Diversity of plant species and the presence of Invasive Alien Species (IAS) in the Sub-Montane Forest at Pakenjeng Region, Southern Part of Garut, West Java

Plant species diversity is an important ecological characteristic, especially to observe the complexity of forest ecosystems. The research is carried out to elaborate on the species composition, species diversity and the forest structure, and to identify the presence of invasive alien species (IAS) in the sub-montane forests at the Pakenjeng region, the southern part of Garut, West Java. The vegetation survey method used was a stratified sampling technique with the transects and line plots as sampling units for inventorying the trees, forest regenerations, and ground cover. These data are further analyzed to obtain information on abundance, dominance, importance value index (IVI), species diversity and evenness. Based on the species composition, the forest formation was categorized as a primary sub-montane forest with high species diversity characterized by the presence of tree species such as Altingia excelsa, Lithocarpus sundaicus, Castanopsis spp. and Podocarpus spp. showing the curve of inversed-J for horizontal structure with A, B and C canopy layers. The species of Eupatorium inulifolium, Musa zebrina, Piper aduncum and Lantana camara are categorized as IAS.