Excerpt from Pinus radiata, Growth and economics

From "Summary" "Results obtained"
"In the first place, the data in Table 11.2 indicated that when the site index is as low as 64 [= the mean height in feet at 20 years of the 100 biggest-diameter trees per acre], radiata-growing cannot be expected to be profitable in the Western Cape ? The treatment which proved the most profitable for both site indices 80 and 99 was to plant the trees at an espacement of 9 feet [2.74 m], to take out respectively 60, 50 and 40 per cent of the trees in thinnings at 6, 11 and 16 years, and to clearfell at 21 years.
Such a treatment may not give as good a sawtimber as could be obtained with lighter thinnings and a longer rotation, but this does not alter the fact that it was found to give a much greater profit. The standard treatment currently applied in the state-owned radiata plantations in the Western Cape no doubt produces a greater proportion of high-quality sawtimber than the optimal treatment described above, but it was found to give a negative net land expectation value [net present value] at average timber values and silvicultural costs." (Pages 216/17)