Can't let it pass. Fact. Paulownias are causing concern with their
potential as environmental weeds. Why jump to the conclusion that seeds are
the problem? Paulownia can sucker like mad. This is a serious enough
possibility for state departments concerned with natural resource management
to have a look at the dangers of paulownia. It is true that they are being
widely grown in plantations, but they will not replace hardwoods. Some
regard the sudden enthusiasm for these trees as the product of clever
marketing. The timber of the Paulownia is much like balsa wood. Soft and
"perishable". Probably okay for throw away chopsticks.
Camphor laurels benign? Perhaps you're not from Queensland. Very large
stretches of lowland creek systems here in SEQ have been almost exclusively
colonised by Camphor laurel, and they most assuredly do exclude other
plants, including the native lauraceae which once grew in lowland riparian
forests. Other plants do not grow as well under Camphor laurel as they
would under other large trees. Fact. The exclusion of other plants is, as
you pointed out, due to competition for water. The heavy shade cast by C.L.
is also an important mechanism. But, chemicals also work to exclude
colonisation by other plants. Leaves, twigs, bark and wood of C.L. contain
turpenes, chemical substances which most certainly do inhibit the growth of
other plants. These same substances are also found in things like pine bark,
which is why this stunts the growth of small garden plants if it is used
fresh, before the turpenes have had a chance to be leached away or break
down. The oils contained in any of the plants you mentioned do not require
distillation for them to be released. The Blue Mountains are proof of that.
The blue hue in the air from which the Blue Mountains take their name from
the turpenes released (naturally) by the eucalypts growing in the forests of
the Blue Mountains. Likewise, any of the other plants you mention release
at least some of their volatile oils without distillation. It doesn't fall
from the sky like rain, but it is released nonetheless.
It is time that people on this list realised the seriousness of the problem
of "ferals". This is not some minor issue. Translocated plants and animals
are causing damage on a great scale. They are now reckoned to be second to
land clearing/conversion for the destruction of biodiversity. At its worst,
we have a process of biological homogenisation occurring. Ask New Zealand.
They now have more exotic plant species growing in the wild than native.
Hawai'I has similar, possibly more serious problems. Go there, and you'll
have to work very hard to see more native birds than naturalised imports.
Have a look at the destruction of riparian forests in north Queensland by
rubber vine, which was brought here as an ornamental. If people are "bored"
with these issues, and stop acting on them, then I fear for our birds, and
all other wildlife. I could say a lot more about bioinvasions, but I'll cut
it off here.
Scott O'Keeffe
-----Original Message-----
From:
On Behalf Of John McLaren
Sent: Thursday, 28 September 2000 3:38
To: ; Max O'Sullivan
Cc: birding-aus
Subject: Honeyeaters and exotic blossoms.
Michael , two points you made below need defending as they are not quite
factual .
Paulonia's have no chance of becoming an * invasive environmental weed * ,
due to the fact that seed germination is extremely difficult and is only
achievable under intense nursery conditions . At present most Paulonias are
being grown in timber plantations and will hopefully one day soon offer an
alternative to much of the hardwood used to-day .
Secondly Camphor laurels do not * exude * camphor , nor do Eucalypts exude
eucalyptus ( also a powerfull insecticide ) , or Melaleuca alternifolia
exude " Tea-tree oil " , and the list goes on , all of these are oils
contained in the plant and need a distillation process to either extract or
release them . As for suppressing other plants growing beneath Camphor
laurels , to the contrary most plants grow exceptionally well , indeed as
well as they would under any large tree with an extensive root area a large
canopy and a fairly high water demand .
This constant " feral bashing ", "farmer bashing ", and "environmental weed"
bashing is totally unproductive , and I believe has become very boring on
this list .
John McLaren .
> I hope that no readers will assume that because Regent
> Honeyeaters and other HEs will feed on Paulonias that therefore
> these are a good thing.
>
> It's a good bet that like so many other horticultural species it
> will become - if it hasn't already done so - an invasive
> environmental weed with unknown consequences. Cf. Camphor
> Laurel: I've only just learnt that it exudes - you've guessed it
> - camphor, a great insecticide which also suppresses most plants
> beneath a tree.
>
> Michael Norris
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