ABSTRACT

The aim of this study was to evaluate the productivity, costs, and tree damage caused by machines in first thinning operations. The study was carried out in a 10 year old pine stand with two thinning operations: TH5, with the removal of each 5^th row and selective thinning between these rows; and TH7, with the removal of each 7^th row and selective thinning between these rows. Harvester and forwarder machines were used in the thinning operations, considering a tree maximum reach of 10 m. Working cycle times, productivity, energy efficiency and production costs were determined through a time–motion study. The tree damage was also quantified in the thinning operations. Cycle time values and tree damage were compared using the Mann–Whitney test for two independent samples (α = 0.05). The highest productivity and lowest cost for the harvester were observed in TH5, while the highest productivity for the forwarder was obtained in TH7, due to the higher log stack volume. On the other hand, TH5 was the most inexpensive operation, with a total of USD$4.62 m⁻³, although only USD$0.37 less expensive than TH7. Furthermore, TH5 and TH7 presented a similar percentage of tree damage of 20.9% and 19.1%, respectively. Therefore, TH5 was most cost-effective, while TH7 enables increasing the selective thinning area and improves the pine stand quality.

摘要

本研究的目的是评估机器在第一次间伐作业中造成的生产力、成本和树木损坏。该研究在一个 10 年生的松林中进行，进行了两次间伐操作：TH5，每行移除^第5行，并在这些行之间进行选择性间伐；和 TH7，每删除^第7^个行和这些行之间的选择性细化。考虑到树木最大可达 10 m，在间伐作业中使用了收割机和转运机。工作周期时间、生产力、能源效率和生产成本是通过时间-运动研究确定的。在间伐操作中也量化了树木损坏。使用 Mann-Whitney 检验对两个独立样本 (α = 0.05) 比较周期时间值和树木损坏。在 TH5 中观察到收割机的最高生产率和最低成本，而在 TH7 中获得了最高生产率，因为更大的原木堆体积。另一方面，TH5 是最便宜的操作，总计 4.62 m ^-3美元，虽然只比 TH7 便宜 0.37 美元。此外，TH5 和 TH7 的树木损坏百分比相似，分别为 20.9% 和 19.1%。因此，TH5 的成本效益最高，而 TH7 可以增加选择性间伐面积，提高松木林分质量。