Eucalyptus – Friend or Foe?
On February 7th, the day of Victoria’s bushfire holocaust, air temperatures broke all records reaching 48ºC. Humidity dropped below 10% and created conditions for unstoppable fires. Alloy wheels of cars melted confirming temperatures reached 1200ºC, demonstrating the eucalypt’s destructive capacity.
Oblivious to this disaster, Penny and I were with a party of friends walking through beech forests (Nothofagus) in Tasmania where it was only 24ºC.
Unlike inflammable eucalypt forests, a rainforest dominated by Nothofagus has tiny dark green leaves that block the sun reaching the forest floor as effectively as an umbrella. The soil was damp and moss covered the branches creating exquisite textures of green disturbed only by the roar of nearby waterfalls. Dotted throughout these cool and idyllic shady forests were patches of light provided invariably by the hanging leaves of sporadic eucalypts where the undergrowth was dry.
Before the pastoralists burned or bulldozed our coastal rainforests there was an uninterrupted 3,500 mile or more lush green coastal strip of virgin forest reaching from Tasmania all the way to Darwin.
But once the eucalypt becomes the dominant species and replaces the rain forest it completely alters the ecology to create conditions in which it thrives. The leaves of eucalypts hang vertically (see picture) to reduce evaporation letting through light that raises soil temperatures and reduces soil moisture which destroys shade loving ferns and mosses. The eucalypt also produces chemicals to prevent plant competition which assists it to become the dominant species. Its leaves are inflammable so its litter of leaves will ignite destroying all living things – soil carbon, soil biota, animals, plants and, of course, us.
The release of carbon into the atmosphere from the ignition of trees and soils was massive. Because it adapts and recovers from fires which destroy its competition it destroys diversity and changes our climate. Eucalypts have demonstrated Darwin’s “Survival of the Fittest” strategy so successfully they have become the predator plant species in Australia, and they are making this continent uninhabitable for humans.
By raising soil temperatures they destroy soil carbon and reduce soil fertility. But worst of all they reduce the fall of rain that has become so precious to our existence.
The eucalypt may be our most cherished plant, but now we must learn to understand its destructive potential.
They do more damage to our ecology than noxious weeds like blackberries, or introduced animals such as foxes.
If we allow the Tasmanian forest exploiter Gunns to have their way we will replace these cool diverse forests with dry inflammable mono-cultures of eucalypts just to provide cardboard boxes to increase their bottom line.
Most gardeners realise that planting eucalypts near houses is like putting an LPG gas bottle near the barbecue – but be aware the eucalypt is a predator that has the capacity to turn our fertile lands into a desert just like the Middle East.
