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Oktavia D, Pratiwi SD, Munawaroh S, Hikmat A, Hilwan I. 2021. Floristic composition and species diversity in three habitat types of heath forest in Belitung Island, Indonesia. Biodiversitas 22: 5555-5563. Exploring plant diversity, structure, and composition of vegetation in forest ecosystems is necessary for understanding the mechanism of species coexistence and forest dynamics, moreover in a unique and vulnerable ecosystem such as tropical heath forest (kerangas). We investigated the composition and structure of vegetation of heath forests in East Belitung, Indonesia in three habitat types, namely primary heath forest (rimba), secondary heath forest (bebak), and grassland (padang). Vegetation analysis was conducted using the combination of transect and plot method to calculate the importance value index (IVI) for all species and biodiversity indicators for each habitat type. We recorded 157, 135, and 31 species in rimba, bebak, and padang, respectively. The top three dominant families of species found were Myrtaceae, Clusiaceae, and Euphorbiaceae. In rimba, Syzygium lepidocarpa had the highest IVI for seedlings, Calophyllum lanigerum had the highest IVI for saplings, and Schima walichii had the highest IVI for trees. In bebak, Guioa pleuropteris had the highest IVI for seedlings, Garcinia hombroniana had the highest IVI for saplings, and Schima walichii had the highest IVI for trees. In padang, Fimbristylis sp. had the highest IVI for seedlings, while Leptospermum flavescens had the highest IVI for saplings and trees. Some pioneer species were found such as Rhodomyrtus tomentosa, Rhodamnia cinerea, Syzygium buxifolium. We also found two carnivorous plants Drosera burmannii and Nepenthes gracilis in padang, indicating that this habitat type is poor in nutrients in the soils. We suggested that the presence of species composition in the three habitat types of heath forest is an essential plant resource to be conserved and sustainably utilized. Establishing reserve areas to protect natural habitat and biodiversity is encouraged to provide proper ecosystem function for the people and nature.

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Rafflesia patma Blume is placed as one of the CRB2c endangered status. It refers to the taxon who face the highest extinction in the short periode of time. The flower scarce is caused by a live factor of R. patma that need specific habitats such as physical and biotic factors. The habitats and population of R. patma will be charge on fluctuation due to the higher human activities and nature's changes. The study on population of R. patma in CA Pananjung Pangandaran (CAPP) was conducted. The results indicated that R. patma founded 312 individuals which distributed in 6 locations. This condition indicated that CAPP is suitable from R. patma. Keywords: Rafflesia patma, population, endangered, extinction, biotoc factor