Yapen rain forests

Content Cover Image

Yapen, Irian Jaya, Indonesia. (Photograph by Erich Kramer)

The Yapen Rain Forests are important for their two restricted-range bird species and unique limestone and ultramafic floras. Although almost one-third of the ecoregion is under some form of protection, the island is subject to population pressure.

Location and General Description

This small ecoregion represents the lowland and montane rain forests of Yapen Island, off the northwestern coast of Irian Jaya, Indonesia, on the island of New Guinea. The climate of the ecoregion is tropical wet, which is characteristic of this part of Melanesia, located in the western Pacific Ocean north of Australia. The surface geology of this ecoregion consists of low mountains of plutonic rock and limestone. The island extends to an elevation 1,430 meters (m) and is a land bridge island that was part of the New Guinea mainland during recent glacial periods.

caption Source: WWF

The vegetation of Yapen Island is tropical lowland (alluvial and hill type) and montane forest.

Biodiversity Features

The overall richness and endemism of this ecoregion are low to moderate when compared with those of other ecoregions in Indo-Malaysia.

The mammal fauna consists of thirty-seven species, including a near endemic that Yapen shares with Biak and Numfoor islands (Yapen rat, Rattus jobiensis) (Table 1).

Table 1. Endemic and Near-Endemic Mammal Species
Family Species
Muridae Rattus jobiensis


Yapen is home to approximately 147 bird species, including two restricted-range species that qualify it as a Secondary Endemic Bird Area (EBA). These two near-endemic species (Table 2), the spice imperial-pigeon (Ducula myristicivora) and the green-backed robin (Pachycephalopsis hattamensis), are also found on the mainland.

Table 2. Endemic and Near Endemic Bird Species
Family Common Name Species
Columbidae Spice imperial-pigeon Ducula myristicivora
Eopsaltriidae Green-backed robin Pachycephalopsis hattamensis


Yapen and nearby Biak Island (part of Biak-Numfoor rain forests ecoregion) share one endemic butterfly species.

The island constitutes the Yapen Island Nature Reserve Centre of Plant Diversity. Several endemic plants have been collected, but the flora of the island is poorly known. The island contains significant limestone and ultramafic floras.

Current Status

Two protected areas, covering 790 km2, protect 32 percent of the island's ecosystems (Table 3).

Table 3. WCMC (1997) Protected Areas That Overlap with the Ecoregion
Protected Area Area (km2) IUCN Category
Yapen Tengah 780 I
Inggresau 10 PRO
Total 790  
Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets

Types and Severity of Threats

The island is subject to population pressure, agricultural development, local sawmilling operations, and human-made fire. Only small, low-grade mineral deposits are present.

Justification of Ecoregion Delineation

Using Whitmore's map of the vegetation of Malesia and MacKinnon's reconstruction of the original vegetation, we delineated the large areas of distinct habitat types as ecoregions. Yapen and Biak islands, which MacKinnon combined within biounit P3c, were delineated as separate ecoregions; Yapen Rain Forests and Biak-Numfoor Rain Forests, respectively, were based on recommendations by Bob Johns (vegetation) and the patterns of mammal distribution. Udvardy placed these ecoregions in the Papuan biogeographic province of the Oceanian Realm.

Additional information on this ecoregion


Disclaimer: This article is taken wholly from, or contains information that was originally published by, the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.





Fund, W. (2014). Yapen rain forests. Retrieved from http://www.eoearth.org/view/article/157173


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