Ecology

Trans Fly savanna and grasslands

Content Cover Image

Wasur National Park, Irian Jaya, Indonesia Photograph by © WWF-Canon/John Ratcliffe

The Trans Fly Savanna and Grasslands ecoregion is one of the most extensive lowlands on the island of New Guinea. Its seasonally dry climate is unusual for the island of New Guinea and more similar to that of northern Australia.

The habitats in this ecoregion are presently relatively intactThe condition of an ecological habitat being an undisturbed or natural environment.

caption Source: WWF

Location and General Description

This ecoregion is comprised of the monsoonal savanna and grassland habitat along the southern coast of New Guinea, in both Indonesia and Papua New Guinea. The climate of the ecoregion is a strongly seasonal tropical dry climate type, a variey that only this portion of New Guinea shares with much of Australia. Although the island of New Guinea is an active tectonic area with a complex geologic history, the geology of the West Papuan shelf, where this ecoregion is located, shows little folding, an indication of relative stability. The surface geology of the ecoregion consists of alluvium on active and relict alluvial plains and fans.

caption Source: WWF

This ecoregion is composed primarily of grasslands, although almost a third of the region is savanna, and there are areas of dry evergreen forest. The pronounced seasonal rainfall, local relief, drainage, and the frequency of burning contribute to the variation in floristic structure. The savannas have strong structural and floristic affinities with those of northern Australia. The dominant trees in the savannas include Eucalyptus, Albizia, and Melaleuca. The Melaleuca forest dominates areas that are submerged in up to one meter of water during the wet season. An extensive belt of bamboo dominated by Schizostachyum occurs along the transitional stage between the adjoining forests and the savanna vegetation of the monsoonal area. The dune and beach communities in this ecoregion contain the uncommon Sea Putat (Barringtonia asiatica).

Biodiversity Features

The overall species richness and endemism of this ecoregion are low to moderate when compared with those of other ecoregions in Indo-Malaysia. There are forty-four mammal species in the ecoregion, including five species that are endemic or near endemic (Table 1). Three of these species, the New Guinean Planigale (Planigale novaeguineae), the Bronze Quoll (Dasyurus spartacus), and the Dusky Pademelon (Thylogale brunii) are considered vulnerable.

Table 1. Endemic and Near-Endemic Mammal Species.
Family Species
Dasyuridae Planigale novaeguineae
Dasyuridae Dasyurus spartacus*
Dasyuridae Sminthopsis archeri*
Macropodidae Dorcopsis luctuosa
Macropodidae Thylogale brunii
An asterisk signifies that the species' range is limited to this ecoregion.

 

The ecoregion represents a portion of the Trans Fly Endemic Bird Area, EBA, which contains six restricted-range bird species. Five bird species are endemic or near endemic, including the vulnerable Fly River grassbird (Megalurus albolimbatus)(Table 2). Tonda Wildlife Management Area is a globally significant wintering ground for migratory waders and waterfowl from Australia and the Palearctic.

Table 2. Endemic and Near-Endemic Bird Species.
Family Common Name Species
Alcedinidae Spangled kookaburra Dacelo tyro
Alcedinidae Little paradise-kingfisher Tanysiptera hydrocharis
Sylviidae Fly River grassbird Megalurus albolimbatus
Estrildidae Grey-crowned munia Lonchura nevermanni
Estrildidae Black munia Lonchura stygia
An asterisk signifies that the species range is limited to this ecoregion.

 

This ecoregion forms the heart of the Southern Fly Platform Centre of Plant Diversity. Its flora is closely related to that of Australia.

The Trans Fly region is also critical habitat for several species of endemic amphibians and reptiles and is the only location of the pitted turtle (Carettochelys insculpta), a unique species in its own family.

The key ecological process in savannas is fire. Although fires can occur during any rainless period, most savannas burn at the end of the dry season, when conditions are most favorable.

Current Status

Although the region is inhabited by a large number of sparsely distributed tribal groups, population pressure is low. Access from the outside of the ecoregion is poor, and there is generally little ecological disturbance. More than 90 percent of the original habitat is still intactThe condition of an ecological habitat being an undisturbed or natural environment in this ecoregion. The five protected areas, well-distributed between Indonesia and PNG, cover 9,530 kilometers2, representing about 36 percent of the ecoregion area (Table 3). Tonda, in Papua New Guinea, and Wasur, in Indonesia, form a transboundary protected area complex that covers most of the coastal habitat.

Table 3. WCMC (1997) Protected Areas That Overlap with the Ecoregion.
Protected Area Area (km2) IUCN Category
Wasur 2,430 II
Wasur (extension) 1,020 PRO
Wasur (extension) 690 PRO
Rawa Biru 100 DE
Tonda 5,290 VIII
Total 9,530  

Types and Severity of Threats

There is some threat on the Indonesian side from transmigration settlements, which result in increased hunting, wildlife trade, agricultural conversion, and unsustainable forestry practices. This would only be exacerbated by new roads, such as the planned Trans-Irian Highway.

The introduction of Rusa Deer (Cervus timorensis) from other areas of Indonesia has had serious impacts on the grasslands of this ecoregion.

Justification of Ecoregion Delineation

Using Whitmore's map of the vegetation of Malesia and MacKinnon's reconstruction of the original vegetation, herein are delineated the large areas of distinct habitat types as ecoregions. The savanna and grasslands in the Trans Fly region were placed in the Trans Fly savanna and grasslands under the Grasslands, Savannas and Shrublands biome. This ecoregion also extends across the Arafura Sea to Australia, which is outside the region of analysis. Udvardy placed these ecoregions in the Papuan biogeographic province of the Oceanian Realm.

References

  • Michele Bowe. 2002. One landscape, two lands: what the international border means for community-based natural resource conservation in southern New Guinea in The New Guinea Tropical Ecology and Biodiversity Digest, Issue 12, 2002,
  • PacLII: Papua New Guinea Consolidated Legislation - Fauna (Protection and Control) Tonda Wildlife Management Area Rules 1976
  • Michele Bowe: Community-Based Conservation in the Trans-Fly Region, in Marshall A.J.: The Ecology of Papua, Periplus, Singapore, 2007, ISBN 0-7946-0483-8
  • G. Hitchcock. 2004. Wildlife is Our Gold: Political Ecology of the Torassi River Borderland, Southwest Papua New Guinea. PhD Thesis, The University of Queensland
  • Satellite images show Papua New Guinea deforestation at critical level, Guardian, 2 June 2008

 

Disclaimer: This article contains some information that was originally published by the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth have edited its content and 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.

 

Glossary

Citation

Fund, W. (2014). Trans Fly savanna and grasslands. Retrieved from http://www.eoearth.org/view/article/156685

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