ABSTRACT
The objectives of this work were: a) to study the effects of cost reduction on the optimal replacement time of Eucalyptus plantations; b) to determine rotation age, keeping income constant and cost decreasing overtime; c) to verify the efficiency of a mathematical model for modelling technological progress effects; d) to verify which would be the substitution cicle if the income had been constant since the sixties; and, e) to project substitution time in the future, considering decreasing cost and constant income at today’s values. Data from forest enterprises located in the Cerrado region were used. The Gompertz Function was employed to calculate timber yield. The economical evaluation method used was the Present Net Worth. The proposed model allowed calculating technological progress effect on costs in the 1960 - 2000 period and to project the cost values for the 2000 - 2040 period. It was concluded that: a) the rotation, with current values is 7 years; b) maintaining the income at the sixties levels, the optimal substitution cycle would be at 6 cuttings; c) the model proved to be efficient for estimates of up 40 years horizon; and, d) the substitution chain showed that the optimal substitution cycle went down along the years, from 6 cuttings in the sixties, 3 in the eighties and 2 currently; the future tendency is to stick with 2 cuttings, reaching 3 cuttings with increase in the coppice yields.
Key words:
technological progress; renewal; forest costs