Courtesy of The Australian National University

Ecosystems worldwide are in danger of losing large, old trees forever, without more research and policy changes to better protect them, warns a new study published in Science.

Boabab Tree, Tanzania

Lead author of the paper, Professor David Lindenmayer from the Fenner School of Environment and Society in the ANU College of Medicine, Biology and Environment, says the threats these trees face are manifold and populations around the world are rapidly declining.

“Just as large-bodied animals such as elephants, tigers, and cetaceans have declined drastically in many parts of the world, a growing body of evidence suggests that large old trees could be equally imperiled,” said Professor Lindenmayer.

“Targeted research is urgently needed to better understand the key threats to their existence and to devise strategies to counter them. Without such initiatives, these iconic organisms and the many species dependent on them could be greatly diminished or lost altogether.”

The study outlines the unique ecological roles large old trees play, roles that younger and smaller tress cannot fulfill.

“Large old trees in Mountain Ash forests of mainland Australia, for example, provide irreplaceable shelter and nesting sites for over 40 species, therefore their decline could have serious implications for ecosystem integrity and biodiversity,” said Professor Lindenmayer.

Mountain Ask Forest, Australia

“They also store large quantities of carbon and play significant roles in local hydrological regimes, disruptions to which are of global concern.

“These trees are among the biggest organisms on Earth, and their importance can continue for decades or even centuries after tree death when they become standing dead trees or large logs.”

The paper cites examples of locations in Europe, North America, Africa, Asia, South America, Latin America and Australia where the loss or large old trees has been identified as a major ecological problem.

“In certain locations we are seeing multiple drivers of large old tree loss interacting to create ecosystem-specific threats,” said Professor Lindenmayer.

“In agricultural landscapes, for example, chronic livestock over-grazing, excessive nutrients from fertilizers, and deliberate removal for firewood and land clearing combine to severely reduce large old trees.

“If we are to ensure the perpetual supply of large old trees, policies and management practices must be put in place that intentionally grow such trees and reduce their mortality rates.”

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