THECNICAL AND ECONOMIC ANALYSIS OF FACTORS AFFECTING THINNED AND UNTHINNED MANAGEMENT REGIMES OF Pinus taeda L.

Abstract

This study presented an economic analysis of management systems in unthinned and thinned Pinus taeda L. stands, where the objective was pulpwood and veneer yield. Simulation results were obtained by a growth and yield simulator called “PISAPRO”, developed from data collected from continuous inventories at the PISA Florestal company. Simulations in unthinned stands considered: (a) initial densities: 2000, 1667, 1333 and 1111 stems per hectare; and, (b) rotation ages: from 9 until 20 years. The regimes simulated with one thinning considered: (a) initial densities: 2,000, 1,667, 1,333 and 1,111 stems per hectare; (b) thinning ages: 6, 9 and 12 years; (c) densities after thinning: 400, 700 and 1,000 stems per hectare; and, (d) rotation ages: 15, 18 and 21 years. The management systems were simulated for five conditions of site. The sensitivity analysis of profitability, carried out with a program called “INVEST”, considered: (a) discount rates: 6% and 8% p.a.; (b) harvesting costs: in stands with good harvest conditions (flat) and stands with steep terrain; (c) pulpwood and veneer transportation distances: 15 km, 50 km and 85 km; and, (d) veneer log prices: medium prices and increase of 20%. Site index and prices and costs parameters produced remarkable effect on the best management system. Pulpwood transportation cost had highly expressive effect on the profitability than veneer transportation cost. The best thinned regime allowed higher profitability than the best unthinned regime, in all the simulated conditions of sensitive analysis. This superiority of oncethinned regimes was greater under best sites and best costs and prices conditions considered in the sensitivity analysis.