CHARACTERISTICS OF FLORA IN NUI CHUA NATIONAL PARK, NINH THUAN PROVINCE: A COMPARATIVE STUDY BETWEEN MOIST AND ARID FORESTS

Abstract

The complete and profound understanding of vegetation has practical significance for the sustainable development of biodiversity resources in Nui Chua National Park. Fourteen typical temporary plots (20 m x 20 m) were equally divided between the moist and arid forests. The study suggested that the species and stand structure of the two forest types were significantly different. The distinctiveness of the moist forest, where the typical tree species of Gymnospermae were Dacrycarpus imbricatus, Podocarpus neriifolius, Nageia wallichiana; while the arid forest with the emergence of low trees, many branches, small DBH; thick bark; stems many small tumours and spines; tiny and thick leaves, spines, and with serrated margins; crown trees were skewed; trees include 3-4 stems, etc. The forest vegetations in Nui Chua National Park are diverse in species composition and conservation value, with fifty-one woody plant species of 26 families belonging to Gymnospermae and Angiospermae; and 18 threatened plant species in Decree 84/2021/ND-CP, Vietnam Red Data Book (2007) and IUCN Red List (2021). Most of the recorded tree species have a regular distribution (over 78%). Ecologically significant trees such as Syzygium zeylanicum, Vatica harmandiana, Ilex cochinchinensis were represented in moist forests. While Terminalia triptera, Diospyros mollis, Sindora siamensis, Albizia corniculata and Millettia brandisiana were found in arid forests. The species richness had significant differences. In contrast, the Magarlef (d), Pielou (J'), and Shannon (H') index had no difference between these two forest types. Quantitative diversity components indicated low plant diversity (1.75-2.17). The study also indicated that the tree species composition, the association between species, and the plant community of the two forests were significantly different. Therefore, it is required to develop different management and conservation approaches for each object in practice.