Western portion of the island of New Guinea

The Vogelkop-Aru Lowland Rain Forests [AA0128] are diverse in terms of both geography and biodiversity, and they constitute the majority of western Irian Jaya, the rest of the region being either montane forest or freshwater swamp forest. These relatively intact lowland tropical rain forests are among the largest and richest forests in the Australasian Realm. Limestone and ultramafic rock formations support unique and restricted-range floras.

  • Scientific Code
  • Ecoregion Category
  • Size
    29,900 square miles
  • Status
  • Habitats

Location and General Description
This ecoregion is made up of the lowland and hill (less than 1,000 m) moist forests of the Vogelkop and Bomberai peninsulas and the surrounding islands, including Misool, Salawati, Waigeo, and Kepulauan Aru in western Irian Jaya. 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 (National Geographic Society 1999). Northern New Guinea is a very active tectonic area with a complex geologic history (Bleeker 1983). The surface geology of this ecoregion is composed predominantly of sedimentary rock and recent alluvium, with some large areas of limestone or ultramafics near Sorong and on Waigeo and Misool islands (Petocz 1989).

This ecoregion of plains and alluvial forests is among the most floristically rich in all of New Guinea and includes many important timber species (Petocz 1989). Most of the ecoregion is composed of a combination of alluvial and hill type tropical wet evergreen forest, with smaller amounts of limestone forest (MacKinnon 1997). Lowland alluvial forest has a canopy that is multitiered and irregular, with many emergents. The forest understory contains a shrub and herb layer with a variety of climbers, epiphytes, and ferns (Petocz 1989). Palms may be common in the shrub layer (Paijmans 1975). The very mixed floristic composition of the canopy trees includes Pometia pinnata, Octomeles sumatrana, Ficus spp., Alstonia scholaris, and Terminalia spp. Additional important genera include Pterocarpus, Artocarpus, Planchonella, Canarium, Elaeocarpus, Cryptocarya, Celtis, Dracontomelum, Dysoxylum, Syzygium, Vitex, Spondias, and Intsia (Paijmans 1975). The somewhat lower-canopy, more closed lowland hill forest contains more open shrub layer but a denser herbaceous layer. Palms are fewer in number. The dominant canopy trees include species of Pometia, Canarium, Anisoptera, Cryptocarya, Terminalia, Syzygium, Ficus, Celtis, Dysoxylum, and Buchanania. Koompassia, Dillenia, Eucalyptopsis, Vatica, and Hopea are locally abundant. Dense stands of Araucaria, the tallest tropical trees in the world, are present in scattered locations (Paijmans 1975; Nightingale 1992).

On Waigeo Island and the adjacent northwest coast of New Guinea, ultramafic rocks result in a serpentine flora, a belt of low shrubby vegetation composed of Alphitonia spp., Dillenia alata, Myrtella beccari, and Styphelia abnormis (Brooks 1987).

Aru Island is composed of rain forest, savanna, and mangroves (R. Johns, pers. comm., 2000).

Biodiversity Features
Generally, this ecoregion exhibits low to moderate richness and endemism compared with those of other ecoregions in Indo-Malaysia. Reptile and amphibian richness, though poorly studied, is thought to be high, however.

Forty-seven mammal species are found in the ecoregion, of which eight are endemic or near endemic (Flannery 1995; Flannery and Groves 1998) (table 1). The mammalian fauna consists of a wide variety of tropical Australasian marsupials, including tree kangaroos (Flannery 1995). The Arfak long-beaked echidna (Zaglossus bruijni) was considered endangered before it was split from the Papuan echidna (Zaglossus bartoni) (IUCN 2000) and presumably would still be considered so because it is a focal prey item for humans (Flannery 1995; Bonaccorso et al., in press). The dusky pademelon (Thylogale bruinji) and New Guinea quoll (Dasyurus albopunctatus) are considered vulnerable (IUCN 2000).

Table 1. Endemic and Near-Endemic Mammal Species.

Family Species
Tachyglossidae Zaglossus bruijni
Dasyuridae Phascolosorex doriae
Macropodidae Dendrolagus ursinus
Macropodidae Thylogale brunii
Macropodidae Dorcopsis muelleri
Muridae Melomys lorentzi
Muridae Pogonomelomys mayeri
Muridae Pogonomelomys bruijni

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

The avifauna of the ecoregion has a clear Australasian flavor, with representatives of several Australasian families including Ptilonorhynchidae, Eopsaltridae, Meliphagidae, and Paradisaeidae There are 366 bird species inhabiting the ecoregion (Beehler et al. 1986; Coates 1985). This ecoregion corresponds almost exactly with the West Papuan lowlands EBA (the EBA also includes the Southern New Guinea Freshwater Swamp Forests [AA0121] ecoregion but does not include Aru Island), which includes nineteen species of restricted-range birds, nine of which are found nowhere else on Earth (Stattersfield et al. 1998). Twenty-one bird species are endemic or near endemic (table 2). Bruijn's brush-turkey (Aepypodius bruijnii) and the western crowned pigeon (Goura cristata) are considered vulnerable (IUCN 2000).

Table 2. Endemic and Near-Endemic Bird Species.

Family Common Name Species
Megapodiidae Bruijn's brush-turkey Aepypodius bruijnii*
Megapodiidae Moluccan scrubfowl Megapodius wallacei
Megapodiidae Red-billed brush-turkey Talegalla cuvieri
Megapodiidae Dusky scrubfowl Megapodius freycinet
Columbidae Western crowned pigeon Goura cristata
Columbidae Wallace's fruit-dove Ptilinopus wallacii
Columbidae Spice imperial-pigeon Ducula myristicivora
Loriidae Violet-necked lory Eos squamata
Loriidae Black lory Chalcopsitta atra
Alcedinidae Spangled kookaburra Dacelo tyro
Alcedinidae Kofiau paradise-kingfisher Tanysiptera ellioti*
Alcedinidae Red-breasted paradise-kingfisher Tanysiptera nympha
Alcedinidae Little paradise-kingfisher Tanysiptera hydrocharis
Corvidae Brown-headed crow Corvus fuscicapillus
Monarchidae Black-backed monarch Monarcha julianae*
Dicaeidae Olive-crowned flowerpecker Dicaeum pectorale
Meliphagidae Olive honeyeater Lichmera argentauris
Meliphagidae Silver-eared honeyeater Lichmera alboauricularis
Paradisaeidae Wilson's bird-of-paradise Cicinnurus respublica*
Paradisaeidae Red bird-of-paradise Paradisaea rubra*
Paradisaeidae Greater bird-of-paradise Paradisaea apoda

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

The North Salawati Island Nature Reserve Centre of Plant Diversity is included in this ecoregion (Davis et al. 1995). Near Sorong several endemic plants have been collected, but the flora is poorly known. Areas of limestone and ultramafic rocks support high concentrations of unique plants near Sorong and on Waigeo and Misool islands (R. Johns, pers. comm., 2000).

Current Status
About 90 percent of the natural habitat in the ecoregion is still intact. The eight protected areas cover 5,410 km2 (7 percent) of the ecoregion (table 3). Three of these are large (more than 1,000 km2) and are still linked by natural habitat (MacKinnon 1997).

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

Protected Area Area (km2) IUCN Category
Batanta Barat 70 I
Salawati Utara 620 I
Sidei-Wibain 30 IV
Misool Selatan 1,160 I
Pulau Waigeo 1,310 I
Pulau Kobroor 1,160 PRO
Pulau Baun 100 IV
Pegunungan Weyland [AA0105], [AA1002] 960 PRO
Total 5,410  

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

Types and Severity of Threats
Logging concessions that overlap with protected areas are a major source of threat. These incursions into the protected area system from logging, when combined with the developments and infrastructure planned as part of the transmigration program (see Petocz 1989), exacerbate the threats to biodiversity in Irian Jaya, especially in the lowland forests, which are more accessible.

Hunting is a problem for some species, especially the western crowned pigeon (Goura cristata), northern cassowary (Casuarius unappendiculatus), and Nicobar pigeon (Caloena nicobarica) (Stattersfield et al. 1998).

On Misool Island, population pressure is responsible for the development and destruction of forests near villages for traditional agriculture, logging, and fire. The Sorong region is the petroleum center of Irian Jaya, and several government-sponsored resettlement initiatives are located in the vicinity (R. Johns, pers. comm., 2000).

Justification of Ecoregion Delineation
Using Whitmore's (1984) map of the vegetation of Malesia and MacKinnon's (1997) reconstruction of the original vegetation, we delineated the large areas of distinct habitat types as ecoregions. Thus, the Vogelkop-Aru Lowland Rain Forests [AA0128] ecoregion represents the tropical lowland moist forests in the Vogelkop region of New Guinea. The ecoregion largely corresponds to subunits P3d and P3b identified by MacKinnon (1997); however, we placed the tropical montane moist forests (more than 1,000) in the Vogelkop Montane Rain Forests [AA0127]. Udvardy (1975) placed these ecoregions in the Papuan biogeographic province of the Oceanian Realm.

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

Prepared by: John Morrison
Reviewed by:

This text was originally published in the book Terrestrial ecoregions of the Indo-Pacific: a conservation assessment from Island Press. This assessment offers an in-depth analysis of the biodiversity and conservation status of the Indo-Pacific's ecoregions.