New Guinea forests

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Landscape view of forest in western Papua New Guinea
© WWF / Albrecht G. SCHAEFER

Still the tropical forest paradise

Stretching from the lowlands to altitudes beyond 3,000 m, New Guinea's forests show an enormous variety in species, aspect and dynamics depending on their location.
A walk through these forests is not just a journey under the canopy but also a trip in time. Some of the plants here are more than 100 million years old.

A profile of the New Guinea lowland forests

Richer and more diverse in species than their montane counterparts, the lowland forests of southern New Guinea are the home of more than 1,200 species of trees and about 2,000 species of ferns.1 Tracts of this kind of forest are most extensive on foothills and the lower slopes of mountains.

Lowland rainforests are demanding ecosystems. They need at least 2,500 mm of rainfall per year, and they only show the greatest species diversity on well-drained sites.

Lowland forests are not uniform in appearance. At higher altitude, the canopy decreases in height (from a maximum of 50 m to 25 m), but trees are more closely bunched than on alluvial lands.

Trees of the lowlands

Canopy trees can reach over 50 m and have straight trunks, which often are supported by buttress roots. Majestic in height and stature, they belong to the Pometia, Canarium, Cryptocarya, Terminalia, Anisoptera, Syzygium, Ficus, Celtis, Dysoxylum and Buchanania genera.
Click here to find out more about some of these species

The primitive Araucaria, a coniferous survivor of Gondwanaland, is the tallest tropical tree in the world and can be found mostly in scattered locations in isolated stands.

In eastern New Guinea, dipterocarps (tall trees with two-winged fruit) can cover large areas, in elevations up to around 500 m. Beyond that point, montane oak (Castanopsis acuminatissima) may form dense forests on ridge crests and upper slopes.

Dipterocarp trees, which account for a majority of the world’s trade in tropical hardwoods, are scarce in the lowland forests. Their relative absence is therefore a blessing for the area’s forests.2

Plant survival skills

Ficus species rely on a treacherous technique to survive: they begin as epiphytes, send down roots and eventually choke their host.

Far below the canopy…

In the dim light of the lowland forest undergrowth, the absence of light keeps vegetation low. As in other tropical rainforests, the topsoil is so thin that trees need buttress roots to firmly anchor themselves to the ground.

At lower altitudes, tall palms are common, along with those in the shrub layer. Ferns, and tree and rattan seedlings are abundant, while woody lianas, fleshy climbers and climbing ferns are common. Climbing rattans are always present, but primarily thrive in forest openings. Epiphytes - mainly orchids and ferns - prefer the crowns of the canopy trees.

Animals of the lowlands

Some of the world’s most peculiar evolutionary adaptations can be found in the southern New Guinea lowland forests: the lesser tube-nosed bat (a small bat with tubular nostrils that whistle when it flies), the spangled kookaburra (a bird with a brown head and brilliant blue feathers on its back and tail), and the greater bird of paradise (sports a stunning array of green, yellow, and maroon feathers, and a dashing white-and-yellow plume).3

Montane forests

Beyond 1,000 m, the lowland forest gives way to montane forests. Here, the canopy is lower than the lowland forests and fewer trees rely on buttresses. Branches also grow lower on the trunks and the shrub layer is denser.

Montane forests do not have as many plant species as the lowlands. In fact, lowland species are poorly represented at higher altitudes, where they are replaced by beech (Fagaceae), laurels (Lauraceae), Elaeocarpuaceae, Cunoniaceae and conifers (Coniferae).

While palms, climbing rattans and woody lianas become rarer with altitude, other plants take dominance, such as epiphytic mosses, ferns and orchids.

Like lowland forests, montane forests are not uniform – based on the species composition and forest physiognomy, specialists divide them into lower montane, mid-montane and upper montane forest.

>Montane forests in slices
 Moss forest at an altitude of 2600 meters in the Arfak Mountains Nature Reserve, Irian Jaya, ... / ©: WWF-Canon / Ian CRAVEN
Moss forest at an altitude of 2,600 m in the Arfak Mountains Nature Reserve, West Irian Jaya Province, Indonesia.
© WWF-Canon / Ian CRAVEN

At home in the montane forests

Six mammal species are endemic or near-endemic in New Guinea's montane forests, including the Cyclops long-beaked echidna (Zaglossus attenboroughi), D’Albertis ringtail possum (Pseudochirops albertisii), Scott’s tree kangaroo (Dendrolagus scottae), the rock-dwelling rat (Xenuromys barbatus) and the northern glider (Petaurus abidi).

Endemic birds include the rare fire-maned bowerbird (Sericulus bakeri), Mayr’s forest-rail (Rallina mayri), and the golden-fronted bowerbird (Amblyornis flavifrons).4
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1 WWF. Southern New Guinea lowland rain forests (AA0122). Accessed 12/01/2006.
2 Muller K. 2004. The Biodiversity of New Guinea. Unpublished document.
3 WWF. Southern New Guinea Lowland Forests - A Global 200 Ecoregion.  Accessed 11/01/2006
4 WWF. Northern New Guinea montane rain forests.  Accessed 13/01/2006.

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