The Growth of Selected Shorea Spp in Secondary Tropical Rain Forest: The Effect of Silviculture Treatment to Improve Growth Quality of Shorea Spp

Dipterocarpaceae is the main species of tropical rain forest in Indonesia, Malaysia, Brunei and Phillippines and it ranges in eastwards as far as eastern New Guinea. This species is primary product in tropical rain forest of forest concessions. Recently, the quality and quantity of tropical rain forest are decreasing because of the land convertion become forest plantation; illegal logging and shifting cultivation. One of the strategies to reduce the forest degradation is enrichment planting on logged over forest (LOA) using dipterocarps species. The plantation trial was established with two (2) spacing, two (2) fertilizer dosages and five (5) Shorea spp as treatment to support the enrichment planting program in LOA. The research design was split-split plot design with 4 replications. The main plot was 2 spacings i.e. 6x2 m; and 6x4 m. The sub plot was 2 dosages of NPK Fertilizer i.e. 0 and 100 gr species-1. The sub-sub plot was 5 species of Shorea spp., i.e. Shorea leprosula, S.platyclados, S.parvifolia, S.virescens and S.johorensis. Each treatment was established in sguare plot (4x10 trees/treatment). The reserach result showed that spacing, fertilizer dosage and interaction between treatmens were not significant, while species was significant at tα=0.05 fertilizer dosage and interaction between treatmens were not significant, while species was significant at dipterocarps early growth. The highest growth was S.leprosula of DBH and high variables where the value of DBH and high variables were 8.90 cm (2.9 cm.year-1 of mean annual increment/MAI) and 6.31 m (2.1 m. year-1 of MAI) respectively. The lowest growth was S.virescens both on high and DBH variables where the value of DBH and high were 2.27 cm. year-1 and 1.40 m. year-1 respectively.