EFFECT OF PROVENANCE VARIATION AND SINGLING AND PRUNING ON EARLY GROWTH OF ACACIA-MANGIUM WILLD PLANTATION ON IMPERATA-CYLINDRICA (L) BEAUVDOMINATED GRASSLAND

Early growth of 20 provenances of Acacia mangium was studied on Impera ta cylindrica dominated grassland in South Kalimantan, Indonesia. Effe ct of climatic factors of the natural habitats of the provenances on g rowth on the trial site was tested. In addition, the effects of singli ng and pruning on the early growth were assessed, Randomized complete block design with four replications was used. At the age of 26 months the yield of the best provenances was almost threefold compared with t hat from bulk seed from Subanjeriji, the most widely used Acacia mangi um seed origin in Indonesia. Provenances from Papua New Guinea showed the best growth (60-90 m(3) ha(-1)) and the lowest growth (30-50 m(3) ha(-1)) was recorded for those from southerly parts of Queensland, Aus tralia, and the local sources, Field performance was closely related t o rainfall seasonality emphasizing the need for careful matching betwe en the rainfall patterns of seed collection sites and those of the pla nting site. The driest quarter precipitation explained 74% of the grow th rate, Growth after singling and pruning was only about 70% of that of untreated plots. Therefore, singling and pruning at 8 months cannot be recommended for the plantations if growth rate is the first priori ty, Studies of the long-term effect of pruning and singling are needed .