Included here is New Guinea, the Aru Islands, Misool Island, Salawati, Weigeo, the Schouten Islands, the Trobriand Isands, Murua Island, the D’Entrecasteaux Islands and the Louisaide Archipeligo. Two types of savanna occur although tree fern savanna is really an upland ecosystem and is therefore also included in the Alpine Biome

Eucalypt Savanna

Savannas dominated by eucalyptus trees occur from sea level to about 1700 m, but only in areas that have a pronounced dry season. They also tend to be confined to hilly terrains like the Port Moresby region on the south coast.  The main species are Eucalyptus confertifolia, E. papuana (not endemic) and E. tereticornis; the latter can reach heights of over 30 m. The general view is that most of the lowland eucalypt savannas represent disclimax communities that have developed in response to a long history of burning by humans. All of these eucalypts originated in Australia and mainly spread outwards from the central south coast.  Nevertheless, pockets of natural eucalypt savanna are thought to have existed prior to human intervention in areas unsuited to forest development.  Lower story trees and shrubs are usually sparsely distributed but may include Albizia procera, Antidesma ghaesembilla, Cycas media, Desmodium umbellatum, Timonius timons and several endemic species such as Albizia carrii (Fabaceae), Grevillea papuana (Proteaceae) and Horsfieldia coryandra (Myristicaceae). 

Tree Fern Savanna

Savanna characterized by tree ferns appears to be unique to Papua New Guinea, and yet here it cover large tracts of land between altitudes ranging from 2700–3300 m and can be found on many of the high mountains.  The tree ferns are all atypical species of the genus Cyathea since most other members of this genus are forest dwellers characteristic of tropical mountain forests.  On Papua New Guinea, however, certain endemic species, such as Cyathea dicksonioides and C. pruinosa (Cyatheaceae) have broken away from this ancestral habitat becoming adapted to open grassland where they need to be tolerant of periodic burning, occasional draughts and large diurnal temperature fluctuations. This has been partly achieved by developing a thick fibrous ‘bark’, but these species are far from stunted and certain species, such as the endemic Cyathea muelleri can reach heights of 10 m. The dominant savanna grasses at these altitudes include the endemic or near endemic species Danthonia archboldii and Deschampsia klossi and to a lesser extent Dichelachne novoguineensis (Poaceae). Other endemic species include trees such as Dacrycarpus expansus (Podocarpaceae), various epiphytic shrubs such as Agapetes costata and Rhododendron caespitosum (Ericaceae), and many herbaceous species like Cynoglossum glabellum (Boraginaceae).

References

Conn, B. J. 1995. Handbook of the Flora of Papua New Guinea. Vol. III. Melbourne University Press.

Henty, E.E. (ed). 1981. Handbook of the flora of Papua New Guinea. Vol. II. Melbourne University Press.

Paijmans, K. (ed). 1976. New Guinea Vegetation. Commonwealth Scientific and Industrial Research Organisation in association with the Australian National University Press, Canberra.

Robbins, R. G. 1971. The montane vegetation of New Guinea. In: World Vegetation Types.  Ed. S. R. Eyre. Macmillan.

Steenis, C. G. G. J. van. 1957. Outline of the vegetation types in Indonesia and some adjacent regions. Proceedings of the Pacific Scientific Congress, 8: 61-97.

Womersley. J. S. (ed). 1978. Handbook of the flora of Papua New Guinea. Vol. I. Melbourne University Press.