Effects of thinning on growth performance of teak (Tectona grandis) plantations in tain ii forest reserve, Ghana
Bertrand Nero, Maxwell Asuenabisa
Kwame Nkrumah University of Science and Technology, Ghana
Plantation establishment has been promoted in the tropics in the last 4-5 decades in a bid to mitigate climate change, timber deficit, and biodiversity loss, as well as restore degraded forests and provide employment incentives to fringe communities. Practitioners require technical information about appropriate cost-effective silvicultural techniques that can achieve higher productivity. In Ghana, government incentives have promoted the commercial establishment of teak and other species plantations, yet information on tree response to silvicultural management is still scarce. The present study evaluates the effects of thinning intensity on the growth response and pruning requirements of teak plantations, two years after thinning. The thinning trial was conducted on a four-year-old stand with initial stocking of 1111 trees per hectare in the Tain II forest reserve of Ghana. Four thinning intensities: 50%, 30%, 0% thinning intensities and 50% de-crowning were the treatments arranged in a completely randomised design. Each treatment had four replicates. ANOVA output for data collected two years after thinning revealed statistically significant difference between the treatments in DBH (p < 0.012) and volume (p<0.017) whereas total height and basal area were not significantly different. The highest DBH, volume, height and BA per tree were found in the 50% thinning intensity (15.57cm, 0.13m3, 12.13m and 0.02m2 respectively) while the lowest was found in the control. Maximum mean annual increment of DBH, height and volume were respectively, 2.66 cm, 2.34m and 16.32 m3 ha-1. Increasing the thinning intensity significantly increased the number of epicormic shoots (p=0.0397), hence increasing the pruning requirement. It is concluded that 50% thinning intensity best favours the growth of residual trees but it increases the pruning requirements and ultimately the pruning costs. Evaluation of this trial over a longer time period is paramount to validate these preliminary conclusions.
Keywords: Epicormic shoots, plantation, pruning, residual trees, thinning intensity
Contact Address: Bertrand Nero, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana, e-mail: nerbefestyahoo.com