Abstract
Forwarding can be divided into separate work elements. These are affected by several factors: forwarding distance, load volume, and types of assortments harvested. For a detailed planning of thinning, productivity models should include these factors. This study analysed the time consumption of forwarder thinning operations in five pine plantations in the north-east of Argentina, determining how the log size and log concentration affect each work element. Time-and-motion studies were carried out, recording the activities with digital video cameras, and tracking the forwarder movements with global navigation satellite system (GNSS) receivers. Different linear mixed models were fitted to estimate the time consumption of each work element in relation to different predictive factors. When driving on the road, the forwarders had an average speed of 71.6 m min-1 empty and 75.7 m min-1 loaded. When driving in the stand, the average speed was 56.9 m min-1 empty and 52.2 m min-1 loaded. These speeds did not correlate with the forwarder size or load volume. For the loading and unloading elements, the linear mixed model explained 56% and 49% of the variability considering only the fixed effect of the logs size and the load volume. For driving while loading, the total volume loaded, and the log concentration of the assortment loaded explained 50% of the time consumption variability, with 17% being explained by random effects. The general time and productivity model developed can be applied to support accurate decisions in the process of thinning planning.
Highlights
Thinning operations of fast-growing pine plantations in the northeast Argentina are carried out with the Cut-to-Length system
This study developed a general model for a group of forwarders working in pine plantations in the northeast of Argentina, to contribute to the understanding of how the forwarded log concentration and log size affected timber forwarding productivity
This study focuses on a group of forwarders of different sizes working in pine thinning operations in the northeast of Argentina to produce general time consumption and productivity models
Summary
Thinning operations of fast-growing pine plantations in the northeast Argentina are carried out with the Cut-to-Length system. In these operations, generally thinning from below, 40–50% of trees with smaller diameter or deficient shape are removed. The margins of the harvesting contractors depend on a constant increase in productivity and a decrease in production costs (Mac Donagh et al 2017). In this scenario, the understanding of the forwarding operation is decisive for good planning of the thinning operation in different sites. Forwarding is a complex activity, consisting of several work elements, each of them affected by seve ral factors (Nieminstö et al 2012, Manner et al 2016a, Croat. j. for. eng. 41(2020)
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