Speaker
Description
Mechanized cut‑to‑length harvest operations with clear cutting as the final operation within the rotation is the predominant harvest method in Fennoscandian forestry. However, interest in continuous-cover-forestry (CCF) methods is increasing. CCF methods such as shelterwoods and patch cuttings can contribute to maintain stand continuity and can provide ecological and social benefits but may also introduce greater operational complexity. Forwarder work in CCF methods is likely to differ from conventional clear cutting due to lower concentration of harvested wood volumes along strip roads and longer extraction distances, but research on the topic is scarce. Therefore, the aim of this study was to determine if forwarder productivity and fuel consumption in fully mechanized shelterwood establishment or checkerboard patch cutting is more time or fuel consuming than in clear cutting, and if so, quantify how much.
The study was conducted on seven harvesting sites in central Sweden, in a block design. Each block contained three treatments: final felling, shelterwood establishment, and patch cutting, covering in total, 9–29 ha, with individual treatment areas ranging from 2.1 to 13.1 ha per block. The patch cuttings were done in a checkerboard pattern over the entire treatment area, in 33 by 33-meters square patches.
Data was collected with the machine control systems as StanForD2010 reports and were collected for each block and treatment area. The reports contained worktime, operator, fuel consumption, driven distance, and forwarded volume. Statistical analysis were done on the work shifts with mixed linear models to predict how time or fuel was explained by meters driven per extracted solid cubic meters under bark (m3sub), treatment and the random effects of operator and block.
Forwarder work in both shelterwood establishment and checkerboard patch cutting required significantly more time and fuel than clear cutting on the same blocks. As a result of different work methods, the mean extraction distance per m3sub in shelterwood establishment was 67 m and not significantly different to the 69 meters per m3sub in clear cutting. In patch cutting, on the other hand, the mean extraction distance was significantly longer (95 meters per m3sub). Based on those mean extraction distances, the patch cutting will consume 26% more time and 27% more fuel while shelterwood establishment will consume 10% more time and 2% more fuel compared in both cases to clear cutting. However, if the methods would be possible to implement with equal driving distances, the study indicates that there would be an 11% increase in forwarding time for both CCF treatments, whereas the fuel consumption would be 2.5% higher in patch cutting and 1.3% higher in shelterwood establishment compared to clear cutting.
These results will be useful when planning shelterwood and patch cutting management, by enabling the differences in fuel and time consumption and, ultimately, costs can be accounted for. Further research could complement the results by further investigating various types of shelterwood removal, patch cuttings of other shapes and sizes, and the total system economy of the management and operations.
| Keywords | Harvest-operations; Continuous-cover-forestry; Performance-studies; Forwarder |
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