AVALIAÇÃO OPERACIONAL DA COLHEITA DE MADEIRA EM DESBASTES DE Pinus taeda L.

Abstract

This study had by objective to carry out an operational comparative analysis involving technical and cost aspects of timber harvesting applying two thinning treatments in Pinus taeda L., in the first thinning at age 10. Data were obtained from the forest area of a company located in the city Quedas of Iguaçu, Paraná State. The treatments were two thinning models determined by the systematic elimination of 5th line (model 1, considered as traditional practices) and 7th line (model 2, alternative thinning model) and selective elimination in the lines that were determined for these intervals. The treatments were executed by two harvesting subsystems: mechanized composed by harvester and forwarder and mixed system compound by chainsaw, harvester and forwarder, the introduction of the chainsaw was the creation of an area outside the range of harvester, called "midfield". The proposed changes by the new model of thinning and mixed harvesting subsystem aimed to increasing productivity, reducing transaction costs and better quality of the remaining stands, in addition prevent the loss of productive area and disturbances in terms of soil compaction. To compare the performance of both harvesting systems working under the same conditions, a stand was selected with homogeneous characteristics. A study of the time and motion machines in both thinning treatments was performed, allowing a comparison of operational cycles and determining productivity, operational efficiency, operational costs and production costs. An evaluation of the quality of operations through the application of damages inventory in remaining population was made. The results showed the main factors that affected the operational cycle of the machines involved in these operations: for the harvester were affected mainly the searching and cutting, displacement and disruption; to the forwarder were affected the empty travel and loading. The subsystem of mechanized harvesting implementing in the thinning model 1 showed the highest productivity (42,3 m³.h-1against 40,5 m³.h-1), lower production costs (R$ 14,98/m³ against R$ 16,25/m³) and better quality of operation due to the less occurrence of damage to remaining trees (13 % versus 17 %). In addition to being defined the damage as minor, the proposed treatment enabled a better distribution of damage in the forest. Comparatively, the thinning treatment 2 did not offer better operational and cost of harvest results, but showed better results in relation to quality with minor damage in remaining trees of the stand.