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Southeastern Asia: Northern Vietnam

The Northern Vietnam Lowland Rain Forests [IM0141] are in a dismal state. Less than 10 percent of the native vegetation of the ecoregion remains, and very little of that is protected. The remaining patches of habitat are small and scattered throughout the ecoregion, so that any natural ecological processes that once occurred have been lost. This ecoregion has lost most of its outstanding biodiversity, although the white-cheeked gibbon and Francois's leaf monkey can still be found locally in these forests.

  • Scientific Code
    (IM0141)
  • Ecoregion Category
    Indo-Malayan
  • Size
    8,700 square miles
  • Status
    Critical/Endangered
  • Habitats

Description 
 Location and General Description
The Northern Vietnam Lowland Rain Forests [IM0141] ecoregion extends from the freshwater swamp forests of the Red River Valley south along the north-central coast of Vietnam to the region south of Tam Ky. Geological formations are varied, but there are extensive limestone substrates. The north-central coastal area of Vietnam typifies the tropical monsoon climate, with high temperatures and abundant precipitation, but rainfall peaks are later in the year than in other parts of southeast Asia, and the dry season is less extreme. Mean annual rainfall at Hanoi and Vinh is about 1,800 mm, with the peak of rainfall in September and October. Every month receives at least 50 mm of rainfall. Peak rainfall is pushed back even further at Quang Tri, along the central coast, where peak rainfall comes in October and November, and mean annual total is higher at about 2,500 mm. The pronounced wet season here extends from September through January, and no month of the year has less than 60 mm of rainfall. Total rainfall continues to increase moving southward down the coast, with about 3,000 mm at Hue, but drops sharply and becomes more seasonal in south-central coastal areas. Moving inland, the boundary between the Northern Vietnam Lowland Rain Forests [IM0141] ecoregion and the Northern Annamites Rain Forests [IM0136] ecoregion is poorly defined as lowland wet evergreen forests grade into montane forest communities.

The high rainfall and short dry season characterizing the coastal habitats of this ecoregion produce conditions that once supported diverse wet evergreen forests. Such forest habitats have largely been cleared and exist only in isolated patches today. This ecoregion is best preserved in Cuc Phuong and Pu Mat National Parks. At Cuc Phuong, 1,800 vascular plant species have been described for a small area with limited topographic diversity. Overall, the flora of these wet evergreen forests shows a stronger affinity to that of northern Vietnam and southern China than to that of southern Vietnam. Although the Dipterocarpaceae is an ecologically significant element of the lower-elevation wet evergreen forests, the species richness in this family is lower than that of similar habitats in the southern Annamite Range.

Primary wet evergreen forest consists of a dense, three-tiered canopy reaching 25-35 m and occasionally 45 m height in undisturbed sites, with large emergent trees extending above this level to give a rough upper surface to the canopy. The upper canopy is dominated by a species of Hopea, Castanopsis hystrix, and Madhuca pasquieri. The fan palm Livistona saribus is a common subcanopy species in small gaps and reaches 20 m in height. Wet evergreen forest stands disturbed by logging show a characteristic presence of Knema erratica, a fast-growing colonizer, and an increased dominance of Livistona saribus in the upper canopy.

Biodiversity Features
Most of this ecoregion's biodiversity has been lost because of the extensive habitat loss. Nevertheless, it still harbors several mammals and birds of conservation significance, including the Owston's banded civet (Hemigalus owstoni), white-cheeked gibbon (Hylobates leucogenys), red-shanked douc langur (Pygathrix nemaeus), and Francois's leaf monkey (Semnopithecus francoisi). One endemic bat species is found here (Paracoelops megalotisl table 56.1). The ecoregion overlaps with a Level II TCU (Dinerstein et al. 1997). There are more than 300 bird species in this ecoregion, including three near-endemic and one endemic species (table 2). The Annamese Lowlands (143) EBA (Stattersfield et al. 1998) overlaps with this ecoregion.

Table 1. Endemic and Near-Endemic Mammal Species.

  Family Species
Rhinolophidae* Paracoelops megalotis*

An asterisk signifies that the species' range is limited to this ecoregion.

Table 2. Endemic and Near-Endemic Bird Species.

  Family Common Name Species
Phasianidae Annam partridge* Arborophila merlini*
Phasianidae Edwards's pheasant Lophura edwardsi
Timaliidae Short-tailed scimitar-babbler Jabouilleia danjoui
Timaliidae Grey-faced tit-babbler Macronous kelleyi

An asterisk signifies that the species' range is limited to this ecoregion.

Current Status
More than 90 percent of the natural habitat in this ecoregion has been converted, and the remaining habitat is scattered as small fragments. The nine protected areas in the ecoregion cover less than 900 km2 (4 percent) of the ecoregion (table 3). And many of these small protected areas (average size 99 km2) are degraded.

Table 3. WCMC (1997) Protected Areas That Overlap with the Ecoregion.

  Protected Area Area (km2) IUCN Category
Cuc Phuong [IM0137] 200 II
Ngoc Trao [IM0137] 7 UA
Chua Huong Tich 40 UA
Tam Quy 40 IV
Den Ba Trieu 10 UA
Ben En 130 II
Ho Ke Go [IM0136] 140 PRO
Bac Hai Van 40 ?
Bach Ma [IM0152] 280 II
Total 887  

Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets.

Types and Severity of Threats
Vietnam's high human population density has taken a heavy toll on its natural habitats. The coastal and alluvial forests in particular have been hardest hit because the human population densities are highest in these lowland habitats. The rampant illegal wildlife trade has also exacerbated the threats to wildlife and other natural resources.

Justification of Ecoregion Delineation
MacKinnon (1997) included the coastal habitats of Vietnam, Cambodia, and Thailand in the Coastal Indochina biounit (05), consisting of four subunits. Each of these subunits includes several biomes. We delineated several ecoregions based on the distribution of these biomes. Like MacKinnon, we chose the Hai Van pass to represent a transition from the tropical south and the subtropical north and placed the lowland evergreen moist forests between the Hai Van pass and the Red River delta, in the Northern Vietnam Lowland Rain Forests [IM0141].

References
References for this ecoregion are currently consolidated in one document for the entire Indo-Pacific realm.
Indo-Pacific Reference List

Prepared by: Eric Wikramanayake and Philip Rundel
Reviewed by: