A value chain comparison of Pinus patula sawlog management regimes based on different initial planting densities and effect on wood quality

摘要

This research provides an economic analysis of different management regimes of Pinus patula plantations destined for saw log production based on land expectation value (LEV). The effect of initial planting density on wood quality is considered in the economic evaluation. Different planting densities (403, 1097, 1808 and 2981 stems per hectare [spha]), thinning ages (10 to 13 years) and thinning intensities (150 to 400 spha remaining) were investigated. An experimental spacing trial was destructively tested to quantify the effect of initial planting density on lumber quality. Sawing simulation software and the FORSAT scenario analysis software were used to create an economic model of the saw log value chain where different management scenarios were analysed. The results indicated that there was an increase in the mean stiffness of lumber with increasing planting density which, in turn, resulted in increased log value recovery for logs from closely spaced trees. When including the effect of planting density on tree growth, mortality, as well as the operational costs, the best management regimes for each of the three lower planting densities (403, 1097, and 1808 spha) returned LEV values relatively close to each other. Despite the results showing that high planting densities result in better value recoveries for the same log sizes, the best LEV was from a medium high planting density (1808 spha) and included a late thinning. The research showed the importance of analysing the complete value chain including the effect of initial planting density on wood end-product quality, when performing economic comparisons of forest management regimes for saw log production.