THINNING SLASH AND LOBLOLLY PINES IN QUEENSLAND

SUMMARY A summary of the main conclusions resulting from twenty years of thinning research in slash and loblolly pines is given, and important principles are illustrated. Competition among the components of a stand commences at a very early age. Thinning on a commercial basis to 350 stems per acre at 12–15 years is recommended for 8 by 8 ft. plantings, and to 450 per acre at 13–15 years in stands planted at 7 by 7 ft. The reason for the difference is explained. A second thinning to 240 stems per acre is required five or six years later. If merchantable thinning is likely to be delayed, early non-commercial thinning is desirable. Thinning to 400–450 stems per acre at 3–4 years is advocated. No plantations are old enough to have been thinned more than twice, except experimentally. Subsequent thinnings are discussed, and it is probable that they will be designed to maintain the basal area of the stand within the range of 100–140 sq. ft. per acre; crop stems may be allowed to develop beyond this figure before the final cut.