Growth and yield of teak (Tectona grandis Linn F.) plantations in Northern Ghana

Abstract

Teak (Tectona grandis Linn F.) is a popular exotic species in Ghana, widely grown in industrial plantations and small scale community woodlots. In spite of its importance, limited information exists on the growth and yield of this species. Presented here are the results of a preliminary study aimed at assessing the growth and yield potential and developing provisional yield models for the management of teak in Northern Ghana. Data were collected from 100 temporary sample plots from plantations in this region, ranging in ages from 3 to 40 years. Local, standard and stand volume equations and tables were constructed from the data. Additive above ground biomass and site index equations, and provisional empirical yield models were also developed and presented. Site index curves were used to classify teak plantations in the region into site classes I, II and III, in order of decreasing productivity. The assessment of growth and yield revealed the potential for growing teak to acceptable timber size on good sites. Yield functions, indicate that teak can be grown on biologically optimum rotations of 31, 38 and 48 years on site classes I, II and III respectively. The diameter distribution was modelled by the three-parameter Weibull function, using the maximum likelihood and the percentile parameter estimators. The diameter distribution showed positive skewness indicating there are more trees in smaller diameter classes. Initial planting spacing of 2 by 2 m could be reduced to accommodate initial mortality and to achieve optimum stocking levels in order to improve form and timber quality.