New Guinea plants

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from left to right: Orchids and mushrooms.
© Brent Stirton/Getty Images / WWF-UK

From towering merbau trees to delicate orchids

Between 15,000 and 20,000 plant species thrive in New Guinea, many in the island’s forests. This extraordinary diversity has been brought about by the favourable soil types, the climate and species migration from other areas.
Of New Guinea's plants, there are more than 2,000 species of orchids and 2,000 species of ferns. Although almost 8 out of 10 of these plants are found nowhere else in the world, New Guinea’s plant numbers are low compared to other tropical areas.1

When seeing the rich canopy and massive trees of the lowland canopy, one is tempted to believe that the soils are very rich. In fact, the soil layer is thin and is easily leached of its nutrients compared to the highlands.

Climbers of the forest

Climbing plants, 90% of which are tropical, comprise many families. They include the climbing palms (rattans), which can reach a length of 240 m; stranglers, belonging mostly to the genera Ficus, Schefflera, Clusia, and Timonius; and epiphytes, a varied group including flowering plants and ferns.

Epiphytes include the orchids, striking plants that have successfully colonized tropical forest canopies, especially in the favourable climate of the mid-montane forests.

Some plants like it cool, cloudy and foggy

Bryophytes stand out from other plants described so far as being non-vascular, and neither flowering nor producing seeds. These small plants reach their greatest diversity in tropical rainforests.

They are particularly diverse and abundant in the mid-to-upper montane forests, before declining again with higher elevations. Many of them are unique to New Guinea, where they are particularly fond of areas dominated by beech (Nothofagus species).2

Trees with million-year histories

In New Guinea, you can still find remnants of most plants of Gondwanaland, a ‘super-continent’ which more than 100 million years ago included most of the landmasses that make up Australia, New Guinea, Antarctica, South America, Africa, Madagascar, India, Arabia and New Zealand.3

How New Guinea’s plant life evolved

After the Australia-New Guinea continental plate broke off from Gondwanaland, it remained isolated for millions of years, preventing the invasion of foreign species. When the larger parts of New Guinea reached their current position about 10 million years ago, the island was in close proximity to others, which made possible the migration of Asian plants.

The plants we see today in New Guinea are predominantly Asian in origin, especially in the lowlands. In montane forests however, the climate favoured the evolution of new species.

Intense volcanic activity, which boomed until 200,000 years ago, resulted in the formation of rich soils at higher altitudes, which also promoted speciation.4

A closer look at…

The ant benefit

The root systems of epiphytes often host ant nests. Ants gather nutritive minerals that are taken up as food by the epiphytes.
1 Wikipedia. Gwondaland. Accessed 12/01/2006.
2 Muller K. 2004. The Biodiversity in New Guinea. Unpublished document.
3 Wikipedia. Gwondaland. Accessed 12/01/2006.
4 Muller K. 2004. The Biodiversity in New Guinea. Unpublished document.

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