A Feasibility Study for the Establishment of Xuan Lien Nature ...

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2. Site Features
2.1 Biogeography
According to the classification of MacKinnon (1996), Xuan Lien proposed nature reserve is located in
sub-unit 10b (North Indochina) of the Indo-Chinese sub-region; and, according to the classification of
Wikramanayake et al. (1997), the proposed nature reserve is situated within the Northern Indochina
Subtropical Forests Ecoregion.
2.2 Location
Xuan Lien proposed nature reserve is located in Thuong Xuan district, Thanh Hoa province, and is
bounded by the coordinates 19°52' to 20°02'N and 104°58' to 105°15'E (Map 1). The proposed
nature reserve includes all or part of six communes: Bat Mot, Yen Nhan, Xuan Khao, Xuan Lien, Xuan My
and Van Xuan.
The proposed nature reserve is bordered by the Cao River to the north, the provincial border with
Nghe An to the south and west, and the Ta Leo and Bu Khong mountains and the confluence of the
Cao and Chu Rivers to the east.
2.3 Topography
The proposed nature reserve is situated in a belt of mountains running from Sam Neua in Laos to
Thuong Xuan and Nhu Xuan districts in Thanh Hoa province. These mountains contain many high
peaks, such as Ta Leo (1,400 m), Bu Cho (1,563 m), Bu Hon Han (1,208 m), and an unnamed
1,605 m peak. The topography of the nature reserve is characterised by low mountains, dissected by
deep, narrow valleys.
Two main topographic forms dominate the area:
(a) Medium High Mountains. Located at elevations of 800 to 1,600 m in the Cao and
Nam Boo River basins, these mountains are dissected by deep, narrow valleys, sloping
from west to east. Slopes are steep, averaging 35°. These areas cover a total of 4,289 ha or
18% of the study area.
(b) Low Mountains and Foothills These areas are located at elevations below 800 m and lie
mainly in the east, in the Cao River basin, and in the south, near the border with Nghe
An province. Slopes in these areas are generally shallower: on average 20 to 25° for the
low mountain areas and 15 to 20° for foothill areas. The topography is less complex
than in the higher areas. These areas cover a total of 19,321 ha, representing 82% of the
study area.
Several other topographic types also occur in the study area, though they cover only small, scattered
areas. Karsts occur at elevations below 800 m and may have extremely steep slopes (60 to 70°) with
vertical cliffs in places. Access to these areas is often difficult. The topography of valleys in the study
area varies: valley floors are narrow in upstream areas, becoming wider in the lower sections of the Cao,
Kue and Chu Rivers. Many of these lower sections have relatively flat, fertile valleys.