The contribution of multi-storied forest rehabilitation on forest productivity and carbon sequestration

Multi-storied forest management (MSFM) is a promising rehabilitation technique to promote forest development and management in the tropics. MSFM was established in Chikus Forest Reserve, Perak in 1992 to convert marginally poor forest into forest plantation in order to meet future demand of general utility timber and also to combat global warming. The experimental plots were set up to demonstrate five different planting designs, namely type A; one row of indigenous high quality timber species (Shorea leprosula) planted and one row of 3 years old exotic trees (Acacia mangium) retained, 1:1, type B; 2:2, type C; 4:4, type D; 8:8 and type E; 16: 16 in two different planting directions north to south and west to east. Each plot had an area of approximately one hectare with 3.0 m x 3.7 m spacing. The direction of planting row was not different from each other for both growth rate and survival. In the early growth up to 8 years old, diameter and height growth tend to increase with increasing number of row from type A to type E, except for tree height of type E, as a result of low inter-specific competition. At 16 years old, S. leprosula was almost dominant in all planting designs of multi¬storied forest, replacing the exotic species of A. mangium. The competition for both inter- and intra-specific was high as depicted by survival rate which decreased with increasing number of row from type B to type E as well as mean annual increment. The best performance of tree growth was type C, which was four rows of S. leprosula and four rows of A. mangium with 21.99 cm, 20.09 m and 66.4% of average diameter, total height and survival rate, respectively. The study also derived specific equations (tier 3) through destructive sampling method of 15 representative trees to estimate stand productivity such as volume, biomass and carbon. Biomass proportions were 56.88, 14.92, 3.48, and 24.85% for stem, branches, leaves and root, respectively while average carbon content were 43.77,42.63,43.55 and 41.02%, respectively. The volume of best planting design was 152.23 m3 ha-1 and the total biomass was 79.42 tonnes ha-1 (=34.76 tonnes net C ha-1), 59.62 tonnes ha-1 of aboveground biomass and 19.80 tonnes ha-1 of root biomass. The best planting design can absorp 124.97 tonnes net CO2 from atmosphere. The study concludes that S. leprosula was sound to be one of the promising species for reforestation as well as replacing exotic species, and type C of planting design is recommended for optimum growth performance, stand productivity and capacity of C02 absorption in multi-stored forest management.