BIOMASS RECOVERY INTEGRATED HARVESTING OPERATIONS Integrating biomass recovery operations into traditional forest harvesting activities is critical for successfully implementing a bioventure. A biomass recovery trial was conducted in the La Tuque area in Québec. The study was realized under the BELT project and supported by the Council of the Atikamekw Nation (CNA) and Neste, a global leader in renewable solutions. The trial aimed to measure how much biomass can be extracted by two different harvesting systems including four topping diameter scenarios. It also validated the BiOS model, an FPInnovations tool that predicts the volume and cost of biomass recovery. Two harvesting systems – full tree (feller-buncher / grapple skidder / roadside stroke delimber) and cut-to-length (harvester and forwarder) – were used in a mixed wood forest. The prescribed silvicultural treatment was harvesting all merchantable stems with protection of advance regeneration, including retention of forest clumps. Biomass manipulation The cut-to-length (CTL) harvester operator was asked to position the tops on the side of the trail to avoid running over them and in such a way as to facilitate their recovery by the forwarder. Tops were placed on the opposite side of the roundwood logs to minimize handling. The full tree harvest (FTH) operator was instructed to add the unmerchantable trees to the bunches instead of crushing them to the ground. The remainder of the felling operation was not affected by the different biomass recovery scenarios since the scenarios differed only during roadside delimbing. The delimbing operation was not affected by handling the tops, and all delimbing residues were recovered by the skidder and piled in heaps behind the tree-length piles. Table 1 shows how topping diameters influenced biomass recovery. More volume per hectare is recovered when the topping diameter is larger. When the topping diameter increased from 10 cm to 14 cm, this trial demonstrated that biomass recovery increased by 74% in the CTL system and by 59% in the FTH system. Table 1: Quantities of biomass available at roadside and left at the stump for the different topping scenarios and comparison with BiOS prediction System Biomass available at roadside ODT/ha 10-cm top, control 1 Cut-to-length (CTL) 10-cm top 12-cm top 14-cm top Average 10-cm top, control 1 10-cm top 12-cm top 14-cm top Average 0 24 36 44 35 23 43 20 45 39 Biomass left at the stump ODT/ha 66 27 28 22 26 25 17 26 26 23 Total biomass ODT/ha 66 51 64 66 61 48 60 46 72 62 Compared to BiOS prediction (%) 180% 130% 96% 97% 109% 112% 102% 70% 123% 101% Scenario Results The preliminary results show that biomass recovery is a feasible and viable operation when integrated into roundwood harvesting operations and proper care is taken to ensure that all activities are coordinated. A key component is that both systems provided the necessary ground residues at the stumps to prevent soil degradation. The CTL system has shown great potential to recover biomass, even though handling big tops was more problematic and required more time due to the forwarder’s limitations. Preparing neat roadside residue piles appeared to be more challenging in an FTH system and would require a better operational set-up. 1 The results indicated that BiOS predictions underestimated the quantity of residues in the CTL 10-cm scenario sites and that they were quite accurate for the 12-cm and the 14-cm scenarios. The BiOS predictions were quite accurate for the FTH system. This allows the model to be calibrated to reflect reality in future predictions. More information Contact: Luc Desrochers, [email protected] “Guidelines for forest fibre collection” is expected to be produced by FPInnovations to support recovery operations in different harvesting systems. Follow us www.fpinnovations.ca Full tree harvest (FTH) Without biomass recovery. blog.fpinnovations.ca
Canadian Biomass Summer 2021: Page 31
