Articles containing the keyword 'stem quality'

Detailed pre-harvest information about the volumes and properties of growing stocks is needed for increased precision in wood procurement planning for just-in-time wood deliveries by cut-to-length (CTL) harvesters. In the study, the non-parametric Most Similar Neighbour (MSN) methodology was evaluated for predicting external quality of Scots pine and Norway spruce, expressed as stem sections fulfilling the saw log dimension and quality requirements of Finnish forest industry, as they affect the recovery of timber assortments and the value of a pre-harvest stand. Effects of external tree quality were evaluated using saw log recovery and saw log reduction caused by stem defects, as well as total timber value (€) and average unit value (€ m^–3) in a stand. Root mean square error (RMSE) of saw log recovery and reduction were 9.12 percentile points (pp) for Scots pine and 6.38 pp for Norway spruce stands. In the unit value considerations, the predictions compared with measurements resulted in the RMSE of 3.50 € m^–3 and the bias of 0.58 € m^–3 in Scots pine stands and 2.60 € m^–3, and 0.35 € m^–3 in Norway spruce stands, respectively. The presented MSN based approach together with the utilization of the external stem quality database included in the ARVO software could provide dimension and external quality predictions usable for pre-harvest assessment of timber stock at a stand level. This prediction methodology is usable especially in analyses where timber assortment recoveries, values and unit prices are compared when different bucking objectives are used.

• Malinen, University of Eastern Finland, School of Forest Sciences, P.O. Box 111, FI-80101 Joensuu, Finland E-mail: jukka.malinen@uef.fi
• Kilpeläinen, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6, FI-80100 Joensuu, Finland E-mail: harri.kilpelainen@luke.fi
• Verkasalo, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6, FI-80100 Joensuu, Finland E-mail: erkki.verkasalo@luke.fi

The objective of the study was to ascertain the effects of tree selection (thinning from below, from above and according to stem quality) and timing of first commercial thinning (early and delayed) on the growth, yield and quality of trees in a Scots pine (Pinus sylvestris L.) stand. A long-term field experiment (25 years) was measured in 5-year periods and the further development was simulated with growth and yield models to final cuttings using alternative rotation periods of 55–85 years. The measurements included also the exact location and type of technical defects detected on all trees in the experimental plots. The measured volume increment per unit area during the study period, 25 years after the early thinning stage was the lowest in the plots thinned from below, and the highest in the plots thinned from above or in the delayed thinning plots. However, the largest volume of saw logs during the whole rotation of 80 years was yielded after early first thinning according to the quality. The largest volume of very high-quality butt logs was produced by pruning connected with early thinning from above, and a smaller volume after early thinning according to stem quality but no after thinning from below or delayed first thinning. Without pruning an early quality thinning with one intermediate thinning was the most profitable thinning treatment in the Scots pine stand regardless the rotation length or the interest rate used. By interest rates of 1% and 2%, the optimal rotations were 80–85 years and 70 years respectively. A late thinning at the age of 60 year with long rotation was profitable only for the pruned pine stands with a low interest rate.

• Niemistö, Natural Resources Institute Finland (Luke), Natural resources, Kampusranta 9 C, FI-60320 Seinäjoki, Finland E-mail: pentti.niemisto@luke.fi
• Kilpeläinen, Natural Resources Institute Finland (Luke), Production systems, Yliopistokatu 6, FI-80100 Joensuu, Finland E-mail: harri.kilpelainen@luke.fi
• Poutiainen, Oulu E-mail: eero1.poutiainen@dnainternet.net

• Kretschmer, Chair of Forest Growth, Albert-Ludwigs-University Freiburg, Tennenbacher Str. 4, 79106 Freiburg, Germany E-mail: ursula.kretschmer@iww.uni-freiburg.de
• Kirchner, VOLKE Consulting Engineers GmbH, Schätzweg 7-9, 80935 München, Germany E-mail: nadeschda.kirchner@volke.muc.de
• Morhart, Chair of Forest Growth, Albert-Ludwigs-University Freiburg, Tennenbacher Str. 4, 79106 Freiburg, Germany E-mail: christopher.morhart@iww.uni-freiburg.de
• Spiecker, Chair of Forest Growth, Albert-Ludwigs-University Freiburg, Tennenbacher Str. 4, 79106 Freiburg, Germany E-mail: instww@uni-freiburg.de

• Kilpeläinen, Finnish Forest Research Institute, Eastern Finland Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: hk@nn.fi
• Lindblad, Finnish Forest Research Institute, Eastern Finland Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: jl@nn.fi
• Heräjärvi, Finnish Forest Research Institute, Eastern Finland Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: henrik.herajarvi@metla.fi
• Verkasalo, Finnish Forest Research Institute, Eastern Finland Research Unit, P.O. Box 68, FI-80101 Joensuu, Finland E-mail: ev@nn.fi

• Huuskonen, University of Helsinki, Department of Forest Ecology, Helsinki, Finland E-mail: saija.huuskonen@helsinki.fi
• Hynynen, Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland E-mail: jh@nn.fi
• Ojansuu, Finnish Forest Research Institute, Vantaa Research Unit, Vantaa, Finland E-mail: ro@nn.fi

• Eskelinen, Lappeenranta University of Technology, Department of Electrical Engineering, P.O. Box 20, FIN-53851 Lappeenranta, Finland E-mail: ari.eskelinen@pp.inet.fi
• Eskelinen, Lappeenranta University of Technology, Department of Electrical Engineering, P.O. Box 20, FIN-53851 Lappeenranta, Finland E-mail: he@nn.fi

The consensus on the factors affecting harvester productivity is generally widely acknowledged in the discipline. However, research results regarding the effect of forking on productivity are diverse. Some studies show that harvester productivity is halved when harvesting double stems compared to single-stem trees, while other studies indicate that forking does not necessarily decrease harvester productivity. These differences in study results can depend on what is considered forking. In our study, the forking occurred above the breast-height level. We defined codominant stems as forked trees too large to be multi-tree handled. In contrast, we defined double crowns as forked trees that could be multi-tree handled. The objective of our study was to analyse how the presence of codominant stems and/or double crowns affects harvester time consumption. The study was conducted in Sweden in 2022, involving two operators and two large harvesters. The 45-year-old Pinus contorta Douglas ex Loudon-dominated stand was clearcut during the study. We found that the presence of codominant stems doubles harvester time consumption per tree, while double crowns had only a minor impact on harvester time consumption. Additionally, total time consumption increased linearly with increasing diameter at breast height. Based on these findings, we recommend that forked trees be removed already during thinning when they can still be time-efficiently multi-tree handled. Dealing with forked trees later during the rotation cycle, when they are too large for multi-tree handling, is excessively time-consuming.

• Manner, Skogforsk, Uppsala Science Park, 751 83 Uppsala, Sweden https://orcid.org/0000-0002-4982-3855 E-mail: jussi.manner@skogforsk.se
• Lundström, Skogforsk, Uppsala Science Park, 751 83 Uppsala, Sweden E-mail: hagos.lundstrom@skogforsk.se

• Viherä-Aarnio, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: anneli.vihera-aarnio@metla.fi
• Velling, The Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland E-mail: pv@nn.fi