EFFECT OF SPACINGS ON GROWTH AND YIELD OF ALSTONIA SCHOLARIS R. BR. PLANTATION

Abstract

The study on effect of spacing on growth and yield of Alstonia scholaris R. Br. plantation were carried out with seven spacings, 0.5x0.5 m²., 0.75x0.75 m²., 1x1 m²., 1.5x1.5 m²., 2x2 m²., 4x4 m². and 6x6 m². The trees were planted in September 1996 at Trat Agroforestry Research Station, Trat Province. Then, data was collected 4 times in March 1997, October 1998, 1999 and 2000 respectively. This investigation aimed to study comparatively growth and yield at different spacing. Base on the growth parameters such as mean annual increment and relative growth rate of stem diameter at ground level, biomass and stem volume, it was found that trees in different spacing had performed insignificantly during the period of 1-2 years old. Therefore, the narrow spacing between 0.5-1.5 meters was suitable for economic planting because of having higher production and more number of trees. For the period of 2-4 years old, trees in spacing of 2-6 meters had higher growth than those of the narrower spacing. At 4 years old, thinning should be applied in the spacing less than 2 meters in order to promote a better growth. For trees growing to a larger size, the spacing of greater than 4 meters is recommended. In case of agroforestry system, the spacing of 6 meters is recommended in which intercropping can be appropriately done for more than 4 years.