Juho Rantala

Quality, productivity and costs of spot mounding after slash and stump removal

Abstract In Nordic countries, the harvesting of slash and stumps from regeneration areas for energy purposes has rapidly increased, and will increase further in the future. This development has unknown technoeconomic effects on soil scarification. This study investigated three spot mounding methods and factors affecting their quality, productivity and costs in regeneration areas after slash and stump removal. The methods were integrated stump lifting and spot mounding (INTE), separate excavator-based spot mounding (BLADE), and separate spot mounding by a continuously working mounding unit (CONT). The average quality of work was worst in INTE, while CONT was the most sensitive to stoniness. Average work times per spot mound were 4.1 and 3.1 times higher in INTE and BLADE, respectively, than in CONT. Altogether, the cost–quality ratio of CONT was better than that of the other methods, except in very small areas.

Mechanized tree planting with an excavator-mounted M-Planter planting device

The efficiency of modern tree planting machines is strongly affected by operational conditions, technical machine performance, and operator. In this study, the aim was to determine the time consumption of mechanical planting work using the M-Planter planting machine in Finnish regeneration areas where stumps were harvested and slash collected. The work of six operators, working with four M-Planter planting machines, was quantified with a stopwatch-study method. A linear mixed-effects model was used to examine the influences of operator, base machine, planting area, and work-difficulty factors on the time taken to complete planting. The quality of the planting work was also evaluated. Including a constant time for refilling seedling cassettes, the mean productivity of operators was 280 seedlings per productive work hour, and the time used to plant a seedling was on average 13.21 seconds (standard deviation 1.4 seconds). There were no significant differences in time consumption between operators; base machine did not have a significant effect on total work time; and surface obstacles was the only work-difficulty factor to slow mechanical planting work. Seedlings were planted to an acceptable quality by all operators. With respect to equipment, the M-Planter has two separate planting units, and results should not be generalized to other devices.

Competitiveness of mechanized tree planting in Finland

Economic pressures and labor shortage are forcing forest owners to minimize silvicultural costs and manage their forests more intensively to enhance wood production and profitability. The need to improve the cost-efficiency of tree planting is spurring its mechanization. The cost-competitiveness and time consumption of mechanized tree planting in Finland were compared to manual planting (MP) in spot mounds formed with a mounding blade and with a continuously advancing spot mounder. The results suggest that mechanized planting must increase its current productivity by 25% and 100% in order to compete with spot mounding or continuously advancing mounder followed by MP, respectively. However, in the hands of skilled operators in optimal conditions, machines can be cost-effective. On average, mechanized planting required 20% less time than MP and excavator-based spot mounding, whereas MP and continuously advancing spot mounder required 30% less time. Effective use of modern machines requires a careful evaluation of the worksite and skilled operators applying optimal operational models.

Effect of Seedling Production and Long-Distance Transportation Planning Strategies on Transportation Costs of a Nursery Company

Abstract In Finland, the number of nurseries has been decreasing year by year, and it seems probable that in the near future this trend will continue. It can be assumed that greater economies of scale could also be achieved in Finnish seedling production by enlarging the size of production units [9, 10]. The management strategies used by a nursery company for long-distance seedling transportation were compared with different allocations of seedling production among nurseries. To determine the optimal transportation costs in different strategies for seedling production and planning of long-distance transportation, linear programming (LP) was applied. To manage spatial information, a geographical information system (GIS) was used. The current development towards seedling transportation managed by nursery companies seems to have marked advantages in the cost-effectiveness of transportation. The relative improvement in cost-effectiveness caused by centralized transportation strategy (CTS) compared to decentralized transportation strategy (DTS), which is the mostly used strategy in seedling transportation planning in Finland, varied from 13.0% to 36.5%, depending on the number of nurseries and the degree of specialization of production among them. These results will be useful for nursery companies and forest owners’ associations (FOAs) when they evaluate the cost effects of production allocation, product specialization and systems of transportation management.

Linear Programming and Mixed Integer Programming in Management of Seedling Transportation

Abstract In this paper, the applicability of linear programming (LP) in management of seedling transportation was compared to that of mixed integer programming (MIP). In the LP model, presented in an earlier paper, a linear objective function was used as a surrogate for the actual objective function, which is intrinsically nonlinear. In the LP model, transportation costs were determined per seedling, whereas in the MIP model they were based on vehicle loads. When the number of transported seedlings within a certain period decreased, for instance, due to planting through the growth period, the computational accuracy of the LP model was clearly lower than that of the MIP model. Despite that, differences in allocation of orders between these two models were small. Thus, in the actual business situation of Finnish nursery companies, standard LP seems to be an adequate tool for management of seedling transportation. From the standpoint of cost-efficient seedling business, planting through the growth period increased optimal transportation costs markedly. In addition to the seedling business, these results can be utilized in other types of business dealing with analogous transportation problems.

A search for better competitiveness in mechanized early cleaning through product development: evaluation of two Naarva uprooters

Naturally regenerated broadleaf saplings are removed from planted spruce stands to enhance their productivity and quality. Early cleaning is typically carried out motor-manually with brush saws, but a shrinking labor force and economic pressures have spurred the development of machinery that can perform this task quickly, cheaply, and to a high standard. In Finland, Naarva uprooters are currently used in early cleaning. The uprooter devices are attached to harvester booms. They grip and lift a bunch of sprouts from the ground and break their roots, thereby preventing their regrowth. However, their efficiency has to be explored in terms of the quality of cleaning in various situations. We evaluated the productivity of two Naarva uprooter models (the P25 and the P55) in a work-study setting and found that an uprooter cleans at an average rate of one hectare per 6.3 productive work hours under average conditions. Productivity and quality of work decreased when the density and mean height of broadleaf saplings increased. There were no significant differences in work rate, costs or quality between the two models. However, the P25 is lighter, smaller, less expensive to purchase, and, according to operators, easier to handle. Mechanized early cleaning with an uprooter was found to perform to a similar standard and at a similar rate to motor-manual techniques, which translates to lower cost efficiency in direct comparison. However, uprooting is more cost-effective when taking into account that motor-manual cleaning must be repeated several times due to sprouting and regrowth of previously cut seedlings.

Bracke- ja M-Planter-istutuslaitteiden teknis-taloudellinen vertailu

Seloste artikkelista: Rantala, J., Harstela, P., Saarinen, V.-M. & Tervo, L. 2009. A techno-economic evaluation of Bracke and M-planter tree planting devices. Silva Fennica 43 (4) : 659– 667.