Woody Species Stand Structure and Regeneration Status in Long Jack (Eurycoma longifolia Jack) Habitat in Batang Lubu Sutam Forest, Padang Lawas, North Sumatra

Abstract

Long jack (Eurycoma longifolia) is a medicinal plant that has become a common target for exploitation, leading to a population decline in natural forests. This study aimed to determine the stand structure and regeneration status of E. longifolia tree habitat in Batang Lubu Sutam Forest, Padang Lawas, North Sumatra. The research was performed through vegetation analysis using a purposive sampling technique with a randomized sample plot based on the presence of E. longifolia. A total of 181 plots were established in this study. The results showed that the horizontal structure of tree species in the research area had an inverted J-shape pattern, indicating that the number of trees decreased as the diameter increased. The vertical structure showed that all strata were found in the research location, dominated by stratum C. This condition indicated that the forest was in good condition. The regeneration status of 48 species in the location showed different categories. Thirty species (62.50%) were classified as good regeneration, ten species (18.75%) as new regeneration, and four species (8.30%) as poor and no regeneration. The high proportion of trees with good regeneration showed that the forest community could survive despite environmental or anthropogenic stress. Keywords: long jack (Eurycoma longifolia), regeneration, species composition, vegetation structure