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permaculture - Re: [permaculture] Exotic Plant Eradication

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  • From: PacificEdge <pacedge@magna.com.au>
  • To: permaculture@lists.ibiblio.org
  • Subject: Re: [permaculture] Exotic Plant Eradication
  • Date: Wed, 14 Aug 2002 13:23:05 +1000

Invasive exotic species have had a detrimental impact on the Australian biota, too, however a landscape architect friend once told me that it is too late to get rid of them and we should accept the presence of the less-damaging plant species as a 'new ecology'.

This seems to be the conclusion that Australian biologist, Tim Low, has reluctantly come to in his recent book 'The New Nature'. Species such as Lantana camara are now being found to have advantages for small native animals and birds because the dense, thorny branches inhibit and discourage the movement of the predatory feral cats that prey on these animals.

Other species, such as privet and camphor laurel, in some places displace local wet forest and rainforest and create something akin to a monoculture in moist gullies on the Australian east coast.


On Wednesday, August 14, 2002, at 01:04 AM, Mark wrote:

At 09:32 AM 8/10/02 -0500, you wrote:
if exotic plants are the number two cause of species extinction
then surely the number one cause is exotic humans.

How can humans be 'exotic' to any place? Humanity has colonised virtually all the regions of the earth with the exception of Antarctica and can themselves be considered an outgrowth of the earth's natural biological systems.

For starters, at least
half of our agriculture consists of exotic plants including the soy bean
which many vegetarians take some ethical refuge in for eating.

We rely on exotic plants simply to survive, just as many of our agricultural crops rely on humanity for their continued existence in their present form. They are often human creations, the result of millenia of cross breeding.

Yes, I agree with the questionable ethics of soy bean monoculture. I have found that it is often advocated as a replacement for meat, sometimes by 'militant' vegetarians (ie. those who are ideologically driven). What these people often miss, however, is the environmental impact of their soy agriculture.

It also seems to me that, the areas hardest hit by all exotic species are
disturbed edges, e.g. road ways, developments butted up to woodlands or
prairies, man made lakes and waterways, etc. It's quite possible, when
looking through another set of lenses that, these exotic plants are the
beginning of natural succession rather than the end of it.

For more on this, see the writings of David Holmgren.

Simplistic look at the issue. Of course disturbed areas sprout more of this stuff, and other pioneer species. This does not change the fact that many exotics are invading non disturbed areas.

No argument here as regards Australia. In my opinion, it gets down to what you are managing the ecosystem for. The pollution of Sydney's remnant urban bushland by exotic species gave rise to a new industry in the 1990s - bushland regeneration. These earnest folk are funded by federal and local government to remove 'weeds' from urban bushland. That's fine where the preservation of the 'natural' bushland is the design objective. But boosted by the green movement, environmentalists and the native plants lobby they have become politically influential at the local and state government level and can sometimes be a little myoptic about exotics (more than one observer has described them as 'ecofascists'; while that description fits some, it certainly does not fit them all). Problem is, they don't seem to recognise that exotics are fundamental to our survival in this land of poor soils and that food grown in the city is part of the sustainability equation.

There is also the fact that bushland regeneration is not financially sustainable on a large scale. As well, I have heard from local government bushland managers that it is becoming more difficult to find the volunteers who form the core of the fight against exotic invaders.

Anyway, the 'natural' bushand they seek to preserve is in actuality a human artifact, the result of tens of millenia of low-intensity Aboriginal burning from which only fire-adapted species came to make up the flora (open eucalypt and acacia bushland and woodland). The more vulnerable wet forest species survived in the protection of the gullies. Now, in the absence of low-intensity burning, the wet-adapted species, such as Pittosporum where I live, are trying to move out of the gullies and colonise the drier open eucalypt forest. The response of some bushland regenerators is to apply Rounbdup to the the colonisers.

My contention is that this treats the bush as a museum of the biota that existed at the conclusion of Aboriginal bushland management, a system trapped in time by the continual effort of regenerators, and denies the reality that bushland is an adaptive, dynamic system responding to the new realities of nature in Australia, such as the greater influx of nutrients into bushland from the residential and industrial areas surrounding it and the spread of the seed of exotic species by wind and avifauna.

This is not an argument in support of the worst of exotics taking over our bushland, rather that we decide how we want to use ecosystems and that we manage for that.

...Russ Grayson


Mark P. Ludwig
Poultry Research Lab
University of Wisconsin -Madison
608-262-1730 WK
608-846-7125 HM

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.........................
Russ Grayson, Australian Community Gardens Network.

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