The Profitability of Cross-Cutting Practices in Butt-Rotten <i>Picea abies</i> Final-Felling Stands

• Main Authors: Kalle Kärhä, Mikko Räsänen, Teijo Palander
• Format: Article
• Language: English
• Published: MDPI AG 2019-10-01
• Series: Forests
• Subjects: <i>heterobasidion annosum</i>; decay; offcut; productivity; value recovery; sawlog
• Online Access: https://www.mdpi.com/1999-4907/10/10/874

<i>Research Highlights</i>: This study offers new information on the cross cutting of decayed stems with the sounding of short (0.5 m) offcuts and the bucking of longer (3.0 m) butt-rotten poles. <i>Background and Objectives</i>: The root and butt-rot fungus <i>Heterobasidion annosum sensu lato</i> (Fr.) Bref. causes wood quality damage to trees in softwood forests. When timber is harvested in butt-rotten forests, it is essential that the decayed part of the tree is recognized and cut away from a stem, while the healthy and good quality log section of a stem is cross cut with precision sawlogs. The objective of the study was to investigate the impact of two off-cutting methods on stem processing time, cutting productivity, sawlog volume, and commercial value at the roadside landing when harvesting timber from the butt-rotten Norway spruce (<i>Picea abies</i> (L.) Karst.) final-felling forests. <i>Materials and Methods</i>: The length of the short offcuts used was 0.5 m. The results of the cross-cutting practices were compared to the decayed pulpwood poles of 3 m from the butt of the rotten stems. Time and motion studies were carried out in stands before the profitability calculations. The study data consisted of 1980 Norway spruce sawlog stems. <i>Results</i>: Sounding of the short offcuts added significantly to the stem processing time of butt-rotten stems, but the sawlog volume and the timber value recovery of the stems were higher than those of the decayed pulpwood poles of 3 m. <i>Conclusions</i>: The study concluded that sounding of butt-rotten Norway spruce stems with one to three offcuts is economically profitable if the diameter of the decayed column at the stem stump&#8217;s height is small (&#8804;5 cm). In contrast, when the width of the decay is larger (&gt;5 cm), it is more profitable to first cross cut the decayed pulpwood pole of 3 m and then to observe the height of the decayed part of the stem.