Articles containing the keyword 'Betula pendula'

The prescribed burning of a 7.3 ha clear-cut and a 1.7 ha partially cut forest (volume 150 m³/ha) was carried out in Evo (61 °12'N, 25°07'E) on 1 June 1992. The forest was a mesic Myrtillus site type forest dominated by Norway spruce (Picea abies (L.) H. Karst.). Practically all the trees and the above-ground parts of the understorey vegetation died in the fire, while the mor layer was thinned by an average of 1.5 cm.

A study was made on the change of germinated seedling population in time and their dependence on environmental factors. Seedlings of Norway spruce, Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth), pubescent birch (B. pubescens Ehrh.) and rowan (Sorbus aucuparia L.) were inventoried in 1993 and in 1994 on permanent plots, four times per growing season. Autoregression models were used to compare regeneration of tree species in the burned forest with regeneration in the burnt clear-cut area, and to study the effect of distance from nearest seed source to regeneration.

The average number of seedlings germinating in 1993 was higher than in 1994, probably because of differences between these consecutive years in regard to the amount of seed rain and weather conditions. The number of Norway spruce and rowan seedling was higher inside the forest area than in the clear-cut area. The distance to the bordering forest and to the closest seed tree did not explain the result. It is suggested that the more stable microclimatic conditions under the shade of dead tree promote germination and seedling establishment in the forest area. As rowan is a bird-dispersed species, it is likely that dead trees help the dispersal of rowan seed by providing birds place to sit and defecate. The shade provided by dead trees may influence the further succession of the tree stand and vegetation composition and diversity.

• Vanha-Majamaa, E-mail: iv@mm.unknown
• Suominen, E-mail: rs@mm.unknown
• Tonteri, E-mail: tt@mm.unknown
• Tuittila, E-mail: et@mm.unknown

The biomass production and nutrient uptake of silver birch (Betula pendula Roth), downy birch (Betula pubescens Erhr.), grey alder (Alnus incana (L.) Moench), native willows Salix triandra L. and S. phylicifolia L. and exotic willows S. x dasyclados and S. ’Aquatica’ growing on a clay mineral soil field (Sukeva) and on two cut-away peatland areas (Piipsanneva, Valkeasuo) were investigated.

Biomass production of downy birch was greater than that of silver birch, and the biomass production of the native willows greater than that of the exotic ones. The performance of S. phylicifolia was the best of the studied willow species. Exotic willows were susceptible to frost damage and their winter hardiness was poor. The production of all species was lower on the clay mineral soil field than on the cut-away peatland areas. Fertilization of birches and alder – on the double dose given to the willows – increased biomass production. After 6 growing seasons the leafless biomass production of fertilized silver birch at Piipsanneca was 21 t ha^-1 (at Valkeasuo 34 t ha^-1) and of grey alder 24 t ha^-1, and that of S. triandra after five growing seasons 31 t ha^-1, S. phylicifolia 38 t ha^-1 and of S. x dasyclados 16 t ha^-1.

6-year-old stands of silver birch bound more nutrients per unit biomass than downy birch stands. Grey alder bound more N, Ca and Co but less Mn and Zn per unit biomass than silver and downy birch. On the field more P was bound in grey alder per unit biomass compared to downy birch. The willows had more K per unit biomass than the other tree species, and the exotic willow species more N than the native ones. Less N, K and Mg were bound per unit biomass of S. phylicifolia compared to the other tree species.

• Hytönen, E-mail: jh@mm.unknown
• Rossi, E-mail: pr@mm.unknown
• Saarsalmi, E-mail: as@mm.unknown

Growth, crown structure, flowering and seed production of silver birch (Betula pendula Roth) seedlings, grafts and micropropagated plants was compared during four years in a polythene greenhouse experiment. The growth of the seedlings was clearly the most vigorous and that of the grafts the weakest, the micropropagated plants being intermediate. The seedlings had the highest and the grafts the lowest number of branches before cutting the tops of the plants, but the differences between the material types were no more significant after cutting the tops. The grafts had significantly shorter and thinner branches than the seedlings and the micropropagated plants, whereas the differences in branch length and branch thickness between the latter two groups were not significant. The grafts started flowering at the age of two years, one year earlier than the other two types of material. At the age of four years the micropropagated plants had abundant seed production, about 75% of that of the seedlings and about two times higher than that of the grafts. Thus, the micropropagated plants can be used instead of grafts when establishing polythene greenhouse seed orchards of birch.

• Ryynänen, E-mail: lr@mm.unknown
• Viherä-Aarnio, E-mail: av@mm.unknown

Micropropagated and seed-borne plants of sliver birch (Betula pendula Roth) were compared for survival and growth in a field trial at the age of six years. Three clones for micropropagation were selected from open-pollinated progenies of selected southern Finnish plus trees at the age of 17 and 20. The three seed-borne lots were of southern Finnish stand origin. The best two lots of the experiment as regards the height and diameter growth at the age of six were the clones. The best of these differed significantly from the best-growing seed-grown lot. The weakest lot of the experiment was also a clone which was clearly slow-growing with a dense and bushy crown. Survival of the material was high (mean = 94%), and there was no damage caused by voles and elks, for example. The results clearly show that the selection of material for clonal propagation should be done carefully. The clones should also be tested for performance in the field before propagation on a large scale.

• Viherä-Aarnio, E-mail: av@mm.unknown

Seed production of micropropagated plants, seedlings and grafts of Silver birch (Betula pendula Roth) in a polyethylene greenhouse experiment was followed for five years. The grafts started flowering and seed production at the age of two years, one year earlier than other two types of material. At the age of three the seed production of both micropropagated plants and seedlings was already more than two times higher than that of the grafts. Variation between the clones was high and plant type x clone interaction was significant. At the age of four, in 1993, seed production was high in all three types of material. Seed production of the micropropagated plants was two times higher than that of the grafts but about 75% of that of the seedlings. In 1994 seed production of all three plant types was very low, which shows large variation between different years. The early development of the plant material types suggests that micropropagated plants have higher seed production than grafts and could well be used instead of grafts in polythene greenhouse seed orchards.

• Viherä-Aarnio, E-mail: av@mm.unknown
• Ryynänen, E-mail: lr@mm.unknown

Budburst timing and the relationship to storage temperature and duration were investigated in four varieties (entries) of 1–2 metres tall silver birch (Betula pendula Roth) trees. A total of 2,160 shoots were sampled, and the material stores in darkness at 0, 3 or 6 °C from November 29, 1993. When the shoots were placed in storage, they had been through a period of 29 days with temperatures below 0°C (since October 15). By that time the autumn dormancy was assumed already broken, and the trees were expected to respond to increased temperature by bud development. On January 4, 1994, and on four subsequent dates, January 19, February 1, March 4 and March 17, shoots were taken out of storage and set in growth chambers at 9, 12 or 15°C. The time to budburst was recorded.

Duration of storage, storage temperatures and varieties were all highly significant for budburst. The interaction terms were of less statistical importance. Based on the contrast between the three different growth chamber environments, three different methods were used to calculate the threshold temperatures for each entry. In spite of the pre-selection of variable budburst performers, the threshold values, varying between 0°C to -2°C, could not be shown to be statistically different. According to the results, the time of budburst changes in accordance with both winter and spring temperatures, being extremely early after a mild winter and warm spring, given sufficient autumn chilling. The similarities in the threshold temperatures indicate that the ranking in earliness between varieties will most likely be the same from year to year without regard to climate change.

• Skuterud, E-mail: rs@mm.unknown
• Dietrichson, E-mail: jd@mm.unknown

Model computations on the management of Scots pine (Pinus sylvestris L.) at the seedling stage showed that a rising temperature due to the suggested climate change could increase the competition capacity of birch species (Betula pendula) more than Scots pine, whose growth could even decline during the course of a rise in temperature. A temperature rise could, thus, bring the time of removal of birches forward when aiming at Scots pine timber stands composed of these tree species. The increasing proportion of birches makes the removal of birches even more urgent and emphasizes the need for careful management of Scots pine stands under rising temperatures. The first thinning of Scots pine is generally brought forward; this is particularly the case when wide spacing is applied in planting. A furthrer rise in temperature magnifies the above patterns by reducing further the competitive capacity of Scots pine in relation to birches.
The PDF includes an abstract in Finnish.

• Kellomäki, E-mail: sk@mm.unknown
• Kolström, E-mail: mk@mm.unknown

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.

• Danell, E-mail: –

Effect of dolomite lime and wood ash (0, 0.5, 1, 2, 4, 8 and 16 kg m^-3) on the chemical composition of low humified Sphagnum peat was studied. Germination of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.) and silver birch (Betula pendula Roth) and the subsequent growth of these seedlings were investigated in a greenhouse experiment. Nutrient concentrations in shoots and roots of pine seedlings were also analysed. The pH of peat increased asymptotically from 3.8 to about 7.0 with increasing lime regimen and to about 8.0 with increasing ash regimen. Wood ash linearly increased electrical conductivity and P, K, and Ca concentrations of peat. Rate of germination, within 7 days, of pine and spruce was best at low pH (<5) while birch seeds had a slightly higher pH optimum (4–6). Germination capacity, within 21 days, was not affected by pH or application regimen of either lime or ash. Pine and spruce seedlings grew best with lime and ash doses of 0.5–2.0 kg m^-3, the pH of peat being 4–5. Lime and ash treatments did not affect the growth of birch seedlings, but wood ash increased nutrient concentration of pine seedlings.

The PDF includes an abstract in Finnish.

• Rikala, E-mail: rr@mm.unknown
• Jozefek, E-mail: hj@mm.unknown

Seven hundred one-year-old Betula pendula Roth seedlings were given different concentrations of potassium fertilizer. Over the study period seedlings were subjected to artificial growing and dormant phases. Frost resistance of the seedlings was assessed by artificial freezing tests and electrical impedance measurements on stem cuttings. In general, high concentrations of potassium fertilizer reflected a low tolerance to frost. Pre-freezing impedance readings decreased with increasing potassium fertilizer dosages. Results from pre-freezing impedance measurements were found to be in broad agreement with the hypothesis that high impedance readings indicate a frost hardy tissue whereas low readings imply the opposite.

The PDF includes an abstract in Finnish.

• Jozefek, E-mail: hj@mm.unknown

Two-year-old silver birch (Betula pendula Roth) seedlings were fertilized with three peat ash dosages (10, 50 and 150 metric t/ha) and planted at three densities (2,000, 10,000 and 25,000 seedlings/ha). The peat and mineral soil were mixed together by deep ploughing before peat ash application. The results indicate that the 10 t/ha of peat ash may be too low a dosage and 150 t/ha too high for the silver birch seedlings. The 50 t/ha ash dosage increased growth markedly, obviously due to an enhancement in soil and foliar P, Mg and Ca content, soil pH, microbial activity and mobilization of soil organic nitrogen. Both foliar and soil P were already enhanced with the 10 t/ha peat ash dosage. The K content of the peat ash was low, however, and it may be that fertilizer K should be applied later.

The PDF includes a summary in Finnish.

• Lumme, E-mail: il@mm.unknown

In the model the regeneration process is derived into three subprocesses: birth, growth and mortality of seedlings. The main emphasis is on the birth process where the following phases are simulated: seed crop, quality of seeds, maturity of seeds, predation of seeds and germination. The parameters are based on data published in Finland. Part of the parameters are obtained directly from the investigations and part is proposed by the author. The model can be calibrated by changing parameter values. The simulation is made with the help of random numbers which have the same means as the estimates and the same distributions as the residuals of the equations used in simulation. The time step of the model is one year. The number of emerged seedlings in one year is obtained by multiplying the seed crop with the probabilities that the seed passes different phases of the birth process. Because of stochasticity the regeneration period is simulated several times. From the results it is possible to evaluate the risk and succeeding probability of the regeneration. The main drawbacks of the simulation method are the lack of empirical parameters and the difficulty of testing. The model could be further developed by including spatiality into the model.

The PDF includes an abstract in Finnish.

• Pukkala, E-mail: tp@mm.unknown

The curly-grained trait of Betula pendula Roth is inheritable, but it is persumably not question of only one Mendelian gene since, for instance, there are a number of different types of curly-birch. The progeny obtained from controlled crossing between two curly-birch individuals do not all posses the curly-grained trait.

Plantlets were produced from adult curly-birch (Betula pendula var. carelica). Murashige and Skoog’s medium was used as the culture medium. Growth was initiated on a medium containing 1 mg/l BAP. Bud formation was induced using a medium containing 10 mg/l BAP and 0.2 mg/l NAA. Development of shoots was achieved on a medium containing ½ x Murashige and Skoog’s macrominerals and sucrose, 1/1 x Murashige and Skoog’s microminerals and vitamins, and 0.5 mg/l BAP and 0.5 mg/l IAA. The medium used for inducing root formation was the same as above, but without any growth regulators. The results indicate that adult deciduous trees can be best propagated through tissue culture when the least differentiated cells, i.e. the initial cells of the promeristem, are used as the startin material. The axillary buds provide easily available study material which can be prepared with little difficulty and are continuously renewed.

The PDF includes a summary in Finnish.

• Ryynänen, E-mail: lr@mm.unknown
• Ryynänen, E-mail: mr@mm.unknown

A model was developed in order to describe the peeling of veneer for determining value relationship for birch veneer logs and stems. The model was based on selling prices of veneer and other products as well as processing costs. The model was utilized for determining the effect of various input variables on the log value.

According to the results, the effect of tree size was important for the value of raw material. Even knottiness had an effect although only in the higher manufacturing costs of knotty veneer were taken into account. Pruning was a method to increase substantially the proportion of knotless veneer.

The PDF includes an abstract in English.

• Kärkkäinen, E-mail: mk@mm.unknown

The susceptibility of Betula pendula Roth and B. pubescens Ehrh. Saplings to stem spot disease caused by Godronia multispora J.W. Groves and Fusarium avenaceum (Fr.) Sacc. was studeied. B. pendula proved to be more susceptible than B. pubescens on all studied soils, especially on peat. G. multispora was more pathogenic than F. avenaceum. Inoculations with G. multispora in the spring and summer induced smaller cancers than in the autumn.

The PDF includes an abstract in Finnish.

• Romakkaniemi, E-mail: pr@mm.unknown

There are great impact forces in mechanized harvesting and wood yard in the mills which can cause breaks in timber. The impact strength of timber in green condition was tested in temperatures of +18°C and -18°C using sawn pieces (20 x 20 x 300 mm) of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), birch (Betula pendula Roth and B. pubescens Ehrh.), grey alder (Alnus incana L.) and aspen (Populus tremula L.). In addition, unbarked naturally round sticks (length 300 mm, diameter 15 and 35 mm) of the same species were tested.

The impact strength of round sticks was 1.5–4.4 times as great as that of sawn pieces. The reasons are possibly the avoidance of cell breaks at the surface as well as growth stresses. The frozen samples were clearly weaker than the unfrozen ones. As a rule, the impact bending strength increased with increased density of the species. However, the correlation varied greatly between species. If density was kept constant, an increase in the growth ring width decreased the impact strength. The reason may lie in the fracture mechanism.

The PDF includes a summary in English.

• Kärkkäinen, E-mail: mk@mm.unknown
• Pietilä, E-mail: jp@mm.unknown
• Vihola, E-mail: rv@mm.unknown

Early growth of four different tree species (Pinus sylvestris L., Picea abies (L.) H. Karst., Larix sibirica Ledeb and Betula pendula Roth) 16–23 years after planting were compared in a field experiment of 16 square plots established on a stony, grove-like upland (Oxalis-Myrtillus forest type) in Southern Finland. This study gives additional results to the publication Folia Forestalia 386/1979.

At this early stage, the growth of the spruce stand was clearly slower than that of the other species for all parameters to be measured (height, diameter, and volume growth). Height growth was most rapid in the silver birch stand and diameter growth in the larch stand. No clear differences were found in the mean volume of the 100 thickest trees in the stand between the larch and silver birch.

The PDF includes a summary in English.

• Parviainen, E-mail: jp@mm.unknown

The aim of this study was to examine the development of the cold acclimation of silver birch (Betula pendula Roth) seedlings. The effect of fertilization was also studied. The seedlings were two-year-old. As a comparison stump sprouts from the near-by forest were used. The seedlings were treated in temperatures of +5°C (= control), –5°C and –15°C four times with conductivity measurements and with ocular inspection.

There were no significant differences in cold acclimation between different fertilization treatments or between the fertilized seedlings and stump sprouts. This may have been due to the rapid cooling rate. The cold acclimation of the seedlings was registered well by the changes in the relative conductivity values. The differences between the relative conductivity values of different temperature treatments in August and the beginning of September were significant. However, in the end of September and especially October the values no longer differed significantly. Correlation proved good between the relative electrical conductivity tests and the ocular inspections of the damages.

The PDF includes a summary in English.

• Romakkaniemi-Niemelä, E-mail: pr@mm.unknown

Curly birch (Betula pendula var. carelica (Merklin) Hejtmanek) is widely distributed over north-western part or Russia, including the Baltic Soviet Republics and Belorussia. Experiences of growing this decorative species in Soviet Karelia and Leningrad region are presented. Commonly used classifications of the species are described, and recommendations for management of curly birch cultures and production of planting stock in greenhouses are given.

The PDF includes a summary in English.

• Jevdokimov, E-mail: aj@mm.unknown

The objective of the study was to compare different reforestation methods on ploughed areas in Finnish Lapland. Four species were compared: Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) H. Karst.), silver birch (Betula pendula Roth) and Siberian larch (Larix sibirica Ledeb.). The experiments were established in different parts of Lapland on different types of sites in 1970–72.

In Scots pine there was a difference of 15 percentage points in survival of seedlings between the best and worst methods of regeneration. Containerized seedlings and paper pot seedlings had the best survival rates. In Norway spruce the respective difference between sowing and planting was about 20 percentage points. In favour of planting. The survival rate can be increased by about 20 percentage points by selecting the right tree species. The average height varied from 25 cm (the sowed Norway spruce) to 179 cm (the planted silver birch) after 10 growing seasons. The birch was planted at the most fertile sites only. The longer time passed from the afforestation the clearer was the effect of the local growing conditions on the development of the seedlings. The elevation of the site was one factor seemed to influence the success of the seedlings.

The PDF includes a summary in English.

• Pohtila, E-mail: ep@mm.unknown
• Pohjola, E-mail: tp@mm.unknown

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.

• Eriksson, E-mail: je@mm.unknown
• Bergholm, E-mail: jb@mm.unknown
• Kvist, E-mail: kk@mm.unknown

The anatomical variation of a lateral root was compared with that of the stem of the same tree at breast height by concentrating on the intrelationships of certain anatomical features in Betula pendula and B. pubescens. The results showed that root wood has several essential features of stem wood, such as gelatinous fibres, growth eccentricity, scalariform perforation plates in the vessels and pith flecks. However, some of the anatomical differences are significant. The differences between the species were more pronounced in the root than in the stem anatomy.

The PDF includes a summary in Finnish.

• Bhat, E-mail: kb@mm.unknown
• Kärkkäinen, E-mail: mk@mm.unknown

Length variation of fibres and vessels was studied in the branches, stems and roots of Betula pendula Roth and B. pubescense Ehrh. The cells were significantly shorter in the branches and roots than in the stems. There was no significant difference in the cell length between the upper and lower radii of the branches and roots. The length increased from the pith to the surface and decreased in the branches and stems from the base onwards. In the roots the length increased in that direction. The differences between the tree species were small although the cells of B. pubescens were a little longer.

The PDF includes a summary in Finnish.

• Bhat, E-mail: kb@mm.unknown
• Kärkkäinen, E-mail: mk@mm.unknown

Variation of cellular proportion within the same growth rings counted from the pith of the stems and branches in four trees of Betula pendula Roth was studied. The fibre percentage decreased from breast height to the crown and then increased in the branches. The reverse trend was found in the percentage of vessels and parenchyma, although the latter varied relatively little. No statistically significant differences were found in the percentages of fibres, vessels and rays within the same growth rings counted from the pith between the stems and branches. In both the stem and the branches, the proportion of fibres increased and that of vessels and rays decreased from the pith to the surface. Even crown formed wood differed from that of stem formed. 

The PDF includes a summary in Finnish. 

• Bhat, E-mail: kb@mm.unknown
• Kärkkäinen, E-mail: mk@mm.unknown

Variation of wood characteristics was studied in two mature trees of Betula pendula Roth and two of B. pubescens Ehrh. by stressing the interrelationships of some of the structural features, basic density and shrinkage. Correlation analysis revealed that basic density was related to some of the variables studied, viz: number of rings (age) and distance from pith, height from the ground, ring width, fibre length and double wall thickness. Multiple regression equation showed that age from pith and height from the ground explained 80% of variation of basic density in B. pendula. Two structural variables, viz: fibre wall thickness and ring width accounted for only 28% of variation of basic density in B. pubescens. No significant relations could be found between shrinkage and any of the wood parameters measured in B. pendula while some of the relationships were significant in B. pubescens. However, only 55% of variation of volumetric shrinkage was explained by two related factors, viz: basic density and moisture content while only 35% of variation of tangential shrinkage was explained by ring width and fibre width. Increase in fibre length was highly associated with the increase in fibre width, double wall thickness and vessel length in either species.

The PDF includes a summary in Finnish.

• Bhat, E-mail: kb@mm.unknown

It was concluded on the basis of the anatomical investigations of four mature trees that Betula pendula Roth can be distinguished from B. pubescens Ehrh. using the number of bars per scalariform perforation plate as an identification factor. If the average number of bars is more than 17.6, the sample is probably from B. pubescens, and if less, from B. pendula. The accuracy can be slightly improved by using the vessel frequency as another factor.

The PDF includes a summary in Finnish.

• Bhat, E-mail: kb@mm.unknown
• Kärkkäinen, E-mail: mk@mm.unknown

Samples that had extensive pith flecks, caused by the larvae of Dendromyza betulae (now Phytobia betulae E.Kang), were collected from two trees of Betula pendula Roth and two B. pubescens Erhr. The age of the trees varied from 45 to 56 years. The effect of larvae injury on the rays was studied. The width of affected rays in both species was more than twice that of normal rays. The height and frequency also increased considerably. When describing the anatomy of Betula species the pith flecks should be treated with caution in order to avoid confusion and misinterpretation. 

The PDF includes a summary in Finnish. 

• Bhat, E-mail: kb@mm.unknown

The aim of the present study was to register the curly birch (Betula pendula f. carelica Sok.) plantations established in Lapland and to determine their location and present condition. The information was obtained by means of interviews and visual observations.

In Lapland, the growing of curly birch started in 1950’s and the early 1960’s. During this period, in the different supervisory areas of Lapland, the National Board of Forestry established curly birch stands totalling approximately 30 ha, including about 34,000 seedlings. The bulk of the plantations have been destroyed by animals. On the other hand, the curly birch experimental stands established by the Finnish Forest Research Institute have thrived. The private sector of Forest Management has been engaged in the production of seedlings on a large scale and, as a result of this, curly birch trees are frequently seen as ornamentals in Rovaniemi and in other localities in Lapland. When taken care of, curly birch thrives in Lapland and produces I-class curly wood.

The PDF includes a summary in English.

• Etholén, E-mail: ke@mm.unknown

The material used in this study was collected in 1975 from a 41-years old curly birch (Betula pendula f. carelica Sok.) stand in Southern Finland, which had been pruned 12 years earlier. While the stand was thinned, 26 felled trees were selected for further study to study occurrence of discoloration originating from of pruned branches.

The study material included 35 pruned branch stumps and 38 naturally pruned branch stumps of curly birch. The mean diameter of the former was 31 mm and of the latter, only 15 mm. Of the pruned branch stumps, 23% had become completely sealed-off within 12 years. The discoloration had spread into the stem as little from pruned branch stumps as from naturally pruned ones even though the former were greater in diameter. Advanced rot was not found in any of the samples studied.

The PDF includes a summary in English.

• Raulo, E-mail: jr@mm.unknown
• Saarnio, E-mail: rs@mm.unknown
• Ylitalo, E-mail: ty@mm.unknown

Carbohydrates of the sap of six curly and four silver birches (Betula pendula f. carelica Sok. and B. pendula Roth) were analysed by gas chromatography as trimethylsilyl derivates both from hydrolysed and unhydrolyzed samples. Sorbitol was identified from silver birch sap only. In each of the two groups there were glucose and fructose. No other carbohydrates were discovered. The hydrolysis had no influence on the results.

The PDF includes a summary in English.

• Pätiälä, E-mail: rp@mm.unknown
• Blomberg, E-mail: kb@mm.unknown
• Paakkanen, E-mail: jp@mm.unknown
• Piepponen, E-mail: sp@mm.unknown

Curly birch (Betula pendula f. carelica Sok.) is characterized by large variations in stem form and the internal structure of the wood, and is generally divided in to four types on the basis of visible external stem characteristics. First plantation experiments in Finland in the 1920’s in experimental areas of the Finnish Forest Institute, had become ripe for cutting and were felled. The study material of this study consists of one 52-year old and three 42–43 -year old stands of curly birch.

The yield suitable for plywood manufacture from the oldest stand was 34,777 kg/ha and that of curly grained branch wood 39,452 kg/ha. The corresponding figures of the other stands were, on average 24,219 and 57,271 kg/ha. The yield from the stands were sold at the present-day price. The result was economically better than from any other forest tree species grown in Finland. The younger stands were obviously cut too early. It was concluded that the genetic quality of the seedlings used in the plantations in the 1920’s and 1930’s was not very high.

The PDF includes a summary in English.

• Raulo, E-mail: jr@mm.unknown
• Sirén, E-mail: gs@mm.unknown

Curly birch, a curly grained variety of birch (Betula pendula f. carelica Sok.), has fetched a higher price than any other Finnish tree species on account of its rarity and decorativeness. Curly graininess has been found in Finland in addition to silver birch, also in Alnus glutinosa and Sorbus aucuparia.

The Curly Birch Society was founded in Finland in 1956. Its purpose is to promote the cultivation and use of curly birch, and to coordinate the activities of curly birch cultivators, forest industry and research. The society has made excursions and held informative meetings every year. Furthermore, the society has arranged exhibitions and participated in more extensive agricultural and forestry fairs.

The PDF includes a summary in English.

• Huuri, E-mail: oh@mm.unknown

During the 1970’s an average of 4 million Betula pendula (Roth) seedlings have been planted annually in Finland. The activities connected with the planting of this tree species, the selection of forestation sites, site preparation, planting out the seedlings and follow-up work on the forestation sites are briefly reviewed in the article. The manuscript is based on the studies into the breeding, seedling production and planting techniques of B. pendula started by the Finnish Forest Research Institute already in 1960’s, as well as on practical observations made at the planting sites. A list of some of the Finnish studies concerning B. pendula which have been published in English and studies with a summary in English is included.

The PDF includes a summary in Finnish.

• Raulo, E-mail: jr@mm.unknown

The study was carried out in order to find out the changes taking place in germination of seeds in certain tree species as a function of gamma irradiation, the height growth of the seedlings produced and the types of phenotypic mutants possibly found in the generation that had received radiation. The tree species studied were Pinus sylvestris L., Picea abies (L.) H. Karst., Betula verrucosa (Betula pendula Roth), B. Pubescens Ehrh., Alnus glutinosa (L.) Gaertn. and Alnus incana (L.) Moench.

Soaked seeds that had received a rather small dose of radiation germinated usually better than storage-dry seeds, B. pubescens being an exception. The damages observed in germination, height growth and the relative number of mutants were greater the higher the irradiation doses. The LD₅₀ dose (germination, 28 days) was as follows in the case of the different tree species (storage dry/soaked): P. Sylvestris 1,500-2,000/2500-3,000, P. abies 1,000-1,500/4,000-4,500, B. pendula 9,500-10,000/7,000-7,500, B. pubescens >10,000/7,500-8,000 and A. Glutinosa 10,000/8,500-9,000 rad. Mass production of different mutants of deciduous trees for ornamental purposes, for example, appears to be easy using gamma-irradiation. On the other hand, the possibility of increasing tree growth remains open for further study.

The PDF includes a summary in English.

• Lehtiniemi, E-mail: tl@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 the present study was to assess whether two-year old Betula verrucosa Ehrh. (now Betula pendula Roth.) transplants can be used in afforestation of drained peatlands and what factors affect the development of the young trees. The seedlings were planted in 1967. The site was repair planted next spring due to mortality caused by a undefined fungal disease, and the plantations were fertilized with NPK fertilizer (soil application. The seedlings were measured twice a year until the autumn 1970.

Only 28% of the original transplants, and 73.4% of the repair plantations were alive in 1970. In some cases, fertilization improved the results, while in others it was detrimental to the trees or had no effect on survival. According to peat analysis, the poor survival and development of the plants could be due to the too high ratios of N/Ca and N/P. Stunted or dead trees displayed often necrosis caused by Godronia multispora. According to the experiences, Betula verrucosa plantations are inferior to those obtained with Scots pine (Pinus sylvestris L.). In addition, the results indicate that in old draining areas calcium and phosphorus are often too low in comparison to nitrogen.

The PDF includes a summary in English.

• Lehtiniemi, E-mail: tl@mm.unknown
• Sarasto, E-mail: js@mm.unknown

The study is continuation of the earlier structure and growth studies of Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) H. Karst.) in Forest Research Institute. The material represents birch stands (Betula verrucosa, now B. pendula, and B. Pubescens L.) in Southern Finland. The stands were treated with different fellings, and in regard to their silvicultural condition classified as good, satisfactory and unsatisfactory. Height of the trees, height of living crown, volume, increment and volume increment and development of stem diameter series was measured.

The most characteristic difference between the silviculturally good and poor stands was that the the annual increment of the good stands concentrated into large size trees, and the increment of unsatisfactory stands into small and inferior trees.

It is concluded that if the aim of stand treatment is to produce large and high quality volume increment, the most favourable stand volume of  birch stands, compared with naturally normal stand volume, seems to be 90-85% at the age of 41-55 years, and 80-70% at the age of 56-65 years. If growth of large size trees is aimed at, the maximum number of the dominant trees per hectares cannot be more than 400 at the age of 50-60 years.

The article includes a summary in English.

• Kuusela, E-mail: kk@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

The objective of the present investigation was to clarify the profitability of pruning silver birch (Betula verrucosa, now Betula pendula Roth) in the growing of raw material for veneer industry. Calculations were made on the grade, value, and price of pruned and untreated butt logs as well as on costs of pruning and the development of pruned trees.

The grade distribution of unpruned veneer butt logs, the grade distribution of the veneer yield, and consequently, the value of veneer yield and log prices at the plant are considerably better than those of average logs. The grade, value and price increased with increasing diameter. The value and price of pruned butt logs depended primarily on the difference between the turning pruning diameters, and their increase with decreasing pruning diameter and increasing turning diameter. The value of pruned butt logs is always considerably higher than that of unpruned logs. The increase in the value correlates to the pruning and turning diameters, and is, for example, in rotary-cut logs which have been pruned when 10 cm in diameter 80–130%.

Pruning increases the stumpage in naturally regenerated silver birch stands on Oxalis-Myrtillus site by 2,000–3,000 Fmk/ha when employed at 20 years of stand age and rotary cutting at 60–80 years of age respectively. The average pruning costs on Oxalis-Myrtillus site are 51–57 Fmk/ha.

The PDF includes a summary English.

• Heiskanen, E-mail: vh@mm.unknown

Growth-promoting effects of enhanced caron dioxide levels upon forest tree seedlings grown in plastic houses was studied in 1964 and 1965 in the Forest Breeding Foundation in Haapastensyrjä near Loppi in Southern Finland. In both years more vigorous height and weight growth, and development of root system was achieved when the CO₂ concentration was increased to 0.2% than in the normal conditions (CO₂ 0.03%). The CO₂ concentration was increased by burning propane in the plastic houses. Burning continued for four hours per day either at 8–10 and 14–16 a clock or 6–10 a clock. Growth was not affected by the time of the treatment, and it was equally high in 0.1% and 0.2% concentrations.

Treatment of the seedlings with 100–200 ppm gibberellic acid (GA) increased the height growth of healthy, well-rooted seedlings. Treatment with a concentrated (600 ppm) dosage, as well as treatment with a combination of GA and 1-naphtyl acetic acid (NAA) caused serious defects in grafts of Scots pine (Pinus sylvestris L.). GA treatments did not induce flower formation in pine. Red light during the night seemed to enhance growth of grafts of silver birch (Betula pendula Roth) and Norway spruce (Picea abies (L.) H. Karst.).

The PDF includes a summary in Finnish.

• Hårdh, E-mail: jh@mm.unknown

The objective of this paper was to study the influence of defects of Betula pendula Roth and Betula pubescens Ehrh. on the quality, value and quantity of veneer cut produced by rotary cutting, to prepare grading rules for veneer birch and to determine the minimum quality for veneer birch, and to assess the quality and quantity of veneer yield in rotary cutting of bolts of different grades. Data for the study was collected in 1953-1963 from six plywood factories in Finland.

The effect of knot marks, knot bumps, dry and rotten knots, sound knots, sweep and crookedness, upright limbs, heart rot, open and overgrown scars and bark peeling defects in the bolt on the quality and yield of veneer is described. Recommendations for grading rules were defined on the basis of the result. The rules include three grades, for which certain defects are allowed. In the first grade are accepted bolts, which of the veneer yield included at least 30% of veneer of grades A and B when all jointing and end-clipped sheets were taken into account. In the second grade were accepted bolts, which of the main part of the veneer yield still is surface veneer on the basis of the wood quality. Of the third-grade bolts at least one third of the veneer yield ought to be surface veneer.

The PDF includes a summary in English.

• Heiskanen, E-mail: vh@mm.unknown

The objective of the investigation was to determine the differences between faultless timber grown on a peatland before and after draining, in respect of compressive strength to the grain, volume weight, and shrinkage. In addition, the influence of the boundary zone between the close-ringed wood formed before draining and the wide-ringed wood produced after draining on strength of the timber was studied. The material consisted of 15 sample trees of Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.), white birch (Betula pubescens Ehrh.) and silver birch (B. Pendula Roth).

The volume weight of wood of the tree species in ascending order is; spruce, pine, white birch, silver birch. The volume weight of Scots pine seems to decrease from the butt end upwards, while no trend was revealed for spruce. In the coniferous trees, the wide-ringed wood formed subsequent to draining was slightly lighter than the close-ringed wood produced prior draining. No distinct trend was seen in the birch species. The volume weight of pine and spruce increased with decreasing width of the growth rings up to a certain limit, after which the conditions inverted.

The compressive strength of the different kinds of wood seems to increase from the butt end upwards, but after height of two meters it begins to decrease considerably. In birch, this point of inversion is in somewhat greater height. In spruce timber, the compressive strength parallel to the grain is lowest for wood which contains exclusively wide-ringed wood formed after draining. The boundary zone between the woods formed before and after draining is very distinguishable, but has no remarkable influence on the compressive strength parallel to the grain. Shrinkage of close-ringed wood is higher in all three principal directions than that of wide-ringed wood. This can be explained by the variations in volume weight and fibrillar orientation of the tracheid walls.

The PDF includes a summary in English.

• Ollinmaa, E-mail: po@mm.unknown

The investigation concerns with the strength of the eccentric growth accompanying formation of tension wood in silver birch  (Betula pendula Roth.) and downy birch (Betula pubescens Ehrh.), behaviour of wood in wood-working machines and its macroscopic characteristics, its microscopic and sub-microscopic structure, chemical composition, resistance against certain chemicals, physical properties, and the strength characteristics of wood.

The most detrimental properties of tension wood used in wood working industry are high longitudinal shrinkage, warping, twisting and checking. The wooliness of the cut is unwanted, for instance, in plywood and furniture. In pulp industry tension wood is better raw material than normal wood because it yields more and purer cellulose than normal wood. However, it has poorer strength properties.

The PDF includes a summary in English.

• Ollinmaa, E-mail: po@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

In South-West Finland the usual method to make leaf fodder for cattle has been to cut the branches and collect the new sprouts again next year. According to this review, the most common tree species to be topped is Betula sp. Downy Birch (Betula pubescens Ehrh.) grows shoots easier than silver birch (B. pendula Roth). The topped forests are usually small and situated near the settlements, next to the fields and meadows. The birch trees are typically cut when they are 15-20 years old. Regularly topped birch rots easily and seldom exceeds 50 years. The capacity to grow shoots depends on the age of the tree, site and time of the cutting. The risk for rotting can be decreased by removing only part of the shoots and cutting the shoots a short distance from the base of the shoot. Collecting leaf fodder decreased in Finland, and was common only in the South-West Finland and Åland.

The PDF includes a summary in German.

• Lukkala, E-mail: ol@mm.unknown

Male flowering was studied at the canopy level in 10 silver birch (Betula pendula Roth) stands from 8 localities and 14 downy birch (B. pubescens Ehrh.) stands from 10 localities in Finland in 1963–73. Distribution of cumulative pollen catches was compared to the normal Gaussian distribution. The basis for timing of flowering was the 50% point of the anthesis-fitted normal distribution. To eliminate effects of background pollen, only the central, normally distributed part of the cumulative distribution was used. Development was measured and tested in calendar days, in degree days (> 5°C) and in period units. The count of the parameters began in March 19.

Male flowering in silver birch occurred from late April to late June depending on latitude, and flowering in downy birch took place from early May to early July. The heat sums needed for male flowering varied in downy birch stands latitudinally but there was practically no latitudinal variation in silver birch flowering. The amount of male flowering in stands of the both species were found to have a large annual variation but without any clear periodicity.

The between years pollen catch variation in stands of either birch species did not show any significant latitudinal correlation in contrast to Norway spruce stands. The period unit heat sum gave the most accurate forecast of the timing of flowering for 60% of the silver birch stands and for 78.6% of the downy birch stands. Silver birch seems to have a local inclination for a more fixed flowering date compared to downy birch, which could mean a considerable photoperiodic influence on flowering time of silver birch. The species had different geographical correlations.

Frequent hybridization of the birch species occurs more often in Northern Finland than in more southerly latitudes. The different timing in the flowering causes increasing scatter in flowering times in the north, especially in the case of downy birch. Thus, the change of simultaneous flowering of the species increases northwards due to a more variable climate and higher altitudinal variation. Compared with conifers, the reproduction cycles of the two birch species were found to be well protected from damage by frost.

• Luomajoki, E-mail: al@mm.unknown

Resistance to browsing by mammals differs among birch species, and among origins and families of European white birch (Betula pendula Roth). The variation in resistance is large even among individual seedlings of the same family.

On the surface of the bark of European white birch seedlings there are resin droplets, and the number of droplets is strongly and positively correlated with resistance to browsing by hares. The resistance of European white birch apparently is not expensive metabolically because the rapid growth rate of seedlings was positively correlated with hare resistance, and no correlation was found between seedling size and vole resistance. In cafeteria experiments voles and hares were very discriminating in their feeding on birch seedlings. In field experiments, however, environmental heterogeneity partly masked differences in vole resistance among birch families. Fertilization of seedlings seems not to have a clear effect on resistance to hares. On the other hand, there were indications that greenhouse temperature had an effect on resistance to voles. Practical forestry applications of differences in resistance, e.g. use of species hybrids and clonal forestry, are discussed. The prospects for resistance breeding are good.

The PDF includes a summary in Finnish.

• Rousi, E-mail: mr@mm.unknown

Water extracts of six common soil lichens, Cladonia alpestris, C. rangiferina, C. arbuscula (sylvatica), C. pleurota, Cetraria islandica, Stereocaulon paschale, inhibited growth of ectomycorrhizae of Pinus sylvestris (L.). Of 17 fungi (12 mycorrhizal) tested, many were inhibited while others were scarcely influenced or even occasionally stimulated by the extracts. Cladonia alpestris extract inhibited most fungi while C. rangiferina showed much less influence.

In pure culture synthesis experiments, 32P uptake of Pinus sylvestris was significantly reduced by C. alpestris extract. Different species of fungi showed widely variant abilities to pick up 32 P. in nursery experiments, much more vigorous growth of P. sylvestris and Picea abies (L.) H. Karst. was obtained on plots without C. alpestris than on paired plots covered with it. Betula verrucosa (B. pendula Roth) showed no difference. Under natural forest conditions, P. sylvestris seedlings grow much more rapidly where C. alpestris had been eliminated by road building or reindeer grazing than do seedlings only one meter distant under undisturbed C. alpestris cover. It is suggested that by properly controlled reindeer grazing, establishment and early growth of P. sylvestris on Cladonia sites can be much enhanced. By the time that C. alpestris could become re-established the pine seedlings would have grown large enough to suffer little from reindeer grazing. This study shows the continuity of the major components of the forest tundra biome – the dependence of pines, mycorrhizae, lichens, and reindeer and their predators (human or otherwise) upon each other for a healthy existence.

The PDF includes a summary in Finnish.

• Brown, E-mail: rb@mm.unknown
• Mikola, E-mail: pm@mm.unknown

• Häggström, Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden https://orcid.org/0000-0002-7738-5493 E-mail: bodil.haggstrom@slu.se
• Lutter, Institute of Forestry and Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu 51006, Estonia https://orcid.org/0000-0001-5847-4282 E-mail: reimo.lutter@emu.ee
• Lundmark, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden https://orcid.org/0000-0003-2271-3469 E-mail: tomas.lundmark@slu.se
• Sjödin, Unit for field-based forest research, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden E-mail: fredrik.sjodin@slu.se
• Nordin, Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, 90183 Umeå, Sweden https://orcid.org/0000-0002-5765-3550 E-mail: annika.nordin@slu.se

Investing in planting genetically improved silver birch (Betula pendula Roth) in Swedish plantations requires understanding how birch stands will develop over their entire rotation. Previous studies have indicated relatively low production of birch compared to Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.). This could result from using unrepresentative basic data, collected from unimproved, naturally-regenerated birch (Betula spp.) growing on inventory plots often located in coniferous stands. The objective of this study was to develop a basal area development function of improved silver birch and evaluate production over a full rotation period. We used data from 52 experiments including planted silver birch of different genetic breeding levels in southern and central Sweden. The experimental plots were established on fertile forest sites and on former agricultural lands, and were managed with different numbers of thinnings and basal area removal regimes. The model best describing total stand basal area development was a dynamic equation derived from the Korf base model. The analysis of the realized gain trial for birch showed a good stability of the early calculated relative differences in basal area between tested genotypes over time. Thus, the relative difference in basal area might be with cautious used as representation of the realized genetic gain. On average forest sites in southern Sweden, improved and planted silver birch could produce between 6–10.5 m³ ha^–1 year^–1, while on fertile agriculture land the average productivity might be higher, especially with material coming from the improvement program. The performed analysis provided a first step toward predicting the effects of genetic improvement on total volume production and profitability of silver birch. However, more experiments are needed to set up the relative differences between different improved material.

• Liziniewicz, The Forestry Research Institute of Sweden, Ekebo, SE-268 90 Svalöv, Sweden E-mail: mateusz.liziniewicz@skogforsk.se
• Barbeito, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Alnarp, Sweden; Université de Lorraine, AgroParisTech, INRAE, UMR Silva, Nancy, France E-mail: ignacio.barbeito@slu.se
• Zvirgzdins, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Box 49, 23053 Alnarp, Sweden E-mail: andis.zvirgzdins@slu.se
• Stener, The Forestry Research Institute of Sweden, Ekebo, SE-268 90 Svalöv, Sweden E-mail: lg.stener@telia.com
• Niemistö, Natural Resources In-stitute Finland (Luke), Natural resources, Seinäjoki, Finland E-mail: pentti.niemisto@luke.fi
• Fahlvik, The Forestry Research Institute of Sweden, Ekebo, SE-268 90 Svalöv, Sweden E-mail: nils.fahlvik@skogforsk.se
• Johansson, Tönnersjöheden Experimental Forest, SLU, Simlångsdalen, Sweden E-mail: ulf.johansson@slu.se
• Karlsson, The Forestry Research Institute of Sweden, Ekebo, SE-268 90 Svalöv, Sweden E-mail: curly.birch@gmail.com
• Nilsson, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Box 49, 23053 Alnarp, Sweden E-mail: urban.nilsson@slu.se

Timber production and profitability were evaluated for spontaneously-regenerated mixtures on two formerly clearcut areas. The abandoned areas developed into birch-dominated (Betula pendula Roth and Betula pubescens Ehrh.) stands with successional ingrowth of Norway spruce (Picea abies (L.) H. Karst.). An experiment with randomized treatments within blocks was established, using three management strategies and one unthinned control, resulting in variation in optimal rotation age, merchantable volume and species composition. The management strategies were evaluated based on total production (volume) by using measured growth data 42 years after clearcutting and the modelled future stand development. The long-term effects of spontaneous regeneration and management strategies were evaluated based on land expectation value (LEV) and compared with a fifth management strategy using artificial regeneration and intense thinnings. 12 years after treatment, at a stand age of 42 years, the unthinned control had produced the highest total stem volume. At interest rates of 2% or higher, the unmanaged forest was an economically viable strategy, even compared to an intensive management strategy with a preferred merchantable timber species. Interest rates clearly impacted the profitability of the different management strategies. This study shows that when spontaneous regeneration is successful and dense, the first competition release can have a high impact on the development of future crop trees and on the species mixture.

• Dahlgren Lidman, Department of Forest Ecology and Management, Swedish University of Agricultural Science, Umeå, Sweden https://orcid.org/0000-0002-2474-1810 E-mail: felicia.lidman@slu.se
• Holmström, Southern Swedish Forest Research Centre, Swedish University of Agricultural Science, Alnarp, Sweden https://orcid.org/0000-0003-2025-1942 E-mail: emma.holmstrom@slu.se
• Lundmark, Department of Forest Ecology and Management, Swedish University of Agricultural Science, Umeå, Sweden https://orcid.org/0000-0003-2271-3469 E-mail: tomas.lundmark@slu.se
• Fahlvik, The Forestry Research Institute of Sweden, Ekebo, Sweden https://orcid.org/0000-0002-2179-7800 E-mail: nils.fahlvik@skogforsk.se

Silver birch (Betula pendula Roth) is classified in diffuse-porous wood category. In this case structure of wood tissue is quite similar across whole cross-sectional area. The aim of this study was to analyse cross-section variability of moisture content (MC) of growing silver birch wood, significant hardwood species in Polish forests. Investigations were performed on 120 model trees. In the trunk of each model tree, an increment core was collected at breast height. Samples were collected of 30 different trees in four different seasons. The greatest MC was observed during winter, lowest MC in summer. Differences in MC were statistically significant only between winter versus spring, summer, and autumn. Distribution of MC on cross-section was similar in each season. The greatest average value was observed close to pith, then it was decreasing in bark direction. The greatest difference between observed in spring – 19.51% (p < 0.05) and lowest in autumn – 4.66%. Distribution of green density (GD) on cross section was inverse proportional to MC value. Variations in GD and MC are relevant for log transport planning, weight-scaling systems, lumber drying and dynamic assessment of stiffness. Therefore, from an environmental loss perspective, it is important to determine changes in MC and GD across the year.

• Tomczak, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0001-5192-0294 E-mail: karol.tomczak@up.poznan.pl
• Arkadiusz, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0003-1140-8282 E-mail: arkadiusz.tomczak@up.poznan.pl
• Naskrent, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0002-0756-4162 E-mail: bartlomiej.naskrent@up.poznan.pl
• Jelonek, Department of Forest Utilization, Faculty of Forestry and Wood Technology, Poznań University of Life Sciences, Wojska Polskiego 71A, 60-625 Poznań, Poland https://orcid.org/0000-0001-9558-9951 E-mail: tomasz.jelonek@up.poznan.pl

Strong wind is the major natural disturbance in European forests, that periodically causes tremendous damages to forestry. Yet, factors that affect the probability of wind damage for birch (Betula pendula Roth and B. pubescens Ehrh.), the most common deciduous tree species in hemiboreal forests, are studied scarcely. This study aimed to assess the effects of several tree- and stand-scale variables on the probability of wind damage to birch using data from the Latvian National Forest Inventory (2004–2018), and determine individual tree characteristics that affect the height of the stem breakage. The data analysis was done using the Bayesian binary logistic generalized linear mixed-effects model and a linear mixed-effects model. The probability of wind damage significantly increased by stand age, basal area, and slenderness ratio. Trees with prior damage had a significantly higher probability (odds ratio 4.32) for wind damage. For wind-damaged trees, the snapping height was significantly decreased by an increase in the slenderness ratio (p = 0.03) and prior damage (p = 0.003). Previously damaged trees were more frequently (73%) snapped in the lowest 40% of tree height than trees without prior damage (54%). The probability of wind damage is largely set by factors related to the selection of site, species composition, and rotation. The damage probability could be decreased by management measures that lower competition within the stand with particular regard to preserving intact remaining trees during these manipulations. Factors that reduce the probability of the damage simultaneously increase the snapping height, emphasizing their relevance for mitigation of the wind damages.

• Kitenberga, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia https://orcid.org/0000-0002-6192-988X E-mail: mara.kitenberga@silava.lv
• Šņepsts, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia E-mail: guntars.snepsts@silava.lv
• Vuguls, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia E-mail: janis.vuguls@silava.lv
• Elferts, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia; Faculty of Biology, University of Latvia, Jelgavas Street 1, LV–1004, Rīga, Latvia https://orcid.org/0000-0002-9401-1231 E-mail: didzis.elferts@lu.lv
• Jaunslaviete, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia E-mail: ieva.jaunslaviete@silava.lv
• Jansons, Latvian State Forest Research Institute ‘Silava’, Rigas Street 111, LV–2169, Salaspils, Latvia https://orcid.org/0000-0001-7981-4346 E-mail: aris.jansons@silava.lv

Novel information on silver birch (Betula pendula Roth) foliar element contents and their seasonal, between-habitat and leaf level variations are provided by applying fine-scaled element mapping with micro X-ray fluorescence. In the monthly leaf samples collected from May to October from six different habitats, pairwise scatter plots and Spearman’s rank correlations showed statistically significant positive correlations between Si, Al and Fe, and covariations between also many other pairs of elements. Of the ten elements studied, seven showed statistically significant changes in their average levels between May and June. The contents of P, S and K decreased in most habitats during the later season, whereas Ca and in some habitats also Mn and Zn increased. Comparing habitats, trees in the limestone habitat had relatively low content of Mg, strongly increasing levels of P until the late season, and high content of Ca and Fe. Other habitats also revealed distinctive particularities in their foliar elements, such as a high relative content of S and a low content of Ca at the seashore. Mn was high in three habitats, possibly due to bedrock characteristics. Except for P, the contents of all elements diverged between the midrib and other leaf areas. Zn content was particularly high in the leaf veins. Mn levels were highest at the leaf margins, indicating a possible sequestration mechanism for this potentially harmful element. Si may help to alleviate the metallic toxicities of Al and Fe. Because the growing season studied was dry, some trees developed symptoms of drought stress. The injured leaf parts had reduced levels of P, S and K, suggesting translocation of these nutrients before permanent damage.

• Kalliola, Department of geography and geology, University of Turku, FI-20014 Turku, Finland https://orcid.org/0000-0003-2454-8217 E-mail: risto.kalliola@utu.fi
• Saarinen, Department of geography and geology, University of Turku, FI-20014 Turku, Finland E-mail: tijusa@utu.fi
• Tanski, Department of geography and geology, University of Turku, FI-20014 Turku, Finland E-mail: niko.tanski@utu.fi

Genetic parameters of growth and stem quality traits were estimated for open-pollinated silver birch Betula pendula Roth progenies in Latvia at the age of 10 and 14 years. Tree height and stem volume were found to be under strong genetic control at both inventories (narrow-sense heritabilities varied from 0.41 to 0.66). Mainly low heritabilities were found for stem defects, yet genetic control of branch diameter, stem straightness and overall stem quality varied from low to high depending on study site. High additive genetic coefficient of variation was found for stem volume (25.3–32.5%). Genetic correlations among growth traits were strong and positive (0.90–0.99). Mainly weak genetic correlations between growth and quality traits implied simultaneous improvement. Still, strong negative correlations between branch angle and stem straightness might result in enlarged knot size for straighter logs. The genetic age-age correlations were strong. Weak genotype by environment interaction and stability of best genotypes over different sites was indicated by strong genetic correlations between trials. Each growth or quality trait alone showed substantial improvement in terms of estimated genetic gain (up to 62% over trial mean for stem volume). Therefore, selection index combining both growth and stem quality may be developed.

• Gailis, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: arnis.gailis@silava.lv
• Zeltiņš, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia https://orcid.org/0000-0002-6286-5814 E-mail: pauls.zeltins@silava.lv
• Purviņš, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: andis.purvins@silava.lv
• Augustovs, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: juris.augustovs@silava.lv
• Vīndedzis, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: valts.vindedzis@silava.lv
• Zariņa, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: inga.zarina@silava.lv
• Jansons, Latvian State Forest Research Institute Silava, 111 Rigas street, Salaspils LV-2169, Latvia E-mail: aris.jansons@silava.lv

This work presents the findings of a study concerning variability in the basic density of silver birch (Betula pendula Roth) wood, depending on the geographical location of tree stands, the age and thickness of the trees, the forest habitat type, and interactions between some of these factors. The study was carried out on wood from trees aged approximately 30, 50 and 70 years in 12 forest districts located throughout Poland. In total 4777 wood samples, taken from 306 trees from 51 test plots, were measured. The location, the age of the trees, the thickness of the trees and the forest habitat type, as well as interactions between these factors, proved to have a significant influence on the basic density of silver birch wood. The highest mean values of the basic density of the birch wood were found in Sokołów forest district on the FBF habitat type (549 kg m^–3) and in Giżycko forest district on the FMBF habitat type (548 kg m^–3). For the entire set of examined material, the average values of the basic density of wood increase with tree age. For the examined material originating in FBF and FMBF habitats the average values of basic density showed no significant differences; however, in the cases of the forest districts of Giżycko, Łobez and Rudziniec, significant differences in the analysed property were observed.

• Lachowicz, Department of Forest Utilization, Warsaw University of Life Sciences SGGW, Nowoursynowska 159 02-787 Warsaw, Poland E-mail: hubert.lachowicz@wl.sggw.pl
• Bieniasz, Department of Forest Utilization, Warsaw University of Life Sciences SGGW, Nowoursynowska 159 02-787 Warsaw, Poland E-mail: anna.bieniasz@wl.sggw.pl
• Wojtan, Laboratory of Dendrometry and Forest Productivity, Warsaw University of Life Sciences SGGW, Nowoursynowska 159 02-787 Warsaw, Poland E-mail: rwojtan@wl.sggw.pl

Silver birch (Betula pendula Roth) seed origins from the Baltic countries and from Finland were compared in terms of growth, wood density, bark thickness and the incidence of darkened core wood, frost cracks and decay, and the effect of seed origin latitude was examined in two Finnish provenance trials. The material consisted of 21 stand and single tree origins ranging from latitudes 54° to 63°N from the Baltic countries and Finland. The trials, measured at the age of 22 years, were located at Tuusula (60°21´N), southern Finland and at Viitasaari (63°11´N), central Finland. The Baltic origins were superior to the Finnish ones in the southern trial regarding height, whereas in central Finland the Finnish origins grew better. There was no consistent difference between the Baltic and the Finnish group of origins in wood density. Bark thickness decreased with increasing seed origin latitude. The Baltic origins had significantly thicker bark than the Finnish origins. A moderate positive correlation was detected between the seed origin latitude and the incidence of darkened core wood in the southern trial, where the darkened core wood was more common in the Finnish origins than in the Baltic ones. The highest proportion of trees with frost cracks was detected in the south-western Latvian origins growing in central Finland. Seed transfers from the Baltic would have an increasing effect on the bark thickness of birch logs, but no or only minor effects on wood density. Based on our results, there is no reason to recommend the use of non-native Baltic seed origins in Finland instead of the native locally adapted seed sources.

• Viherä-Aarnio, Natural Resources Institute Finland (Luke), Green technology, P.O. Box 2, FI-00791 Helsinki, Finland E-mail: anneli.vihera-aarnio@luke.fi
• Velling, E-mail: pike.velling@phnet.fi

The specific pattern of the wood of Karelian birch (Betula pendula Roth var. carelica (Merckl.) Hämet-Ahti), is created mainly by dark-coloured inclusions of parenchyma tissue. Our study revealed that the greatest density of parenchyma inclusions in Karelian birch wood is observed above branch attachments to the trunk and below forks. In the place of branch attachment, phloem flows of photoassimilates (sucrose) from the branch and along the trunk merge into one pathway, causing a rise in sucrose content in tissues there. In the area below the fork, sucrose flows from two (or more) trunk axes are combined. Many studies have demonstrated that elevated sucrose level is associated with the differentiation of parenchyma. We believe that where large phloem fluxes merge a high level of sucrose promotes mass differentiation of parenchyma cells instead of fibers and vessels. As a result, the density of the figured pattern in the wood increases. The obtained data have a practical value and can be used in developing recommendations for Karelian birch cultivation.

• Novitskaya, Forest Research Institute, Karelian Research Center, Russian Academy of Sciences, Pushkinskaya str. 11, 185910, Petrozavodsk, Russia E-mail: ludnovits@rambler.ru
• Nikolaeva, Forest Research Institute, Karelian Research Center, Russian Academy of Sciences, Pushkinskaya str. 11, 185910, Petrozavodsk, Russia E-mail: kar-birch@mail.ru
• Galibina, Forest Research Institute, Karelian Research Center, Russian Academy of Sciences, Pushkinskaya str. 11, 185910, Petrozavodsk, Russia E-mail: galibina@krc.karelia.ru
• Tarelkina, Forest Research Institute, Karelian Research Center, Russian Academy of Sciences, Pushkinskaya str. 11, 185910, Petrozavodsk, Russia E-mail: karelina.t.v@gmail.com
• Semenova, Forest Research Institute, Karelian Research Center, Russian Academy of Sciences, Pushkinskaya str. 11, 185910, Petrozavodsk, Russia E-mail: mi7enova@gmail.com

• Huttunen, Section of Ecology, Department of Biology, University of Turku, FI-20014 Turku, Finland E-mail: liisa.huttunen@utu.fi
• Ayres, Biological Sciences, Dartmouth College, Hanover, NH 03755, USA E-mail: matt.ayres@dartmouth.edu
• Niemelä, Section of Biodiversity and Environmental Science, Department of Biology, University of Turku, FI-20014 Turku, Finland E-mail: pekka.niemela@utu.fi
• Heiska, The Finnish Forest Research Institute, Punkaharju Unit, Finlandiantie 18, FI-58450 Punkaharju, Finland E-mail: susanne.heiska@metla.fi
• Tegelberg, Digitarium - Digitization Centre of the Finnish Museum of Natural History and the University of Eastern Finland, Joensuu Science Park, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: riitta.tegelberg@helsinki.fi
• Rousi, The Finnish Forest Research Institute, Vantaa Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: matti.rousi@metla.fi
• Kellomäki, Faculty of Science and Forestry, School of Forest Sciences, University of Eastern Finland, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: seppo.kellomaki@uef.fi

• Rousi, The Finnish Forest Research Institute, Finland E-mail: matti.rousi@metla.fi
• Possen, The Finnish Forest Research Institute, Finland E-mail: bjhmp@nn.fi
• Hagqvist, The Finnish Forest Research Institute, Finland E-mail: rh@nn.fi
• Thomas, University of Alberta, Dept of Renewable Resources, Edmonton & Alberta-Pacific Forest Industries Inc., Boyle, Alberta, Canada E-mail: brt@nn.ca

• Kilpeläinen, Finnish Forest Research Institute, Eastern Finland Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: hk@nn.fi
• Lindblad, Finnish Forest Research Institute, Eastern Finland Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jl@nn.fi
• Heräjärvi, Finnish Forest Research Institute, Eastern Finland Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: henrik.herajarvi@metla.fi
• Verkasalo, Finnish Forest Research Institute, Eastern Finland Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: ev@nn.fi

• Bargen, Humboldt-Universität zu Berlin, Department für Nutzpflanzen- und Tierwissenschaften, Fachgebiet Phytomedizin, Lentzeallee 55/57, 14195 Berlin, Germany E-mail: susanne.von.bargen@agrar.hu-berlin.de
• Grubits, Humboldt-Universität zu Berlin, Department für Nutzpflanzen- und Tierwissenschaften, Fachgebiet Phytomedizin, Lentzeallee 55/57, 14195 Berlin, Germany E-mail: eg@nn.de
• Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: risto.jalkanen@metla.fi
• Büttner, Humboldt-Universität zu Berlin, Department für Nutzpflanzen- und Tierwissenschaften, Fachgebiet Phytomedizin, Lentzeallee 55/57, 14195 Berlin, Germany E-mail: cb@nn.de

• Viherä-Aarnio, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: anneli.vihera-aarnio@metla.fi
• Velling, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: pv@nn.fi

• Martín, Departamento de Biología Vegetal, Escuela Técnica Superior de Ingenieros Agrónomos de Madrid, Universidad Politécnica de Madrid, Ciudad Universitaria s/n, 28040-Madrid, Spain E-mail: mariacarmen.martin@upm.es
• Parra, Departamento de Ciencias y Recursos Agrícolas y Forestales, Universidad de Córdoba, Avda. Linneo s/n, 14004-Córdoba, Spain E-mail: tp@nn.es
• Clemente-Muñoz, Departamento de Ciencias y Recursos Agrícolas y Forestales, Universidad de Córdoba, Avda. Linneo s/n, 14004-Córdoba, Spain E-mail: mcm@nn.es
• Hernández-Bermejo, Departamento de Ciencias y Recursos Agrícolas y Forestales, Universidad de Córdoba, Avda. Linneo s/n, 14004-Córdoba, Spain E-mail: ehb@nn.es

• Schatz, Peltotievantie 27, FI-99440 Leppäjärvi, Finland E-mail: us@nn.fin
• Heräjärvi, Finnish Forest Research Institute, Joensuu Research Unit, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: henrik.herajarvi@metla.fi
• Kannisto, Finnish Forest Research Institute, Parkano Research Unit, Kaironiementie 54, FI-39700 Parkano, Finland E-mail: kk@nn.fi
• Rantatalo, Peltotievantie 27, FI-99440 Leppäjärvi, Finland E-mail: mr@nn.fi

• Kalliokoski, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: tuomo.kalliokoski@metla.fi
• Nygren, Department of Forest Ecology, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: pn@nn.fi
• Sievänen, The Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: rs@nn.fi

• Aphalo, University of Helsinki, Department of Biological and Environmental Sciences E-mail: pja@nn.fi
• Lahti, The Finnish Forest Research Institute E-mail: ml@nn.fi
• Lehto, University of Joensuu, Faculty of Forestry, Box 111, FI-80101 Joensuu, Finland E-mail: tarja.lehto@joensuu.fi
• Repo, The Finnish Forest Research Institute E-mail: tr@nn.fi
• Rummukainen, University of Joensuu, Faculty of Forestry, Box 111, FI-80101 Joensuu, Finland E-mail: ar@nn.fi
• Mannerkoski, University of Joensuu, Faculty of Forestry, Box 111, FI-80101 Joensuu, Finland E-mail: hm@nn.fi
• Finér, The Finnish Forest Research Institute E-mail: lf@nn.fi

• Hytönen, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FI-69101 Kannus, Finland E-mail: jyrki.hytonen@metla.fi
• Jylhä, Finnish Forest Research Institute, Kannus Research Station, P.O. Box 44, FI-69101 Kannus, Finland E-mail: pj@nn.fi

• Siipilehto, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: jouni.siipilehto@metla.fi

• Viherä-Aarnio, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box. 18, FIN-01301 Vantaa, Finland E-mail: anneli.vihera-aarnio@metla.fi
• Velling, Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box. 18, FIN-01301 Vantaa, Finland E-mail: pv@nn.fi

• Karlsson, Swedish University of Agricultural Sciences, Department of Silviculture, S-901 83 Umeå, Sweden E-mail: anders.karlsson@ssko.slu.se
• Albrektson, Swedish University of Agricultural Sciences, Department of Silviculture, S-901 83 Umeå, Sweden E-mail: aa@nn.se
• Forsgren, Swedish University of Agricultural Sciences, Department of Silviculture, S-901 83 Umeå, Sweden E-mail: af@nn.se
• Svensson, Swedish University of Agricultural Sciences, Department of Silviculture, S-901 83 Umeå, Sweden E-mail: ls@nn.se

Populations of tree species with a wide geographic range, such as silver birch (Betula pendula Roth), show genetic specialization to native environments, while maintaining high phenotypical plasticity. Accordingly, assessment of local specialization is essential for adaptive management. The aim of the study was to detect geographic patterns of local adaptation of growth and stem quality based on two open-pollinated progeny trials in Latvia testing local material. Two provenance regions differing by continentality were distinguished, which also differed in genetic control of growth traits, likely originating from the post-glacial recolonization of vegetation and subsequent natural adaptation. Heritability of the traits was estimated for each of the distinguished regions, indicating differing patterns of genetic adaptation and potential for future selection. Trees from the more continental inland showed superior growth and possessed higher heritability. The coastal provenance region showed slower growth and intermediate heritability of the respective traits. Moderate to high heritability for stem quality traits was estimated irrespectively of region. Overall, better growth and higher heritability suggests that anthropogenic selection within the best inland provenances may constitute better performing and adaptable breeding population compared to the coastal one. Still, overlapping phenotypical variation and heritability of quality traits implies improved stemwood quality for plywood regardless of the provenance region. High adaptive capacity of silver birch genotypes suggests ability to cope with climatic changes, highlighting its potential for climate-smart forestry.

• Gailis, Latvian State Forest Research Institute Silava, 111 Rigas street, LV-2169, Salaspils, Latvia E-mail: arnis.gailis@silava.lv
• Zeltiņš, Latvian State Forest Research Institute Silava, 111 Rigas street, LV-2169, Salaspils, Latvia E-mail: pauls.zeltins@silava.lv
• Matisons, Latvian State Forest Research Institute Silava, 111 Rigas street, LV-2169, Salaspils, Latvia https://orcid.org/0000-0002-4042-0689 E-mail: roberts.matisons@silava.lv
• Purviņš, Latvian State Forest Research Institute Silava, 111 Rigas street, LV-2169, Salaspils, Latvia E-mail: andis.purvins@silava.lv
• Augustovs, Latvian State Forest Research Institute Silava, 111 Rigas street, LV-2169, Salaspils, Latvia E-mail: juris.augustovs@silava.lv
• Vīndedzis, Latvian State Forest Research Institute Silava, 111 Rigas street, LV-2169, Salaspils, Latvia E-mail: valts.vindedzis@silava.lv
• Jansons, Latvian State Forest Research Institute Silava, 111 Rigas street, LV-2169, Salaspils, Latvia https://orcid.org/0000-0001-7981-4346 E-mail: aris.jansons@silava.lv

• Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: risto.jalkanen@metla.fi
• Büttner, Humboldt Universität zu Berlin, Institut für Gartenbauwissenschaften, Fachgebiet Phytomedizin, Lentzeallee 55/57, 14195 Berlin, Germany E-mail: Carmen.Buettner@agrar.hu-berlin.de
• Bargen, Humboldt Universität zu Berlin, Institut für Gartenbauwissenschaften, Fachgebiet Phytomedizin, Lentzeallee 55/57, 14195 Berlin, Germany E-mail: susanne.von.bargen@agrar.hu-berlin.de

• Viherä-Aarnio, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: anneli.vihera-aarnio@metla.fi
• Velling, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: pv@nn.fi