Do gum trees and people mix?

Very interesting article from this morning's edition of The Australian, especially as we call to mind last year's Black Saturday bush fires in Victoria, and at a time when we still have a simple-minded idiot up a gum tree here in Perth because the local council, quite properly, wants to remove it because of another unfortunate characteristic of many of them, that is the fact that they can drop large branches without warning. (It's not for nothing that they are known as "widow makers.")

So I've posed this question of whether people and gum trees, (I wont use the name eucalypt because apparently the old genus Eucalyptus has now been split in two, so that not all gum trees are eucalypts anymore), actually go together a number of times in recent years.

Not so much for urban and most suburban areas where trees tend not to be planted close together over large areas intermingled with houses, but certainly for most outer-suburban and rural settings.

(Though I do have objections to the near ideological and 'nationalist' fervour that sees ugly and scraggly gum trees, that give little good summer shade, planted in street scapes where broadleaved introduced species would be much better, not only giving better shade in the hot months but also more light during winter.)

Summer fires in a Mediterranean climate anywhere are inevitable.

But we live in an environment that was changed forever by aboriginal people when they started to burn the landscape regularly tens of thousands of years ago.

Plants, (and there would have been a much greater diversity of plant types across Australia back then, with gum trees only part of a much richer mix - the palms found in isolated locations in the interior of the continent are the faint echoes of this much more biodiverse land), had to go from an environment that was burned only every so often due to lightening strikes to one that was burned several times a year by aboriginal people seeking to produce new grass growth to attract animals to be hunted.

Many did not survive this drastic change and disappeared altogether or, like those isolated palms, hung on in much smaller areas that offered them some protection from people (and of course the simultaneous slow drying of the continent).

Gums however thrived. So we now live in an impoverished environment (in terms of types of plants) dominated by a type of tree that makes fires not only more likely, but also much worse when they do happen.

And yet we have country and outer-suburban councils, driven by the new green religion, telling people they cannot remove gum trees that are close to their properties and that any tree that is planted must be native, ie a gum tree.

This is a recipe for inevitable disaster.

The Canberra fires from a few years ago were a perfect example of this.

The botanical nationalism I mentioned before required that much of the city be set in a "natural" bush setting. Many homes were thus placed within areas heavily wooded with gum trees.

When the fire started it could jump from one gum tree to the next as the volatile oils in the foliage exploded into flames and the highly inflammable leaf (and bark) litter on the ground provided even more fuel for it.

But not everywhere:

The three plantations of cork oaks on the western edge of Canberra not only survived the firestorm, but checked its advance; the stand on the northwest corner of Curtin slowed the fire and protected the homes behind, not one of which was damaged. Further up the hill, where eucalypts took over, several houses were burnt.

The ACT Department of Municipal Services notes that, unlike gum trees, "Cork oak is essentially fire resistant and the foliage results in a relatively non-flammable, low-level ground fuel".

As well as oaks, there are many trees originating in dry areas of the Middle East and southern Asia that would do the job - quinces, pistachios, pears and apricots, for example, and the ubiquitous peppercorn tree, once an inevitable feature of every rural homestead. Suitable native species include the kurrajong and several varieties of wattle and casuarina.

Non-eucalypts offer other advantages. A plantation of wet-leaf trees is more effective as a firebreak than a strip of cleared or burnt ground, since their foliage blocks flying embers. During the Canberra fire large manchurian pears in Morehead Street, Curtin, stopped flaming embers from reaching several houses.

Unlike eucalypts, whose roots release acids that limit the growth of rival plants, and whose dead leaves lie around until consumed in the next fire, leaf litter from deciduous trees rots down into compost and enriches the soil.

You can read the full article here.

My own views on native versus non-native have been undergoing a change for a few years now.

I used to be one of the ecological nationalists, but am probably not one anymore. Having read both of Peter Andrews' books - Back From the Brink and Beyond the Brink - I am not as convinced anymore that introduced is necessarily bad.

It is interesting that at a time when the government was paying farmers to remove willows from creeks and rivers, he was planting them because they helped him to restore his badly degraded creeks.

One of his points is that we do indeed have an environment that has been robbed of diversity, first by aboriginal people and then by European settlement. Who knows how many different types of palms, deciduous and evergreen trees and vines have been driven to extinction by the effects of human beings on this country?

Apparently we do have settler accounts of things like vines etc that are not there anymore, our sheep and goats and cattle having finished them off.

But certainly for areas where people have their homes I now think that at most gum trees should only be a relatively small part of a much more diverse mix of trees, whether from other parts of Australia or from overseas.

Broadleaved deciduous trees need to be brought back into this mix.

And maybe, in a sense, we can start to repair damage done to this land that started thousands of years ago and restore some of the biodiversity that has been lost.

Posted via email from Garth's posterous