EVALUATION OF ASSORTMENTS CONSIDERING DIFFERENT STUMP AND PRE-BUCKING DISC HEIGHTS IN MECHANIZED HARVESTING OPERATIONS OF A Pinus taeda L. FOREST

Abstract

This study aimed to evaluate assortments by adopting distinct stump heights and pre-bucking disc heights in the mechanized harvesting operations of a Pinus taeda L. forest, which is owned by a company located in Campo Belo do Sul (SC). To that end, the simulation of six scenarios was carried out after the forest’s clear-cutting. The scenario 1 includes the company's specifications. Scenario 2 includes the real situation, that is, the measurements made in sample units installed on the field and scenario 3 includes stump heights of 10 cm and pre-bucking disc heights of 5 cm. In the other scenarios, stump and pre-bucking disc heights with values higher than the ones specified by the company were included. Then, using a taper function, we calculated the assortments in tons per hectare (t ha-1) and monetary value per hectare (R$ ha-1), considering the price of wood with bark (R$ t-1) for each assortment. Results show that Scenario 1 presented a larger amount of wood, however, Scenario 3 represented higher revenue due to the higher wood quantity of the value-added assortments. On the other hand, Scenario 6 presented the lowest amount of wood comparing to the others, and Scenario 2 presented the lowest economic return. All things considered, the company performs its activities below what is planned, but with production higher than the other evaluated scenarios. Regarding the economic return, the other scenarios are more feasible than Scenario 2, which shows that the company needs to seek process improvements with the implementation of another scenario that could bring better results.

ASSORTMENT DOWNGRADE CORRECTION FOR CLEAR CUT OF Pinus taeda L. WITH USE OF TRANSITION MATRIX

“…In some situations, the volumes of the assortment classes S5 were upgraded to S4 (9.5%), S4 to S3 (4.8%) and S3 to S2 (1.6%), not attributing to a factor characteristic for this change that are not the same caused by the disqualification. Works such as those by Oliveira et al (2020) generated scenarios of volumetric and economic gain from changes in the height of the tree stumps, or even in few changes in the length of the logs. Such changes may be caused unintentionally by the forest machine operator and may cause the transition (upgrade or downgrade) of assortments in some cases.…”

“…In this context, volumetric estimates made with the use of tapering functions, are indicated, mainly because they make estimates of the total volume of the tree and its multiproducts (Miguel et al 2011;Figueiredo Filho et al 2015;Kohler et al 2013;Oliveira et al 2020). However, it has been observed that the estimates made by these models, present certain inconsistencies with the values measured after the forest harvest (Serpe et al 2018), and these errors are often considered not as a biased estimate of the models, but as defects in the logs or insipient quality of forest harvesting activities.…”