The secret forest: an expedition discovers giant trees at high altitude

JCU’s Professor Michael Bird said the team found trees in the Highlands of PNG that were up to 40 metres tall, at a height above sea level where most forests don’t top 15 metres.

“We set up 193 forest plots along an elevation spanning from the coastal lowland forests at 50 metres above sea level to those which were 3100 metres above sea level. Unexpectedly, forest biomass had a major peak at altitudes of 2400-3100 m, an altitude where forests fail to grow more than 15 metres tall in other parts of the world,” he said.

Lead author Dr. Michelle Venter, a former JCU PhD student and currently a post-doctoral fellow at the University of Northern British Columbia, said that forests at this altitude are often typified as squat and gnarly.

“Mountains make small trees, is the thinking. But we recorded more than 15 tree families with individuals growing up to 40 metres tall at extreme altitudes which brings this assumption into question,” she said.

Most of PNG’s forests lie beyond the reach of roads, coastal or river access, meaning they remain some of the most under-researched areas of tropical forest.

The findings of the first-ever field study surveying PNG’s lush primary forests from the coast to clouds was published today in the journal Global Change Biology.

John Dwyer from The University of Queensland said after finding the giant mountain trees, the scientists made a connection.

“We got excited when we realised that the unique climate conditions found on the mountain tops of PNG were remarkably similar to those of temperate coastal areas known to grow the largest trees in the world. Think of the foggy mid-west coast of the USA, which boasts the epically large coastal redwoods,” he said.

Professor Bird said mystery still surrounds large trees generally.

“Believe it or not, why and how trees grow large is still under investigation, and reasons for the persistence of large old trees are still not clearly known.”

Link to image here.