Any grey water to spare for the tree in the street or park?

Doctor's plea for trees

* Denise Gadd
* February 19, 2009 The Age

VICTORIA has lost 12 per cent of its trees during the drought, with up to 50 per cent under threat if it continues, a leading arboriculturist has warned.

Dr Greg Moore, a special guest at a water crisis symposium being held tonight in Melbourne, is concerned the economic, health and environmental values of trees are seriously underestimated.

Trees and urban vegetation have been assets for years and their benefits should not be taken for granted, he said.

A study of trees in South Australia showed they had a value of $200 each in shade and carbon sequestration, Mr Moore said. "If there are 70,000 public trees in Melbourne, that's $14 million worth of value to the city. I'm worried that if we don't understand these benefits it will be at our peril. Suddenly you'll find Melbourne is not the liveable city it was because our trees, green spaces and vegetation have been lost."

He said localised warming due to the increase in paved and dark-coloured surfaces reduced significantly when cities had adequate green belts.

This meant the appropriate use of resources was needed to maintain these assets, such as water, especially in a drought.

Mr Moore said most councils had acted quickly to protect their parks and gardens, even though they faced hostility from residents opposed to such a "waste" of water.

"Melburnians can be wonderfully self-righteous yet the councils have stood their ground. Turf too has had a terrible time and yet it's an effective ecosystem in its own right and good at holding carbon.

"I'm worried about our obsession with water, and it's a justified and reasonable obsession, but sometimes it blinds us to other components in this overall environmental equation. It's glib to the point of dangerous to say we've got problems with water but we're not going to look at these other elements."

While most of Melbourne's trees are shedding their leaves early to survive, other trees are being removed for high-density developments, he said.

"There are pockets dotted around Melbourne where housing density is so great that you can't plant a tree of any substantial size in gardens."

Mr Moore said Sir William Guilfoyle, the second director of the Royal Botanic Gardens, understood that his creation had a functioning role as the lungs of the city.

Many Melburnians, though, consider trees to be ornaments rather than environmental protectors, Mr Moore said.

The symposium is on at 6pm at BMW Edge, Federation Square. Free entry.