Growth of Ensideroxylon zwageri seedlings and Silvicultural Changes in Logged-Over and Burned Forests of Bukit Soeharto, East Kalimantan, Indonesia
Ulin (Eusideroxylon zwageri) is an ironwood species whose growing stock has decreased due to overexploitation. Ulin trees occur in lowland forests as scattered individuals in Kalimantan and naturally regenerated seedlings are usually restricted in the area near seed parents. They are recruited almost every year although the recruitment rates fluctuate. Seedlings of ulin in a closed rain forest seldom die. However, as they grow slowly, natural regeneration appears to be poor in terms of timber production. Canopy opening and weeding (release cutting) accelerate the seedling growth by improving the light conditions. Release cutting applied to seedling about 5 years old and 92 ± 36 cm tall in this study enabled to increase seedling growth rates and possibly decrease the time required for the ulin stem to reach 10 cm in dbh (diameter at breast height) from 78 to 26 years. However, sudden felling caused an increase in the death rate of the seedlings. Since seedlings less than 3 years old are sometimes more sensitive to sunlight and dry weather conditions than older seedlings, release cutting should be carried out in the case of 3-year-old seedlings or older. Ulin is fire-resistant after becoming large. However, it is still sensitive during small seedling stages. Appropriate release cutting should thus shorten the time required for ulin to become fire-resistant.
|作成者||Yoshiyuki KIYONO HASTANIAH|