IMPORTANCE OF WEED CONTROL PRIOR TO PLANTING FOR THE ESTABLISHMENT OF PLANTED FORESTS IN SABAH, MALAYSIA

The establishment of fast-growing trees in the production forests of Sabah, Malaysia may be severely compromised if weed control, during the initial months following site preparation, is inadequate. A twoway factorial experimental design, comparing levels of manual and chemical weed control, with and without fertilisation at planting, was used to demonstrate significant impacts on the mean tree volume of Acacia mangium trees, 3½ years after plantation establishment. Eliminating weeds at 23 months, with remedial treatment across the factorial experiment, demonstrated little residual effects. No productivity benefit was observed at 14 months, after remedial weed control at 23 months post-establishment, nor was there any productivity gain observed at 10 months, after remediation application of fertiliser at 26 months post-establishment. The results emphasised the need for weed control during site preparation, including complete chemical weed control prior to planting and quarterly until canopy closure.