The Vogelkop-Aru lowland rain forests 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.
Location and General Description
This ecoregion is made up of the lowland and hill (less than 1,000 meters) 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. Northern New Guinea is a very active tectonic area with a complex geologic history. 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.
This ecoregion of plains and alluvial forests is among the most floristically rich in all of New Guinea and includes many important timber species. Most of the ecoregion is composed of a combination of alluvial and hill type tropical wet evergreen forest, with smaller amounts of limestone forest. Lowland alluvial forest has a canopy that is multi-tiered and irregular, with many emergents. The forest understory contains a shrub and herb layer with a variety of climbers, epiphytes, and ferns. Palms may be common in the shrub layer. 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. 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.
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.
Aru Island is composed of rain forest, savanna, and mangroves.
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.
|Table 1. Endemic and Near-Endemic Mammal Species.|
|An asterisk signifies that the species' range is limited to this ecoregion.|
Forty-seven mammal species are found in the ecoregion, of which eight are endemic or near endemic (Table 1). The mammalian fauna consists of a wide variety of tropical Australasian marsupials, including tree kangaroos. The Arfak long-beaked echidna (Zaglossus bruijni) was considered endangered before it was split from the Papuan echidna (Zaglossus bartoni) and presumably would still be considered so because it is a focal prey item for humans. The dusky pademelon (Thylogale bruinji) and New Guinea quoll (Dasyurus albopunctatus) are considered vulnerable.
|Table 2. Endemic and Near-Endemic Bird 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 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. This ecoregion corresponds almost exactly with the West Papuan lowlands Endemic Bird Area (EBA) (the EBA also includes the Southern New Guinea freshwater swamp forests ecoregion but does not include Aru Island), which includes nineteen species of restricted-range birds, nine of which are found nowhere else on Earth. 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.
The North Salawati Island Nature Reserve Centre of Plant Diversity is included in this ecoregion. 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.
About 90 percent of the natural habitat in the ecoregion is still intact. The eight protected areas cover 5,410 square kilometers (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.
|Table 3. WCMC Protected Areas That Overlap with the Ecoregion.|
|Protected Area||Area (km2)||IUCN Category|
|Pegunungan Weyland [AA0105], [AA1002]||960||PRO|
|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, 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).
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.
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. Thus, the Vogelkop-Aru lowland rain forests 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; however, we placed the tropical montane moist forests (more than 1,000 m) in the Vogelkop montane rain forests. Udvardy placed these ecoregions in the Papuan biogeographic province of the Oceanian Realm.
Additional Information on this Ecoregion
- For a shorter summary of this entry, see the WWF WildWorld profile of this ecoregion.
- To see the species that live in this ecoregion, including images and threat levels, see the WWF Wildfinder description of this ecoregion.
- World Wildlife Fund Homepage
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