Articles containing the keyword 'production'

A new approach for modelling plant growth using the software AMAPpara is presented. This software takes into consideration knowledge about plant architecture which has been accumulated at the Plant Modelling Unit of CIRAD for several years, and introduces physiological concepts in order to simulate the dynamic functioning of trees. The plant is considered as a serial connection of vegetative organs which conduct water from the roots to the leaves. Another simple description of the plant as a network of parallel pipes is also presented which allows an analytical formulation of growth to be written. This recurring formula is used for very simple architectures and is useful to understand the role of each organ in water transport and assimilate production. Growth simulations are presented which show the influence of modifications in architecture on plant development.

• de Reffye, E-mail: pd@mm.unknown
• Barthélémy, E-mail: db@mm.unknown
• Blaise, E-mail: fb@mm.unknown
• Fourcaud, E-mail: tf@mm.unknown
• Houllier, E-mail: fh@mm.unknown

A gap-model was used with forest inventory data in taking ground-true site, soil and tree characteristics into account in predicting the effects of climate change on forests. A total of 910 permanent sample plots established in the course of national forest inventory (NFI) in Finland and located on mineral soil sites in southern Finland were selected as the input data. The climatological input used in the simulations consisted of interpolated means of and deviations from long-term local temperature and precipitation records. The policy-oriented climate scenarios of SILMU (Finnish Research Programme on Climate Change) were used to describe the climate change. The temperature changes in the climate scenarios were increases of ca. +1.1 °C (low), +4.4 °C (medium) and +6.6 °C (high) compared to the current climate in 110 years. The simulation period was 110 years covering the time years 1990–2100.

Southern Finland, divided into fifteen forestry board districts, was used as the study region. Regional development of stand volume, cutting yield, and total wood production of forests under different climate scenarios were examined. The annual average growth in simulations under current climate was close to that observed in NFL Forests benefited from a modest temperature increase (Scenario 2), but under Scenario 1 the growing stock remained at a lower level than under the current climate in all parts of the study region. In wood production and cutting yield there were regional differences. In the southern part of the study regional wood production under Scenario 1 was ca. 10% lower than under the current climate, but in the eastern and western parts wood production was 5–15% higher under Scenario 1 than under the current climate. The relative values of total wood production and cutting yield indicated that the response of forests to climate change varied by geographical location and the magnitude of climate change. This may be a consequence of not just varying climatic (e.g. temperature and precipitation) and site conditions, but of varying responses by different kind of forests (e.g. forests differing in tree species composition and age).

• Talkkari, E-mail: at@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

The effects of repeated fertilizer treatment on biomass production and nutrient status of willow (Salix ’Aquatica’) plantations established on two cut-away peatland areas in western Finland were studied over a rotation period of three years. Comparisons were made between single fertilizer applications and repeated annual fertilization.

The annually repeated fertilizer application increased the amounts of acid ammonium acetate extractable phosphorus and potassium in the soil as well as the concentrations of foliar nitrogen, phosphorus and potassium compared to single application. Depending on the fertilizer treatment and application rate, annual fertilizer application resulted in over two times higher biomass production when compared to single fertilizer application over a three-year rotation period. The effect of phosphorus fertilizer application lasted longer than that of nitrogen. The optimum fertilization regime for biomass production requires that nitrogen fertilizer should be applied annually, but the effect of phosphorus can last at least over a rotation of three years. Potassium fertilizer treatment did not increase the yield in any of the experiments during the first three years. The leafless, above-ground yield of three-year-old, annually NP-fertilized willow plantations was 9.5 t ha^-1 and the total biomass, including stems, leaves, roots and the stump, averaged 17 t ha^-1.

• Hytönen, E-mail: jh@mm.unknown

The effects of fertilized treatment on the soil nutrient concentrations, biomass production and nutrient consumption of Salix x dasyclados and Salix ’Aquatica’ were studied in five experiments on three cut-away peatland sites in western and eastern Finland during three years. Factorial experiments with all combinations of N (100 kg ha^-1 a-¹⁾, P (30 kg ha^-1 a^-1) and K (80 kg ha^-1 a^-1) were conducted.

The application of P and K fertilizers increased the concentrations of corresponding extractable nutrients in the soil as well as in willow foliage. N-fertilization increased foliar nitrogen concentration. An increase in age usually led to decreases in bark and wood N, P and K concentrations and increases in bark Ca concentrations. N-fertilization increased the three-year biomass yield 1.5–2.7 times when compared to control plots. P-fertilization increased the yield only in those experimental fields whose substrates had the lowest phosphorus concentration. K-fertilization did not increase the yield in any of the experimental fields. The highest total biomass yield of NPK-fertilized willow after three growing seasons, 23 t ha^-1, was distributed in the following way: wood 42%, bark 19%, foliage 17%, stumps 6% and roots 16%. As the yield and stand age increased, more biomass was allocated in above-ground wood. Three-year-old stands (above-ground biomass 18 t ha^-1) contained as much as 196 kg N ha^-1, 26 kg P ha^-1, 101 kg K ha^-1, 74 kg Ca ha^-1 and 37 kg Mg ha ^-1. By far the highest proportion of nutrients accumulated in the foliage. The bark and wood contained relatively high proportions of calcium and phosphorus. With an increase in age and size, the amount of nitrogen and potassium bound in one dry-mass ton of willow biomass decreased while that of phosphorus remained unchanged.

• Hytönen, E-mail: jh@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

After a presentation of basic biodiversity concepts, reviews are made of studies reporting genetic implications of tree improvement activities: seed treatments, seedling production, provenance transfers, plus tree selection, seed production in seed orchards and progeny testing.

Several of the activities may influence the genetic structure and diversity of the planted forests. The general conclusion is, however, that planted forests are at least as genetically diverse as the natural stands that they replace. The diversity in forest management and use is best assurance for the future adaptability of the forests.

• Skrøppa, E-mail: ts@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

For biomass forestry in the inland parts of Southern and Central Finland, the obvious choice of willow species is Salix myrsinifolia. However, selection of clones of indigenous species has not yet been completed and more research and selection is needed. In the Piipsanneva old peatland trial, indigenous species of willow, mostly clones of S. myrsinifolia and S. phylicifolia, were compared in terms of biomass production, coppicing, height growth and diameter distributions. In this trial, the mean annual biomass production was not particularly high; more important results were attained in the ranking of clones. The trial strengthens the hypothesis that, over the long-term, the biomass production of S. myrsinifolia is higher than that of S. phylicifolia. It was supposed that behind the highest yield there was a clone with uniform quality, one whose diameter distribution would be narrow and positively skewed. Comparisons of parameters of Weibull functions showed that the distributions of the best clones were wide, indicating that those clones use the whole growth space better than those with narrow distribution.

• Honkanen, E-mail: ah@mm.unknown

In the method presented in this study, a group of experts evaluate, in a pairwise manner, a set of forest areas with respect to the game species considered. On the basis of these comparisons, relative priorities of forest areas are estimated using the eigenvalue technique. Using regression analysis, a habitat suitability function is estimated in which the priority is predicted by measures already familiar in forest planning. As a case study, a habitat suitability function was estimated for black grouse (Tetrao tetrix, Lururus tetrix L.). The function is applicable in forestry planning carried out using modern planning techniques.

The PDF includes an abstract in Finnish.

• Kangas, E-mail: jk@mm.unknown
• Karsikko, E-mail: jk@mm.unknown
• Laasonen, E-mail: ll@mm.unknown
• Pukkala, E-mail: tp@mm.unknown

Coniferous and non-coniferous fine root and rhizome production was measured after one growing season using the ingrowth bag method in Scots pine (Pinus sylvestris L.) stands differing in ages from 7 to 105 years in Southern Finland. Total fine-root production decreased from the 7-year to 20-year-old stands, and then increased slightly in the 85- to 105-year-old stands. Most of the total fine-root biomass in the youngest age groups came from non-conifer species, whereas most of the total fine-root biomass in the three older age groups came from conifer species. The maximum coniferous fine-root production was found to occur at crown closure in the 11- to 13-year-old stands. Rhizome production was the lowest and highest in the 20- and 85- to 105-year-old stands, respectively. The increase in rhizome production in the 85- to 105-year-old stands was associated with an abundant understory cover of Vaccinium myrtillus and V. vitis-idaea and an increase in light penetration. The ingrowth bag method was found to be useful in assessing the relative fine-root production among species-group and successional stages of Scots pine stands.

The PDF includes an abstract in Finnish.

• Messier, E-mail: cm@mm.unknown
• Puttonen, E-mail: pp@mm.unknown

The water retention characteristics and their variation in tree nurseries and related physical properties were determined for commercially produced growth media made of light slightly humified Sphagnum peat. A total of 100 samples of peat media were collected from filled seedling trays in the greenhouses of four Finnish nurseries in 1990. In addition, the physical properties were determined for two growth media made of compressed peat sheets and chips. The variation in water retention characteristics in nurseries was described using linear models with fixed and random effects. The sources of variation in the mixed linear models were producer, grade, batch (greenhouse) and sample (tray).

The water retention of the peat media at different matric potentials was comparable to that given in the literature. The media shrank an average of 0–16% during desorption. The peat grades were finer than the Nordic quality standards for peat growth media. Particles < 1 mm increased and particles 1–5 mm decreased the water retention characteristics measured. The greatest total variation in water retention was at -1 kPa. The water retention of the peat media differed least at -5 and -10 kPa. The water retention characteristics of media from different producers usually differed significantly. The grades, on the other hand, did not differ from each other in their water retention characteristics nor were there significant interactions between producer and grade. The batch effect was marked but was lower than the effect within batches, where the sample (tray) effect was greater than the effect due to random measurement error. At -10 kPa, the measurement error was, however, clearly greater than the sample effect. The random measurement error was comparable to the batch effect. Aeration of the growth media is dependent on the water content retained between saturation and -1 kPa. The water availability to seedlings at the nursery phase is affected mainly by water retention between -1 and -10 kPa.
The PDF includes an abstract in Finnish.

• Heiskanen, E-mail: jh@mm.unknown

Speed and load sizes presented in three study reports on sulky skidding were compared with estimates based on ergonomic models. Speed and load size estimates were closely correlated with the observed values, when a 400 W energy expenditure of the subject was used. This corresponds to less than half of his submaximal oxygen intake and matches well with the heart rate given in one of the time studies. It seems possible to develop methods for evaluating the work pace/production rate for sulky skidding in varying terrain conditions.

The PDF includes an abstract in Finnish.

• Saarilahti, E-mail: ms@mm.unknown

Application of growth regulators, primarily gibberellins, has become an efficient method of flowering regulation in many coniferous forest trees. In this paper some results are discussed with respect to various genetic processes in seed orchards. It is concluded that there are still several unsolved problems in the regulation of flowering in forest seed orchards. These problems are related to different genetic processes occurring in the seed orchards and they should be taken into account in endeavouring to produce genetically improved seeds. 

• Chalupka, E-mail: wc@mm.unknown

Crown characteristics and the distribution of three years’ (1986–88) biomass production of 20 pendulous Norway spruce (Picea abies f. pendula (Lawson) Sylvén) trees with heritable narrow crown and 15 normal-growned spruces (Picea abies (L.) H. Karst.) were studied in a 19-year-old mixed stand.

The form of the crown is conical in normal-crowned trees, columnar and narrow in pendulous trees. The partitioning of aboveground biomass to stems during the studied 3-year period was significantly higher in pendulous (0.281) than in normal-crowned trees (0.255) and also the ratio between growth of stemwood and growth of needle biomass during three years was higher in pendulous trees (0.67 g g^-1) than in normal-crowned trees (0.52 g g^-1). The needle biomass was distributed higher in the crown in pendula than in normal-crowned trees and they had a higher needle biomass/branchwood biomass ratio than normal trees. The difference in harvest increment between the two crown types are mostly due to the significantly lower branchwood biomass values in pendulous than in normal-crowned trees. The higher needle ’efficiency’ in pendulous trees is probably connected with high partitioning of needle biomass to the upper part of the crown in pendulous trees.

The PDF includes an abstract in Finnish.

• Pulkkinen, E-mail: pp@mm.unknown

The development of shoot number and shoot properties was examined in successive shoot cohorts of young widely-spaced Scots pine trees (Pinus sylvestris L.) growing in a progeny trial. This was accomplished by reconstructing the branching process of the trees over a period of five years, from tree age 4 to 8. During this time the number of shoots in successive shoot cohorts increased rapidly, while at the same time the mean shoot length decreased. The decrease in shoot lengths from older to younger shoots was accompanied by a decline in the bifuraction frequency of the shoots. In general, rapid changes occurred in the branching characteristics during the yearly development of the trees. The variation in the branching characteristics was reflected in the development of the architecture and biomass production of the trees.

The PDF includes an abstract in Finnish.

• Kuuluvainen, E-mail: tk@mm.unknown

The architecture of Scots pine (Pinus sylvestris L.) was studied in an eight-year-old progeny test. The measurements included characteristics of crown structure, spatial distribution of shoots and yield components. The spatial distribution of shoots showed striking between-tree differences, and two extreme distribution patterns were detected. One represented a non-layered structure with a vertically relative even shoot distribution, and the other a layered structure with a vertically highly uneven shoot distribution.

Close correlations existed between several components of tree architecture and it is suggested that changes in the phenotypic architecture in Scots pine follow an epigenetic pattern, which enables the prediction of adaptational changes in structural components. The structural characteristics related to high above-ground biomass were a long crown, high total shoot length, high number of branches per whorl and big shoots of low needle density occupying a big share of the crown volume.

The PDF includes a summary in Finnish.

• Kuuluvainen, E-mail: tk@mm.unknown
• Kanninen, E-mail: mk@mm.unknown
• Salmi, E-mail: js@mm.unknown

Possibilities of developing suitable willow (Salix spp.) clones for short-rotation forestry on mined peatlands in the north-western area of Finland were studied in a field experiment in which 300 willow clones were tested during 1985–87. Most of the tested clones started to grow from cuttings on limed and fertilized peat soil. Salix viminalis L. clones of southern origin had a higher leafless above ground biomass production than the well adapted control clone and the local Finnish willows, but their winter hardiness was not satisfactory. The growth habit of some southern willows was also better than that of the control clone. It was also possible to select clones with good sprouting capacity. There were few Salix myrsinifolia Calisb. clones of Finnish origin, which had better cold tolerance than all other willows tested and higher biomass production than that of the control clone. The most critical factor to be selected for this is the optimal combination of winter hardiness and biomass production. This is attempted by selecting clones on the basis of this experiment for a breeding program.

The PDF includes a summary in Finnish.

• Lumme, E-mail: il@mm.unknown
• Törmälä, E-mail: tt@mm.unknown

Four teams of two workers were time-studied in clearcutting of a cypress plantation and three teams in sulky skidding. The heart rate was recorded every 30 s. The average heartrate in timber cutting was 117.5 ± 13.4 P/min, and it was mainly dependent on worker’s working capacity. Average work load index was 41 ± 3% when working at 97% performance. The production rate was then 2.5 m³/h (crew). In sulky skidding the heart rate was lower, 106 ± 1.1 P/min, as well as the work load (WLI 30 ± 1%) and performance rating (87%). The low production rate (1.1 m³/h) (crew)) over 45 m distance is mainly due to under-dimensioned load size. The energy expenditure in timber cutting was 21.4 kJ/min and in sulky skidding 16.3 kJ/min. Daily energy expenditure was 15.0 MJ/d, and most of the timber cutters belonged to the class ”exceptionally active”.

The PDF includes an abstract in Finnish.

• Saarilahti, E-mail: ms@mm.unknown
• Bakena, E-mail: eb@mm.unknown
• Mboya, E-mail: gm@mm.unknown
• Minja, E-mail: tm@mm.unknown
• Ngerageze, E-mail: tn@mm.unknown
• Ntahompagaze, E-mail: jn@mm.unknown

A team of 2 experienced workers was time-studied and their heart rate recorded under 4 days in clearcutting of a highly self-pruned Pinus patula Schltdl. & Cham. plantation. Task work and bonus payment systems were compared, but there was no difference in production rate, only the workplace time was extended from 2.3 h/d in task work to 3.9 h/d in bonus payment. The heart rate was 115–116 P/min in felling, 105–109 P/min in debranching and 109–114 P/min in bucking. The average heart rate in timber cutting was 108–109 P/min. Work load index was 34–37%, and the workers did not show any symptoms of accumulated stress. The production rate was 3.2 m³/h, (WPT, crew), which corresponds average piecework rate, the comparable walking speed being about 6.0 km/h. There are possibilities to increase the daily task by ergonomic grounds.

The PDF includes an abstract in Finnish.

• Saarilahti, E-mail: ms@mm.unknown
• Ole-Meiludie, E-mail: ro@mm.unknown

In Japan many governmental projects have been promoted during 35 years since 1950, which were most active in the history of our forestry and wood industry. They were pushed forward for and by high economic growth. This article refers to the development of our forest policy and projects in those days. But as for the future of the forest economics, it is an urgent question to develop the comparative study between every nation’s experience. In order to contribute to this problem, the forest policy is divided into three fields and experiences are discussed.

• Handa, E-mail: rh@mm.unknown

The Forest 2000 Programme is a long-term programme for forestry and the forest industries in Finland. It attempts to obtain a better integration of timber production and other forms of forest use. The total annual cut is to be increased by 15 million m³ by the year 2010. This is almost one third greater than the level during the first few years of the 1980’s. In order to achieve the cutting targets, the cut area will have to be increased by almost one third by the turn of the century. The area of thinnings will experience the greatest increase. Considerable changes are proposed in silvicultural and basic improvement work. According to the programme, the growth of the raw-material base and the consumption of the wood-based products will permit an annual increase of about 3% in the production of the forest industries as a whole until the end of the century. This would be the same as the target growth rate of the GNP.

The PDF includes an abstract in Finnish.

• The Forest 2000 Programme sub-commitee, E-mail: –

The paper discusses the evaluation of timber production policies with different income (timber drain) schedules. Special attention is given to the temporal smoothness of the income flow. A utility model is formulated in which the objective is to maximize a fixed consumption pattern, and money can be saved and borrowed at different interest rates. We thus have smoothness requirements only for consumption, the capital market then determines the smoothness of the optimal income flow. Present discounted value and maximization of even income flow criteria are special cases of the utility model. Consumption can be maximized by linear programming. A sample problem is presented.

The PDF includes a summary in Finnish.

• Lappi, E-mail: jl@mm.unknown
• Siitonen, E-mail: ms@mm.unknown

Increased prices on oil have resulted in the search for alternative energy sources, e.g. coal, peat, biomass, different types of waste. Combustion especially of waste, coal and peat emits large quantities of air pollutants such as heavy metals but also harmful organic substances. Heavy metals are not easily separated from the smoke, and the concentrations are often high in the emissions even with advanced fly-ash separators.

Ecological investigations carried out around a coal burning power plant in Finland using mosses and pine needles as parameters are presented in the paper. Increased concentrations of Pb, Cd, Cr, Ni, Cu and V have been found near the plant. Often a clear gradient was found with increased concentrations at decreased distance from the power plant.

• Bramryd, E-mail: tb@mm.unknown

The purpose of the present study is to explore the applicability of some methodological approaches to empirical policy analysis in evaluating the effectiveness of public forest policy. From the perspective of effectiveness analysis we can distinguish in forest policy, aiming at the promotion of timber production, two principal objective levels in forestry: the quantity of silvicultural investments and their allocation and the quantity (sufficiency) together with the structure of timber supply. This paper is restricted to the exploration of the effect of forest policy measures directed to silvicultural investments in private forestry. First, the effects of state subsidies in silvicultural investments are analysed. The analysis is macro analysis of quantitative forest policy means, in which aggregated time series data are used as study material. Second, an attempt is made to provide a causal interpretation of the impacts of qualitative forest policy means at the woodlot level. This micro analysis utilizes an approach characteristic to the behavioural sciences.

It is concluded that like quantitative forest policy means the qualitative means, coupled with the activities of the forest promotion organizations, play a significant role in attaining the timber production goals. Of these, the professional advice given by forestry experts, has a direct effect on silvicultural activities. Extension and training activities have an indirect effect by increasing the willingness of forest owners to employ experts on their woodlots.

• Tikkanen, E-mail: it@mm.unknown

The structural matter production of selected plant species of a ground cover community was determined in relation to light available for photosynthesis. The resulting functions were applied in a situation where the light reaching the ground cover was controlled by the dynamics of the tree crown strata, and the occurrence of different plant species at different stages of succession was determined on the basis of their production of structural matter in actual light conditions. The possible strategies involved in adaptation to a successional environment have been discussed.

The PDF includes a summary in Finnish.

• Kellomäki, E-mail: sk@mm.unknown
• Hari, E-mail: ph@mm.unknown
• Kauppi, E-mail: pk@mm.unknown
• Väisänen, E-mail: ev@mm.unknown

The object of the study was to give a tentative indication of the realized economic significance of the principal forest (forestry land) uses in Finnish Lapland. Data concerns the years of the 1970s. Nowadays timber harvesting generates a major part of the total value of production. Recreation (tourism) is in second place. Reindeer husbandry, collection of berries and mushrooms and hunting together produce, in the best years, an output value which is about one fifth of that of timber harvesting. Non-timber uses together produce a rather significant portion on the total value of the integrated forestry output.

The PDF includes a summary in Finnish.

• Saastamoinen, E-mail: os@mm.unknown

Peat industry is rapidly expanding in Finland. Consequently, during next decades peat will be removed from thousands of hectares. Because timber production probably is the most rational use of this area after the peat production has ended, some experiments of afforestation of such areas have already been conducted. This article reports results of two experiments which were started in Kihniö, Western Finland, in 1953 and 1964.

In the first experiment fertilization with wood ash proved very effective whereas seeding and planting without fertilization resulted in almost complete failure. In the second experiment, interplanting with grey alder (Alnus glutinosa L. Gaertn.) greatly promoted the growth of Scots pine (Pinus sylvestris L.). The effect of slight fertilization lasted a few years only. The reasons for the remarkable effect of alder need further research. Although alder is known as a nitrogen-fixing plant, its beneficial effect was most clearly seen in the K and P contents of pine needles. Inoculation with mycorrhizal fungi was beneficial but not necessary. Experiments hitherto show that afforestation of bogs after peat removal is possible although some additional measures like fertilization or interplanting with alder may be needed.

The PDF includes a summary in English.

• Mikola, E-mail: pm@mm.unknown

The planning of timber production in a forestry unit is divisible into two phases. In the first phase, planning provides the decision-maker with a number of possible timber production policies; these policies define the production possibility boundary. After the decision-maker has chosen one of these policies, planning moves to the second phase, in which a detailed programme is prepared with a view to meeting the requirements of the timber production policy accepted. The paper indicates one possibility of solving these two tasks simultaneously. In the first phase, the solution of the primal linear programming problem is employed and in the second phase the respective dual or shadow price solution.

The PDF includes a summary in English.

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

The study deals with economic significance of forest landscape planning models used in regional planning in Finland. The »judge»-method is used among professional foresters working on private forestry boards in Southern Finland to define their view of what would be moderate level of costs of landscape management for private forest owners. A sample of 154 forest professionals working in district forestry boards in Southern Finland was sent a sociological questionnaire.

It was possible to form three hierarchical moderation classes by statistical grouping of judgement distributions. Prolongations in rotation ages and restrictions concerning ditching of forested bogs, forest read building and clear-cutting were considered the most immoderate models. Rather or wholly insignificant were evaluated such management models, which mean restrictions in »old fashioned» methods or which are already used in practice.

The PDF includes a summary in English.

• Lovén, E-mail: ll@mm.unknown

Male and female flowering, cone crop, and some vegetative characteristics were studied in grafts 10 to 16 years of age in a clonal seed orchard of Scots pine (Pinus sylvestris L.). Genetic variation was found between clones in flowering as well as in cone production. Clone evaluation resulted in similar classifications of clones in different years. A regression analysis showed that crown size clearly increased but previous height growth slightly decreased flowering and cone production. The percentage of pollinated female strobili did not differ between clones.

The PDF includes a summary in English.

• Tormilainen, E-mail: mt@mm.unknown

The article is a report of a study tour of five Finnish foresters in Germany on September 27 – October 2. 1971. As in most industrial countries, the recreation use of forests is rapidly expanding and, therefore, its needs are considered in the management of forests. Two examples of intensively used recreation forests are described, Schönbuch near Stuttgart and the Bavarian Forest National Park at the Czechoslovakian border. These forests are effectively used for both timber production and recreation at the same time. Some other effects of urbanization on forests also are discussed in the article.

The PDF includes a summary in English.

• Mikola, E-mail: pm@mm.unknown

Under the soil bank act, which took effect in 1969, 85,000 hectares of agricultural land were withdrawn from agricultural production in order to cut down the heavy surpluses of grain and butter in Finland. The farmers have a possibility to afforest their soil bank land partly on public funds, and if they choose to do so they receive a compensation of 250 Fmk for 15 years, instead of the nine years which is the maximum duration of a soil bank contract.

The study involved interviewing of 136 farmers sampled from the total of 13,368. The farmers were planning to afforest a total of 18,600 ha by the end of 1972. The main species were birch (Betula sp.) 40%, Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) both 30%. The main reasons (mentioned by 65% of the farmers) for afforestating the soil bank land were the unfavourable conditions for agriculture. On the other hand, 43% of those who had decided not to afforest felt that their land is too good to be planted with trees. One fifth of those not afforesting said that they themselves would not benefit from the afforestation and therefore were not interested in investing in forestry. The attitudes of the farmers seem to have also influenced their decision on afforestation. Those who had taken a positive decision on afforestation appeared to take more positive attitude in regard to forestry than other farmers.

The soil bank act does not seem to solve permanently Finland’s problem of the surpluses of agricultural products since the soil bank farmers planned to revert two thirds of the soil bank land under cultivation on the expiration of the soil bank act.

The PDF includes a summary in English.

• Numminen, E-mail: jn@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

Silva Fennica Issue 80 includes presentations held in 1952 in the 7th professional development courses, arranged for foresters working in the Forest Service. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.

This presentation describes principles of breeding of forest trees and the selection of fast growing, healthy and qualitatively good trees, named plus trees, for seed production in Finland.

• Sarvas, E-mail: rs@mm.unknown

Silva Fennica issue 52 includes presentations held in professional development courses, arranged for foresters working in public administration in 1938. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.

This presentation describes a study of forest management practices suitable for in Hylocomnium-Myrtillus site type forests, typical for Northern Finland. A special problem for the forest site type is poor regeneration due weak seed production of Norway spruce (Picea abies L. Karst.) and thick moss layer.

• Heikinheimo, E-mail: oh@mm.unknown

Silva Fennica Issue 39 includes presentations held in professional development courses in 1935 that were arranged for foresters working in public administration. The presentations focus on practical issues in forest management and administration, especially in regional level. The education was arranged by Forest Service.

This presentation studies the food supply and economic situation of the farmers in the remote parts of Finland.

• Kinnunen, E-mail: ek@mm.unknown

Seasonal variation in the sawmill industry of Finland was studied in an investigation based on questionnaires answered by a random sample of sawmills concerning the time period of 1958-1960. The method is described in detail in a separate article in Acta Forestalia Fennica issue 75 no. 1.

The seasonal variations in purchase of roundwood was largest in big sawmills, which purchase the main part of the timber as standing sales and buy most of the wood from the State Forest auctions at the end of September. Also, they can afford to reserve their material earlier than the smaller companies. The saw logs are mainly felled in the winter in Finland because the climatic conditions and availability of labour are best at that time. Small sawmills begin fellings a little earlier than the larger ones.

In long-transport of timber the proportion of floating decreased from 47% in 1958 to 38% in 1960. At the same time, proportion of truck transport increased from 48% to 55%. Small sawmills use almost exclusively land transport. They received almost three-fourths of their logs between January and May, because the sawing is concentrated in the first half of the year. Therefore, floating does not suit for their transport method. The larger the sawmill, the later is the seasonal peak of log deliveries. The output of the big sawmills is distributed more evenly thoughout the year. The smaller the sawmill, the quicker is the turnover of raw material and the smaller the sawlog inventories.

The seasonal variation in output is sharper at small sawmills where sawing is concentrated in the first half of the year. The seasonal peak of the early spring is due to the aim at getting the sawn wood to dry early enough for shipments in the summer. Air drying takes an average of 4 ½ months. Kiln drying is more common at the larger sawmills, and gives them more flexibility. Due to the large seasonal variation in operation, the capacity of the small mills is poorly utilized. Domestic sales of sawn wood levels up the seasonality of the deliveries. Export sales are concentrated at the end and turn of the year. Also, the seasonal peak of expenditure occurs in the winter, but that of income in the summer.

The PDF includes a summary in English.

• Ervasti, E-mail: se@mm.unknown

Short run market forecasting is desirable both for adjusting production and for regulating the national employment policy. In this study a forecast is made for one product. The purpose of the study is to develop a short run model describing newsprint sales in Finland that will combine mathematical simplicity, accuracy of description and universality.

Two methods of selecting variables seemed to be available. According to the first, newsprint consumption is divided into components, each of which is considered separately. The second method, which proved more fruitful, starts out directly from factors influencing the publishers’ decisions in purchasing newsprint, eliminating the least significant intuitively and simultaneously determining the lags.

The models developed in this study are capable of forecasting potential consumption. Even the best models in this study are multicollinear. The further into the future a forecast is extended, the greater is the possibility that relationships between the explanatory variables will change. It is intended that the newsprint seller will profit from the models achieved by using them to forecast sales in a future period, so that he can avoid both loss of interest due to acquiring a surplus of raw material or acute shortages of raw material.

The PDF includes a summary in Finnish.

• Riihinen, E-mail: pr@mm.unknown

Planning of large central tree nurseries, which has become topical in Finland, means that the seedlings will be used in a wide geographical area. The nursery must decide which proveniences of seeds of the different tree species it will use. This concerns also the customer that buys the seedlings. The planting and lifting of the seedlings in the nursery have to be timed so that the seedlings are in a right state of growth at the time of planting.

The growth of the seedlings can, under certain conditions, be promoted by using a slightly southerly seed provenience, and large-sized seeds. There are, however, limitations to how much the seeds can be transferred northwards. If the nursery lies much south of the planting site, the seedlings have started height growth at the time of planting. This applies especially larch (Larix sp.), Scots pine (Pinus sylvestris L.) and birch (Betula sp.), but affects less Norway spruce (Picea abies (L.) Karst.). The problem can be handled by using a cool storage space for the seedlings waiting for a delivery in the nursery.

According to an international study, seedlings grown from seeds collected in countries south from Finland usually die already during the first two years in the nursery. Within Finland the seeds can be transferred at least by two latitudes. Spruce seems to tolerate longer transfer. Seed orchards should be planted south of the seed’s origin to ensure better yield and better quality seeds.

The Silva Fennica issue 61 was published in honour of professor Eino Saari‘s 60th birthday.
The PDF includes a summary in German.

• Heikinheimo, E-mail: oh@mm.unknown

One of the factors that influence if a peatland is suitable for draining is the time required until fellings bring income, even if it the discounting calculations has uncertainties. This article discusses the factors that affect the economic profitability of draining peatlands.

The profitability of draining increases the more the yield or increase of the yield exceeds the costs of draining. Estimation of the yield is in Finland based on the peatland type, which reflects production capacity of the site. In addition, the growing stock of the site can vary in peatlands within same peatland type. The density and size of ditches affects the draining costs. Thus, productivity based on a peatland type alone does not describe well enough the drainability of a peatland area.

In Finnish classification of site quality of the peatlands, the treeless bogs and rich fens have been given too high a class compared to well stocked spruce swamps and pine swamps. Also, the drainability of two spruce and pine swamps can differ markedly in economic point of view if the tree’s quality, volume and ability to recover differ. The article discusses different methods to assess profitability of draining that have been descibed in the previous studies. It is suggested that the classification of peatlands by their drainability should be more selective.

The PDF includes a summary in German.

• Keltikangas, E-mail: vk@mm.unknown

Department of plant pathology of University of Helsinki conducted studies in the surrounding forests of Viikki test farm and on the Hyytiälä forest training station to find about occurrence and spore production of pine needle rust.

The damages have been minor. Most often the infection did not cause yellowing of the needles, only individual needles might have dried up. There were no dead young trees.

The spore production was strongest at the more fertile sites, with abundant occurrence of cow-wheat (Melanpyrum spp.). The infection caused more harm on the cow-wheat than on the pines. In many cases the foliage died prematurely. Melanpyrum spp. were more strongly infected on sites with more light. However, there was no difference found with the fertility of the site.

The PDF contains a summary in Finnish. 

• Pohjakallio, E-mail: op@mm.unknown
• Vaartaja, E-mail: ov@mm.unknown

Temperatures needed in extracting Scots pine (Pinus sylvestris L.) seeds is relatively high, however, there is little information on its effect on germination of the seeds. This survey aimed at studying how different temperatures affect both extraction result and germination of Scots pine seeds. Comparisons between different temperatures (20, 30, 40, 50, 60 and 70 ºC) were made from cones collected from same sample trees, three trees in total.

Temperatures 20 and 30 ºC resulted in incomplete opening of the cones, and gave thus smaller amount of seeds. Complete extraction requires at the least the temperature of 40 ºC. The result is slightly better in 50 ºC, but germination of the seeds is little lower. Temperatures 60 and 70 ºC improve the results, but in the cost of germination. The main reason for lower germination percentage was that the higher temperatures release more empty and defective seeds from the cones. Results of different sample trees were different due to, for instance, quality and size of cones. Higher temperatures accelerated the extraction. According to the study, perfect extraction in 40 ºC requires longer extraction time than when the temperature of 50 ºC is used. In practice, 50 ºC temperature or even little higher temperatures can be used when the extraction time is shorter. Decessive factors in choosing the temperature would be the humidity of cones and length of extraction time.

The PDF includes a summary in German.

• Kangas, E-mail: ek@mm.unknown

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

The PDF includes a summary in German.

• Hertz, E-mail: mh@mm.unknown

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

The PDF includes a summary in German.

• Ilvessalo, E-mail: li@mm.unknown

The study deals with the preconditions for natural regeneration of the pine at the polar tree line in northern Finland and Sweden. The data has been collected in three summers from 1909 to 1911 in areas of Inari and Utsjoki in Finland and Kaaresuvanto, Jukkasjärvi und Pajala in Sweden. The yearly variation of seed production of pine is studied and compared with the age of the stand, site factors and weather conditions.

Intensity of reproduction is dependent on different preconditions for pistils and stamens and hence the total reproduction (formation of cones) can vary very much depending on the weather.

• Renvall, E-mail: ar@mm.unknown

The first three-year effects of PK(MgB) and NPK(MgB) fertilization on the dry mass accumulation and nutrient cycling were studied in a Scots pine (Pinus sylvestris L.) stand growing on a drained low-shrub pine bog in Eastern Finland. The total dry mass of the tree stand before fertilization was 78 tn/ha, of which the above-ground compartments accounted for 69%. The annual above-ground dry mass production was 6.3 tn/ha, 51% of it accumulating in the tree stand.

The study period was too short for detecting any fertilization response in the stems. The total dry mass accumulation was not affected, because the increase in foliar and cone dry masses after both fertilization treatments, and that of the living branches after NPK fertilization, were compensated by the decrease in the dry mass of dead branches.

The nutrients studied accounted for 392 kg/ha (0.49%) of the total dry mass of the tree stand before fertilization. The amounts were as follows; N 173 kg/ha (44%), Ca 90 kg (23%), K 58 kg/ha (15%). The rest (18%) consisted of P, Mg, S and micronutrients combined. The unfertilized trees took up the following amounts of nutrients of the soil: N 15.6, Ca 12.8, K 4.1, P 1.3, MG 1.7, and S and Mn 1.5 kg/ha. The uptake of Fe and Zn was 510 and 130 g/ha and that of B and Cu less than 100 g/ha. More than 50% of the nutrient uptake, except for that of K and Fe, was released in litterfall. The results indicated very efficient cycling of K, Mn and B between the soil and trees.

The fertilized stands accumulated more N, P, K and B than the unfertilized ones during the tree-year study period. The increased accumulation corresponded to 35% (52 kg/ha) of the N applied on the NPK fertilized plots, 10% of the P, 25% of the K and 10% of the B on the PK and NPK fertilized plots. The increased amount of B released in litterfall after fertilization was equivalent to 4% of the applied B. Fertilization inhibited the uptake of Mn and Ca.

The PDF includes a summary in Finnish.

• Finér, E-mail: lf@mm.unknown

Willow (Salix sp.) species and clones have been selected in Finland, originally for basket willow husbandry, since 1910's. Screening for biomass willows started in 1973 by the Foundation for Forest Tree Breeding. Biomass willow research for energy started in 1978. The objective of the study was, based on theoretical background, on historical record of Finnish willow research between 1910–80 and on analysis of the Finnish biomass willow research of the 1980s, a further selection of exotic and indigenous willows for energy and chemicals.

Swedish selection of 63 exotics, mainly of Salix viminalis L. and S. burjatica Nazarov, was screened in Kompparnäs willow research site in the southern coast of Finland in 1983–89. S. viminalis showed both high yield potential and good crop certainty. The yield variation in S. burjatica were big due to rust (Melampsora sp.) infection followed by lowered winter hardiness. Three recommendable S. viminalis clones for Southern Finland were found.

Finnish indigenous species were screened based on collection (375 clones) in 1974–74 of the Foundation for Forest Tree Breeding, and the Finnish 4H-organization (566 clones) in 1978–79 in test sites in Suomusjärvi, Nurmijärvi, Kannus and Haapavesi. Salix myrsinifolia Salisb. was most productive of the indigenous willows. Five recommendable clones were selected. The second most productive indigenous was S. phylicifolia, with three recommendable clones. Based on willow hybridization studies in the Finnish Forest Research Institute, a considerable additional selection effect, boosted by heterosis, was found from the progenies. Further intraspecific crossings of geographically distant clones of S. myrsinifolia are recommended.

Based on the results, S. viminalis is recommended for practical biomass forestry application in the southernmost agroclimatic zone of Finland. S. myrsinifolia is recommended for further research and development in the other zones.

The PDF includes a summary in Finnish.

• Pohjonen, E-mail: vp@mm.unknown

The process of capital accumulation in timber production has been examined in this study. A detailed explanation of new investment in forest industry in terms of productive capacity as the determinant of national forest policy target growing stock and silviculture is presented. The basis of the explanation of forest industry productive capacity was a linear vertically integrated input-output production model. The model was used to derive a macroeconomic equilibrium condition specifying forest sector aggregate demand as an integral part of the national economy. Timber production has been constructed as a state variable system and the Maximum Principle used to derive silvicultural investment criterion. The derivation of the investment criterion was formulated as a dynamic problem in a labour surplus economy with linkage between savings and choice of silvicultural technology defined via income distribution between wages and profit. Maximization of aggregate consumption was specified as the goal of timber production.

By assuming a state of sub-optimal savings rate, it is shown that the real cost of labour is not zero in a labour surplus economy. Because unemployment labour is not a free commodity, it is concluded that capital-intensive silvicultural technology represents an optimal means of maximizing aggregate consumption in labour surplus economy, contrary to the recommendation of social marginal productivity theory.

The PDF includes a summary in Finnish.

• Omwami, E-mail: ro@mm.unknown

Flowering time and characteristics of cones and seed development of Scots pine (Pinus sylvestris L.) plus tree clones originating from various parts of Finland and planted (grafts) in Southern Finland (61° 48’ N, 29° 19’ E) were studied during 1976-1978.

The flowering time (in terms of period unit (p.u.) sums for flowering) of the Scots pine plus tree clones showed characteristics specific to each population and the characteristics appear mainly adapted to the local temperature factor within Finland. Generally, the development of floral organs, cones and seed in the spring and summer seasons also showed a temperature dependence in that the reproductive organs are developed rapidly and/or favourably under higher temperature conditions within its optimum range.

In this respect, establishment of northern Scots pine seed orchards in Central or Southern Finland or an optimum flowering, and a favourable seed development with an optimum physiological reproductive isolation from surrounding Scots pine populations can be justified. Problem arising from the north-south transfer of seed orchards and the significance of trees’ growth rhythm are discussed in connection with tree improvement.

The PDF includes a summary in Finnish.

• Chung, E-mail: mc@mm.unknown

The aim of the present study was to explain how the Finnish paper industry increased its production and its exports, broadened its markets and managed to show a profit in its activities during the period between the two world wars, despite the restrictive international commercial policies then prevailing, and despite the economic depression of the thirties. Newsprint has been treated as a subject for detailed examination.

The study is based on a comparative investigation of the price received by the paper mills for their paper and the costs of production. Since the market price of paper fell during the twenty years in question, one must examine how the mills responded to the reduction in selling price. Technically the study ranges from the valuation of the standing timber to the handing over of the finished product to the buyer. Between 1929 and 1933 the cost of producing newsprint fell by 387 marks per ton.

The most significant factor in maintaining competitive power was the technical development and increased output brought about in the mills. That alone accounted for half the savings achieved. The reduction in the buying price of wood and in delivery costs accounted for about a third of the difference in production costs, and other factors for the remaining fifth. In addition, the devaluation of the Finnish mark was crucial. Measures taken to reduce costs were effective in so far as the paper mills, with only one or two exceptions, maintained their competitiveness in international markets and managed not only to retain but also to extend their markets.

The PDF includes a summary in English.

• Ahvenainen, E-mail: ja@mm.unknown

The aim of the present study was to describe the forest types of Finnish mineral forest lands as a uniform whole in the light of stand development and wood production.

The study shows that it has been possible to work out uniform age-based development series for different stand characteristics for forest types on mineral forest lands in Finland. There is generally a clear difference in the development series of various stand characteristics and their average values between different forest types. The exceptions in a few places have been explained as depending on certain factors. The differences between adjacent forest types in order of their quality are of varying magnitude, thus differing from a schematic site quality classification obtained through calculation. Consequently, each forest type has its own development series with regard to the stand characteristics.

The number of forest types in the whole country is rather high. However, the different forest types are limited to different parts cf the country in such a way that there is no need for more than 5–6 forest types and 4 northerly sub-forms (-types) in each region, except in the border areas between the regions. In Finland the forest types have been the basis of forest site classification in forest research and practical forestry over a period of half a century. In pointing out the necessity of further study of forest types, Cajander has stressed the examination of differences in the compositions of vegetation between different classes of density of tree-stand and building up average descriptions of vegetation in such classes in young, middle-age and old stands. The same may be caused by some other factors which also are of essential influence to the composition of the vegetation.

The PDF includes a summary in English.

• Ilvessalo, E-mail: yi@mm.unknown
• Ilvessalo, E-mail: mi@mm.unknown

A long-term timber production model was developed. The model is based upon numerical simulation and it is viewed only as a means of providing the decision-maker with values of the predicting variables in his utility function. Special attention was paid to the development of automatic cutting decision rules. The model was applied to the area of 2,752,000 hectares of forest land in Central Finland. The measurement data were extracted from the Sixth National Forest Inventory, which was made in 1973. Utilities from a hypothetical utility function were attained to a number of feasible timber production policies. The Bayes and maximin criteria were employed to evaluate these policies.

The PDF includes a summary in Finnish.

• Kilkki, E-mail: pk@mm.unknown
• Pökälä, E-mail: rp@mm.unknown

Reproduction in masting species is characterised by long intervals between good cone and seed production years, and only sparse reproduction between mast years. The physiological mechanisms behind masting, and how these are linked to internal resource status and external weather factors, is still a subject of scientific exploration and debate, as is the effect of climate change on masting. This study investigates cone production in one operational seed orchard in Sweden which was established with two different spacings and has since been subject to three tree thinning experiments. The spacings before thinning varied between 800 and 400 stems ha^–1, and then thinning reduced the stand density in all trials to half, i.e. between 400 and 200 stems ha^–1. In all three experiments cone production per tree was equal in un-thinned and thinned treatments, both in mast years and in non-mast years. Thus, the cone production per unit area was twice as high in the un-thinned areas. The conclusion from these experiments is that the establishment of Picea abies (L.) H. Karst. seed orchards with wide tree spacing is both a misuse of good orchard locations and bad economics.

• Almqvist, Skogforsk, Uppsala Science Park, SE-75183 Uppsala, Sweden https://orcid.org/0000-0001-5739-4854 E-mail: curt.almqvist@skogforsk.se

After a decades-long increasing trend, the recent results of the National Forest Inventory (NFI) reported a decline of forest growth in North Finland. The aim of this study was to assess climatic and reproduction influences behind the growth decline. We used tree-ring data that had been collected by NFI using systematic sampling. The tree-ring width series were detrended using the regional curve standardisation (RCS) removing age-related trends. The resulting tree-ring indices of Scots pine (Pinus sylvestris L.) showed decadal variations with low increment in the 1990s, and high increment in the 1980s and the early years of the current century. Thereafter, a prolonged growth reduction for pine started both on the mineral soil sites and peatlands. The tree-ring indices of Norway spruce (Picea abies (L.) Karst.) had less pronounced decadal variations and no trend-like reduction over the last 15 years. High spring and summer temperatures were found to enhance radial growth, but high winter temperatures were related to low growth for pine and spruce in the following summer. Temperature variation, accompanied by variables indicating years of drought and intensive flowering, accounted for 34% annual growth variance of pine and 21–44% for spruce. Thus, the results imply that climatic factors may have to some extent contributed to the recent growth reduction of pine. Due to its ecological and economic consequences growth decline needs to be further monitored and investigated. Moreover, analyses of stand and age structure, potentially affecting the growth decline, were beyond the scope of this paper, but also warrant further investigation.

• Mäkinen, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, 00790 Helsinki https://orcid.org/0000-0002-1820-6264 E-mail: harri.makinen@luke.fi
• Nöjd, Natural Resources Institute Finland (Luke), Latokartanonkaari 9, 00790 Helsinki E-mail: pekka.nojd@luke.fi
• Helama, Natural Resources Institute Finland (Luke), Ounasjoentie 6, 96200 Rovaniemi, Finland https://orcid.org/0000-0002-9777-3354 E-mail: samuli.helama@luke.fi

Management of Scots pine (Pinus sylvestris L.) in Norway requires a forest growth and yield model suitable for describing stand dynamics of even-aged forests under contemporary climatic conditions with and without the effects of silvicultural thinning. A system of equations forming such a stand-level growth and yield model fitted to long-term experimental data is presented here. The growth and yield model consists of component equations for (i) dominant height, (ii) stem density (number of stems per hectare), (iii) total basal area, (iv) and total stem volume fitted simultaneously using seemingly unrelated regression. The component equations for stem density, basal area, and volume include a thinning modifier to forecast stand dynamics in thinned stands. It was shown that thinning significantly increased basal area and volume growth while reducing competition related mortality. No significant effect of thinning was found on dominant height. Model examination by means of various fit statistics indicated no obvious bias and improvement in prediction accuracy in comparison to existing models in general. An application of the developed stand-level model comparing different management scenarios exhibited plausible long-term behavior and we propose this is therefore suitable for national deployment.

• Kuehne, Norwegian Institute of Bioeconomy Research, Division of Forestry and Forest Resources, P.O. Box 115, NO-1431 Ås, Norway E-mail: christian.kuehne@nibio.no
• McLean, Norwegian Institute of Bioeconomy Research, Division of Forestry and Forest Resources, P.O. Box 115, NO-1431 Ås, Norway E-mail: paul.mclean@nibio.no
• Maleki, Norwegian Institute of Bioeconomy Research, Division of Forestry and Forest Resources, P.O. Box 115, NO-1431 Ås, Norway E-mail: kobra.maleki@nibio.no
• Antón-Fernández, Norwegian Institute of Bioeconomy Research, Division of Forestry and Forest Resources, P.O. Box 115, NO-1431 Ås, Norway E-mail: clara.anton.fernandez@nibio.no
• Astrup, Norwegian Institute of Bioeconomy Research, Division of Forestry and Forest Resources, P.O. Box 115, NO-1431 Ås, Norway E-mail: rasmus.astrup@nibio.no

Colchicine is widely used as a mutagen to induce production of diploid gametes in plants. However, whether colchicine affects induced pollen viability remains unclear. To clarify whether colchicine affected the viability of induced pollen, we induced production of diploid pollen by colchicine, followed by pollen germination in vitro and crossing induced pollen with normal gametes to produce triploid in Populus tomentosa Carrière. The results showed that the predominant meiotic stages and the number of colchicine injections had significant effects on the occurrence rates of induced 2n pollen. When the colchicine injection was given at diakinesis, a significant decrease in the pollen production per bud was observed (p < 0.001). The morphology of the colchicine-induced 2n pollen was similar to that of the natural 2n pollen in its ectexine structure. The pollen germination experiments revealed that there was also no significant difference in germination rates between the induced diploid pollen and natural 2n pollen grains, and 68 triploids were created by crossing colchicine-induced pollen. Our findings revealed that colchicine injection could induce P. tomentosa to produce 2n pollen and will not lead to dysfunction of induced diploid pollen.

• Liu, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083, China; College of Bioscience and Biotechnology, Beijing Forestry University, Beijing 100083, China E-mail: 342767649@qq.com
• Zhang, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083, China; College of Bioscience and Biotechnology, Beijing Forestry University, Beijing 100083, China E-mail: 409192881@qq.com
• Zhou, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083, China; College of Bioscience and Biotechnology, Beijing Forestry University, Beijing 100083, China E-mail: 876034493@qq.com
• Wu, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083, China; College of Bioscience and Biotechnology, Beijing Forestry University, Beijing 100083, China E-mail: 1269485709@qq.com
• Zhang, National Engineering Laboratory for Tree Breeding, Beijing Forestry University, Beijing 100083, China; College of Bioscience and Biotechnology, Beijing Forestry University, Beijing 100083, China E-mail: zhangpd@bjfu.edu.cn

Light is an important environmental factor for all green plants. Its intensity, spectral composition and photoperiod can affect the regulatory pathways in plants that lead to floral initiation. In this report, results are presented from three experiments in which supplemental light with metal halide lamps (250 µmol m^–2 s^–1, 20 hours day^–1, approx. 6 weeks) was tested as a complement to other flowering stimulation treatments (elevated temperature, treatment with gibberellin A₄ and A ₇ (GA_4/7), restricted water supply) applied to potted Picea abies (L.) Karst. in the greenhouse. Flower stimulation in a greenhouse resulted in more floral initiation compared to flower stimulation outdoors. Supplemental light treatment increased floral initiation further, and to a larger extent in female than in male flowers. It also increased the proportion of trees and genotypes that induced reproductive buds. In a practical application of the supplemental light treatment to potted Picea abies breeding material, 90.6% of the clones produced either female or male flowers, or both. A subset of the same material kept outdoors, and thus subjected to natural light and temperatures, produced no flowers despite being treated with GA_4/7 and receiving a restricted water supply. In conclusion, supplemental light treatment facilitates breeding programmes, and seed production of highly improved base material from new selections for vegetative production programmes, to be more efficient.

• Almqvist, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, 751 83 Uppsala, Sweden http://orcid.org/0000-0001-5739-4854 E-mail: curt.almqvist@skogforsk.se

The impacts of weed control, ash fertilization and their interaction were tested for the afforestation of former agricultural peat-based soil with Scots pine (Pinus sylvestris L.) in northern Finland in a factorial arrangement of four treatments. Weed control with herbicides was carried out in July 1 and 2 years from planting, and wood ash (5 Mg ha^–1) was applied in the spring of the 2nd year. Various vegetation, tree growth and nutrient assessments were made over the 21-year study period. Weed control decreased the weed cover by 36–56 percentage points, vegetation height by 4–26 cm and thus shading of seedlings by vegetation for at least 4 years after planting. For the same period, ash fertilization increased vegetation height by 6–15 cm and shading of seedlings. Weed control reduced seedling mortality by 27 percentage points in 21 years, but ash fertilization had no significant effect. Ash fertilization increased foliar potassium and boron concentrations, but its effect declined, and severe K-deficiency was recorded 21 years after planting. Up to the 9th year, weed control had a greater influence on growth than fertilization. Later the significance of fertilization increased due to an aggravated K-deficiency. Stand volume at year 21 for the untreated control plots was 8 m³ ha^–1. Weed control and fertilization increased stand volume by 20 and 35 m³ ha^–1, with a combined effect of 55 m³ ha^–1. The effects of weed control and fertilization were additive and no significant interactions were found. Due to severe K-deficiencies, re-fertilization of all treatments would be necessary for the continued survival and growth of Scots pine.

• Hytönen, Natural Resources Institute Finland (Luke), Management and Production of Renewable Resources, Teknologiakatu 7, FI-67100 Kokkola, Finland http://orcid.org/0000-0001-8475-3568 E-mail: jyrki.hytonen@luke.fi
• Jylhä, Natural Resources Institute Finland (Luke), Green technology, Teknologiakatu 7, FI-67100 Kokkola, Finland E-mail: paula.jylha@luke.fi
• Little, Nelson Mandela Metropolitan University, George Campus, Western Cape, South Africa E-mail: keith.little@nmmu.ac.za

Boom corridor thinning (BCT) has been proposed as a cost-effective technique for biomass thinning (BT) in young dense stands. The objective of this study was to determine how various BCT operations affect stand structure following biomass thinning and to compare the results with conventional selective thinning methods. Two series of field experiments were established; BCT 1-series: Three sites in south of Sweden (9 and 11 m in mean and dominating tree height) with five treatments, including a control, conventional selective thinning and three BCT treatments (1 m and 2 m wide corridors and selective BCT). The second BCT series: Three regions in Sweden (in the north, centre and in the south), with two stand sites in each region with different tree heights (4/9 m and 5/10 m in mean/dominating tree height). Treatments were control, pre-commercial thinning (PCT), conventional selective thinning and BCT (high and low thinning). Following the first biomass thinning, BCT regimes and selective thinning methods resulted in similar stand structures based on the number of possible future crop trees (>80 mm in diameter at breast height). However, BCT maintained a higher diversity of tree sizes as well as more stems per hectare, including deciduous species, than the selective thinning approaches. The stands after BCT should have more vertical complexity, especially when compared to pre-commercial thinning. The structural heterogeneity resulting from BCT may also increase stand biodiversity and ecosystem service values.

• Ahnlund Ulvcrona, Swedish University of Agricultural Sciences (SLU), Department of Forest Biomaterials and Technology (SBT), Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: kristina.ulvcrona@slu.se
• Bergström, Swedish University of Agricultural Sciences (SLU), Department of Forest Biomaterials and Technology (SBT), Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: dan.bergstrom@slu.se
• Bergsten, Swedish University of Agricultural Sciences (SLU), Department of Forest Biomaterials and Technology (SBT), Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: urban.bergsten@slu.se

Despite the numerous studies on year-to-year variation of tree growth, the physiological mechanisms controlling annual variation in growth are still not understood in detail. We studied the applicability of data-driven approach i.e. different regression models in analysing high-dimensional data set including continuous and comprehensive measurements over meteorology, ecosystem-scale water and carbon fluxes and the annual variation in the growth of app. 50-year-old Scots pine stand in southern Finland. Even though our dataset covered only 16 years, it is the most extensive collection of interactions between a Scots pine ecosystem and atmosphere. The analysis revealed that height growth was favoured by high water potential of the tree and carbon gain during the bud forming period and high water potential during the elongation period. Diameter growth seemed to be favoured by a winter with high precipitation and deep snow cover and a spring with high carbon gain. The obtained models had low generalization performance and they would require more evaluation and iterative validation to achieve credibility perhaps as a mixture of data-driven and first principle modeling approaches.

• Kulmala, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: liisa.kulmala@helsinki.fi
• Žliobaitė, Aalto University, Department of Computer Science and Helsinki Institute for Information Technology, P.O. Box 11000, FI-00076 Aalto, Finland; University of Helsinki, Department of Geosciences and Geography, P.O. Box 64, FI-00014 University of Helsinki, Finland E-mail: zliobaite@gmail.com
• Nikinmaa, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: eero.nikinmaa@helsinki.fi
• Nöjd, Natural Resources Institute Finland (Luke), Bio-based business and industry, Tietotie 2, FI-02150 Espoo, Finland E-mail: pekka.nojd@luke.fi
• Kolari, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland; University of Helsinki, Department of Physics, P.O. Box 64, FI-00014 University of Helsinki, Finland E-mail: pasi.kolari@helsinki.fi
• Kabiri Koupaei, University of Helsinki, Department of Forest Sciences, P.O. Box 27, FI-00014 University of Helsinki, Finland E-mail: kourosh.kabiri@helsinki.fi
• Hollmén, Aalto University, Department of Computer Science and Helsinki Institute for Information Technology, P.O. Box 11000, FI-00076 Aalto, Finland; University of Helsinki, Department of Geosciences and Geography, P.O. Box 64, FI-00014 University of Helsinki, Finland E-mail: jaakko.hollmen@aalto.fi
• Mäkinen, Natural Resources Institute Finland (Luke), Bio-based business and industry, Tietotie 2, FI-02150 Espoo, Finland E-mail: harri.makinen@luke.fi

At present, there are no means for reliably comparing the wood fiber contents of different material streams within the paper industry material chain with each other. The aim of this article is to introduce conversion factors that make it possible to quantify the volume of wood expressed in roundwood equivalent (RWE) values for different paper industry-related materials in the material chain. These conversion factors apply to wood pulp, paper, and recovered paper. European data are used in quantifying the paper industry material streams and calculating the RWE conversion factors. The introduced conversion factors can be used to estimate RWE volumes at a global scale. With assumption that paper recycling did not occur and that paper production volume remained unchanged, an additional volume of 666 million m³ RWEs would be required globally per annum to produce 167 million tons of virgin wood pulp to replace 222 million tons of recovered paper utilized by the paper industry in 2010. This volume is approximately the same as 1.6 times the total removal of wood in Europe (EU27), or the total annual removal of wood in the USA, Canada, and Brazil combined.

• Ervasti, Aalto University, Industrial Engineering and Management, Maarintie 8, 02150 Espoo, Finland E-mail: ilervasti@gmail.com

Changes in the structure and development of managed Scots pine (Pinus sylvestris L.) stands with respect to changing environmental conditions were set for the period 1979–2015. The study was conducted in conditions of natural pinewoods and pine-oak sites on five permanent research plots (0.25 ha) in Eastern Bohemia, Czech Republic (CR). Studied forest stands showed positive development of stand structural characteristics related to their diversity, number of regeneration individuals and growth characteristics. The standing volume of regularly distributed tree layer in 2015 was in the range of 320–434 m³ ha^–1, which indicates an increase by 5.9–20.0% over 10 years. Correlation between pine radial increment and the amount of precipitation was generally the strongest one. Positive statistically significant correlation between diameter increment and temperature was demonstrated only for the average March temperature of the current year. Within the CR, study site can be characterised as a medium polluted area both for sulphur and nitrogen, despite this SO₂ concentrations and N deposition in combination with extreme climate events caused severe defoliation in pine stands. Conversely, radial growth was positively significantly correlated with mean NO_x concentrations. Drought mainly in combination with even medium environmental pollution can further worsen the health status of pine stands in lowland areas of Central Europe. Thus, formulation of silvicultural techniques able to mitigate the impact of these stress factors is needed.

• Vacek, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: vacekstanislav@fld.czu.cz
• Vacek, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: vacekz@fld.czu.cz
• Bílek, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: bilek@fld.czu.cz
• Simon, Mendel University in Brno, Faculty of Forestry and Wood Technology, Zemědělská 3, 613 00 Brno, Czech Republic E-mail: jaroslav.simon@mendelu.cz
• Remeš, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: remesj@email.cz
• Hůnová, Czech Hydrometeorological Institute, Na Šabatce 17 143 06 Prague, Czech Republic E-mail: hunova@chmi.cz
• Král, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: kraljan@fld.czu.cz
• Putalová, Czech University of Life Sciences Prague, Faculty of Forestry and Wood Sciences, Kamýcká 129, 165 21 Prague, Czech Republic E-mail: putalova@fld.czu.cz
• Mikeska, University of Hradec Králové, Faculty of Science, Rokitanského 62, 500 03 Hradec Králové, Czech Republic E-mail: Mikeska.Miroslav@uhul.cz

Seed orchards are the link between tree breeding and reforestation. This paper presents data on cone, seed and pollen production and seed quality gathered over 21 years in a Pinus sylvestris (L.) experimental seed orchard containing plots with 14 different combinations of stand density and targeted pruning height. The treatments’ stand densities ranged from 267 to 4000 stems ha^-1, and the target graft heights ranged from 2 to 6 meters. Pollen production began at the same orchard age for all studied combinations of stand density and target height but the level of pollen production per hectare increased more rapidly in treatments with higher stand densities. In treatments with dense spacing, cone and seed production initially increased more rapidly than in treatments with wider spacing, thereby providing an earlier return on investment and a shorter seed production lag time. However, the levels of cone and seed production in such treatments over the entire study period were not appreciably different to those achieved in treatments with wider spacing and higher target height. The treatments did not differ substantially with respect to seed quality. These results show that comparable levels of seed production can be obtained with different combinations of stand density and target height, giving seed orchard owners and managers a wide range of viable management options.

• Almqvist, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: curt.almqvist@skogforsk.se
• Jansson, Skogforsk (The Forestry Research Institute of Sweden), Uppsala Science Park, SE-751 83 Uppsala, Sweden E-mail: gunnar.jansson@skogforsk.se

• Hytönen, Natural Resources Institute Finland, Silmäjärventie 2, FI-69100 Kannus, Finland E-mail: jyrki.hytonen@luke.fi
• Saarsalmi, Natural Resources Institute Finland, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: anna.saarsalmi@luke.fi

• Lindbladh, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: matts.lindbladh@slu.se
• Hedwall, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: per-ola.hedwall@slu.se
• Wallin, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: ida.wallin@slu.se
• Felton, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: annika.felton@slu.se
• Böhlenius, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: henrik.bohlenius@slu.se
• Felton, Southern Swedish Forest Research Centre, SLU – Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden E-mail: adam.felton@slu.se

• Hytönen, Finnish Forest Research Institute, Kannus, Finland E-mail: jyrki.hytonen@metla.fi
• Aro, Finnish Forest Research Institute, Kannus, Finland E-mail: lasse.aro@metla.fi

• Lu, Deparment of Forestry, University of Missouri, Columbia, MO, USA E-mail: ml@nn.us
• Nygren, The Finnish Society of Forest Science, P.O. 18, FI-01301 Vantaa, Finland E-mail: pekka.nygren@metla.fi
• Perttunen, Finnish Forest Research Institute, Vantaa, Finland E-mail: jp@nn.fi
• Pallardy, Deparment of Forestry, University of Missouri, Columbia, MO, USA E-mail: sgp@nn.us
• Larsen, Deparment of Forestry, University of Missouri, Columbia, MO, USA E-mail: drl@nn.us

• Gan, Department of Ecosystem Science and Management, Texas A&M University, Texas, USA E-mail: j-gan@tamu.edu
• Smith, Faculty of Forestry, University of Toronto, Ontario, Canada E-mail: cts@nn.ca

• Mola-Yudego, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: blas.mola@uef.fi

• Hänninen, Finnish Forest Research Institute, Unioninkatu 40 A, FI-00170 Helsinki, Finland E-mail: riitta.hanninen@metla.fi
• Kallio, Finnish Forest Research Institute, Unioninkatu 40 A, FI-00170 Helsinki, Finland E-mail: maarit.kallio@metla.fi

• Kurkela, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: timo.kurkela@metla.fi
• Aalto, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: ta@nn.fi
• Varama, Finnish Forest Research Institute, Vantaa Research Unit, P.O. Box 18, FI-01301 Vantaa, Finland E-mail: mv@nn.fi
• Jalkanen, Finnish Forest Research Institute, Rovaniemi Research Unit, P.O. Box 16, FI-96301 Rovaniemi, Finland E-mail: rj@nn.fi

• Rantala, Finnish Forest Research Institute, Suonenjoki Research Station, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: juho.rantala@metla.fi

• Hoen, Agricultural University of Norway, Dept. of Forest Sciences, P.O. Box 5044, N-1432 Ås, Norway E-mail: hans.hoen@isf.nlh.no
• Eid, Agricultural University of Norway, Dept. of Forest Sciences, P.O. Box 5044, N-1432 Ås, Norway E-mail: te@nn.no
• Økseter, Agricultural University of Norway, Dept. of Forest Sciences, P.O. Box 5044, N-1432 Ås, Norway E-mail: po@nn.no

• Roos, Swedish University of Agricultural Sciences, Department of Forest Management and Products, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: anders.roos@sh.slu.se
• Flinkman, Swedish University of Agricultural Sciences, Department of Forest Management and Products, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: mf@nn.se
• Jäppinen, Swedish University of Agricultural Sciences, Department of Forest Management and Products, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: aj@nn.se
• Warensjö, Swedish University of Agricultural Sciences, Department of Forest Management and Products, P.O. Box 7060, SE-750 07 Uppsala, Sweden E-mail: mw@nn.se

• Nuutinen, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: tuula.nuutinen@metla.fi
• Hirvelä, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: hh@nn.fi
• Hynynen, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: jh@nn.fi
• Härkönen, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: kh@nn.fi
• Hökkä, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: hh@nn.fi
• Korhonen, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: ktk@nn.fi
• Salminen, Finnish Forest Research Institute, Joensuu Research Station, P.O. Box 68, FIN-80101 Joensuu, Finland E-mail: os@nn.fi

• Johansson, Swedish University of Agricultural Sciences, Department of Forest Management and Products, P.O. Box 7060, S-750 07 Uppsala, Sweden E-mail: tord.johansson@sh.slu.se

Abiotic stress is one of the major factors in reducing plant growth, development, and yield production by interfering with various physiological, biochemical, and molecular functions. In particular, abiotic stress such as salt, low temperature, heat, drought, UV-radiation, elevated CO2, ozone, and heavy metals stress is the most frequent study in Betula platyphylla Sukaczev. Betula platyphylla is one of the most valuable tree species in East Asia facing abiotic stress during its life cycle. Using transgenic plants is a powerful tool to increase the B. platyphylla abiotic stress tolerance. Generally, abiotic stress reduces leaves water content, plant height, fresh and dry weight, and enhances shed leaves as well. In the physiological aspect, salt, heavy metal, and osmotic stress disturbs seed germination, stomatal conductance, chlorophyll content, and photosynthesis. In the biochemical aspect, salt, drought, cold, heat, osmotic, UV-B radiation, and heavy metal stress increases the ROS production of B. platyphylla cells, resulting in the enhancement of enzymatic antioxidant (SOD and POD) and non-enzymatic antioxidant (proline and AsA) to reduce the ROS accumulation. Meanwhile, B. platyphylla upregulates various genes, as well as proteins to participate in abiotic stress tolerance. Based on recent studies, several transcription factors contribute to increasing abiotic stress tolerance in B. platyphylla, including BplMYB46, BpMYB102, BpERF13, BpERF2, BpHOX2, BpHMG6, BpHSP9, BpUVR8, BpBZR1, BplERD15, and BpNACs. These transcription factors bind to different cis-acting elements to upregulate abiotic stress-related genes, resulting in the enhancement of salt, drought, cold, heat, osmotic, UV-B radiation, and heavy metal tolerance. These genes along with phytohormones mitigate the abiotic stress. This review also highlights the candidate genes from another Betulacea family member that might be contributing to increasing B. platyphylla abiotic stress tolerance.

• Ritonga, State Key Laboratory of Tree Genetics and Breeding, Forestry College, Northeast Forestry University, Harbin 150040, China E-mail: ritongafaujiah@ymail.com
• Ngatia, College of Wildlife and Protected Areas, Northeast Forestry University, Harbin 150040, China E-mail: jacob.ngatia3@gmail.com
• Song, State Key Laboratory of Tree Genetics and Breeding, Forestry College, Northeast Forestry University, Harbin 150040, China E-mail: 13359850710@163.com
• Farooq, College of Life Science, Northeast Forestry University, Harbin 150040, China E-mail: uf@nn.ch
• Somadona, College of Agriculture, Riau University, Pekanbaru 28293, Indonesia E-mail: sonia_hut@yahoo.co.id
• Lestari, Forestry Major, College of Agriculture, Mataram University, Mataram 83125, Indonesia E-mail: atlestari@unram.ac.id
• Chen, State Key Laboratory of Tree Genetics and Breeding, Forestry College, Northeast Forestry University, Harbin 150040, China E-mail: chensu@nefu.edu.cn

This study compares the responses of two Swedish 5-year predictive stand-level functions with the observed responses in 721 fertilization experiment plots in Norway fertilized with nitrogen (N). All plots are single-species consisting of Norway spruce (Picea abies (L.) H. Karst.) or Scots pine (Pinus sylvestris L.) fertilized with ammonium nitrate (AN) or urea. The correlations between the observed and the two predicted responses were 0.34–0.40 for all plots taken together. One response function performed well on average, but underestimated the response in pine plots and overestimated the response in spruce plots. The second function overpredicted the response on the full dataset, in spruce plots and old forest, but performed well in pine plots. Both functions overestimated the growth response in high-productive plots. Higher N deposition in Norway than in Sweden may count for parts of the deviations. Testing of fertilization functions on new datasets is rare, but important part of the evaluation of functions. As the functions are not well fit for predicting the growth response in spruce and high-productive plots in our sample, new functions that include N deposition are welcome.

• Sjølie, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway E-mail: hanne.sjolie@nmbu.no
• Sørlie, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway E-mail: hans.asbjorn.sorlie@slf.dep.no
• Tveite, Norwegian Forest and Landscape Institute, P.O. Box 115, NO-1431 Ås, Norway E-mail: bjorn.tveite@skogoglandskap.no
• Solberg, Department of Ecology and Natural Resource Management, Norwegian University of Life Sciences, NO-1432 Ås, Norway E-mail: birger.solberg@nmbu.no

• Ahnlund Ulvcrona, SLU, Forest Biomaterials and Technology, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: kristina.ulvcrona@slu.se
• Karlsson, SLU, Forest Biomaterials and Technology, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: lars.karlsson@slu.se
• Backlund, SLU, Forest Biomaterials and Technology, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: ingegerd.backlund@slu.se
• Bergsten, SLU, Forest Biomaterials and Technology, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: urban.bergsten@slu.se

• Backlund, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: ingegerd.backlund@slu.se
• Bergsten, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd, SE-901 83 Umeå, Sweden E-mail: urban.bergsten@slu.se

• 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