Abstract
The prescription of forest management determines the number of trees to be cut and, consequently, the harvested wood volume, which directly influences the forest operations dynamic. The objectives of this paper were (i) to analyze the effect of process factors on wood extraction performance with forwarder in first thinning and clearcutting of Pinus taeda L. plantations; and (ii) to economically determine the optimal road density to manage these plantations. Time and motion studies at the cycle element level were conducted to quantify and model the time consumption, productivity, and operational costs of the extraction. The optimal road density (ORD) for both operation types (OT) was determined based on the transport geometry model, considering the minimization of the sum of unitary costs with construction and maintenance of roads, loss of productive area, and wood extraction. The extraction distance (ED), slope (SL), average log volume (LV), and OT had a significant effect on the time consumed in travels, and therefore, on productivity (PPMH). In clearcutting, the average PPMH was 12.17 m3ob PMH0-1, while, in thinning, it was 10.94 m3ob PMH0-1; however, as the ED increased, the difference of PPMH and the cost of extraction between the operations decreased, which highlighted a greater effect of this factor on forwarder’s work in clearcutting. For this reason, the ORD for clearcutting (37.76 m ha-1) was higher than for thinning (27.84 m ha-1). Therefore, we demonstrated in this study that the type of operation and forest management regime, as well as their interaction with process factors, affect the sizing of the number of roads per unit area, and also the costs of the forest activity.
Highlights
The implantation and management of planted pine forests is a consolidated activity in Brazil, but the management strategies adopted by verticalized companies are different from those used by independent producers
On the other hand, when the intention is to produce the maximum volume per unit area, the forests are usually managed in shorter rotation often of 15–20 years, without thinnings, and they are mainly directed to pulpwood or energy wood (Scolforo and Maestri 1997, Dobner et al 2013)
The number of valid forwarding cycles has been greater in clearcutting (n=42), the relative sampling error was higher in this type of operation (10.63%) due to greater variation in the productivity values compared to the first thinning
Summary
The implantation and management of planted pine forests is a consolidated activity in Brazil, but the management strategies adopted by verticalized companies are different from those used by independent producers. On the other hand, when the intention is to produce the maximum volume per unit area, the forests are usually managed in shorter rotation often of 15–20 years, without thinnings, and they are mainly directed to pulpwood or energy wood (Scolforo and Maestri 1997, Dobner et al 2013). Different management prescriptions influence the dynamics in forest operations, once it entails differences in the harvested number of trees and wood volume per unit area, types of assortments, etc. In this sense, management regimes with thinning show more complex and costly operational conditions, especially in initial interventions, where the remaining trees limit the machinery access and mobility inside the stand. Due to such conditions, the harvesting costs, added to the logistics costs (roads and transportation), are higher than the revenue from the timber trade, making the forest operations economically unfeasible
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