Vietnam Primate Conservation Status Review 2002 - Hoang Lien ...

Vietnam Primate Conservation Status Review Part 2: LEAF MONKEYS
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1.2 Background
Vietnam extends about 1,600 km from north to south, along the eastern coast of Indochina from
23 O N to 8 O 30’N. The country covers about 331,689 km 2 . Altitude varies from sea level to 3,143 m at
the summit of Mount Phan Si Pan in the extreme north-west of the country. Plains are principally
found in the Mekong and Red River deltas, which are linked by a narrow coastal plain. The rest of the
country comprises hills and high mountain ranges.
A geological feature of major interest is the limestone karst formations that are mainly found in the
central and northern parts of the country. These areas support a high degree of endemic fauna and
flora. Almost all of Vietnam’s endemic and critically endangered primate species live either in limestone
forests or montane forests, the exception being the Grey-shanked douc langur.
In 1995, natural forest covered 8,769,000 ha, or 27.5% of the land area of Vietnam. Following the
classification used by Wege et al. (1999), three forest types should be considered of particular importance
for biodiversity. Evergreen forest, which is found in areas with a regular, high rainfall, is the main forest
type in Vietnam, accounting for 64% of the total area of natural forest. Semi-deciduous and deciduous
forests, which occur in lowland areas experiencing a distinct dry season, are largely restricted to central
and southern parts of the country. In areas dominated by deciduous and semi-deciduous forests, leaf
monkeys and gibbons are limited to evergreen forest patches along streams and on hills. A third forest
type of interest is limestone forest, restricted to karst formations. Bamboo and coniferous forests, while
natural, are essentially secondary in nature and their biodiversity value is lower than other natural
forest types (Wege et al., 1999).
8.6% of Vietnam’s natural forest is now within the protected areas network. Special-use forests,
including national parks, nature reserves and cultural and historical sites cover 2,370,270 ha (Nguyen
Ba Thu, 2001).
1.3 Vietnam Primate Conservation Status Review
The Vietnam Primate Conservation Status Review began implementation in July 1999, with the
objective of collating a comprehensive data set for leaf monkeys and gibbons in Vietnam. The results
are contained within two publications. This publication covers leaf monkeys, whilst gibbons are
covered by a separate publication (Geissmann et al., 2000. Vietnam Primate Conservation Status
Review 2000. Part 1: Gibbons).
Methods
Data on the status of leaf monkey species in Vietnam was collated from several sources:
✱ Scientific reports. Most available reports about leaf monkeys, their habitats or their
conservation status in Vietnam were analysed. Field survey records were considered reliable
where they were given by a reliable surveyor, and the source of the information and the
exact date and location were given. However, given the scarcity of information, all data
detailing the source and its level of evidence were included in this work.
✱ Museum specimens. The origin of each museum specimen of Vietnamese leaf monkeys was
collated from the museum itself or from scientific literature. The exact location or the method
of collection are often unknown and, therefore, these data should be considered as provisional.
However, this type of data provides invaluable information regarding the historical distribution
of given species, particularly in areas where the animals no longer occur.