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THE OPTIMAL TIME FOR SUBSTITUTION OF Eucalyptus spp. PLANTATIONS –THE TECHNOLOGICAL PROGRESS CASE

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Author(s): José Luiz Pereira de Rezende | Álvaro Nogueira de Souza | Antônio Donizete de Oliveira

Journal: Cerne
ISSN 0104-7760

Volume: 11;
Issue: 1;
Start page: 1;
Date: 2005;
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Keywords: Technological progress | cutting age | forestry economy.

ABSTRACT
The importance of technological progress for the Brazilian forest enterprises cannot be denied. Its influencecomprehends all the activities, but can be summarized in the increase of income via yield increase or cost reduction and, mainly,in the two cases occurring together. Technological effects influence, among other aspects, the cutting age and the optimal time torenewal (a new plantinting or “reforma”) Eucalyptus plantations. Studies to determine these times are not so common in theliterature since it requires both forestry and economic knowledge. Before renewing an Eucalyptus stand, it is necessary totechnically and economically to define the optimal cut age the original planting and the coppicings and after how many cuttingsthe substitution of the plantations should be done. This study aimed at studying the optimal time to substitute Eucalyptus spp.Plantations, considering the gains earned through technological progress; to determine the cutting age of the population, theincome being increasing and the cost being decreasing; to propose and verify the efficiency of a mathematical model whichallows modeling the effects of technological progress; to study the substitution chain between 1960 and 2000 and between 2000and 2040, considering technological progress; and to test the results in a case study. The Gompertz Function was employed toobtain the volumes at the various ages. The criterion employed for the economic evaluation of the projects was the Presente NetValue (PNV). The proposed model allowed the calculation of yields and costs through time, study the effect of yield increaseand cost reduction and determine the rates of these increase and, or, reductions as well as determining rates which served asmoderators so that the yield and costs did not reach unreal values. It was concluded that: The rotation, with current values, is at 7years of age; the model proved to be efficient for estimates up to 40 years; with the income and costs from the sixties, consideringtechnological progress from that point on, the number of cuttings before the renewal is currently 2; the substitution chain showedthat the optimal substitution time went down with time, going from 18 cuttings in the sixties to 4 cuttings in the eighties,currently getting to 2 cuttings; a tendency to stick with 2 cuttings before substitution was verified for future cultivation, althoughlittle technological improvement in the coppice yield brings the optimal substitution Point to after the third cutting.
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