Abstract
AbstractThe aim of this study was to assess the influence of some operational variables on the forwarder productivity and production cost in thinned Pinus taeda L. stands by means of mathematical modeling. This study was carried out in a forest company located at Quedas do Iguaçu, state of Paraná, Brazil. Two stands at 9 and 10 years old from sites with high productivity and similar soil and relief features were studied. A time-motion study was applied to determine the operational cycle time, operational efficiency, productivity, and production costs. By means of mathematical modeling, we verified the influence of the variables: age of stand; cycle time; load volume; and extraction distance on the forwarder productivity and production costs. Models were fitted for estimating the forwarder productivity using cycle time, load volume, and extraction distance. Thus, we obtained the determination adjusted coefficients of 0.88 and 0.94, with an estimate standard error between 6.9% and 13.5%. Models for estimating production cost through the load volume variable presented a determination coefficient of 0.64 and 0.86, with an estimate standard error of 23.1% and 26.7%. Such results have shown the possibility of using mathematical models to estimate the performance of forest machines as a tool for planning the timber harvesting operations.
Highlights
As a silvicultural practice, thinning is the partial harvesting of trees in forest stands from spatial criteria, in order to provide growth continuity of tree remnants by means of reducing intraspecific competitiveness for environmental elements, such as water, light, and nutrients
The aim of this study was to verify the influence of some operational variables on the forwarder productivity and production costs in thinned Pinus taeda L. stands by means of mathematical modeling, in order to contribute to forest operation and harvesting planning
In order to increase the forwarder productivity, the results showed that it is necessary to adopt procedures to optimize the operation through the quality of log piles, use of crane with long reach, and extraction of the assortments separately (LOPES et al, 2010; LOPES et al, 2016; MAZÃO et al, 2017)
Summary
As a silvicultural practice, thinning is the partial harvesting of trees in forest stands from spatial criteria, in order to provide growth continuity of tree remnants by means of reducing intraspecific competitiveness for environmental elements, such as water, light, and nutrients. Thinning is carried out from below, by removing some lower trees, so that the trees with superior features in vitality, stem quality and growth remain, and the production of wood of the best quality increases (SCHNEIDER; SCHNEIDER, 2008; CARNEIRO et al, 2012). The removal of trees from stands through thinning is a complex and costly process due to the low mobility of machines within the stand, low individual volume, quantity of removed trees, and necessity to produce several assortments. Mechanized operations of forest harvesting in stands under thinning result.
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