Plant biodiversity, value, and distribution of Rubiaceae at Hon Ba Nature Reserve, Khanh Hoa province, Vietnam

Rubiaceae is the most prominent plant family after Orchidaceae, Asteraceae, and Fabaceae. It is important for all vegetation, especially tropical rainforests. Moreover, they also have uses and conservation values: food, timber, medicinal, and species threatened to varying degrees. This article presents the study outcomes of the Rubiaceae family in Hon Ba Nature Reserve Khanh Hoa province, Vietnam. The methods of transect surveys and sample plots were utilized in this investigation to collect data. Of 94 species, 42 genera were recorded; Lisianthus was the most diverse genus. Twelve species were listed in Viet Nam Red Data Book (2007), Viet Nam Red List of Medicinal Plants (2019), and IUCN Red List (2021). The phytogeographical factor highest were endemic to Vietnam (38.30%), the Indochina-India (20.21%), and the Asian tropical element (12.77%); the remaining factor was deficient. The Spectrum of Biology (SB) of Rubiaceae family was summarized as follows: SB = 94.68Ph + 4.26Ch + 1.06Th. There were five use-value groups identified, and the medicinal plants were the highest number of species (25.53%), followed by timber (6.38%), edible plants (4.26%), dyes, and other groups was the lowest number of species (5.32%). The species plant distributed was from below 200 m to above 1400 m, the number of species highest at 200 m - 400 m, and the lowest above 1400 m. The medium forest was the most diverse species and genera; the lowest was a vibrant forest. These were important results underpinning strategies and solutions for sustainable conservation of this natural resource.