Relationships between spacing, productivity and profitability of eucalypt plantations in a small rural property in south-eastern Brazil

Abstract

Tree cultivation spacing can influence productivity and wood quality, with silvicultural, technological and economic implications. This study aimed to estimate the production and provide an economic analysis of Eucalyptus urophylla × Eucalyptus grandis stands as a function of planting spacing in a small rural property. The study was carried out in the Zona da Mata of Minas Gerais state, with the hybrid clone (GG100) established in 2 × 1 m, 2 × 2 m, 3 × 2 m and 3 × 3 m spacing. Inventories were carried out at 14, 54 and 84 months in four plots from each spacing, with 24 plants. Diameter at breast height (DBH), total height and survival rate were evaluated. The study evaluated the logistic model of growth and yield for the different spacings and analysed production costs, characterising the expenditure elements related to inputs and labour. For the economic analysis, we considered a discount rate of 8% p.a. and the valuation methods of net present value (NPV), annual equivalent value (AEV), average production cost (APC), and cost–benefit ratio (CBR). Spacing influenced diameter distribution, tree height and productivity. The optimal harvest age showed a tendency to decrease in smaller spacing. The increase in plant density (smaller spacing) did not promote a proportional increase in volumetric production. Our results indicated economic viability from 60 months onwards for all spacing, except for 2 × 1 m.