Silvicultrual practices and growth of jabon tree (Anthocephalus cadamba Miq) in Community Forest, West Java, Indonesia

Abstract

Jabon (Anthocephalus cadamba Miq.) is a native species in Indonesia. This fast growing tree is now preferred for the local community to plant because of its good adaptability and economic profitability. However, the information of this tree and silvicultural practices is still lacking. Therefore, there are three main objectives of this research: 1) to document the existing silvicultural practices of jabon implemented by local communities in West Java. 2) to investigate tree growth performance among different sites in West Java. 3) to examine the linkage of silvicultural practices and soil fertility for stand quality. This research covered following aspects; stand inventory, soil sampling and interview with local communities who planted jabon in the districts of Bogor, Sukabumi, Sumedang and Purwakarta. With 0.02 or 0.04 ha size sample plots, a stand inventory has been conducted and the diameter and height are measured. In addition, pest investigation also has been carried out at same sample plots. In addition, soil sampling and interview have done to collect site information and silvicultural practices in each site. After collecting various data from jabon plantation in West Java, those data are analyzed in forms of tabulation and regression graph. According to the results of the interview, most jabon plantations are owned by outsiders from Jakarta or other cities. There are three types of management: partnership, hiring employees and direct management. There are only a few practitioners have participated in silvicultural training. In spite of the absence of systematic silvicultural training, all practitioners have implemented basic silvicultural practices: land preparation and planting, fertilizing, maintenance and pest and disease control. Moreover, most of sites in same village have same or similar silvicultural practices because usually only one manager or farmer maintains all plantations. After an inventory of jabon plantations in West Java, there are totally 56 plots have been inventoried in 20 sites. The age of jabon tree ranges from 0.5-year to 3.5-year because jabon tree has been introduced in Java since 2008. The mean diameter ranges from 2.45 cm to 14.57 cm with maximum 29.3 cm and the mean height of 1.29 m to 12.62 m with maximum 18.68m in Situgede. As a result of regression modeling with dominant height, one Chapman model has been selected to calculate site index curve.: Hd 􀵌 10. 6982􁈺1 􀵆 exp􁈺􀵆0.8915t􁈻􁈻􀀀.􀀀􀀀􀀀􀀀 with 0.6513 R-square value. This curve helps to divide 20 sites into three categories: good, medium and poor. Based on analysis, there are two good sites, twelve medium and six poor sites. There are three DBH-age equations can be estimated based on site classifications. As a result of comparison between good and poor sites, it seems that site conditions and soil fertility have a more significant impact on growth of jabon than silvicultrual practices like fertilization and maintenance.