Forest Vegetation Cover in Yok Don National Park, Vietnam

Yok Don National Park is located in the tropical rainforest zone on the Central Highlands of Vietnam. The obtained results from the study undertaken on the composition of plant species and forest vegetation in National Park indicated a record of 856 species, 473 genera and 129 families that belongs to the four divisions of vascular plants. These includes: Lycopodiophyta, Polypodiophyta, Pinophyta and Magnoliophyta. Useful plants of 856 taxonomy species listed consists of 498 species of medicinal plants, 157 species of timber plants, 144 species of edible plants, 60 species of ornamental plants, 19 species of industrial plants, 10 species of fiber plants and 38 species of unknown use plants, respectively. During the duration of investigation, Peliosanthes teta Andrews was newly recorded in the forest vegetation of National Park. A variety of forest vegetations in the area under study is described. In this study, four major vegetation types of forest were identified in Yok Don National Park.


Introduction.
In accordance with Decision № 352/СТ of 29/10/1991, Yok Don National Park (hereafter YDNP) was recognized as a specially protected natural area of Vietnam by the Prime Minister of the Republic of Vietnam (Nguyen Viet Luong et al, 2017). The object of study is located in Dak Lak province, with an area of 115 545 ha, between 12045&apos; -13010&apos; north latitude and 107029&apos; -107048&apos; east longitude ( fig. 1). The forest vegetation at Yok Don National Park is dominated by a mosaic of deciduous forest and semi-evergreen (mixed deciduous) forest, with smaller areas of evergreen forest, particularly on hills and along watercourses. 856 vascular plant species have been recorded in National Park. YDNP is the only remaining natural of deciduous dipterocarp forest, located on the central highland of Vietnam. Rare, valuable and endemic species of flora and fauna, listed in the Red Book of Vietnam (2007) and the International Union for Conservation of Nature (IUCN, 2002), live in YDNP. However, in recent years, the structure of forest vegetation cover in YDNP has changed. This led to a change in the habitat of plants and animals, the number of individuals decreased, and many rare and endangered species were threatened. Therefore, the issue of forest conservation in YDNP plays an important role.
Materials and Methods. The objects for research were forest ecosystems on the territory of YDNP. Ecological and geographical analysis of the species composition of forests in the National Park indicates certain links between regions and environmental conditions reveals their environmental specificity. Geobotanical and floristic study was carried out on the 25 plots (20×20 м) (Nguyen & Baker, 2016). We established 8 transects, which covered the whole surface area of YDNP. The total length of these transects combined is about 15 km. In each transect we marked all species and collected specimens of plants which could not be identified in the field. We also collected many plants outside the plots and traverses, to make sure that our inventory was as representative of the entire area with species of the local flora (Hoang Van Sam, Baas & Keßler, 2008b).
Voucher species were sent to the Herbarium of Vietnam National University of Forestry -Dong Nai campus and other specialists for identification. Plant species were identifed with reference to An Illustrated of Flora of Vietnam (Pham, 1999).
The vegetation types of YDNP were classified according to Thai Van Trung (Thai, 1999). Additionally, the human disturbance levels of the vegetation were determined by noting the number of tree stumps and number of foot paths in the plots (Nguyen & Baker, 2016).
From 10/2020-2/2021, the research team conducted many surveys in Ea Po, Dak Wil, Ea Bung, Chư M'Lan, Krong Na, Ea Huar and Ea Wer villages in YDNP. Field research was conducted to gain intensive understanding of people through discussions and interactions. Primary data was gathered initially through household interviews based on questionnaires, Rapid Among the investigated 856 species, 4 endemic species in Vietnam were also included. Many plant species are endemic to Vietnam (the species were first records in Vietnam and scientific names take the places of Vietnam) and endemic plants of local (the first records of species in YDNP) such as Vietnamosasa darlacensis (Table 2).  Table 3. The plant resources of YDNP are valuable not only because of the great diversity, but also have great environmental importance. As part of the flora of YDNP, 16 species of 856 plant species were listed in the Red book of Viet Nam (2007). In the red book of IUCN (2021), 2 species were classified as endangered species (EN), 1 species were classified as vulnerable species (VU) and 2 species were classified as least concern (Table 4). Conclusions. YDNP is characterized by 4 major vegetation types of forest: deciduous dipterocarp forest, tropical evergreen broad-leaved, tropical evergreen broad-leaved semi-deciduous and mixed forest.
The diversity of plant species in YDNP was studied to provide baseline information for conservation and sustainable management processes that will prolong the the life of National Park. A total of 856 species of vascular plants are recorded in YDNP belonging to 473 genera and 129 families. From the indicated species Peliosanthes teta is new record species for the flora in YDNP.