Flora
Hustai National Park (HNP), which is 506 square kilometers (km²) in size, encompasses high mountains, hills and valleys. Differences in soils and microclimates are reflected in a vegetation zonation that includes steppes, mountain steppes and forest steppes. Historically, about 88 percent of the park was covered by steppes; 95 percent was suitable for grazing. In recent years, the HNP forests started to dry out significantly and the entire landscape has changed. The area covered by mountain steppes increased. Today, steppe and mountain steppe habitats are now the dominant habitat types, encompassing approximately 179 km² and 267 km² respectively, in the park.
The flora of the region is relatively rich compared to other sites in Mongolia. Manibazar (1996), Manibazar et al. (1999), Bulgan (2002) and others studied the vascular plant flora and the vegetation cover (Wallis de Vries et al. 1996and Van Staalduinen 2007) and published lists of vascular plants as well as a vegetation map of the park. In addition, Kherlenchimeg (2001), Enkhtuya (2001) and Tsegmed (2003) studied the fungi, lichens and mosses of HNP, respectively. Sanjid (1999) found 217 species of medicinal plants (Sanjid 1999) in the park; Ochirbat (1999) found 236 species of mellifluous plants. In addition, 200 species of forage vascular plants have been recorded in the park. The following information provides an updated and comprehensive list of vascular plant species in the park as well as an analysis of the flora with respect to life-form and ecological group composition and biogeography.
As shown in Table 1, a total of 493 vascular plant species belonging to 247 genera and 65 families have been recorded in HNP with Dicotyledons being the main group. As shown in Table 2, the principal plant families in terms of species numbers are Asteraceae (67 species), followed by Poaceae (56 species), Fabaceae (51 species), Rosaceae (33 species) and Ranunculacea (24 species). These 5 largest families comprise 47.1 percent of the total flora. Artemisia is the largest genus represented by 19 species, followed by Astragalus (14 species), Potentilla (13 species), Carex (11 species), Allium (10 species) and Oxytropis (10 species). Together, they account for 16 percent of all species.
Table 1. Floristic richness of HNP.
| Plant group | Families | Genera | Species |
| Pteridophyta | 5 | 5 | 7 |
| Gymnosperms | 3 | 3 | 4 |
| Angiosperms | 57 | 239 | 482 |
| Monocotyledons | 9 | 43 | 97 |
| Dicotyledons | 48 | 196 | 385 |
| Total vascular flora | 65 | 247 | 493 |
There are 7 species of Pteridophyta in HNP, all of which are herbaceous. Each of these species is considered vulnerable because of their dependence on forest habitats. Currently, forests cover only 13.1 km² of the park (Tuwshintogtokh et al. 2013). The dominate tree species are Betula platyphylla (Siberian silver birch) and Populus tremula (Eurasian aspen).
The next larger families (6 through 8th) are Brassicaceae (21 species), Amaranthaceae (19 species) and Polygonaceae, while 34 families are represented by only 1 and/or 2 species each and 10 families are represented by 3 or 4 species. As a result, 68 percent of the families are represented by 4 species or less (which is considered rare). They therefore account for only 17 percent of species composition.
Table 2. Species richness of the main vascular plant families in HNP
| Biggest families of flora of HNP | Number.
genera |
Number species | Percent of flora | |
| 1 | ASTERACEAE | 30 | 67 | 13.8 |
| 2 | POACEAE | 27 | 56 | 11.4 |
| 3 | FABACEAE | 14 | 51 | 10.3 |
| 4 | ROSACEAE | 14 | 33 | 6.7 |
| 5 | RANUNCULACEAE | 11 | 24 | 4.9 |
The dominant species in the steppes and mountain steppe include: Stipa krylovii, S. klemenzii, Artemisia frigida, A. dracunculus, Carex duriuscula, C. korshinskyi and Cymbaria dahurica. Festuca ovina and F. lenensis dominate in the summit regions of the mountains. Two species are endemic; 24 species are subendemic. The conservation status of ten species is recorded as regionally threatened; 19 species are relict (Urgamal et al. 2014).
