Southern New Guinea Lowland Rainforests

The vast lowland plains of Southern New Guinea support diverse tropical forests roamed by crowned pigeons, southern cassowary, and tree kangaroos. Huge palm cockatoos and bird-of-paradise are two of the many spectacular residents. These are among the largest remaining forested landscapes in Australasia and one of the richest areas for vascular plants in Indo-Malaysia.

The Southern New Guinea Lowland Rain Forests ecoregion stretches across the lowland forests south of the Central Cordillera of Indonesian Irian Jaya and Papua 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. Although the remainder of the ecoregion is lower than most parts of New Guinea, the area's low relief and large rivers draining the nearby Central Ranges result in this ecoregion's inundation during the wet season

Lowland forests predominate, though foothill forest, limestone forest, peat swamp forest, and freshwater swamp forest occur under the right conditions. Pometia, Octomeles, Ficus, and Alstonia are some important tree genera. The tall Diptercocarp trees occur, but not in the dominant stands found in Southeast Asia. Dense stands of Araucaria, the tallest tropical trees in the world, are present in scattered locations.

The mammalian fauna consists of a wide variety of tropical Australasian marsupials, including a tree kangaroo. The ecoregion contains sixty-nine mammal species, thirteen of which are endemic or near endemic. Bulmer's fruit bat and the large pogonomelomys are critically endangered, whereas the lesser tube-nosed bat, New Guinea sheathtail-bat, Fly River horseshoe-bat, and Papuan mastiff bat are considered vulnerable. There are 344 bird species in the ecoregion, including 5 endemic and near-endemic species. The red-billed brush-turkey, greater bird-of-paradise, and Little paradise-kingfisher are largely restricted to this ecoregion. The ecoregion intersects two separate Endemic Bird Areas, the South Papuan lowlands and the Trans Fly. Plant diversity is high for the region, but little explored to date. 

The Papuan Plateau and the Purari River Basin are major wilderness areas in this ecoregion. Much of the habitat remains in large, contiguous blocks. However, large areas near the western town of Timika and the central town of Asike have been cleared for palm oil plantations. Palm oil plantations are exploding in New Guinea and have the potential to destroy large swaths of this ecoregion over the coming decades. In the eastern region and much of the central coastal forests north of the Digul River, large areas have been cleared for traditional agriculture. Logging is ongoing in the eastern region, particularly north of Kikori. 

Lorentz National Park (5,300 km²) protects a large section of this ecoregion along an altitudinal gradient from the coast to the highlands. A few other smaller protected areas occur, such as the Bupul Nature Reserve and Danau Bian Wildlife Reserve, but these are quite small and much of the ecoregion remains unprotected against the juggernaut of palm oil expansion. 

The priority conservation actions for the next decade are to: 1) protect larger blocks of rainforest habitats from palm oil expansion; 2) maintain water flows within natural regimes; and 3) engage indigenous community members for protected area and resource management planning.

Citation

1. Adams VM, VI Tulloch, HP Possingham. 2017. Land-sea conservation assessment for Papua New Guinea. A report on the work undertaken to fulfil the terms of the project Review and Integration of the Terrestrial and Marine Program of Works on Protected Areas. PNG CEPA, University of Queensland, Global Environment Facility, UNDP, Brisbane. 75 pp.
2. Beehler BM, TK Pratt. 2016. Birds of New Guinea Distribution, Taxonomy, and Systematics. Princeton University Press, Princeton.
3. Davis SD, VH Heywood, AC Hamilton (eds). 1994-1997. Centres of plant diversity: a guide and strategy for their conservation. World Wide Fund for Nature (WWF) and ICUN - World Conservation Union, Cambridge.