by simulating around 100 different treatment schedules during the rotation in a naturally regenerated even-aged stand located on a site of medium fertility in North Karelia, Finland. Both thinning from below and thinning from above were applied. Optimum rotations were determined by maximising the net present value calculated to infinity and different treatment schedules were compared with the net present value over one rotation as per rotation applied. In the optimum treatment programme, the proportion of pines was decreased by half of the basal area in the first thinning stage and by the end of the rotation to about one third. In thinning from above, the proportion of pines can be maintained at a slightly higher level. It is economically profitable to maintain the growing stock capital at approximately the level recommended by Forest Centre Tapio, a semi-governmental forestry authority. With non-optimum species composition, the loss in net present value over one rotation can be about 10 % in thinning from below and about 20 % in thinning from above.

• Vettenranta, E-mail: jv@mm.unknown

Based on literature this paper describes the natural afforestation of Finland that took place after the last ice age and the changes which have taken place during the last 10,000 years. The origin and development of the vegetation and trees are related to the changes in the edaphic and climatic factors. The first tree species to arrive in Finland were the primary colonizing species, birch and Scots pine. The appearance of Norway spruce dates back to about 5000 B.P. There have been great changes in the species composition of Finnish forests during the last several thousands of years but some 2,000–3,000 years ago the various species reached their present balance. The epoch of naural forests, which had lasted some 9,500 years, came to a conclusion, however, when man started to have a marked effect on the forest’s development 300–400 years ago.

The PDF includes an abstract in English.

• Alho, E-mail: pa@mm.unknown

In laboratory studies the heartwood content seems to be the only natural property of a wood of different tree species influencing the decay resistance. Moistening and drying by diffusion happen quite slowly. Scots pine (Pinus sylvestris L.) sapwood takes moisture by capillary action quicker than pine heartwood and Norway spruce (Picea abies (L.) H. Karst.) wood. Swelling and shrinkage are also greatest in pine sapwood. Impregnation of pine sapwood can give it better hydrophobic and dimensional stability than that of pine heartwood.

The PDF includes an abstract in English.

• Kärenlampi, E-mail: pk@mm.unknown

Especially in forest vegetation studies, the light climate below the canopy is of great interest. In extensive forest inventories, direct measurement of the light conditions is too time-consuming. Often only the standard tree stand parameters are available. The present study was undertaken with the aim to develop methods for estimation of the light climate on the basis of readily measurable tree stand characteristics. The study material includes 40 sample plots representing different kinds of more or less mature forest stands of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.).

In each forest stand, a set of hemipherical photographs was taken and standard tree stand measurements were performed. A regression approach was applied in order to elaborate linear models for predicting the canopy coverage. The total basal area of the stand explained 63% of variance in the canopy coverage computed from hemipherical photographs. A coefficient representing the relative proportion of Norway spruce in the stand increased the explanatory power into 75%. When either the stand density (stems/unit area) or dominant age of the stand was included into the model, increment of the explanatory power into 80% was achieved. By incorporating both of the preceding predictors, an explanatory power of 85% was reached.

The PDF includes a summary in Finnish.

• Kuusipalo, E-mail: jk@mm.unknown

The aim of this study was to establish from the literature the purposes and for which aspen (Populus tremula L.) and related poplar species are used and can be used.  According to the literature, numerous Populus species can be utilized in the industry with success instead of light softwood species in addition to them. The main emphasis is in the growing of large-sized timber, and there is no clear trend to changing to the short-rotation forestry of poplar. However, the utilization of the good sprouting properties of Populus species will probably increase as this regeneration method is cheap.

The PDF includes a summary in English.

• Kärkkäinen, E-mail: mk@mm.unknown

The development of the scientific basis for the production of high-quality seed led to the introduction of a large part of the research findings in forest genetics and forest tree breeding into practical forest seed production in the USSR. Since 1971, work has begun in forest enterprises on the establishment of a permanent seed supply for the main tree species – Pinus sylvestris, Picea ssp., Larix ssp. Quercus robur, Haloxylon ssp. and nut trees.

The basis for forest tree improvement is a gene pool which is built up using mass and individual selection of valuable forms in natural populations. In accordance with a long-term programme up to 1990, an inventory of 13.2 million ha of the best high-productive stands has been carried out for breeding purposes in the state forests. About 7,000 ha of plus stands have been selected, and a total of 9,453 ha of seed orchards and 141,253 ha of seed collection stands have been established. The first stage of the programme is planned to be complete in 1980, and in the second stage clonal high-quality seed orchards will be established.

The PDF includes a summary in Finnish

• Novoselceva, E-mail: an@mm.unknown

The ash content has been found to correlate with the fertility of peatlands. Relationship between height of 80-year-old stands and ash content of peat in topmost 30 cm layer was examined in Lithuanian conditions. On drained peatlands with ash content of peat from 3% to 8% pine stands increase in height. Ash content of peat being about 7% Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) stands on drained sites are found to be of equal height. Ash content of peat more than 8–9% has no significant effect on growth of pine or spruce stands. Birch (Betula verrucosa (B. Pendula Roth.) and Betula pubescens Erhrh.), stands are less sensitive to ash content of peat compared with other species. Black alder (Alnus glutinosa L. Gaertn.) stands occurred in sites with ash content of peat more than 8–10%. The height of the stands become equal both in drained and undrained sites in the cases where ash content of peat is about 16–18%. Ash (Fraxinus exelsior L.) stands attain high productivity on drained sites with ash content of peat about 20%.

The PDF includes a summary in English.

• Kapustinskaité, E-mail: tk@mm.unknown

The aim of this present study was to elucidate the quality of seed of foreign tree species grown in Finland, and the factors which have affected the quality of the seed yields. Due to the smallness of the material, however, no far-fetching conclusions can be drawn. The bulk of the seeds were collected in the fall of 1964. The samples of seeds were X-rayed and their classification to empty seeds and full seeds of four quality classes was done on the basis of the anatomical structures. The species studied (a total of 34 species) belonged to the following genera: Abies, Chamaecyparis, Larix, Picea, Pinus, Pseudotsuga, Thuja and Tsuga.

The percentage of empty seeds was throughout quite high. The reasons for the generation of empty seeds probably originate from the special nature of the stands from which the seeds were collected. As a rule, the stands were young and small in area, which may have caused weak pollination and self-pollination leading to embryo mortality. Also, insect damages were observed.

Seeds with albumen still discernible, although the embryo had died, occurred to some extent. In some Larix species, even the bulk of the seeds recorded as full belonged in this group.

The ripening of seeds with embryos was quite successful in spite of the fact that the temperature sum of the year of ripening was slightly below the average in Finland. For instance, all Abies species ripened almost completely.

According to the results, it can be expected that the tree species examined in this study are able to produce rich yields of good-quality seed in Finland, provided that the ovules are well pollinated and self-pollination does not take place to a large extent.

The PDF includes a summary in English.

• Tiililä, E-mail: pt@mm.unknown

Stand precipitation and stemflow studies became necessary in connection with hydrologic studies, for instance, to explain the deviations resulting from rains in the ratios between the water content of peat and the groundwater level, throughfall during rains of variable heaviness, and effect of stand treatment on soil moisture level. In this project the distribution of rainfall in stands differing in species composition and density was studied in Central Finland in 1963–1965 in fifteen stand precipitation sample plots. In addition, rain gauges were situated under individual Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) and birch (Betula sp.) trees.

The average precipitation in the open was 4.8 mm, the corresponding precipitation in the stand was 77% for birch, 71% for pine and 62% for spruce. Measurements of stemflow from individual sample trees showed that less than ¼ mm (about 1.5%) during a 15 mm rain in a pine stand. In the spruce stands stemflow is negligible. A part of the sample plots was in drained peatlands with a dense vegetation of small shrubs. The shrub layer retention was about 10% even during heavy rain. In a small forest clearing, the bordering effect of the forest was seen up to the distance of 5 metres from the edge of the forest. During the period of study, on an average 3% more precipitation was recorded in the clearing than in the open, the difference being probably due to the stronger wind effect in the open.

The PDF includes a summary in English.

• Päivänen, E-mail: jp@mm.unknown

The aim of this project was to investigate the cellulose decomposition rate in the soil on the ecological conditions created by different tree species, particularly birch (Betula sp.) and Norway spruce (Picea abies (L.) H. Karst.). Therefore, comparable sample plots were established in adjoining birch and spruce stands. Data on the stands, the vegetation, and the soil in the sample plots were collected. The experiment was carried out in the Ruotsinkylä Experimental Forest near Helsinki in Southern Finland.

Five pieces (3x5x0.15 cm) of cellulose (bleached sulphite pulp) were dried, weighed, and fastened in a row into a nylon bag. The bags were placed into the soil at a slant so that the upmost piece of cellulose was in the depth of 0–1.5 cm and the bottom one 6–7.5 cm. The weight losses of the pieces were measured after periods ranging from 6 to 12 months.

The results show that even within the same forest type, decomposition is much more rapid in birch stands than in spruce stands. In all the stands the decomposition rate decreased rapidly with increasing depth. The difference between birch and spruce stand, as well as the decrease with increasing depth, was probably mainly due to different thermal conditions.

The PDF includes a summary in English.

• Lähde, E-mail: el@mm.unknown

Understanding the growth of trees is the prerequisite for meaningful forest management. Hence the studies on the ways the trees grow is important. The growth of roots and sprouts was studied by Larix leptolesis, Pinus silvestris, Betula pendula, Robinia pseudoacasia, Populus euramericana, Pseudotsuga taxifolia, Quercus borealis and some other species. The results of still ongoing experiments on pine, birch and larch are presented for root and shoot growth.

The results indicate that the amount of light or shade the tree is having plays an important role in the growth. Hence some tree species are better adapted to shade than others, there are differences in their growth depending whether they are in light or in shade. 

• Lyr, E-mail: hl@mm.unknown
• Hoffmann, E-mail: gh@mm.unknown

Foreign tree species have been planted in Finland since 1900s, the most famous being Larix sibirica plantations in Raivola in Karelia, which now belongs to Soviet Union. One of the largest larch plantations of Finland today is situated in Tuomarniemi, in Central Finland. Ten larch stands were established in Tuomarniemi between 1912 and 1937 mainly by planting. The stand established in 1937 was sown. The trees represent five larch species: Larix sibirica Ledeb. (5 stands), Larix gmelinii var. kurilensis (2 stands, current name probably Larix gmelinii var. gmelinii), Larix americana Michx. (1 stand, now Larix laricina), Larix decidua Mill. (1 stand) and Larix occidentalis Nutt. (1 stand). The total area of the larch stands is 82.5 ha. This paper reports the studies made in the plantations in 1958.

In Tuomarniemi larch grows well in many types of soil from Vaccinium type sites to fresh mineral soil sites. The age of the stands varies from 19 to 48, height from 12 to 24 metres and annual growth from 5 to 12 m³/ha. Larix sibirca has the best stem form of the species, followed by L. gmelinii var. kuriliensis. Easiest to split is the straight-grained L. gmelinii var. kuriliensis. L. sibirica is almost as easy to process. The wood of L. decidua, on the other hand, is often spiral-grained and tough. The trees are seldom infected with decay fungi.

The PDF includes a summary in German.

• Kolehmainen, E-mail: vk@mm.unknown

Successful cultivation of a tree species outside its natural area of distribution involves that the original climate is similar to that of the area where it will be cultivated. Seeds should be procured from an area, where the climate is most similar to the area of cultivation. In addition, the site requirements should be met. To be worth of cultivation, the exotic tree species should offer advantages over the native species, such as wood quality, higher productivity, modest site requirement, greater endurance against spring frosts and cold in the winter, valuable by-products, resistance against grazing, insects or fungi, or improvement of soil.

In Finland, successful examples are Larix europaea Lam. & A. DC. and Larix sibirica Lebed, which both give better yield than the native species, and have better resistance against decay. In Central Europe, Pseudotsuga mentziesii (Mirb.) Fnanko, Pinus strobus L. and Pinus sitchensis (Bong.) Carriére have proved to be good forest trees. In Hungary, Robinia pseudoacacia L. has become economically important. Eucalyptus spp. have been cultivated in the Mediterranean countries, South America and California.

A summary in Finnish is included in the PDF.

• Ilvessalo, E-mail: li@mm.unknown

The present study proposes to calculate the economic sequence of two of Finland’s three main tree species, Norway spruce (Picea abies (L.) H. Karst.) and silver birch (Betula pendula Roth) when planted on Oxalias-Myrtillus type sites where both species are equally suitable, on biological grounds. In addition, the accuracy and applicability of the present Finnish yield tables to an economic comparison is tested. Benefit/cost ratio was selected as criterion of profitableness. All future net incomes and costs were discounted into the planting time and added together. The ratio between the discounted net revenues and the discounted investment costs (later called profit ratio) was the criterion. There is no reliable method to forecast the future wood prices, therefore two price ratios, birch veneer timber to spruce pulpwood and birch cordwood to spruce pulpwood, were chosen as free variables. The economic sequence of the tree species was determined as the function of these variables.

The main conclusions are, first, that under the present price ratios spruce appears to be the better choice for the forest owner, and the most promising policy for changing the situation seems to decrease the production costs of plants in birch nurseries. Second, the present Finnish yield tables are not consistent or accurate enough to enable any sufficiently reliable economic comparisons of tree species in artificial regeneration. The possible error of difference between two rather uncertain estimates is big. More work is needed to construct a uniform system of yield tables covering all main tree species, all site types, all macro climate conditions and all types of regeneration.

The PDF includes a summary in English.

• Keltikangas, E-mail: mk@mm.unknown
• Tiililä, E-mail: pt@mm.unknown

This paper presents a study on the works of ancient writers that deal with trees, forests and the use of forest before the time of actual forest sciences. The work describes the development of knowledge pertaining to the forest and trees and the progress made on utilizing them. This first part of a series of two articles is primarily concerned with biological information in ancient times. The article first describes the most important sources of information and concentrates then on the information on the structure of trees, on the vital functions of trees, on the factors affecting the growth of trees and tree species.

• Makkonen, E-mail: om@mm.unknown

There has not been complete agreement as to what is meant by ectendotrophic mycorrhizae, and there is a wide variety of opinion among authors on mycorrhizal terminology. In this paper ectendotrophic mycorrhizae are defined to be short roots with Hartig net and intracellular hyphae in the cortex. A mantle and digestion of intracellular hyphae may be found but are not necessary. In the study of Mikola (1965) ectendotrophic mycorrhiza was found to be common in Scots pine (Pinus sylvestris L.) seedlings in Finnish nurseries. The mycorrhizae had always similar structure and the mycelium isolated from the seedlings (E-strains) was similar. The aim of this study was to find out what kind of ectendotrophic mycorrhizae exist in forests and nurseries outside Finland, what kind of mycorrhizae do the E-strains isolated from Scots pine form with other tree species, and are these associations symbiotic.

Only one type of ectendotrophic mycorrhiza was found on the 600 short roots collected from the continents of Europa and America. The type was similar to the one described by Mikola: the mycelium is coarse and forms a strong Hartig net, and intracellular infection is heavy. Evidence is convincing that this structure was formed by the same fungus species. The species is unidentified. Mycorrhizae synthesized by E-strain with six spruce species, fir, hemloch and Douglas fir were all ectotrophic.

The E-type ectendotrophic mycorrhizae proved to be a balanced symbiosis. The seedlings of 13 tree species inoculated with the E-strain grew in the experiment better than the controls. The observation that ectendotrophic mycorrhizae dominates in the nurseries but is seldom found in forests, and then only in seedlings growing in the forest, was confirmed in the study. In synthesis experiments E-strain formed either ecto- or ectendotrophic mycorrhiza depending on the tree species.

• Laiho, E-mail: ol@mm.unknown

Trees and shrubs of foreign origin have been grown in Finland at least from the 1700th century. At the State Horticultural Institute in the neighbourhood of the town Turku in southwestern coast of the country, a number of ornamental trees and shrubs have been planted since 1927. During the first decade, weather conditions were quite favourable, but the winters in 1939–1940 were so severe, that only the hardiest plants survived.

It would be important to study hardiness and suitability of the various woody plants cultivated in the different parts of the country. This paper includes notes of the survival of the tree species and shrubs so far planted at the Institute.

The PDF includes a summary in English.

• Meurman, E-mail: om@mm.unknown

The tendency of successional development from young vegetation, rich in species and exposed to chance factors, towards regular plant communities, is found all around the world. Thee ecological groups of trees seem to be present in all forest regions in the world, namely the pioneer and the climax species, and a group of pre-climax species that can be ecologically either near the pioneer or the climax species. The succession of tree species in forest always leads to a climax stand, determined by climate, quality of soil and the mutual biotical strengths of the tree species in the region.

This division into ecological groups greatly facilitates choosing among different methods of treating stands and understanding the silvicultural methods of foreign regions. Stands formed by species of the same group must follow the same lines in their silvicultural treatment. For instance, mixed stand consisting of both pioneer and climax species represents a transition stage, in which the climax species strive for dominating position, and preservation of pioneer species is difficult. This indicates the broad lines for management of the stand. Also, regeneration methods of pioneer and climax species must be different. Studying the succession of natural forests can be used as a means to reach the highest possible silvicultural level. This is one reason why the preservation and study of virgin forests still in existence is indispensable.

The PDF includes a summary in Finnish.

• Kalela, E-mail: ek@mm.unknown

The article discusses the thermal conditions in the northern limits of trees and some bushes in Finland. Temperature is the most important limiting factor for distribution of plant species. Precipitation variations, however, are small in Finland. The article lists the main features of thermal conditions during the different seasons in different parts of Finland. The northern limits and the thermal condition of the area are described for the following species: Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.), mezereon, buckthorn, common alder, linden, elm, maple, hazel, ash, oak, hybrid mountain ash, yew and Swedish whitebeam.

The PDF includes a summary in English.

• Keränen, E-mail: jk@mm.unknown

The paper presents preliminary results of paleobotanical studies on vegetation in Åland, south-west Finland. The investigations concentrated on studying arrival of tree species and stratigraphy of peatlands. According to the studies, some plant fossils found in the peat (Ceratophyllum submersum, Sparagnium neglectum, Najas flexilis) indicate that climate of the region has earlier been warmer than at the present. The present forests in Åland are dominated by coniferous species, but the pollen analysis of the peat indicate that Norway spruce (Picea abies (L.) H. Karst.) became a common species in the region about by the time of Christ’s birth. The species has reached its present distribution in Åland relatively late. The pollen analyses give relatively little information about the arrival of birch (Betula sp.) and Scots pine (Pinus sylvestris L.), but it seems obvious that occurrence of birch reached its culmination just before spruce. During the warm period common alder (Alnus glutinosa (L.) Gaertn.) was the most important species, and also pollen of oak (Quercus robur L.), kinden (Tilia cordata L.) and elm (Ulmus sp.) was relatively common in the peat of some of the studied peatlands. An interesting finding was the pollen of Carpinus betulus in many sites in Åland.

The PDF includes a Finnish and German summary.

• Backman, E-mail: ab@mm.unknown

Pollen analysis has given information on development of the tree species composition after the ice age, but this kind of studies have not been published in Finland. In this study, pollen analysis was performed in five peatlands in the southwest Finland. According to the analysis, the forests of the area have had similar tree species composition for many thousands of years. Scots pine (Pinus sylvestris L.) has been the dominant species as long as there has been Norway spruce (Picea abies (L.) H. Karst.) in the area. Norway spruce seems to have arrived about 4,500 years ago. It increased slowly in the beginning, and after reaching a maximum has been slowly decreasing. Before spruce arrived, Betula sp. was more abundant, and seemed to be the dominant tree species in some places. Traces of fire in the peat layers indicate that forest fires have been common before people arrived in the area, and may have beneficial to birch. Like Betula sp., also Alnus sp. were more common before spruce arrived. Also pollen of other broadleaved species, for example, Tilia sp., Ulmus sp. and Corylus could be found. However, Quercus pollen was not found. The paludification of the peatlands had begun at different times which indicates that there has not been a common cause for the development of the peatlands in the area.

The PDF includes a summary in German.

• Lukkala, E-mail: ol@mm.unknown

Forest site type classification based on the vegetation has not been developed in India. The classifications made by forest officers have been based on the upper storeys of trees. Shrubs have been used to class such sites where grasses are the dominant species. However, some observers in India have used grass and bamboo species to identify sites suitable on unsuitable for certain valuable tree species. In Burma, some bamboo species have been noticed to be good indicators for sites suitable or unsuitable for teak (Tectona grandis L. f.). Studies in the western sub-Himalayan area suggest that certain grasses could be used as indicators for sites suitable for sal (Shorea robusta Gaertn.). Grasses have also been identified as indicators for certain kinds of forests and soils in the area between Ganges and the Jumna.

The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.

• Osmaston, E-mail: ao@mm.unknown

The vegetation in the Pacific coasts of British Columbia and Southeastern Alaska resemble the vegetation in the northern Fennoscandia. The national forests have been divided in two parts: Tongass and Chugach national forests. Both of the forests are fairly uniform in their vegetation. The forests have few coniferous tree species as the dominant species from south to north, Sitka spruce (Picea sitchensis (Bong.) Carrière) and western hemloch (Tsuga heterophylla (Raf.) Sarg.). It is difficult to distinguish forest site types, but it is probable that the forest lands in Alaska and British Columbia could be delimited to similar forest site types as professor Cajander established in Finland.

The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.

• Harshberger, E-mail: jh@mm.unknown

­In different altitudes of the Mount Fuji in Japan occur succession of different tree species. For instance, at an altitude of 2,000 meters are pure stands of Tsuga diversifolia (Maxim.), under which is generally found young trees of Abies veitchii (Lindl.), but not of Tsuga. Abies veitchii is in its turn replaced perhaps with Larix sp. The succession of the forests of the volcano have reached maturity, which is not the case in the east–north-east flank of the mountain, where the Hōei eruption destroyed all vegetation in 1707. The vegetation had not revived even by the 1920s. The Hōei eruption site is compared to the much faster return of vegetation in mount Krakatau in the warmer tropical region. The succession of forests in the other parts of the mountain is described in detail. Finally, a succession theory is proposed that is opposed to the natural selection theory. The theory suggests that there is an Innermost Factor that controls the plant succession. According to the theory, every species, every formation, should die its natural death owing to the Innermost Factor.

The volume 34 of Acta Forestalia Fennica is a jubileum publication of professor Aimo Kaarlo Cajander.

• Hayata, E-mail: bh@mm.unknown

The article gives examples of hybridization of forest tree and shrub species in the forests of New Zealand. According to the article, many of the 498 vascular plant species in the forest communities of the New Zealand region must be excluded from the standpoint of hybridism, because they belong either to genera of one species or are unable to cross owing to geographical or biological isolation. The hybrids are in most cases jordanons which cross, and may be more or less distantly related or closely related. The hybrids occur usually in polymorphic groups. Most of the hybrids in New Zealand are fertile. The hybrids can affect the forest communities in two ways; by effecting their composition or their structure. The article includes a list of hybrid groups.

Jubileum publication of professor Aimo Kaarlo Cajander.

• Cockayne, E-mail: lc@mm.unknown

The article describes experiences in exotic tree and shrub species in Mustila arboretum in 1901-1921, situated in Southern Finland. Mustila is the first arboretum of the country, established in 1901. The tree species have mostly been planted as small stands or groups of trees. The objective has been to find species that suit the Finnish climate. The article describes experiences of cultivation trials of coniferous tree species from the genus of Taxus, Tsuga, Pseudotsuga, Abies, Picea, Larix, Pinus, Thyopsis, Thuya, Chamaecyparis and Juniperus, in total 100 different species. The climate of Finland ranges from maritime to semi-maritime and semi-continental, becoming more continental towards the eastern parts of the country. According to the experiments, in Mustila area most promising are the Western American species from regions that are suitable distance from the Pacific Ocean. The exact origin of the seeds in the America is important for the survival of the species in Finland.

The PDF includes a summary in English.

• Tigerstedt, E-mail: at@mm.unknown

The distribution and occurrence of plant species, including trees, in the nature show that living and splendor of them is constrained by climatic factors. They have their minimum, optimum and maximum for the temperatures they can survive in. The tree species, at least mostly are divided into different varieties in different areas of the world so that the species are most suitable for the climatic conditions of their site.

The article presents the main climatic zones with their tree species according L. Ilvessalo and they suitability to Finland. More accurate areas of suitable species are also listed. 

The referred results show that alongside the climatic conditions, the conditions of soil and relief must be taken into account when using exotic tree species for forestry purposes.  

• Cajander, E-mail: ac@mm.unknown

The most abundant tree species occur in different variants in different geographical regions. They differ in their genetic, biological and partly also in morphological characters, however making clear difference between these subspecies is not possible. The different subspecies have developed according the respective areas' climatic and soil conditions, developing adaptive characters. These subspecies play a great role in practical forest management, since they differ in for forestry important characters, such as cold tolerance or stem form. 

The subspecies hybridize with each other in areas where their distribution areas overlap. In these areas the subspecies cannot be always clearly defined.   

• Cajander, E-mail: ac@mm.unknown

The article includes a dendrological review on the effect of climate to the success of cultivation of exotic tree species, based on literature and analysis of the existing Finnish field tests. The cultivation of an exotic tree species succeeds only if the seed has been procured from an area, which climate is similar to the place of cultivation. Climate is even more important than site quality.

Finnish climate is boreal and continental, and thus tree species of similar climate suit here best. In favorable site conditions it is possible to grow also species from boreal marine, and temperate climates. Finnish summers are not warm enough for species from temperate continental climate to get prepared for the winter, and the shoots can get frost damages. This may be compensated with a warm and sheltered site. If the species tolerates shading, it can be planted under sheltering trees. For species from maritime boreal climate, the Finnish summer tends to be too short, and the winters too cold. A suitable site is rich, warm and sheltered, and has preferably a protective sparse tree cover. Species from southern maritime climate cannot be grown in Finland. The provenance of the seeds is also very important. An important source of seeds are the successful plantations in Finland.

The PDF includes a summary in German.

• Ilvessalo, E-mail: li@mm.unknown

A strip survey was made to define the forest and peatland site class distribution and the condition of the forests in Savo and Karelia in central and eastern parts of Finland. According to the survey, 24% of the forested lands are peatlands. Fresh mineral soil sites (26%) were the most common mineral soil site type. Intermediately dry forest soil sites covered 22% of the area, forest sites with grass-herb vegetation 12,79%, rich grass-herb forest soil sites 3,16% and dry forest soil sites 9,59% of the forested area. The most common tree species were Scots pine (Pinus sylvestris L.), 39%, Betula sp., 26%, Norway spruce (Picea abies (L.) H. Karst.), 18%, and grey alder (Alnus incana (L.) Moench), 10% of the forest land. The article includes a review about the wood harvesting in the forests, and their present silvicultural state. According to the study, about 30% of the forested lands (not including peatlands) were unproductive; mostly mixed alder and birch stands of poor quality or open lands.

The PDF includes a summary in German.

• Multamäki, E-mail: sm@mm.unknown

The article is a review on shifting cultivation, its methods and use in Finland, and its effect on the condition of forests. Shifting cultivation decreases forest reserves not only by burning large amounts of wood. Of the area used for shifting cultivation, 10-50% can be open land. The older age classes of forests are often missing, and range of tree species shift towards deciduous trees. This causes lack of large timber. The shorter the rotation, the less well the most valuable trees survive on the area. One reason is lack of seed trees. Of the coniferous trees, Scots pine (Pinus sylvestris L.) is able to survive in the burnt-over lands better than Norway spruce (Picea abies (L.) H. Karst.), because it can produce seeds at a relatively young age. Betula sp. and especially grey alder (Alnus incana (L.) Moench) regenerate well on burnt-over lands. Also the frequency of good seed years determine which tree species become the dominant species on a burnt-over site.

When shifting cultivation is abandoned, deciduous trees keep their advantage over coniferous trees, because the wood of coniferous trees is used more in the surrounding villages. Pine and spruce spread to the burnt-over areas from the poorer sites that often had remained unburned. In densely populated areas in some counties in Savo in eastern Finland, where shifting cultivation was practiced intensively, Norway spruce became rare. Dominant tree species in the burnt-over areas became birch and pine.

• Heikinheimo, E-mail: oh@mm.unknown

The effective heating values of the above and below ground biomass components of mature Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), downy birch (Betula pubescens Ehrh), silver birch (B. pendula Roth), grey alder (Alnus incana (L.) Moench), black alder (A. glutinosa (L.) Gaertn.) and aspen (Populus tremula L.) were studied. Each sample tree was divided into wood, bark and foliage components. Bomb calorimetry was used to determine the calorimetric heating values.

The species is a significant factor in the heating value of individual tree components. The heating value of the wood proper is highest in conifers. Broadleaved species have a higher heating value of bark than conifers. The species factor diminishes when the weighted heating value of crown, whole stems or stump-root-system are considered. The crown material has a higher heating value per unit weight in comparison with fuelwood from small-sized stems or whole trees. The additional advantages of coniferous crown material are that it is non-industrial biomass resource and is readily available. The variability of both the chemical composition and the heating value is small in any given tree component of any species. However, lignin, carbohydrate and extractive content were found to vary from one part of the tree to another and to correlate with the heating value

• Nurmi, E-mail: jn@mm.unknown

The environmental preferences of recreationists were studied at the forest stand level in this study. The hypothesis which has been drawn up on the basis of the literature has been studied by attempting to elucidate the environmental preferences of groups using two recreation areas owned by the City of Helsinki using interviews and questionnaires. The material consisted of 1,323 interviews supplemented by questionnaires.

The replies to the questionnaires showed that recreationists consider birch and Scots pine to be more beautiful than Norway spruce, and stands made up of several tree species to be more beautiful than stands of single tree species. They also consider mature stands to be more beautiful than young stands.

During the interviews, the attention of the recreationists was directed at the view formed by the interview stand. The scenic preferences for the stands were measured using adjectives which the interviewee was asked to use in describing his or her impression of the view which was pointed out. First of all, the results clearly indicated that from the point of view of the scenic value of the stand, the way in which the stand is organised to form a scenic aspect or a stand view is more important than its ecological structure. However, it is obvious that stands containing large sized trees in particular are in many ways more preferred than stands which are younger in their development stage. This should therefore be the case when changes in the stand view resulting from management measures are insignificant or difficult to see. The main tree species in the stand does not seem to have from the point of view of scenic preference as much significance as would have been expected judging by the questionnaire material.

The PDF includes a summary in Finnish.

• Kellomäki, E-mail: sk@mm.unknown

The purpose of this study was that of providing a long-term timber production model (Kilkki and Pökkälä 1975) with growing stock models. The paper is divided into two parts; the first is concerned with generation of the stand data through Monte-Carlo simulation. The growing stock of each stand was described by a DBH-height distribution. The necessary information on the relationships between the stand characteristics was derived from sample plots measured in the national forest inventory of Finland. A total of 1,500 Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst), and birch (Betula sp.) stands, each comprising 100 trees were provided by simulation.

In the second part, models predicting the form factor, timber assortment distribution, and value of the growing stock were derived through regression analysis for each species of tree. The predicting variables included the form factor of the basal area median tree, basal area median diameter, and height in the form factor models. In the timber assortment and value models, the only predicting variable was the volume of the basal area median tree. The Matchcurve-technique (Jensen 1973) was employed in derivation of the regression models.

The PDF includes a summary in English.

• Kilkki, E-mail: pk@mm.unknown
• Siitonen, E-mail: ms@mm.unknown

Norway’s most common tree species, Picea abies (L.) Karst. (Norway spruce), is often infected with Heterobasidion parviporum Niemelä & Korhonen and Heterobasidion annosum (Fr.) Bref.. Because Pinus sylvestris L. (Scots pine) is less susceptible to rot, it is worth considering if converting rot-infested spruce stands to pine improves economic performance. We examined the economically optimal choice between planting Norway spruce and Scots pine for previously spruce-dominated clear-cut sites of different site indexes with initial rot levels varying from 0% to 100% of stumps on the site. While it is optimal to continue to plant Norway spruce in regions with low rot levels, shifting to Scots pine pays off when rot levels get higher. The threshold rot level for changing from Norway spruce to Scots pine increases with the site index. We present a case study demonstrating a practical method (“Precision forestry”) for determining the tree species in a stand at the pixel level when the stand is heterogeneous both in site indexes and rot levels. This method is consistent with the concept of Precision forestry, which aims to plan and execute site-specific forest management activities to improve the quality of wood products while minimising waste, increasing profits, and maintaining environmental quality. The material for the study includes data on rot levels and site indexes in 71 clear-cut stands. Compared to planting the entire stand with a single species, pixel-level optimised species selection increases the net present value in almost every stand, with average increase of approximately 6%.

• Aza, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, PO Box 5003, NO-1432, Ås, Norway https://orcid.org/0000-0002-6416-6697 E-mail: anfe@nmbu.no
• Kallio, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, PO Box 5003, NO-1432, Ås, Norway E-mail: maarit.kallio@nmbu.no
• Pukkala, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: timo.pukkala@uef.fi
• Hietala, Norwegian Institute of Bioeconomy Research, PO Box 115, NO-1431 Ås, Norway E-mail: ari.hietala@nibio.no
• Gobakken, Norwegian University of Life Sciences, Department of Ecology and Natural Resource Management, PO Box 5003, NO-1432, Ås, Norway E-mail: terje.gobakken@nmbu.no
• Astrup, Norwegian Institute of Bioeconomy Research, PO Box 115, NO-1431 Ås, Norway E-mail: rasmus.astrup@nibio.no

Current remote sensing methods can provide detailed tree species classification in boreal forests. However, classification studies have so far focused on the dominant tree species, with few studies on less frequent but ecologically important species. We aimed to separate European aspen (Populus tremula L.), a biodiversity-supporting tree species, from the more common species in European boreal forests (Pinus sylvestris L., Picea abies [L.] Karst., Betula spp.). Using multispectral drone images collected on five dates throughout one thermal growing season (May–September), we tested the optimal season for the acquisition of mono-temporal data. These images were collected from a mature, unmanaged forest. After conversion into photogrammetric point clouds, we segmented crowns manually and automatically and classified the species by linear discriminant analysis. The highest overall classification accuracy (95%) for the four species as well as the highest classification accuracy for aspen specifically (user’s accuracy of 97% and a producer’s accuracy of 96%) were obtained at the beginning of the thermal growing season (13 May) by manual segmentation. On 13 May, aspen had no leaves yet, unlike birches. In contrast, the lowest classification accuracy was achieved on 27 September during the autumn senescence period. This is potentially caused by high intraspecific variation in aspen autumn coloration but may also be related to our date of acquisition. Our findings indicate that multispectral drone images collected in spring can be used to locate and classify less frequent tree species highly accurately. The temporal variation in leaf and canopy appearance can alter the detection accuracy considerably.

• Hardenbol, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland https://orcid.org/0000-0002-0615-505X E-mail: alwin.hardenbol@uef.fi
• Kuzmin, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland; University of Eastern Finland, Department of Geographical and Historical Studies, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: anton.kuzmin@uef.fi
• Korhonen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: lauri.korhonen@uef.fi
• Korpelainen, University of Eastern Finland, Department of Geographical and Historical Studies, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: pasi.korpelainen@uef.fi
• Kumpula, University of Eastern Finland, Department of Geographical and Historical Studies, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: timo.kumpula@uef.fi
• Maltamo, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: matti.maltamo@uef.fi
• Kouki, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: jari.kouki@uef.fi

The main aim of the current study was to estimate the annual net nitrogen mineralization (NNM) flux in stands of different tree species growing on drained peatlands, as well as to clarify the effect of tree species, soil properties and litter on annual NNM dynamics. Three study sites were set up in May 2014: a downy birch (Betula pubescens Ehrh.) stand and a Norway spruce (Picea abies (L.) Karst.) stand in Oxalis full-drained swamp (ODS) and a Scots pine (Pinus sylvestris L.) stand in Myrtillus full-drained swamp (MDS). The NNM flux was estimated using the in situ method with incubated polyethylene bags. The highest value of NNM was found in stands that were growing on fertile ODS: 127.5 kg N ha^–1 yr^–1 and 87.7 kg N ha^–1 yr^–1, in the downy birch stand and in the Norway spruce stand, respectively. A significantly lower annual NNM flux (11.8 kg N ha^–1 yr^–1) occurred in the Scots pine stand growing in MDS. Nitrification was highest at fertile ODS sites and ammonification was the highest at the low fertility MDS site. For all study sites, positive correlation was found between soil temperature and NNM intensity. The difference in annual NNM between the downy birch stand and the Norway spruce stand growing on similar drained fertile peatlands was due to litter quality. The annual N input into the soil through leaf litter was the highest at the downy birch site where also the C/N ratio of litter was the lowest. The second highest N input into the soil was found in the spruce stand and the lowest in the pine stand.

• Becker, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia E-mail: hardo.becker@emu.ee
• Aosaar, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia E-mail: jyrgen.aosaar@emu.ee
• Varik, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia E-mail: mats.varik@emu.ee
• Morozov, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia E-mail: gunnar.morozov@emu.ee
• Aun, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia E-mail: kristiina.aun@emu.ee
• Mander, Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, Ülikooli 18, 50090 Tartu, Estonia E-mail: ulo.mander@ut.ee
• Soosaar, Department of Geography, Institute of Ecology & Earth Sciences, University of Tartu, Ülikooli 18, 50090 Tartu, Estonia E-mail: kaido.soosaar@ut.ee
• Uri, Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Friedrich Reinhold Kreutzwaldi 1, 51014 Tartu, Estonia E-mail: veiko.uri@emu.ee

The occurrence of moose damage was studied using data from three National Forest Inventories (NFIs) accomplished between 1986 and 2008 in Finland. The combined data included a total of 97 390 young stands. The proportion of moose damage increased from 3.6% to 8.6% between the 8th NFI (1986–1994) and the 10th NFI (2004–2008). The majority (75%) of the damage occurred in Scots pine-dominated stands. The proportion of damage was higher in aspen-dominated stands than in stands dominated by any other tree species. The tree species mixture also had a clear effect on the occurrence of damage. Pure Scots pine stands had less damage than mixed Scots pine stands, and moose damage decreased linearly with the increasing proportion of Scots pine. Stands on mineral soil had more frequent moose damage than stands on peatlands. The fertility class of the site had no straightforward effect on the damage frequency. Artificially regenerated stands had more damage than naturally regenerated stands. Accomplished soil preparation measures and the need for thinning or clearing operations increased moose damage. High proportions of moose damage in young stands were found around the country. In the 10th NFI, the largest concentration of damage was found in southwestern Finland. Our study shows the temporal and spatial changes in the occurrence of moose damage and pinpoints some important silvicultural factors affecting the relative risk of young stands over a large geographical area.

• Nevalainen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: seppo.nevalainen@luke.fi
• Matala, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: juho.matala@luke.fi
• Korhonen, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: kari.t.korhonen@luke.fi
• Ihalainen, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: antti.ihalainen@luke.fi
• Nikula, Natural Resources Institute Finland (Luke), Economics and society, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: ari.nikula@luke.fi

• Omoro, Viikki Tropical Resources Institute, Department of Forest Sciences, P.O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland E-mail: loice.omoro@helsinki.fi
• Starr, Department of Forest Sciences, P. O. Box 27 (Latokartanonkaari 7), FI-00014 University of Helsinki, Finland E-mail: mike.starr@helsinki.fi
• Pellikka, Department of Geosciences and Geography, P. O. Box 64 (Gustaf Hällströminkatu 2), FI-00014 University of Helsinki, Finland E-mail: petri.pellikka@helsinki.fi

• Stendahl, Department of Soil and Environment, P.O. Box 7001, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden E-mail: johan.stendahl@mark.slu.se
• Johansson, Department of Soil and Environment, P.O. Box 7001, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden E-mail: mbj@nn.se
• Eriksson, Department of Energy and Technology, P.O. Box 7061, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden E-mail: ee@nn.se
• Nilsson, Department of Soil and Environment, P.O. Box 7001, Swedish University of Agricultural Sciences, SE-75007 Uppsala, Sweden E-mail: an@nn.se
• Langvall, Unit for Field-based Forest Research, Asa Experimental Forest and Research Station, Swedish University of Agricultural Sciences, SE-36030 Lammhult, Sweden E-mail: ol@nn.se

• Islam, University of Joensuu, Faculty of Forest Sciences, FI-80101 Joensuu, Finland E-mail: nurul.islam@joensuu.fi
• Kurttila, Finnish Forest Research Institute, Joensuu Research Unit, FI-80101 Joensuu, Finland E-mail: mk@nn.fi
• Mehtätalo, University of Helsinki, Dept. of Forest Resource Management, FI-00014 University of Helsinki, Finland E-mail: lm@nn.fi
• Haara, University of Joensuu, Faculty of Forest Sciences, FI-80101 Joensuu, Finland E-mail: ah@nn.fi

• Levula, University of Helsinki, Department of Forest Ecology, FIN-00014 University of Helsinki, Finland E-mail: janne.levula@helsinki.fi
• Ilvesniemi, University of Helsinki, Department of Forest Ecology, FIN-00014 University of Helsinki, Finland E-mail: hi@nn.fi
• Westman, University of Helsinki, Department of Forest Ecology, FIN-00014 University of Helsinki, Finland E-mail: cjw@nn.fi

• Sundström, Swedish University of Agricultural Sciences, Dept. of Silviculture, S-901 83 Umeå, Sweden E-mail: erik.sundstrom@ssko.slu.se

The Nordic and Baltic countries are in the frontline of replacing fossil fuel with renewables. An important question is how forest management of the productive parts of this region can support a sustainable development of our societies in reaching low or carbon neutral conditions by 2050. This may involve a 70% increased consumption of biomass and waste to meet the goals. The present review concludes that a 50–100% increase of forest growth at the stand scale, relative to today’s common level of forest productivity, is a realistic estimate within a stand rotation (~70 years). Change of tree species, including the use of non-native species, tree breeding, introduction of high-productive systems with the opportunity to use nurse crops, fertilization and afforestation are powerful elements in an implementation and utilization of the potential. The productive forests of the Nordic and Baltic countries cover in total 63 million hectares, which corresponds to an average 51% land cover. The annual growth is 287 million m³ and the annual average harvest is 189 million m³ (65% of the growth). A short-term increase of wood-based bioenergy by utilizing more of the growth is estimated to be between 236 and 416 TWh depending on legislative and operational restrictions. Balanced priorities of forest functions and management aims such as nature conservation, biodiversity, recreation, game management, ground water protection etc. all need consideration. We believe that these aims may be combined at the landscape level in ways that do not conflict with the goals of reaching higher forest productivity and biomass production.

• Rytter, The Forestry Research Institute of Sweden (Skogforsk), Ekebo 2250, SE-26890 Svalöv, Sweden E-mail: lars.rytter@skogforsk.se
• Ingerslev, Copenhagen University, Department of Geosciences and Natural Resource Management, Rolighedsvej 23, DK-1958, Frederiksberg C, Denmark E-mail: moi@ign.ku.dk
• Kilpeläinen, Finnish Environment Institute, Joensuu Office, P.O. Box 111, FI-80101 Joensuu, Finland; University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: antti.kilpelainen@ymparisto.fi
• Torssonen, University of Eastern Finland, Faculty of Science and Forestry, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: Piritta.Torssonen@uef.fi
• Lazdina, Latvian State Forest Research Institute “Silava”, 111 Riga str, Salaspils, LV 2169 Latvia E-mail: Dagnija.Lazdina@silava.lv
• Löf, Swedish University of Agricultural Sciences, Southern Swedish Forest Research Centre, Box 49 SE-230 53 Alnarp, Sweden E-mail: magnus.lof@slu.se
• Madsen, Copenhagen University, Department of Geosciences and Natural Resource Management, Rolighedsvej 23, DK-1958, Frederiksberg C, Denmark E-mail: pam@ign.ku.dk
• Muiste, Estonian University of Life Sciences, Institute of Forestry and Rural Engineering, Dept. Forest Industry, Kreutzwaldi 5, Tartu 51014, Estonia E-mail: Peeter.Muiste@emu.ee
• Stener, The Forestry Research Institute of Sweden (Skogforsk), Ekebo 2250, SE-26890 Svalöv, Sweden E-mail: Lars-Goran.Stener@skogforsk.se

• Päätalo, Faculty of Forestry, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland E-mail: mlp@nn.fi

Use of fast-growing tree plantations on dedicated areas is proposed as a means of reconciling fibre production with conservation objectives. Success of this approach however requires fine-tuning silvicultural scenarios so that survival and growth are optimized while management and environmental costs are minimized. This is particularly challenging for hybrid larch (Larix × marschlinsii Coaz), a shade-intolerant species planted on fertile sites in Quebec (Canada) where legislation prevents the use of chemical herbicides. In this context, multiple motor-manual release treatments are often required, with high impacts on costs and social issues related to the scarcity of a qualified workforce. We established a split-split-plot design on a recently harvested site to assess the main and interaction effects of mechanical site preparation (MSP) intensity (five modalities of trenching or mounding), motor-manual release scenario (one or two treatments) and planting depth (0–3 cm or 3–10 cm) on hybrid larch seedling growth and survival six years after planting. Mechanical site preparation intensity and planting depth did not influence seedling growth after 6 years. The lack of significant interaction between MSP and release scenarios indicates that these operations should be planned independently. A more intensive MSP treatment cannot replace a second motor-manual release on fertile sites, as proposed to reduce costs. Our results also show the significant advantage of performing two motor-manual release treatments two years apart (the first one early in the scenario), over performing a single treatment. Our study provides silvicultural guidelines for the establishment of high-yield exotic larch plantations.

• Thiffault, Direction de la recherche forestière, Ministère des Forêts, de la Faune et des Parcs du Québec, 2700 rue Einstein, Québec, QC, Canada G1P 3W8; Centre d’étude de la forêt, CP 8888, Succursale Centre-ville, Montréal, QC, Canada H3C 3P8 http://orcid.org/0000-0003-2017-6890 E-mail: nelson.thiffault@mffp.gouv.qc.ca
• Paquette, Centre d’étude de la forêt, CP 8888, Succursale Centre-ville, Montréal, QC, Canada H3C 3P8; Université du Québec à Montréal, Département des sciences biologiques, CP 8888, Succursale Centre-ville, Montréal, QC, Canada H3C 3P8 http://orcid.org/0000-0003-1048-9674 E-mail: alain.paquette@gmail.com
• Messier, Centre d’étude de la forêt, CP 8888, Succursale Centre-ville, Montréal, QC, Canada H3C 3P8; Université du Québec à Montréal, Département des sciences biologiques, CP 8888, Succursale Centre-ville, Montréal, QC, Canada H3C 3P8; Institut des Sciences de la Forêt tempérée (ISFORT), 58 rue Principale, Ripon, QC, Canada JOV 1V0 E-mail nelson.thiff E-mail: christian.messier@uqo.ca