Climate change 'flattens' treetops

September 11, 2013: - The Earth is not flat nor are the forests that live upon it but according to a new study just published in Proceedings of the Royal Society B, climate change may ‘flatten’ the Earth’s rainforests.

Lead researcher Brett Scheffers of the Centre for Climate Change and Tropical Biology at James Cook University in Townsville, Australia, says “our findings suggest that the biodiversity that lives in the treetops of rainforests may be pushed toward the cooler and wetter ground as the climate warms”.

This ‘flattening’, he said, could seriously alter the way tropical rainforests function.

Almost half of all known species in the tropics live in rainforest canopies but according to the researchers, climate change may create an extinction zone in the lowlands that starts in the canopy and moves down towards the ground. As the Earth continues to warm, this zone will then expand upwards in elevation.

Mr Scheffers said that species were already moving uphill or towards the poles in search of cooler and wetter climates as the Earth warms and dries from climate change.

But he and his colleagues are the first to suggest that before this happens, species will first move out of the trees and towards the ground.

To collect data, Mr Scheffers and a large group of field researchers traversed a mountain in the tropical rainforests of the Philippines in search of frogs and other animals that live in the tree-tops.

“A major reason why our study is unique is that rainforests consist of towering trees that are incredibly difficult to access with some over 50 metres in height,” he said.

“This discourages many researchers from conducting canopy research. Over the course of several months, we had to climb hundreds of trees to get our data.”

The researchers ‘flattening’ forest hypothesis is based on a century-old debate over what causes patterns of biodiversity.

“We show that trees are as tall as mountains and as long as latitude in shaping biological patterns,” he said.

Their report says that rainforest vegetation creates a climate gradient over a distance of just 20-30 metres that is far steeper than the changes in climate that may occur over hundreds of meters of elevation or kilometres of latitude.

Biodiversity in tropical rainforests was found to organize along this height gradient—from the tops of trees down to the ground. The organisation of species from ground to canopy changes with altitude as species tend to move upwards in the rainforest strata as elevation increases.

“We discovered a whole new dimension to biodiversity on Earth but in doing so we uncovered new consequences of climate change. We should carefully monitor for downward movements of rainforest species as this could be an early warning that rainforests are under stress,” he said.

“The Earth’s rainforests are certainly not flat but if citizens and governments do not take the necessary actions to prevent strong changes in climate… they could be”.

Reference (PDF available on request)

For further information contact:

Brett Scheffers James Cook University

Email: schefbr0@gmail.com

Phones: +01-708-717-4366 (USA number from present – October 1 2013)

Professor Stephen Williams  07 47815580 or  0428 690280

JCU Media: Jim O’Brien +61 7 4781 4822 or 0418 892449

Issued: September 11, 2013