Effects of precommercial thinning on the forest value chain in northwestern New Brunswick: Part 2 – Efficiency gains in cut-to-length harvesting

Abstract

The Green River precommercial thinning trials were established between 1959 and 1961 in naturally regenerating balsam fir (Abies balsamea [L.] Mill.)-dominated stands an average of eight years after overstory removal. Three nominal spacings of 4 ft (1.2 m), 6 ft (1.8 m) and 8 ft (2.4 m) were compared to an unthinned control in six replicate blocks. In the fall of 2008, following completion of the ninth sequential evaluation of the study’s 48 permanent sample plots, three of the six replicates were clearcut harvested using a cut-to-length system; data were collected on harvesting, forwarding and loading efficiency. Largely due to increased average tree size, precommercially thinned stands were associated with improvements in both harvesting and forwarding productivity, proportional to thinning intensity. For example, the nominal 6-ft spacing yielded 30% to 35% gains in harvesting productivity, and 16% to 39% gains in forwarding productivity (p ≤ 0.04), these ranges spanning the different levels of operator expertise and block conditions observed. In total, estimated harvesting costs were $12.58/m3 in the unthinned stands, compared to $9.10/m3 in the 6-ft spaced stands (p = 0.02). Such a difference represents a $3.48/m3 savings, which translates into just over $1000 per ha, based on the gross merchantable volume produced in the 6-ft spaced stands.

Effects of precommercial thinning on the forest value chain in northwestern New Brunswick: Part 1 – Roundwood production and stumpage value

“…Blocks were selected for harvest based on stand and tree age (Table 1) and availability within the provincial forest management planning system. A detailed description of the harvesting equipment used can be found in Plamondon and Pitt (2013).…”

“…into pulpwood (mostly, but not exclusively, tops) (PWV h ), studwood (SWV h ), sawlogs greater than 2.4 m in length (SLV h ), and volume discarded for rot (stems were jumped by 40-cm sections until <30% of the stem basal area contained advanced decay) or other defect (e.g., forks or excessive knots) (UMV h ) (see Plamondon and Pitt (2013) for exact product specifications). Calibration of the harvester heads was verified prior to the study and the above volumes were later corrected for inside bark.…”

Evaluating harvest costs and profit of commercial thinnings in softwood stands in west-central Maine: A case study

“…A long-term PCT study from New Brunswick, Canada found that PCT increased diameter growth rates with responses proportional to the thinning intensity (Pitt et al 2013a). Half the plots were clearcut in 2008 at ages 55 and 62, and results showed that harvester productivity increased in proportion to PCT intensity due to the positive effect of PCT on average stem size (Plamondon and Pitt 2013). Another benefit of PCT is that it can increase regeneration and thus function similar to a shelterwood establishment cut (Olson et al 2014).…”

Systems Analysis of Ten Supply Chains for Whole Tree Chips

“…A recent state-of-the-art report points out that for Finland, 45% of technical biomass harvesting potential of 6.3-9 Mm 3 s can be obtained from small tree harvesting, while the potential in Sweden is estimated at around 6.5 Mm 3 s [4]. In Norway, this resource has been roughly estimated at 2 Mm 3 s [7] while in Canada, it has been assessed that at least 100 kha require pre-commerical thinning annually [8]. The characteristics of whole-tree fuel stocks are described as good by Nurmi and Hillebrand [9] with transpiration drying bringing moisture content below 30% over one summer, and the presence of mesophillic fungi being at only 1% of that found in harvesting residues.…”

“…The characteristics of whole-tree fuel stocks are described as good by Nurmi and Hillebrand [9] with transpiration drying bringing moisture content below 30% over one summer, and the presence of mesophillic fungi being at only 1% of that found in harvesting residues. However, the harvesting of small diameter trees is expensive and is still not economically feasible without incentives [10], although a comprehensive study recently showed that the carrying out of pre-commercial thinning (small tree harvesting) also had a significant effect on harvester productivity at subsequent thinning, increasing it by 0.57 m 3 s PMh −1 for each 10 dm 3 increase in mean tree volume [8].…”