Teak is an obligate light-demanding species throughout its life cycle. Inferior trees are readily suppressed if stand density is too high. Accordingly, plantations must be thinned regularly and heavily, particularly in the first half of the rotation. Initial planting density is generally between 1,200 and 1,600 plants per hectare.
The spacing of trees and the number, timing and intensity of thinnings strongly affect the pattern of growth and the yield of the plantation. If thinning is practiced late, growth rates decline or cease, whereas if the stand is thinned too early or too heavily, the trees have a greater tendency to produce side branches and epicormic shoots. This also reduces the potential yield of the plantation since growth is diverted from the main stem, which should be free from defects such as those caused by side branches and epicormic shoots.
The timing of the first thinning is often determined by the height of the trees and is commonly carried out when the trees reach 9.0 to 9.5 m. The second thinning may be carried out when the trees reach 17 to 18 m.
The site generally has a carrying capacity independent of initial stocking rates and thinning regimes. The carrying capacity is measured in terms of the basal area (the average cross-sectional area of all trees per unit of land). It is possible to identify the thinning regime necessary to achieve a certain basal area on an area of land by retaining a minimum number of trees. The mean basal area is often allowed to reach 20 to 22 m2 per hectare after the second thinning. A third thinning is then carried out to reduce the mean basal area to 13 to 15 m2 per hectare. Thinning and pruning operations have a strong effect on the yield and quality of timber. To produce long boles free from knots, the usual strategy is to keep stands closed using high-density plantings, which remain untwined for the first three or four years of the plantation. The objective is to minimize the size of the crowns and the side branches in order to improve the quality and appearance of the timber and, thereby, its value.
Overall, it is desirable to thin the stand to the number that is optimal for reduction of undue competition and for the best growth of the remaining trees. A final stocking of about 300 trees per hectare would be the ideal.