CLEAR BOLE LENGTHS AND CROWN CHARACTERISTICS OF LINE-PLANTED AND NATURALLY-REGENERATED SHOREA LEPROSULA TREES: A CASE STUDY FROM KALIMANTAN, INDONESIA

Shorea leprosula seedlings planted at 5-m intervals along 3-m wide cleared lines at 20-m intervals through twice-logged forests in Kalimantan grew rapidly in dbh (diameter at 1.3 m) but at age 14-15 years, had branch-free stems that averaged 11% shorter than those of naturally-regenerated trees of the same dbh (20-40 cm). There was no relationship between clear bole length and terrain slope or current crown exposure. If low branches continue to be maintained until the harvest (planned at 25 years), commercial timber yields will be lower than predicted from allometrical relationships calculated using data from naturally-regenerated trees. Even if low branches on the planted trees are shed before harvest, log values will be reduced due to the presence of large knots. Pruning and manipulation of light exposure are possible ways to avoid long-term branch retention.