Linear Programming Approach to Sustainable Management of Gmelina Arborea Plantations in a Nigerian Lowland Rainforest

Abstract

A linear programming (LP) model was used to prescribe timber harvest in the management of even-aged Gmelina arborea plantations in Omo Forest Reserve, Southwestern, Nigeria. The plantations now being managed for timber production are to be exploited within fifteen years based on a 5-year harvesting period. Data was generated from eight compartments which were established between 1991 and 2000, and covering an area of 9489 hectares with a total volume of 9,716,726.0m³. Sample plots (20m X 20m) were randomly laid out in each compartment. In each sample plot, tree diameters and heights were measured and tree volumes estimated. The maximization problem of wood volume on compartmental level was formulated and solved. The solution of the LP showed that about 12.5m³ million of wood was maximized. The optimal solution prescribed 3500ha (4,703,426.0m³) to be cut in period I (2008 –2012); 3000ha (3,400,946.0m³) is to be cut in period II (2013 – 2017) while 2989ha (4,402,982.0m³) will be cut in period 2018 – 2022). Sensitivity analysis and opportunity costs were used to highlight the effects of changing some of the model parameters on the prescribed optimal solution. Key words: Linear programming, timber harvest, Gmelina arborea, Omo forest reserve, optimal solution, sensitivity analysis