What is killing the Earth’s oldest and biggest trees?
Scientists say the largest living organisms on the planet, our giant trees, are dying in larger numbers than even before – and they don’t know why.
A report by three of the world’s leading ecologists in the journal Science warns of an alarming increase in deathrates among trees 100-300 years old in many of the world’s forests,
woodlands, savannahs, farming areas and even in cities.
‘It’s a worldwide problem and appears to be happening in most types of forest,” said Professor David Lindenmayer of the Australian National University, who led the study.
‘Large old trees are critical in many natural and human-dominated environments. Studies of ecosystems around the world suggest populations of these trees are declining rapidly,’ he and
colleagues Professor Bill Laurance of James Cook University, Australia, and Professor Jerry Franklin of Washington University, USA, say in their paper.
‘Research is urgently needed to identify the causes of rapid losses of large old trees and strategies for improved management. Without… policy changes, large old trees will diminish or disappear in many ecosystems, leading to losses of their associated biota and ecosystem functions.’
Prof. Lindenmayer says they were first tipped off to the loss of big old trees while examining Swedish forestry records going back to the 1860s.
Then a 30-year study of Mountain Ash (Eucalyptus regnans) forest in Australia confirmed not only that big old trees were dying en masse in forest fires, but also perishing at ten times the normal rate in non-fire years – apparently due to drought, high temperatures, logging and other causes.
Looking round the world, the scientists say they found similar trends at all latitudes, in California’s Yosemite
National Park, on the African savannahs, in the rainforests of Brazil, the temperate forests of Europe and the boreal forests of the far north.
Losses of large trees were also pronounced in agricultural landscapes and even cities, where people make efforts to preserve them.
‘It is a very, very disturbing trend. We are talking about the loss of the biggest living organisms on the planet, of the largest flowering plants on the planet, of organisms that play a key role in regulating and enriching our world,’ says Professor Bill Laurance of James Cook University.