P.N.G Expedition Discovers Largest Trees at Extreme Altitudes

They studied 195 forest plots in the rugged and remote Morobe Province along an elevation gradient spanning from the coastal lowland forests (50 m) to upper montane tropical forests (3100 m).   
 (Image:  eGuide Travel  via  flickr /  CC BY 2.0 )
They studied 195 forest plots in the rugged and remote Morobe Province along an elevation gradient spanning from the coastal lowland forests (50 m) to upper montane tropical forests (3100 m). (Image: eGuide Travel via flickr / CC BY 2.0 )

The first field campaign surveying Papua New Guinea’s lush primary forests from the coast to clouds has revealed the high mountain tops may house the largest trees recorded globally at such extreme altitudes.

The study — which involved The University of Queensland’s Dr. John Dwyer and James Cook University’s Professor Michael Bird — was led by Dr. Michelle Venter, a postdoctoral fellow at the University of Northern British Columbia, Canada. Dr. Dwyer, a UQ School of Biological Sciences’ lecturer and CSIRO researcher, said in a statement:

Dr. Venter led seven field expeditions in areas far from roads and villages, with the help of more than 70 field assistants from five forest-dependent communities, working on slopes of up to 88 degrees.

The research team recorded more than 15 tree families with individual specimens growing 30-40m tall at extreme altitudes. (Image: via The University of Queensland)

The research team recorded more than 15 tree families with individual specimens growing 30-40 m tall at extreme altitudes. (Image: The University of Queensland)

They studied 195 forest plots in the rugged and remote Morobe Province along an elevation gradient spanning from the coastal lowland forests (50 m) to upper montane tropical forests (3,100 m).

Unexpectedly, the researchers found that the forest biomass had a major peak at altitudes of 2,400-3,100 m, altitudes where forests struggle to reach more than 15 m tall in other parts of the world. Dr. Venter said:

The tallest trees included a 41 m high Nothofagus starkenborghii, one of the southern beeches whose ancestors dominated Gondwanan forests for millions of years.

Dr. Dwyer said the researchers became excited when they realized the unique climate conditions found on mountain tops of P.N.G were remarkably similar to those of temperate maritime areas known to grow the largest trees in the world:

The world’s tallest known tree is a 115.8 m (380 ft) coast redwood (Sequoia sempervirens) found in California, and the second-tallest reliably measured specimen is a 99.82 m (327.5 ft) mountain ash (Eucalptytus regnans) from the Arve Valley in Tasmania.

Several Australian gums from Tasmania and Victoria are also in the top 20 monument trees list. Coast redwoods occur in elevations up to about 920 m, while the Australian mountain ash occurs in cool mountainous areas to 1,000 m altitude, considerably less than the P.N.G altitudes.

James Cook University’s Professor Bird said: “Believe it or not, why and how trees grow large is still a topic for investigation, and reasons for the persistence of large old trees are still not clearly known.”

Provided by: The University of Queensland

[Note: Materials may be edited for content and length.]

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