Back Tomas Ersson, Linus Jundén, Urban Bergsten, Martin Servin. (2013). Simulated productivity of one- and two-armed tree planting machines. Silva Fennica vol. 47 no. 2 article id 958. https://doi.org/10.14214/sf.958

Keywords: discrete-event simulation; mechanized planting; forestry; silviculture; automation; terrain model; root model

Highlights: Using discrete-event simulation and detailed terrain and machine models, the productivities of excavator-based one- and two-armed tree planting machines were simulated; The machines’ arms were equipped with one-and two-headed planting devices; Two planting heads per arm rather than two arms per base machine is better for increasing the productivity of intermittently advancing planting machines on Nordic clearcuts.

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

To increase mechanized planting, planting machine productivity must increase in order to improve cost-efficiency. To determine if excavators with two crane arms could potentially help to increase planting machine productivity under Nordic clearcut conditions, we modelled one-armed and semi-automated two-armed excavators with one- and two-headed planting devices. Using a recently developed tool for discrete-event simulation, these machine models then mounded and planted seedlings on terrain models with moraine soil having various frequencies of obstacles (stumps, roots and stones). Compared to if the two heads were mounted pairwise on only one arm, the results showed that productivity did not increase if two planting heads were attached individually to two separate crane arms. But productivity did increase if the planting machine had four planting heads mounted pairwise on two separate arms. However, despite assuming automated mounding and crane motion between planting spots, the two-armed, four-headed model never achieved high enough productivity levels to make it more cost-efficient than one-armed machines. The simulations illustrate that our terrain models generate realistic root architecture and boulder content distributions in moraine soil, while our machine models functionally describe mechanized planting work. Based on our assumptions, we conclude that further development work on two-armed excavator-based planting machines for Nordic clearcut conditions is not warranted. Our simulations reveal that increasing the number of planting heads per crane arm rather than number of crane arms per base machine offers the greatest potential to raise the productivity of intermittently advancing planting machines.

Ersson, Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE-901 83 Umeå, Sweden E-mail: back.tomas.ersson@slu.se
Jundén, UMIT Research Lab, Umeå University, SE-901 87 Umeå, Sweden E-mail: linus.junden@gmail.com
Bergsten, Swedish University of Agricultural Sciences, Department of Forest Biomaterials and Technology, SE-901 83 Umeå, Sweden E-mail: urban.bergsten@slu.se
Servin, UMIT Research Lab, Umeå University, SE-901 87 Umeå, Sweden E-mail: martin.servin@physics.umu.se

article id 108, category Research article

Back Tomas Ersson, Urban Bergsten, Ola Lindroos. (2011). The cost-efficiency of seedling packaging specifically designed for tree planting machines. Silva Fennica vol. 45 no. 3 article id 108. https://doi.org/10.14214/sf.108

Keywords: logistics; mechanized planting; containerized seedlings; seedling transport; cost analysis; seedling feed; nursery technology

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Today’s crane-mounted planting heads plant seedlings with biologically similar or better results than operational manual planting. However, the total cost of mechanized tree planting in southern Sweden must decrease at least 25% to compete economically with manual planting. Although seedlings packed in machine-specific packaging increase the productivity of planting machines by reducing seedling reloading time, they also increase logistics and investment costs. In this study, we analyzed the total cost of outplanting seedlings with an excavator-mounted Bracke Planter and seedlings packed according to four different concepts: cultivation trays, cardboard boxes, band-mounted seedlings in cardboard boxes and linked pots in container modules. The total cost per planted seedling was calculated for each packaging system as the sum of all costs from nursery to the recovery of empty packaging. The results showed that today’s system of transporting seedlings in cultivation trays is the most cost-efficient of the four alternatives. Machine-specific seedling packaging was 16–23% costlier per planted seedling than cultivation trays when trucking distances were 100 km. Sensitivity analyses indicated that machine-specific seedling packaging increased in cost-efficiency relative to cultivation trays primarily when more planting machines were contracted, but also as planting machine fixed costs and productivity increased. Moreover, the relative cost-efficiency of band-mounted seedlings, but not seedlings in container modules, increased with increasing trucking distance. Thus, we show that investments in machine-specific seedling packaging for today’s planting machines are justified only when the fixed costs, productivity and number of contracted planting machines increase substantially.

Ersson, Swedish University of Agricultural Sciences, Department of Forest Resource Management, SE-90183 Umeå, Sweden E-mail: back.tomas.ersson@slu.se
Bergsten, Swedish University of Agricultural Sciences, Department of Forest Resource Management, SE-90183 Umeå, Sweden E-mail: ub@nn.se
Lindroos, Swedish University of Agricultural Sciences, Department of Forest Resource Management, SE-90183 Umeå, Sweden E-mail: ol@nn.se

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