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Articles containing the keyword 'young stand'

Category : Research article

article id 22027, category Research article

Timo Saksa, Jari Miina, Olli Luukkonen. (2023). Uprooting as a pre-commercial thinning operation in young Norway spruce stands. Silva Fennica vol. 57 no. 2 article id 22027. https://doi.org/10.14214/sf.22027

Keywords: Picea abies; simulation; precommercial thinning; mechanical young stand management

Highlights: The number of competing birches varied considerably according to the operating conditions; The main factors reducing the quality of uprooting were early operation timing, soil moisture and site fertility; With careful selection of the timing and conditions for uprooting, the quality obtained by uprooting can be improved.

Abstract | Full text in HTML | Full text in PDF | Author Info

Uprooting, as a mechanical pre-commercial thinning operation (PCT), removes competitive, undesired trees with roots to prevent or reduce the need for a second PCT. The state of 66 young Norway spruce (Picea abies (L.) H. Karst.) stands was explored 3–5 years after uprooting to assess the quality of uprooting in terms of the number of competing birches (Betula spp.) and the probability of freely growing crop tree spruce (no competing trees taller than 2/3 of the crop tree’s height). In the uprooted spruce stands, the number of birches was, on average, about 3800 stems ha⁻¹, and in every fifth stand, it was less than 2000 stems ha⁻¹. The number of birches increased with increasing site wetness (TWI), site fertility and thickness of the humus layer. In 80% of the stands, there were at least 1000 freely growing spruces ha⁻¹, which is approximately the stem number to be left growing after first thinning in a spruce stand. If the height of crop tree spruces was 125 cm at uprooting, the probability of freely growing stems varied from 0.6 to 0.8 in typical cases. According to simulations at the first thinning stage, in most stands, birch was less than 10% taller than spruce, and the volume of birches was low enough that, in the future, spruce and birch would grow in the same crown layer as a mixed spruce–birch stand. The results showed that uprooting can serve as the only PCT operation in a planted spruce stand. The quality obtained by uprooting can be improved with careful selection of timing and conditions for uprooting; the optimal uprooting time is when crop tree spruces have reached about breast height.

Saksa, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, 77600 Suonenjoki, Finland https://orcid.org/0000-0002-1776-2357 E-mail: ext.timo.saksa@luke.fi
Miina, Natural Resources Institute Finland (Luke), Natural resources, Yliopistokatu 6 B, 80100 Joensuu, Finland https://orcid.org/0000-0002-8639-4383 E-mail: jari.miina@luke.fi
Luukkonen, Metsäsydän Oy, Junninmäentie 53, 52200 Puumala, Finland E-mail: olli.p.j.luukkonen@gmail.com

article id 10507, category Research article

Karri Uotila, Timo Saksa. (2021). Cost-efficient pre-commercial thinning: effects of method and season of early cleaning. Silva Fennica vol. 55 no. 4 article id 10507. https://doi.org/10.14214/sf.10507

Keywords: productivity; young stand management; cost-effectiveness; release treatment

Highlights: The first stage of multistage pre-commercial thinning, early cleaning, took 27–30% less time when carried out in the spring instead of the summer; The two stage pre-commercial thinning program was 11% less expensive to apply when early cleaning had been applied in the spring instead of the summer.

Abstract | Full text in HTML | Full text in PDF | Author Info

This study’s aim was to identify how the application season and the method of early cleaning (EC), the first stage of multistage pre-commercial thinning (PCT), affected the time consumption in EC and in the subsequent second PCT operation. The worktime in EC was recorded in the spring, summer, and autumn in 22 sites, which were either totally cleaned or point cleaned. Later, these sites were measured at the time of the second PCT. Time consumption was estimated in PCT, based on the removal of the sites. The time consumption in EC was 5.3 productive work hours (pwh) ha^–1, 7.3 pwh ha^–1, and 6.2 pwh ha^–1 respectively in the spring, summer, and autumn. EC in the spring instead of the summer saved 27–30% of working time, depending on the cleaning method. Point cleaning was 0.8 pwh ha^–1 quicker than total cleaning, but the difference was statistically insignificant. The second stage, PCT, was 1 pwh ha^–1 slower to conduct in sites which had been early cleaned in the spring instead of the summer. However, at the entire management program level, EC applied in the spring or autumn instead of the summer saved 11% or 5% respectively of the total discounted costs (3% interest rate) of multistage pre-commercial thinning. Today, the commonest time to conduct EC is in the summer, which was the most expensive of the analyzed management alternatives here. We can expect savings in juvenile stand management in forestry throughout boreal conifer forests by rethinking the seasonal workforce allocation.

Uotila, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: karri.uotila@luke.fi
Saksa, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: timo.saksa@luke.fi

article id 10447, category Research article

Marian Schönauer, Stephan Hoffmann, Martin Nolte, Dirk Jaeger. (2021). Evaluation of a new pruning and tending system for young stands of Douglas fir. Silva Fennica vol. 55 no. 2 article id 10447. https://doi.org/10.14214/sf.10447

Keywords: thinning; time study; Pseudotsuga menziesii; body posture; heart rate; OWAS; physical workload; young stand

Highlights: Electric pruning shears combined with workflow re-organization reduced time demand for pruning; Thinning by chainsaw was more productive than using the clearing saw Husqvarna 535FBX, which on the other hand showed lower physical workload; Overall cost savings through the use of the new system were quantified at 6%.

Abstract | Full text in HTML | Full text in PDF | Author Info

In Germany, management restrictions for Norway spruce (Picea abies (L.) H. Karst.) due to climate change lead to increasing interest in Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) as a potential substituting species. However, Douglas fir requires cost-intensive silvicultural treatments, such as periodic thinnings and, in particular, pruning. In order to improve the efficiency of such treatments, a new tending system with an adapted two-step work system was analyzed. The new system, using electric pruning shears and the backpack clearing saw Husqvarna 535FBX ‘Spacer’, was compared to the conventional three-step work system, using handsaw and chainsaw and characterized by tree selection previously conducted as an independent work step. Time and motion studies to determine productivity and costs, as well as ergonomic analysis through heart rate measurements and posture analysis were conducted. Overall, the new system was found to be more productive and to have lower costs, with 8.9 trees per scheduled system hour (4.17 € tree^–1), compared to the conventional system with 8.1 trees per scheduled system hour (4.44 € tree^–1). Ergonomic improvements with the new system could be mainly observed during the felling of competing trees, when the level of heart rate reserve was reduced by 9.3 percent points, compared to the conventional system. However, significant advantages in reducing unfavorable body postures expected for the ‘Spacer’ could not be confirmed. Since time savings within the new system were mainly attributed to the adaptation of workflow and the use of the electric shears during pruning, it should be considered to replace the ‘Spacer’ within the new system by light chainsaws for best results under the conditions investigated.

Schönauer, Department of Forest Work Science and Engineering, University of Göttingen, Göttingen/Germany E-mail: marian.schoenauer@uni-goettingen.de
Hoffmann, Department of Forest Work Science and Engineering, University of Göttingen, Göttingen/Germany; School of Forestry, University of Canterbury, Christchurch/New Zealand https://orcid.org/0000-0002-8077-967X E-mail: stephan.hoffmann@uni-goettingen.de
Nolte, Forest Education Center FBZ / State Enterprise Forestry and Timber NRW, Arnsberg/Germany E-mail: Martin.Nolte@wald-und-holz.nrw.de
Jaeger, Department of Forest Work Science and Engineering, University of Göttingen, Göttingen/Germany E-mail: dirk.jaeger@uni-goettingen.de

article id 10369, category Research article

Tiina Laine, Ville Kankaanhuhta, Juho Rantala, Timo Saksa. (2020). Effects of spot mounding and inverting on growth of conifers, exposed mineral soil and natural birch regeneration. Silva Fennica vol. 54 no. 5 article id 10369. https://doi.org/10.14214/sf.10369

Keywords: boreal forest; regeneration; site preparation; mounding; young stand management

Highlights: There were 21% fewer naturally regenerated birches ha^–1 in inverted areas (22 951) compared to spot mounded areas (29 086); Spot mounding exposed slightly, but not statistically significantly, larger area of mineral soil than inverting; There was no difference in seedling mortality or growth between the site preparation methods.

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In Nordic forests, consistent evidence about better seedling survival rate and increased growth due to site preparation have been obtained in numerous studies. Proper site preparation method can reduce costs of the whole regeneration chain through its effects on survival of planted seedlings, abundance of natural regeneration and competition in early stand development. This study compared the natural regeneration of birches (silver birch (Betula pendula Roth) and downy birch (B. pubescens Ehrh.)), amount of exposed mineral soil, and growth of planted seedlings between spot mounding and inverting site preparation methods. Present study was conducted in eight forest stands established in 2012 or 2015. Even though difference was not statistically significant, inverting exposed less mineral soil than spot mounding and thus reduced the natural regeneration of birch seedlings by 6135 seedlings ha^–1 compared to spot mounding. However, the variation between regeneration areas was remarkable. There was no difference in seedling mortality or growth between the site preparation methods. In order to achieve high growth of conifers, moderate amount of exposed mineral soil and thus less naturally regenerated birch, inverting should be favored over spot mounding.

Laine, Metsä Group, P.O. Box 208, FI-70101 Kuopio, Finland E-mail: tiina.laine@metsagroup.com
Kankaanhuhta, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: ville.kankaanhuhta@luke.fi
Rantala, Metsä Group, P.O. Box 10, FI-02020 METSÄ, Finland E-mail: juho.rantala@metsagroup.com
Saksa, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: timo.saksa@luke.fi

article id 1665, category Research article

Lauri Haataja, Ville Kankaanhuhta, Timo Saksa. (2018). Reliability of self-control method in the management of non-industrial private forests. Silva Fennica vol. 52 no. 1 article id 1665. https://doi.org/10.14214/sf.1665

Keywords: forest management; soil preparation; quality control; young stand management; forest regeneration; boreal silviculture; forest planting

Highlights: Self-control method was found reliable at the main stages of the forest regeneration process; Only slight overestimation was found in self-control results of soil preparation and planting and small underestimation in self-control of young stand management; Diverse utilizing of self-control data is possible in support of service providers operations.

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This study seeks to determine the extent to which self-control data can be relied upon in the management of private forests. Self-control (SC) requires the forest workers to evaluate their own work quality to ensure the clients’ needs are met in terms of soil preparation, planting and young stand management. Self-control data were compared to an independent evaluation of the same worksites. Each dataset had a hierarchical structure (e.g., sample plot, regeneration area and contractor), and key quality indicators (i.e., number of prepared mounds, planted seedlings or crop trees) were measured for each plot. Self-control and independent-assessments (IA) were analyzed by fitting a multi-level multivariate model containing explanatory variables. No significant differences were observed in terms of soil preparation (number of mounds) or young stand management (number of crop trees) between self-control and independent-assessments. However, the self-control planting data included a slight but significant overestimation of the number of planted seedlings. Discrepancies are discussed in terms of sampling error and other explanatory factors. According to overall results, self-control methods are reliable at every stage of the forest regeneration process. As such, the diverse utilizing of self-control data is possible in support of service providers operations.

Haataja, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: lauritapiohaataja@gmail.com
Kankaanhuhta, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: ville.kankaanhuhta@luke.fi
Saksa, Natural Resources Institute Finland (Luke), Natural resources, Juntintie 154, FI-77600 Suonenjoki, Finland E-mail: timo.saksa@luke.fi

article id 1689, category Research article

Juha Laitila, Eeva Lehtonen, Tapio Ranta, Perttu Anttila, Saija Rasi, Antti Asikainen. (2016). Procurement costs of cereal straw and forest chips for biorefining in South-East Finland. Silva Fennica vol. 50 no. 5 article id 1689. https://doi.org/10.14214/sf.1689

Keywords: supply chains; stumps; young stands; logging residues; delimbed stems; agrobiomass

Highlights: Procurement cost at the plant was 59 € dry tonne ^–1 when the annual procurement volume of biomass was 100 000 tonnes. Of that amount, the proportion of logging residues was 58.4%, stumps 24.3% and delimbed stems 17.3%; Cereal straw represents an important source of biomass in Kouvola but the cost competiveness is poor compared the procurement costs of forest chips due to high baling and transporting costs.

Abstract | Full text in HTML | Full text in PDF | Author Info

In Finland the increasing use of biofuel in transport presupposes a search for new raw material sources for biorefining. The aim of this study was, at the regional level, to compare the procurement costs of logging residues, stumps, delimbed stems and cereal straw for biorefining. The accumulation and procurement costs of forest chips and cereal straw were estimated within a 100-kilometre transporting distance via existing road network from an end-use-facility located in Kouvola in South-East Finland. The analyses were performed as simulated treatments in thinnings of young stands, cereal fields and regeneration fellings using existing productivity and cost functions and yield calculations based on crop statistics, the forest industry stand data and the sample plots data of the National Forest Inventory of Finland. Accumulation of raw material assortments and costs of production stages were defined per dry tonnes. Subsidies and raw material prices were excluded from consideration in the study. The results indicate that recovering logging residues requires lower costs than utilization of stumps, delimbed stems or cereal straw. Cereal straw represents an important source of biomass in Kouvola but the cost competiveness is poor compared the procurement costs of forest chips. When the annual procurement volume of biomass was 50 000 dry tonnes the cost at the plant was 49 € dry tonne ^–1 and biomass was comprised totally of logging residues. Procurement cost grew to 59 € dry tonne ^–1 when the annual procurement volume of biomass was doubled to 100 000 dry tonnes. Of that amount, the proportion of logging residues was 58.4%, stumps 24.3% and delimbed stems 17.3%. First cereal straw dry tonnes were delivered to end-use-facility, when procurement cost grew to 60 € dry tonne ^–1 and annual procurement volume of biomass was 110 000 dry tonnes.

Laitila, Natural Resources Institute Finland (Luke), Bio-based Business and Industry, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: juha.laitila@luke.fi
Lehtonen, Natural Resources Institute Finland (Luke), Green Technology, Halolantie 31A, FI-71750 Maaninka, Finland E-mail: eeva.lehtonen@luke.fi
Ranta, Lappeenranta University of Technology, LUT School of Energy Systems, Laboratory of Bioenergy, Lönnrotinkatu 7, FI-50100 Mikkeli, Finland E-mail: tapio.ranta@luke.fi
Anttila, Natural Resources Institute Finland (Luke), Bio-based Business and Industry, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: perttu.anttila@luke.fi
Rasi, Natural Resources Institute Finland (Luke), Bio-based Business and Industry, Survontie 9A, FI-40500 Jyväskylä E-mail: saija.rasi@luke.fi
Asikainen, Natural Resources Institute Finland (Luke), Bio-based Business and Industry, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: antti.asikainen@luke.fi

article id 142, category Research article

Helmer Belbo. (2010). Comparison of two working methods for small tree harvesting with a multi tree felling head mounted on farm tractor. Silva Fennica vol. 44 no. 3 article id 142. https://doi.org/10.14214/sf.142

Keywords: Norway spruce; cost functions; forest biomass harvesting; multi-tree handling; young stands

Abstract | View details | Full text in PDF | Author Info

In this study, the efficiency of a small multi-tree felling head, mounted on a farm tractor with a timber trailer was studied, when harvesting small trees for energy in thinnings. Both separate loading and direct loading of the felled trees was studied. Time studies were carried out in a mixed stand of Norway spruce (Picea abies (L.) Karst) and birch (Betula pubescens Ehrh.). The time consumption of the work elements in the different work methods was formulated by regression analysis, where the independent variables were tree size and degree of accumulation. The average size of the harvested trees was 0.035 m3. The time consumption for the harvesting and loading were similar for the two studied methods, 20 minutes per m3 at a tree size of 0.035 m3, but the two methods showed different characteristics for different tree sizes and level of accumulation. The direct loading method had the highest productivity when more than 0.1 m3 were collected in the felling cycle, whereas the separate loading method had the highest productivity when less than 0.05 m3 were collected in the felling cycle. The total effective time consumption for harvesting and forwarding the biomass 300 meters to roadside landing was 27 minutes per m3. The efficiency of the initial felling and collecting of the small trees was the main challenge. Both the harvesting technique and harvesting technology needs further development to provide a feasible production chain for woodfuel from energy thinning.

Belbo, Norwegian Forest and Landscape Institute, Box 115, 1431 Ås, Norway E-mail: helmer.belbo@skogoglandskap.no

article id 245, category Research article

Saija Huuskonen, Jari Hynynen, Risto Ojansuu. (2008). Stand characteristics and external quality of young Scots pine stands in Finland. Silva Fennica vol. 42 no. 3 article id 245. https://doi.org/10.14214/sf.245

Keywords: Scots pine; growth and yield; precommercial thinning; external stem quality; young stand management

Abstract | View details | Full text in PDF | Author Info

The effects of silvicultural practices (regeneration method and young stand management) on the stand characteristics of young Scots pine (Pinus sylvestris (L.)) stands were studied. Stand density, mean diameter, crown ratio and external quality of young Scots pine stands were analysed on the basis of extensive inventory data. The study material consisted of 181 stands containing inventory growth plots, representing the most common site types for Scots pine and covering all the important wood production areas in Finland. Intensive management practices, i.e. artificial regeneration and precommercial thinning, clearly enhanced mean diameter development of the stand. The overall stand density of the crop trees was relatively low in the material (1925 trees ha–1). In more than one third of the stands, the stem number of crop trees was below 1500 trees ha–1. Stand density was not affected by forest management, but it was slightly higher in Southern than in Northern Finland. The geographical location, in terms of annual effective temperature sum, affected the average slenderness and crown ratio. At a given mean stand diameter, the dominant height of the stand was lower, and the mean crown ratio was higher, in Northern than in Southern Finland. The average external quality of the Scots pine trees was relatively low. The proportion of trees without any observed defects was 54%. The most common external defects were curved stems (23%) and branchiness (9%). Branchiness was more frequent among the largest trees, while curved stems were more common in smaller trees. Defects were the most frequent in planted stands, and in stands growing on fresh sites. The defects were more frequent in Northern Finland than in Southern Finland. The relatively low stand density and poor external quality of the young stands emphasize the importance of stem quality as a tree selection criterion in commercial thinnings of Scots pine stands, if the goal is to produce high quality timber.

Huuskonen, University of Helsinki, Department of Forest Ecology, Helsinki, Finland E-mail: saija.huuskonen@helsinki.fi
Hynynen, Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland E-mail: jh@nn.fi
Ojansuu, Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland E-mail: ro@nn.fi

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