Productivity curve models in eucalypt timber forwarding

Abstract

Extraction is the most costly and complicated stage of timber harvest operations. The forwarder’s productive capacity in timber harvesting, from planted forests, is influenced by several operational variables, especially by extraction distance and tree volume. Prior knowledge about the effect of these variables on the operation is required for efficient planning. The goal of this research was to model and simulate a forwarder productivity curve for timber extraction in scenarios with different tree average volumes (TAV) and average extraction distances (AED). The research was carried out in a forestry company in the state of Mato Grosso do Sul, Brazil, in clonal eucalyptus stands with TAV varying from 0.186 to 0.310 m3 tree−1 and AED from 0 to 280 m. We performed a time and motion study of the forwarder, following the operation with a DJI-Phantom 4 Advanced drone. Productivity simulations were carried out in different operational scenarios. The models were evaluated using the adjusted determination coefficients (R 2 adj.), standard error of absolute estimate and F-value. Results have shown that as the TAV increased, productivity also increased 14% while the AED presented a relationship inversely proportional to productivity. The highest productivity of the machine occurred in the forest condition with a TAV of 0.31 to 0.36 m3 tree−1 and in the shortest extraction distances. The best-adjusted model explained 46.3% of the machine’s productivity variation. We concluded that TAV and AED variables had a significant impact on the forwarder’s productivity and that it is important to obtain the machine’s productivity curves for efficient forest operations planning.