Re: Weeds and biodiversity

To: Marcus Pickett <>
Subject: Re: Weeds and biodiversity
From: George Appleby <>
Date: Mon, 3 Aug 1998 14:27:29 -0816 (UTC)
I would think that if an enlightened land manager (with 
some money and time to spare) planted native "thicket" 
species of similar form to gorse or blackberry (presumably 
this vegetation structure is an original one for the area) 
and progressively removed the weeds, then he/she should end 
up with habitat that maintains biodiversity if not 
increasing it (since a greater variety of native birds would
use the resultant native vegetation)! Why sit on your hands 
and be satisfied with the status quo of biodiversity at a 
site when it can be increased? 

Also, we should be continuing to eradicate weeds since 
current weed infestations can always act as a source for 
further colonisation of less weedy land.

On Mon, 03 Aug 1998 12:01:09 -0700 Marcus Pickett 
<> wrote:

> I have to disagree with Paul 
Peake's point that "weeds do not enhance
> biodiversity - they destroy it" (3 Aug 1998).
> Rather than damn weeds outright, I feel that weeds should be considered
> in the context of a given landscape, ie., its degree of modification and
> its biota.  I would expect that many naturalists could provide examples
> of plant-animal interactions which involve plants declared as weeds and
> native birds.
> Consider the following simple example.  A highly modified landscape (in
> the eastern Mt Lofty Ranges, S. Aust.), ie., woodland converted to open
> grazing for sheep with only a scattering of old eucalypts, has patches of
> Gorse (Ulex europaeus) and blackberry (Rubus spp.) which provide dense
> prickly-shrub type habitat utilised by birds such as Red-browed Finch,
> Diamond Firetail, Southern Whiteface, Superb Fairy-wren, and
> Yellow-rumped Thornbill.  This is biodiversity in my opinion.  Not ideal,
> not what might have occurred there ~200 years ago, but biodiversity now,
> in the area concerned.  One land manager was about to remove an extensive
> area of the above mentioned weeds using an air-tractor to apply
> herbicide, but fortunately, when it was pointed out that the weeds were
> providing locally important bird habitat, he agreed to 'tolerate' most
> areas of the perceived weeds for the sake of the birds.  The alternative
> landscape in this case, ie., without the Gorse and blackberry, and
> given the current land use and its management, would be rough
> pasture, itself, not at all suitable for the avian species listed
> above,...that is, a landscape with less avian biodiversity than at
> present.
> Obviously, there are examples of weeds undermining the integrity of
> biotic communities and populations, and many require appropriate
> treatment (possibly weed eradication), but the point I make is that weeds
> do not neccessarily destroy biodiversity, they sometimes enhance
> biodiversity by providing certain organisms with food or habitat
> resources in landscapes otherwise devoid of such.  There needs to be an
> understanding and recognition of the important role that many so-called
> weeds sometimes play in ecosystems which are highly modified by humans,
> before we damn all weeds.
> Marcus Pickett

George Appleby
Arthur Rylah Institute
123 Brown Street
(P.O. Box 137)
Victoria 3084
telephone 03 9450 8656
fax 03 9450 8799

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