ABSTRACT

The study compared the cut-to-length (CTL) and the whole-tree-harvesting (WTH) methods under two alternative log length specifications (2 m vs. 4 m) as deployed in the new medium-rotation poplar plantations. The goal of this study was to determine if any of the four combinations of harvesting method and log length incurred lower cost and/or better log yield than the others. The test was conducted in a 6-year-old plantation with a stocking between 30 and 60 bone-dry tons (BDT) per hectare. Each treatment was repeated 8 times – each repetition consisting of one sample plot with a 700 m² surface area (115–130 trees). Researchers determined the mass obtained from each sample plot, as well as the time necessary to turn standing trees into logs and biomass piled at the landing. A calculator was developed for estimating harvesting costs as a function of variable machine rates. Under the conditions of the study, CTL harvesting into 4-m long logs was the most effective solution, because it offered a better log yield compared with WTH (60% vs. 50%) and incurred the same harvesting cost (∼ 33 € BDT⁻¹). Shortening log length to 2 m determined a 25% increase of harvesting cost.

摘要

该研究比较了在新的中等轮伐期杨树人工林中部署的两种备选原木长度规格（2 m 与 4 m）下的定长切割 (CTL) 和整树采伐 (WTH) 方法。本研究的目的是确定采伐方法和原木长度的四种组合中的任何一种是否比其他组合产生更低的成本和/或更好的原木产量。该测试是在一个拥有 6 年历史的种植园中进行的，每公顷放养量在 30 至 60 干吨 (BDT) 之间。每个处理重复 8 次——每次重复由一个 700 m ^{2的样地组成}表面积（115-130 棵树）。研究人员确定了从每个样地获得的质量，以及将站立的树木变成原木和堆放在平台处的生物量所需的时间。开发了一个计算器来估算收获成本作为可变机器率的函数。在研究条件下，将 CTL 采伐成 4 米长的原木是最有效的解决方案，因为与 WTH 相比，它提供了更好的原木产量（60% 对 50%）并且采伐成本相同（∼ 33 € BDT ^-1）。将原木长度缩短至 2 m 会使采伐成本增加 25%。