Improvements in value recovery through low stump heights: Mechanized versus manual felling

Stump heights were measured on two blocks harvested during the summer of 2000 in north-central British Columbia. Each block was of similar stand and terrain characteristics, consisting mainly of subalpine fir (Abies lasiocarpa) with minor components of white spruce (Picea glauca × P. engelmannii) on gentle slopes. The blocks were harvested by two different contractors using different felling methods: mechanized felling with a feller-buncher and manual felling with a chainsaw. The average measured stump height from mechanized felling was 8.8 cm lower than that of manual felling, measuring 21.9 and 13.1 cm, respectively. When the saw kerf of felling equipment and stump-pull were included, the average stump height of mechanized felling was shown to be 5.8 cm (17%) lower than manual felling. High-end and low-end potential value losses were determined based on average sawlog values (Canadian [CN] $60/m³) and pulp log values (CN$40/m³), respectively. The potential value loss from manual felling was estimated to be up to CN$0.33/tree more than from mechanized felling. This result indicated that mechanized felling recovered up to CN$160/ha over manual felling when an average sawlog value and the stand density information from the study site were used in the calculation. The study demonstrated that lower stump heights than the 30 cm maximum stump height set by the Forest Practices Code of British Columbia are attainable with both falling methods. Sensitivity analysis was performed to determine the potential value and volume gains for a ran,ge of stump heights from 0 to 30 cm. Operational constraints were identified in the study, and recommendations for minimizing stump heights are presented.