Manual planting of forest seedlings remains the dominant planting method in Swedish forests, especially among minor private forest owners. A new licentiate thesis by Trees For Me’s PhD student Erik Arvidsson presents some of the latest updates related to technology which could be used in autonomous planting vehicles, but also on forwarders performing mechanical site preparation.
The technology is state-of-the-art and the first of its kind to enable planting of broadleaves in the development. Erik Arvidsson, PhD student at Luleå University of Technology and within Trees For Me, has focused on comparing coverage path planners for autonomous planting with manual operators.
”The results showed that automatically generated coverage path planners can achieve higher coverage and shorter path lengths than manual operators”, says Erik Arvidsson.
There’s an increased interest in mixed-species forest regeneration as one way to increase the forests’ resilience to pest, pathogens and the effects of climate change. Increased forest diversity can contribute to ecological benefits and reduce economic risks but brings operational and financial challenges related to e.g. planting. Integrating autonomous planting technology, such as in the existing research and industrial projects Autoplant and the smaller but similar vehicle Södra BraSatt, with digital decision-support and planning tools could contribute to more diverse forests and make site-adapted regeneration strategies more efficient.
More sustainable planting despite obstacles
Erik Arvidsson has developed a digital precision planning tool which can be used to determine the distribution of mixed-species planting based on species-specific site productivity and density constraints identified by the user. The technology can predict which tree species is the most suitable for the exact planting spot, promoting increased biodiversity and improved forest resilience while sustaining site productivity. The tool can also contribute to cost savings by calculating the number of plants required for each site.
“A well-designed coverage path planner will suggest a route that maximizes the proportion of the area that the planting machine can access, while reducing the path length. Higher coverage, in turn, implies that more seedlings can be planted,” Erik Arvidsson explains.
The planning tool facilitates for the vehicle to avoid rolls, pitches and soil moisture thresholds, while considering the turning radius. Tests have shown the tool’s effective contribution to safely planning paths through challenging sites while minimizing the vehicle path length and ensuring operational safety. The reduced path length and avoidance of sensitive areas such as wet zones can reduce the fuel consumption and minimize soil disturbance. Autonomous technology also allows for operators to work remotely which can reduce work environment issues affecting manual operators, such as full body vibrations and other hazards.
Future testing and market implementation
The tools that have been developed are not limited to specific vehicle types. Therefore, implementing them on commercial machines such as soil preparation and planting machines is also feasible.
Additional testing of the technology is ongoing and planned for in the future. Erik Arvidsson explains that for the technology to become more profitable the planting vehicles must be able to operate with minimal intervention while maintaining performance.
“There are several significant hurdles to overcome before we see the technology widely commercialized. Some of the main challenges are reliability and efficiency, as these projects have so far performed low scale planting with heavy supervision”, Erik Arvidsson concludes.