Current issue: 53(2)

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Silva Fennica 1926-1997
Acta Forestalia Fennica

Articles containing the keyword 'rotation'.

Category: Research article

article id 10034, category Research article
Yan Ao, Peter M. Hirst, Guolei Li, Yahui Miao, Runzhe Zhang. (2018). Combined effects of provenance and slow-release fertilizer on nursery and field performance of yellowhorn seedlings. Silva Fennica vol. 52 no. 5 article id 10034.
Highlights: Combining slow-release fertilizer (SRF) and provenance in the nursery has large effects on most seedling characteristics in yellowhorn; Stem and root P contents in the nursery, and height at the end of the second growing season (T3) in the field were mainly affected by provenance; Higher rates of SRF tended to increase root N, stem and root P contents in the nursery, diameter, and biomass at T3; The combination of AQ provenance with 120–200 mg N seedling–1 SRF yielding better nursery and field performance was recommended.

Yellowhorn (Xanthoceras sorbifolium Bunge) has been widely planted for biodiesel production in China, but has frequently shown poor field performance. Container-grown yellowhorn seedlings originating from three Chinese provenances, Wengniute Qi (WQ), Alukeerqin Qi (AQ), and Shanxian (SX), were fertilized with slow-release fertilizer (SRF) at 40, 80, 120, 160 or 200 mg N seedling–1. Tree growth, survival and nutrient content were measured after one year’s growth in a greenhouse followed by two years in a field site. Plants from AQ and SX tended to have higher stem and root P contents in the nursery. Higher rates of SRF increased root N, and stem and root P contents. After one year in the nursery, there were a number of interactions between provenance and SRF for plant growth responses and nutrient content in the nursery, however after two years of additional growth in the field, plants from the different provenances generally responded similarly to applied SRF in the nursery, with few interactions. Final plant height was approximately 10% lower in trees from provenance SX but was not affected by application of SRF. Conversely, final trunk diameter and stem and root biomass were unaffected by provenance but increased with higher rates of applied SRF. Our results indicate that application of SRF may be a useful tool to nutrient load yellowhorn in the nursery and facilitate transplanting performance in the field. Overall, optimal nursery and field performance of yellowhorn were observed in provenance AQ at 120–200 mg N seedling–1 SRF. We suggest that growers consider a wider range of yellowhorn provenances and SRF rates (above 200 mg N seedling–1) to yield even better growth response.

  • Ao, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing Forestry University, 35 East Qinghua Road, Haidian District, Beijing 100083, China ORCID ID:E-mail: (email)
  • Hirst, Department of Horticulture and Landscape Architecture, Purdue University, West Lafayette, IN 47907, USA ORCID ID:E-mail:
  • Li, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing Forestry University, 35 East Qinghua Road, Haidian District, Beijing 100083, China ORCID ID:E-mail:
  • Miao, Key Laboratory for Silviculture and Conservation, Ministry of Education, Beijing Forestry University, 35 East Qinghua Road, Haidian District, Beijing 100083, China ORCID ID:E-mail:
  • Zhang, College of Forestry, Beijing Forestry University, 35 East Qinghua Road, Haidian District, Beijing 100083, China ORCID ID:E-mail:
article id 9985, category Research article
Antonín Martiník, Robert Knott, Jan Krejza, Jakub Černý. (2018). Biomass production of Betula pendula stands regenerated in the region of allochthonous Picea abies dieback. Silva Fennica vol. 52 no. 5 article id 9985.
Highlights: Biomass equations for individual components of above-ground wood biomass estimation are presented for stands at the age of 4, 8, 17 and 22 years; Peak of the mean annual increment was found at the age from 15 to 20 years and reached over 5.0 t ha–1 y–1 of dry biomass; The share of the stem to the total biomass increased with stand age.

The paper deals with production of above-ground biomass of silver birch (Betula pendula Roth) stands in the Czech Republic. One-year biomass dynamics was studied within chronosequence of birch stands at the age of 4–5, 8–9, 17–18 and 22–23 years. With the exception of the youngest stand, which was established by seeding, all experimental birch stands were regenerated naturally after the allochthonous spruce stands. Above-ground biomass (AB) was calculated from plot inventory data and biomass equations were parameterized from destructive sampling of biomass component of sampled trees. Results reveal that the peak of the mean annual increment (MAIABtotal) of birch stands can be expected at the age from 15 to 20 years. Additionally, the stand age, the value of basal area (BA) should be considered as a predictor of stand productivity. If the value of BA varied from 25 to 35 m2 ha–1, the MAI of the birch stands reached the range from 5.0 to 6.5 t of dry biomass per ha y–1 at the age ranging between 15 and 25 years. The stem/branch proportion increased with stand age, the stem relative proportion ranging from 75 to 90% of total above-ground biomass. According to the results of this study, birch stand biomass production and utilization is one of the approaches in terms of forest recovery management in large disturbed areas. Although, no silvicultural treatments were occurred in all analysed stands, the pre-commercial thinning method could increase stand productivity and stability as well.

  • Martiník, Department of Silviculture, Faculty of Forestry and Wood Technology, Mendel University in Brno, 613 00 Brno, Czech Republic ORCID ID: E-mail: (email)
  • Knott, Department of Silviculture, Faculty of Forestry and Wood Technology, Mendel University in Brno, 613 00 Brno, Czech Republic ORCID ID:E-mail:
  • Krejza, Global Change Research Institute CAS, v.v.i., Bělidla 4a, 603 00 Brno, Czech Republic ORCID ID:E-mail:
  • Černý, The Forestry and Game Management Research Institute, Research Station at Opočno, Na Olivě 550, 517 73 Opočno, Czech Republic ORCID ID:E-mail:
article id 1448, category Research article
Andrew McEwan, Natascia Magagnotti, Raffaele Spinelli. (2016). The effects of number of stems per stool on cutting productivity in coppiced Eucalyptus plantations. Silva Fennica vol. 50 no. 2 article id 1448.
Highlights: Double- and single stem coppice stools were harvested mechanically; Stem size had the strongest impact on productivity; An experienced operator performed equally well with both stool treatments; Cost was ~10% higher with double stems for the less experienced operator; Operator experience may play a major role when cutting coppice stands.

A time study was conducted to determine whether stem crowding had any impact on harvester productivity in Eucalyptus grandis stands. This represents an important element when trying to balance the advantages and disadvantages of coppice management in fast growing plantations designated for mechanized harvesting (i.e. machine felling, delimbing, debarking and cross-cutting). The study material consisted of 446 coppice stems, half of which grew as single stems per stool and half as double stems per stool as a result of different coppice reduction strategies. The dataset was balanced and randomized, with both subsets replicating exactly the same stem size distribution and the single and double stems alternating randomly. Harvester productivity ranged between 6 and 50 m3 under bark per productive machine hour, following the variation of tree diameter from 10 to 40 cm at breast height (1.37 m according to South African standards). Regression analysis indicated that both tree size and stem crowding (e.g. one or two stems per stool) had a significant effect on harvester productivity, which increased with stem size and decreased with stem crowding. However, operator experience may overcome the effect of stem crowding, which was not significant when the harvester was manned by a highly experienced operator. In any case, the effect of stem size was much greater than that of stem crowding, which resulted in a cost difference of less than 10%. However, this figure excludes the possible effects of stem crowding on volume recovery and stem development, which should be addressed in the future.

  • McEwan, Nelson Mandela Metropolitan University – George Campus, Saasveld, 6529, George, South Africa ORCID ID:E-mail:
  • Magagnotti, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino (FI), Italy ORCID ID:E-mail:
  • Spinelli, CNR IVALSA, Via Madonna del Piano 10, I-50019 Sesto Fiorentino (FI), Italy ORCID ID:E-mail: (email)
article id 459, category Research article
Tomi Tulokas, Jawdat Tannous. (2010). Research method and improvement of log rotation in sawmills. Silva Fennica vol. 44 no. 1 article id 459.
Log rotation studies were performed at 14 Finnish sawmills during the years 2003–2005. In the investigation of automatic log rotation, the materialized degree of log rotation for each log was calculated from photos captured from a digital video recording. Rotation errors (D) for individual logs and again the accuracy of the automatic log rotator was determined from optimized angle values of the log measuring system and materialized angle values calculated from the still photos. The accuracy of the log rotation varied considerably between sawmills. The rotation error average of the automatic log rotation varied from –23.6° to +11.4°. This means that in some cases the logs were under-rotated and in some they were over-rotated, on an average. Standard deviation of the rotation error (s) of the automatic rotator varied from 4.4° to 22.9°. The results of the simulation indicated that the performance of the log rotation system can be improved by adjusting the log rotator control. In addition to the zero degree error on an average rotation (or near to zero), the corrected values have a significantly smaller standard deviation of the rotation error, and the number of correct rotations was significantly higher compared to the situation before the adjusted rotation commands. At Sawmill 1, standard deviation of the rotation error was reduced by 40.9% from 14.9 degrees to 8.8 degrees. At the same time the number of correct rotations (–10°≤ D ≤ +10°) increased 4.0 fold from 20.1% to 79.4%. At Sawmill 2, standard deviation of the rotation error was reduced by 23.8% from 10.5 degrees to 8.0 degrees. At this sawmill, the rate of accepted rotations increased 1.9 fold from 42.6% to 81.0%. According to previous research, 2.5° decrease in standard deviation of the rotation error (from 10.5 to 8.0°) in square sawing means about 0.5% increase in value yield. For example with 10 million Û annual sales of sawn timber this means 50 000 Û extra profit.
  • Tulokas, Centre for Timber Engineering, Edinburgh Napier University, 10 Colinton Road, Edinburgh EH10 5DT, UK ORCID ID:E-mail: (email)
  • Tannous, School of Engineering and the Built Environment, Edinburgh Napier University, 10 Colinton Road, Edinburgh EH10 5DT, UK ORCID ID:E-mail:
article id 163, category Research article
Blas Mola-Yudego. (2010). Regional potential yields of short rotation willow plantations on agricultural land in Northern Europe. Silva Fennica vol. 44 no. 1 article id 163.
The development of short rotation forestry for bioenergy requires accurate and reliable yield estimates. This paper analyses the current, expected and potential regional productivity of short rotation willow plantations for six countries in Northern Europe. The estimations for present productivity are based on empirical models, using data regarding management, and local productivity based on the regional cereal yields. The estimates of expected yield rely on the current trends of yield increase from commercial willow plantations in the region. The estimates for potential yield are based on climatic restrictions. The results show potential average yields of 9.5, 6.8, 7.9, 9.0, 9.3, and 8.0 odt ha–1 yr–1 for Denmark, Finland, Estonia, Latvia, Lithuania and Sweden, respectively. The results of the study also show that there is a wide regional variation between the different countries. In Denmark, Finland and Sweden there is a convergence between the future forecasts and the climatic potential yields in the areas of high productivity. The Baltic countries seem to present lower estimates of present productivity, reflecting possible socio-economic restrictions, although they show a high biomass potential. The methods presented in this study can be further developed in other areas where willow cultivation is considered, and can serve as a basis for future economic considerations.
  • Mola-Yudego, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland ORCID ID:E-mail: (email)
article id 171, category Research article
Takuo Nagaike. (2009). Snag abundance and species composition in a managed forest landscape in central Japan composed of Larix kaempferi plantations and secondary broadleaf forests. Silva Fennica vol. 43 no. 5 article id 171.
Larix kaempferi is the main plantation species in the low-snow, cool-temperate zone of Japan. I studied L. kaempferi plantations of various stand ages in central Japan to examine and compare the effect of stand age on the abundance, size, and species composition of snags (standing dead trees) compared to those in secondary broadleaf forests. Plantations that were older than the standard rotation age had more and larger snags than young plantations, and the species diversity of snags was positively correlated with stand age. Because the density of living planted L. kaempferi showed little correlation with snag variables, whereas that of naturally regenerated tree species was positively correlated with snag variables, the density dependence of snag occurrence was stronger in naturally regenerated trees than in planted L. kaempferi. Snag species that were positively correlated with stand age were the main species in secondary broadleaf forests in this area. Basal area, density, and number of species of snags in standard-rotation plantations were significantly lower than in long-rotation plantations and secondary broadleaf forests. Long-rotation plantations are useful for retaining snags compared to standard-rotation plantations.
  • Nagaike, Yamanashi Forest Research Institute, Masuho, Yamanashi 400-0502, Japan ORCID ID:E-mail: (email)
article id 272, category Research article
Jonas Rönnberg, Mattias Berglund, Ulf Johansson. (2007). Incidence of butt rot at final felling and at first thinning of the subsequent rotation of Norway spruce stands in south-western Sweden. Silva Fennica vol. 41 no. 4 article id 272.
The incidence of butt rot in Norway spruce stands at final felling and at first thinning of the subsequent rotation was investigated at 20 sites in south-western Sweden. There was a negative correlation between the incidence at first thinning and the basal area of decayed trees at final felling. Using incidence of decay or basal area of decayed trees to predict disease transfer between rotations is difficult and requires the inclusion of several factors, making predictions uncertain. The level of infection found at final felling in this study varied between 7 and 71.8%, indicating that the risk of spore infection transfer to the next rotation was probably quite low. Long-term experiments are required to reveal the effect of stump treatment on disease transmission between rotations.
  • Rönnberg, SLU, Southern Swedish Forest Research Centre, P.O. Box 49, SE-23053 Alnarp, Sweden ORCID ID:E-mail: (email)
  • Berglund, SLU, Southern Swedish Forest Research Centre, P.O. Box 49, SE-23053 Alnarp, Sweden ORCID ID:E-mail:
  • Johansson, Tönnersjöheden Experimental Forest, P.O. Box 17, SE-31038 Simlångsdalen, Sweden ORCID ID:E-mail:
article id 294, category Research article
Ülle Püttsepp, Krista Lõhmus, Andres Koppel. (2007). Decomposition of fine roots and α-cellulose in a short rotation willow (Salix spp.) plantation on abandoned agricultural land. Silva Fennica vol. 41 no. 2 article id 294.
Decomposition of fine roots (<1 mm in diameter) of the clones of Salix viminalis, S. dasyclados and α-cellulose sheets (50 x 10 x 1 mm) was studied in a 6-years old Salix spp. plantation established on abandoned agricultural land in Estonia. The substrates were incubated in litterbags (mesh size 0.14 mm) in 5–10 cm topsoil, in non-fertilised plots for one year. Changes in the ash-free weight of the fine roots were best described by negative exponential models (S. viminalis R2 = 0.98, S. dasyclados R2 = 0.96), and by a linear model for α-cellulose (R2 = 0.63). The sheets of α-cellulose decomposed roughly twice as rapidly as the fine roots (S. viminalis k = 0.325, S. dasyclados k = 0.165). The remaining (of the initial) ash-free weights of the fine roots were 73.3 ± 0.8% (mean ± SE) and 85.8 ± 2.2% respectively, and of the α-cellulose 35.9 ± 8.5%, in the end of the one year of decomposition. The amount of acid detergent (AD) lignin in the fine-roots of S. viminalis increased significantly and did not change in S. dasyclados, suggesting higher activity of microbial decomposers in the first substrate. Of the studied quality parameters, the AD lignin was the major factor determining the different rate of decomposition of the fine roots of S. viminalis and S. dasyclados. Nitrogen was recycled in the fine root sub-system in both Salix species. This knowledge can be applied in the management of Salix plantations, aimed at bioenergy production.
  • Püttsepp, Department of Ecology, Swedish University of Agricultural Sciences, P.O. Box 7072, SE-75007 Uppsala, Sweden; Estonian University of Life Sciences, Kreuzwaldi 64, Tartu 51014, Estonia ORCID ID:E-mail: (email)
  • Lõhmus, Institute of Geography, University of Tartu, Vanemuise 46, Tartu 51014, Estonia ORCID ID:E-mail:
  • Koppel, Estonian University of Life Sciences, Kreuzwaldi 64, Tartu 51014, Estonia ORCID ID:E-mail:
article id 637, category Research article
Hirofumi Kuboyama, Hiroyasu Oka. (2000). Climate risks and age-related damage probabilities – effects on the economically optimal rotation length for forest stand management in Japan. Silva Fennica vol. 34 no. 2 article id 637.
We estimated the damage probability according to age class and major climatic disasters based on ‘Statistical Yearbook of National Forest Insurance’ from 1960 to 1996. The probability of snow damage is high for young stands, then gradually decreases with age. On the other hand, the risk of wind damage gradually increases with age. Decisions about rotation age should be based on the distribution of damage probability with stand age. Risk of damage has two contradictory effects on the optimal rotation period; one is that the rotation-shortening effect caused by risk of damage around harvest age; another is the rotation-extending effect due to decrease of rent by the risk of damage through the raising period. Change of optimal rotation depends on the relative magnitude of these effects. We examine this by calculating land expectation value (LEV) using a simulation model with the empirical damage probability, price and cost. Change of the optimal rotation period obtained from the national average damage probability is not significant. However, the optimal rotation is shorter in high wind risk areas and is longer in high snow risk areas. It is because the damage probability for a mature stand is high in the case of wind and low in the case of snow. In addition, the extent of decrease in LEV is smaller for wind than for snow. The results of simulation based on empirical data confirm that the optimal rotation period can become either shorter or longer through incorporating risk in decision making, depending on the damage probability distribution with stand age.
  • Kuboyama, Forestry and Forest Products Research Institute Tohoku Center, Nabeyashiki 72, Shimo-Kuriyagawa, Morioka, Iwate, 020-0123 Japan ORCID ID:E-mail: (email)
  • Oka, Forestry and Forest Products Research Institute Tohoku Center, Nabeyashiki 72, Shimo-Kuriyagawa, Morioka, Iwate, 020-0123 Japan ORCID ID:E-mail:

Category: Research note

article id 1126, category Research note
Rebecka Mc Carthy, Per Magnus Ekö, Lars Rytter. (2014). Reliability of stump sprouting as a regeneration method for poplars: clonal behavior in survival, sprout straightness and growth. Silva Fennica vol. 48 no. 3 article id 1126.
Highlights: Clonal differences were found in stump sprout survival; Clonal differences occurred in sprout straightness; It is uncertain if the ability to produce a high number of stump sprouts is beneficial.
The interest in poplars (Populus spp.) has increased globally as a result of the current incentive to expand the use of biomass for energy. So far, knowledge about poplar stump sprouting is generally poor. The objective of this study was to investigate poplar stump sprouting as regeneration method in harvested plantations. A 19-year-old poplar clonal test, including 23 different clones, on former arable land was harvested in the winter. After one year, stumps were assessed for sprout survival, sprout straightness, number of sprouts, sprout height and basal diameter. Differences between clones were found for survival and sprout straightness. Clonal differences were also found in mean size of sprouts (basal diameter and height). However, no differences were found between clones when comparing size of the tallest sprout or number of sprouts produced on stumps. This study indicates that stump sprouts from various poplar clones differ in survival, sprout straightness and mean growth, which should be taken into account when planning for the next tree generation. The study needs to be complemented with other studies to better assess sprouting characteristics for different clones.
  • Mc Carthy, Forestry Research Institute of Sweden, Skogforsk, Ekebo 2250, SE-268 90 Svalöv, Sweden & Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail: (email)
  • Ekö, Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, P.O. Box 49, SE-230 53 Alnarp, Sweden ORCID ID:E-mail:
  • Rytter, Forestry Research Institute of Sweden, Skogforsk, Ekebo 2250, SE-268 90 Svalöv, Sweden ORCID ID:E-mail:
article id 914, category Research note
Ingegerd Backlund, Urban Bergsten. (2012). Biomass production of dense direct-seeded lodgepole pine (Pinus contorta) at short rotation periods. Silva Fennica vol. 46 no. 4 article id 914.
Lodgepole pine (Pinus contorta) is a fast-growing species that is suitable for producing woody biomass in Nordic countries. Direct seeding of this species is cheaper than planting and creates dense, stable stands. The objective of this study was to quantify the stem volume and biomass production of direct seeded lodgepole pine stands grown under different site conditions with different stem densities, at an age that would permit extensive harvesting of biomass. A circle-plot inventory was performed in 16 of the oldest direct seeded lodgepole pine stands in mid-northern Sweden. Stemwood production of almost 200 m3/ha was achieved on average on the best sites, rising to about 300 m3/ha for the best circle-plots within 30 years of direct seeding despite the fact that pre-commercial thinning was made once or twice. This corresponds to 100 and 140 tons of dry weight biomass/ha, respectively. Higher stand stem densities (≥3000 st/ha) yielded more biomass with only slight reductions in diameter at breast height. The development of stem volume with respect to dominant height in direct seeded stands was becoming comparable to that in planted stands with similar spacing. It therefore seems that there is an unutilized potential for cost-effectively growing lodgepole pine in dense stands for biomass production after direct seeding. It may be possible to devise regimes for short(er) rotation forestry that would yield substantial amount of inexpensive biomass for biorefineries within a few decades.
  • Backlund, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd, SE-901 83 Umeå, Sweden ORCID ID:E-mail: (email)
  • Bergsten, Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Skogsmarksgränd, SE-901 83 Umeå, Sweden ORCID ID:E-mail:

Category: Article

article id 7473, category Article
Kustaa Kallio. (1957). Käenkaali-mustikkatyypin kuusikoiden kehityksestä Suomen lounaisosassa. Acta Forestalia Fennica vol. 66 no. 3 article id 7473.
English title: On the development of spruce forests of the Oxalis-Myrtillus site type in the south-west of Finland.

In this investigation was studied 1) Volume growth and yield of timber in managed Norway spruce (Picea abies (L.) Karst.) forests under different rotations. 2) Value growth, net forest income and soil expectation value of managed forests under different rotations, and 3) The rotations of spruce forests managed on different rotation principles. The data was collected from Oxalis-Myrtillus type forests in South-West Finland.

Two developmental series of stands were constructed for the research, one of which were of better sites than the other. Sample plots were pure, even-aged spruce stands in well-managed forests. The stands had been thinned from below. The age varied from 25-30 years to the age of final cutting.

According to the study, in the artificially regenerated spruce stands the highest mean annual volume growth, 9.7 m3/ha, and also the highest net annual income of 14,50 Finnish marks/ha (calculated from average stumpages) was reached in rotation of 70 years. In the other managed spruce forests a mean annual volume growth of 6.6-8.8 m3/ha and the net annual income of 10,500-14,500 Finnish marks/ha were reached in the rotation of 70-100 years. The rotation for the maximum mean annual volume growth varied in the different series between 67-92 years. The maximum mean annual forest rent was only achieved in series B in a rotation of about 100 years, and in a naturally normal stand in a rotation of about 120 years. The intensity of thinnings and silviculture had a greater effect on value growth and on net income than on volume growth.

The PDF includes a summary in English.

  • Kallio, ORCID ID:E-mail:
article id 7219, category Article
W. E. A. Hiley. (1929). A financial analysis of a money yield table. Acta Forestalia Fennica vol. 34 no. 6 article id 7219.

The aim of the study was to compare the theories of Soil Rental and Forest Rental. There is a controversy between the theories that is associated to the issues of length of rotation and grade of thinning. For the basis of the analysis was chosen Schwappach’s money yield table for Scots pine (Pinus sylvestris L.) Quality II, published in 1908. Based on the table was calculated the financial yield, the net annual income from a normal forest managed on various rotations, the capital value, and the net income expressed as the rate of interest on the capital value. According to the study, it is the rotation at which any money invested in lengthening the rotation still further, would yield no return. In the case of Scots pine, the highest income is achieved approximately with a rotation of 140 years, and the income per hectares would decrease if longer rotations were used, though the capital invested would increase.

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

  • Hiley, ORCID ID:E-mail:
article id 5551, category Article
Jyrki Hytönen, Pekka Rossi, Anna Saarsalmi. (1995). Biomass production and nutrient uptake of short-rotation plantations. Silva Fennica vol. 29 no. 2 article id 5551.

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, ORCID ID:E-mail:
  • Rossi, ORCID ID:E-mail:
  • Saarsalmi, ORCID ID:E-mail:
article id 5550, category Article
Jyrki Hytönen. (1995). Effect of repeated fertilizer application on the nutrient status and biomass production of Salix ’Aquatica’ plantations on cut-away peatland areas. Silva Fennica vol. 29 no. 2 article id 5550.

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, ORCID ID:E-mail:
article id 5544, category Article
Jyrki Hytönen. (1995). Effect of fertilizer treatment on the biomass production and nutrient uptake of short-rotation willow on cut-away peatlands. Silva Fennica vol. 29 no. 1 article id 5544.

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, ORCID ID:E-mail:
article id 5532, category Article
Anu Honkanen. (1994). Selection of Salix myrsinifolia clones for biomass forestry in Finland. Silva Fennica vol. 28 no. 3 article id 5532.

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, ORCID ID:E-mail:
article id 5531, category Article
Anneli Viherä-Aarnio, Anna Saarsalmi. (1994). Growth and nutrition of willow clones. Silva Fennica vol. 28 no. 3 article id 5531.

Growth and nutrition of 20 clones representing different species and interspecific hybrids of willows (Salix spp.) growing on an abandoned field were studied. There were highly significant differences between the clones as regards the survival, number of sprouts per stool, sprout mean height and diameter and stem biomass production per stool. The differences between the clones in the concentration of all nutrients in both the leaves and stems were highly significant. 

  • Viherä-Aarnio, ORCID ID:E-mail:
  • Saarsalmi, ORCID ID:E-mail:
article id 5342, category Article
Ilari Lumme, Timo Törmälä. (1988). Selection of fast-growing willow (Salix spp.) clones for short-rotation forestry on mined peatlands in northern Finland. Silva Fennica vol. 22 no. 1 article id 5342.

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, ORCID ID:E-mail:
  • Törmälä, ORCID ID:E-mail:
article id 5315, category Article
Seppo Kellomäki, Matti Seppälä. (1987). Simulations on the effects of timber harvesting and forest management on the nutrient cycle and productivity of Scots pine stands. Silva Fennica vol. 21 no. 2 article id 5315.

Effects of varying rotation, thinning, fertilization and harvest intensity on the productivity and nitrogen cycle of Scots pine (Pinus sylvestris L.) stand were studied on the basis of computer simulation. The increasing intensity of management increased the loss of nitrogen in the cycle. Short rotation, associated with early thinning by means of the whole tree harvest, proved to be especially detrimental regarding the productivity of the forest ecosystem. Fertilization associated with thinnings is of great importance in maintaining the productivity of a forest ecosystem during an intensive timber harvest.

The PDF includes an abstract in Finnish.

  • Kellomäki, ORCID ID:E-mail:
  • Seppälä, ORCID ID:E-mail:
article id 5309, category Article
Veli Pohjonen. (1987). Salix "Aquatica Gigantea" and Salix x dasyclados Wimm. in biomass willow research. Silva Fennica vol. 21 no. 2 article id 5309.

Salix 'Aquatica Gigantea', widely experimented and promising species for temperate zone short rotation forestry, has since 1950 recorded in Finland 23 times with different clone numbers. Salix x dasyclados Wimm., by morphological, cultivational and productivity characteristics similar willow has been recorded 16 times.

The nomenclature and origin of both willows have remained unclear in field research. Recent observations, based on morphological analyses and chromosome studies suggest that ’Aguatica gigantea’ and most S. x dasuclados clones can be collected under one Siberian species: Salix burjatica Nasarov. The true Salix x dasyclados Wimm. is a female hybrid S. x viminalis x cinerea, famous West-European basket willow that has been very little experimented in Finland.

The PDF includes an abstract in Finnish.

  • Pohjonen, ORCID ID:E-mail:
article id 4923, category Article
Olli Makkonen. (1975). Puiden lyhytkiertoviljelyn varhaishistoriaa. Silva Fennica vol. 9 no. 3 article id 4923.
English title: Early history of short-rotation forestry.

In the first place the term short-rotation forestry is being used in the sense of intensive tree growing during a short rotation time using reproduction by coppice shoots from broad-leaved tree material which has been specially bred for this purpose, or of producing fast-growing varieties from planted stock during the course of somewhat longer rotation time (maximum 20 years). However, short-rotation forestry as such has already a long history.

In the Fertile Crescent in ancient Egypt grew no tree species suitable for short-rotation production, but reeds and bulrushes were used for the same purpose as willow-twigs, e.g. wickerwork or binding. At least in the Fertile Crescent reed harvesting using a rotation of one year was practiced already very long ago. The earliest information about coppice-shoot cultivation is found in Greek literature, but it was the Romans who developed short-rotation forestry based on the trees’ capacity of reproducing through coppice shoots into an extensive economic activity. Willows were by far the most important species used. Twigs intended for wickerwork were harvested once a year and thicker material, to be used for support and in basket framework, every fourth year. Chestnut and oak were used for the production of slightly thicker poles employing a longer rotation. Cypress poles were produced from seedlings using a rotation time of 12–13 years. Roman scholars give us plenty of information concerning the tending of plantations in short-rotation forestry.

The PDF includes a summary in English.

  • Makkonen, ORCID ID:E-mail:
article id 4901, category Article
Veli Pohjonen. (1974). Istutustiheyden vaikutus eräiden lyhytkiertoviljelyn puulajien ensimmäisen vuoden satoon ja pituuskasvuun. Silva Fennica vol. 8 no. 2 article id 4901.
English title: Effect of spacing on the first-year yield and height increment of some species undergoing short rotation culture.

The effect of spacing on the first-year yield and height increment of Alnus incana (L.) Moench, Populus tremula L. x Populus tremuloides Michx. (Populus x wettsteinii), Salix ’Aquatica Gigantea’, and Salix phylicifolia L. was studied at the Arctic Circle Agricultural Experimental Station in Northern Finland. S. ’Aquatica Gigantea’ gave yields which were twice as high as those of the other species in the study. The highest yields were of the order of 60 tons per hectare (fresh yield including foliage). The annual height growth in S. ’Aquatica Gigantea’ was about 100 cm, in the others about 30–50 cm. S. ’Aquatica Gigantea’ had a maximal height growth when the distance between the seedlings was 25 cm.

The PDF includes a summary in English.

  • Pohjonen, ORCID ID:E-mail:
article id 4774, category Article
Pekka Kilkki. (1968). Some economic aspects of growing forest stands. Silva Fennica vol. 2 no. 4 article id 4774.

The aim of this paper was that of studying the optimum growing schedules of forest stands, with the classic Faustmann formula as starting point. The study is mainly theoretical in nature. The study shows that the net present-value of the future revenues from a forest stand can be calculated, not only by means of the harvesting revenues, but also by a more theoretical concept, here termed the current gross soil rent. The current gross soil rent represents the difference between the current value growth and the rent of the growing stock.

By use of the concepts described here, it is theoretically possible to find the growing schedule for the stand which maximizes the net present-value of the stand. To make the formulae simpler, a one-year period has been adopted for discussion of the concepts involved in determination of the optimum structure and density of the growing stock, and the financial maturity. However, these concepts can be extended to cover periods of any length.

The method for determination of the optimum growing schedule for a forest stand can be summarized as follows: Thin the stand as the internal rate of return on the marginal increase in ’timber capital’ falls below the guiding rate of interest. Clear-cut and regenerate the stand as the internal rate of return on the sum of the ’timber and soil capital’ falls below the guiding rate of interest.

The PDF includes a summary in Finnish.

  • Kilkki, ORCID ID:E-mail:
article id 7678, category Article
Lauri. Valsta. (1992). An optimization model for Norway spruce management based on individual-tree growth models. Acta Forestalia Fennica no. 232 article id 7678.

A nonlinear programming algorithm was combined with two individual-tree growth simulators consisting of distance-independent diameter and height growth models and mortality models. Management questions that can be addressed by the optimization model include the timing, intensity and type of thinning, rotation age, and initial density. The results were calculated for Norway spruce (Picea abies (L.) H. Karst.) stands on Oxalis-Myrtillus site in Southern Finland, where the stand density after clearing of a seedling stand is about 2,000 trees/ha.

The optimum thinning programs were characterized by late first thinnings (at dominant height of 15–17 m) and relatively high growing stock levels. It was optimal to thin from above, unless mean annual increment was maximized instead of an economic objective. In most cases, the optimum number of thinnings was two or three. Compared to a no-thinning alternative, thinnings increased revenues by 15 –45% depending on the objective of stand management. Optimum rotation was strongly dependent on the interest rate.

Hooke and Jeeves’ direct search method was used for determining optimum solutions. The performance of the optimization algorithm was examined in terms of the number of functional evaluations and the equivalence of the objective function values of repeated optimizations.

The PDF includes a summary in Finnish.

  • Valsta, ORCID ID:E-mail:
article id 7613, category Article
Pekka Kilkki, Unto Väisänen. (1969). Determination of the optimum cutting policy for the forest stand by means of dynamic programming. Acta Forestalia Fennica no. 102 article id 7613.

The purpose of this study was determining the optimum cutting program for forest stands by the application of dynamic programming. Calculations have been made for even-aged Scots pine (Pinus sylvestris L.) stands in Southern Finland, aged 50-100 years. Three logging cost levels, thinning from below and from above, and rates of interest of 1, 2, 3, 4, and 5% was applied. Both optimum routes and the economic results of different cutting programs was analysed.

According to the results, the higher the rate of interest is, the lower the density remains, and shorter the rotation is. The starting level of the growing stock may influence the treatment of the stand for tens of years. If logging costs change, so that harvesting small wood becomes relatively more expensive in the future, the density of growing stock will increase. However, heavy thinnings today are recommendable, to avoid expensive thinnings in the future.

The density of the growing stock should be higher if thinning from above is applied, instead of thinning from below. The growth of the stands thinned from below needs to be greater than the growth of stands thinned from above, to justify thinnings from below. Too high density often results in larger losses than do too low a density or the wrong rotation. Thinnings seem to be profitable even at much higher logging costs than those of today. The maturity of the stand is determined both by the age and the density of the growing stock. The stand may be mature because of great age, high density combined with a relatively high age, or because the growing stock is too low in density.

The PDF includes a summary in Finnish.

  • Kilkki, ORCID ID:E-mail:
  • Väisänen, ORCID ID:E-mail:

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