Mechanized tree planting in Nordic forestry: simulating a machine concept for continuously advancing site preparation and planting

As labour for manual tree planting becomes scarcer, regeneration costs are steadily increasing in Nordic forestry. Today’s intermittently advancing tree planting machines provide excellent silvicultural results, but are expensive to operate because of poor productivity. In contrast, continuously advancing planting machines, thanks to high productivities, are increasingly being regarded as a solution to these runaway regeneration costs. The Silva Nova was a historical, continuously advancing tree planting machine with high productivity. However, Silva Nova’s weaknesses included high labour costs (it required two operators) and the random nature of how it chose planting spots. In contrast, SuperSilva, a purely conceptual modernisation of Silva Nova, involves both automation and microsite identification to make the machine more efficient. We used discrete-event simulation to analyse the stocking rate and spatial distribution of tree planting with SuperSilva. The simulation results showed that introducing sensors for identifying suitable microsites will allow continuously advancing planting machines (like SuperSilva) to plant seedlings in a numerically and spatially adequate manner on moraine soils. Hence, these sensors will increase the competitiveness and versatility of tree planting machines. Unfortunately, such reliable and robust sensor technology (unaffected by a wide variety of operating conditions) is not yet commercially available

Automatic and experimental methods to studying forwarding work

Although forwarding has been carried out for 50 years, much is still unknown about this work. This is partly because there are numerous influential factors, and relevant data are often difficult to gather. In current forwarding productivity literature, there is generally a trade-off between representativeness and work element-specificity. Follow-up studies and standardized experiments represent the two extremes, while work observation studies are compromises. A further complication is the lack of consistent nomenclature to facilitate comparisons of findings from different studies. These issues were explored in four studies reported in this thesis. Study I assessed the utility of standardized test paths for enhancing our understanding of the main factors influencing forwarding work, causal relationships among them, and trade-offs. Such knowledge is essential for refining future research. In Studies II and III, the utility of a forest machine manufacturer’s built-in automatic follow-up datalogger was assessed. Study II focused mainly on the suitability of a standard commercial monitoring system for comparative operator-level studies. In Study III, forwarder work element-specific follow-up data were gathered in as detailedly as currently possible using an automatic system. In Study IV, the utility of sensors and dataloggers for gathering technical information on forwarder crane work was assessed. The main conclusions are summarized below. Automated data collection has well known advantages, but such automation for forwarding work is still ongoing. Data from the forwarder’s own monitoring system alone are not, currently, sufficient for unbiased work performance analysis. In addition, access to spatial data on the harvester’s production is needed. Use of untapped technological potential would enable, in many cases, replacement of manual data gathering with automatic methods. However, automatic gathering of data with some important features, e.g. assortment-specificity (load-specific assortment proportions), is currently impossible. Automation enables large datasets to be gathered, but increasing the sample size beyond a certain saturation point provides no further benefits. Instead, including more factors is preferable, even at the cost of slightly smaller datasets. Finally, various innovations and modifications to work practices could substantially improve forwarding efficiency; however, they should be evaluated cautiously, initially by theoretical analysis, to ensure resources are efficiently channelled

Cost analysis of seedling supply systems adapted for mechanized tree planting: a case study from southern Sweden

Because today's tree planting machines do a good job silviculturally, the Nordic forest sector is interested in finding ways to increase the planting machines' productivity. Faster seedling reloading increases machine productivity, but that solution might require investments in specially designed seedling packaging. The objective of our study was to compare the cost-efficiency of cardboard box concepts that increase the productivity of tree planting machines with that of today's two most common seedling packaging systems in southern Sweden. We modelled the total cost of these five different seedling packaging systems using data from numerous sources including manufacturers, nurseries, contractors, and forest companies. Under these southern Swedish con-ditions, the total cost of cardboard box concepts that increase the productivity of intermittently advancing tree planting machines was higher than the cost of the cultivation tray system (5-49% in the basic scenario). However, the conceptual packaging system named ManBox_fast did show promise, especially with increasing primary transport distances and increased planting machine productivities and hourly costs. Thus, our results show that high seedling packing density is of fundamental importance for cost-efficiency of cardboard box systems designed for mechanized tree planting. Our results also illustrate how different factors in the seedling supply chain affect the cost-efficiency of tree planting machines. Consequently, our results underscore that the key development factor for mechanized tree planting in the Nordic countries is the development of cost-efficient seedling handling systems between nurseries and planting machines

Forest management in northern Fennoscandia: the need for solutions that mitigate conflicts during forest regeneration and increase the use of continuous cover forestry

Today, conflicts often occur in northern Fennoscandia (also known as Sápmi) between forestry and reindeer husbandry. Continuous cover forestry (CCF) is requested by both reindeer herding communities and the general public and is becoming more common, but the forest industry criticizes CCF for lower wood production. Mechanical site preparation (MSP) increases regeneration success and, thus, increases wood production in CCF. To reduce the conflict between forestry and reindeer husbandry, MSP in Sápmi should destroy as little ground lichen as possible. Today, there are no solutions for gentle and lichen-adapted MSP in CCF. Thus, there is a strong need to develop and test new technical solutions that increase regeneration success in a lichen-adapted way during CCF in Sápmi. We suggest that MSP solutions be developed which are gentle, work selectively and function in shelterwoods, gap cuts, and selection cutting stands. We envision that these solutions could fill the gap between the desired adaptivity on the part of the reindeer herding communities and the desired efficiency on the part of the forest industry. Such MSP technology would contribute to increased acceptance of CCF in the forest industry, higher biodiversity, and considerably reduce the conflict between forestry and reindeer herding communities

Innovative productivity improvements in forest operations: a comparative study of the Assortment Grapple using a machine simulator

Because of generally small log piles, loading forwarders during thinning is time consuming. The Assortment Grapple, an innovative grapple with an extra pair of claws which facilitates the handling of two assortments during one loading crane cycle, has been designed to decrease forwarders’ loading time consumption. A standardized experiment was performed in a virtual thinning stand using a machine simulator with the objectives to form guidelines for working with the Assortment Grapple and to analyse its development potential. Four experienced operators participated in the study. According to the results, the Assortment Grapple’s accumulating function is beneficial only when there are no remaining trees between piles loaded during the same crane cycle. In such cases, none of participating operators lost time, and 3 of 4 operators saved time notably. The problem with the remaining trees is the extra time required to steer the crane tip around them. Therefore, a harvester should place those log piles that are later to be forwarded together in the same space with no remaining trees between the piles. Furthermore, we recommend that the Assortment Grapple’s usability will be improved by adding an own rocker switch on the forwarder’s controls to command the extra claws

Forest management in northern Fennoscandia: the need for solutions that mitigate conflicts during forest regeneration and increase the use of continuous cover forestry

Today, conflicts often occur in northern Fennoscandia (also known as Sápmi) between forestry and reindeer husbandry. Continuous cover forestry (CCF) is requested by both reindeer herding communities and the general public and is becoming more common, but the forest industry criticizes CCF for lower wood production. Mechanical site preparation (MSP) increases regeneration success and, thus, increases wood production in CCF. To reduce the conflict between forestry and reindeer husbandry, MSP in Sápmi should destroy as little ground lichen as possible. Today, there are no solutions for gentle and lichen-adapted MSP in CCF. Thus, there is a strong need to develop and test new technical solutions that increase regeneration success in a lichen-adapted way during CCF in Sápmi. We suggest that MSP solutions be developed which are gentle, work selectively and function in shelterwoods, gap cuts, and selection cutting stands. We envision that these solutions could fill the gap between the desired adaptivity on the part of the reindeer herding communities and the desired efficiency on the part of the forest industry. Such MSP technology would contribute to increased acceptance of CCF in the forest industry, higher biodiversity, and considerably reduce the conflict between forestry and reindeer herding communities