In article , Tumbleweed thisaccountneverr
writes

"Kay" wrote in message
...
In article , BAC
writes

"Kay" wrote in message
...
In article , Franz Heymann
notfranz.
writes


It would be unwise for a pragmatist like me to say yes or no to such a
possible false generalisation.
There are circumstances where I would be prepared to participate in
the eradication of some species in certain places for the sake of
humans, or domesticated animals, for example

Prickly pears for the sake of grazing field
The common cold virus
Malaria-carrying mosquitoes
Bracken in the Lake District
Hedgehogs in N Uist and Benbecula
Cats on Marion Island

Well, out of that lot, nos 1, 5 and 6 could be regarded as putting
things right after introduction of species to places where they don't
belong,

What do you mean by 'places where they don't belong'?

They didn't get there without human intervention.

Whether it "didnt belong there' is a human value judgement. Had, in
pre-human times, a chance event carried prickly pear seed to Oz, and it had
become established, presumably you'd now be saying it did 'belong there'?


It wouldn't have arrived there as a result of human activity. OK, you
can say that it's irrelevant which species brought it there - whether it
came on a duck's foot or in a human's hand baggage, for example, but
what this discussion is leading me to believe is that there is a
quantitative difference between us and other species - we do things more
purposefully and on a larger scale, and therefore have a larger effect.

Had Opuntia arrived in Oz as chance seeds in pre-human times, they would
have established more slowly, other things would have evolved around
them. They would not have become the problem that they did.

--
Kay
"Do not insult the crocodile until you have crossed the river"

"Kay" wrote in message
...
In article , Tumbleweed thisaccountneverr
writes

"Kay" wrote in message
...
In article , BAC
writes

"Kay" wrote in message
...
In article , Franz Heymann
notfranz.
writes


It would be unwise for a pragmatist like me to say yes or no to
such a
possible false generalisation.
There are circumstances where I would be prepared to participate in
the eradication of some species in certain places for the sake of
humans, or domesticated animals, for example

Prickly pears for the sake of grazing field
The common cold virus
Malaria-carrying mosquitoes
Bracken in the Lake District
Hedgehogs in N Uist and Benbecula
Cats on Marion Island

Well, out of that lot, nos 1, 5 and 6 could be regarded as putting
things right after introduction of species to places where they
don't
belong,

What do you mean by 'places where they don't belong'?

They didn't get there without human intervention.

Whether it "didnt belong there' is a human value judgement. Had, in
pre-human times, a chance event carried prickly pear seed to Oz, and it
had
become established, presumably you'd now be saying it did 'belong there'?


It wouldn't have arrived there as a result of human activity. OK, you
can say that it's irrelevant which species brought it there - whether it
came on a duck's foot or in a human's hand baggage, for example, but
what this discussion is leading me to believe is that there is a
quantitative difference between us and other species - we do things more
purposefully and on a larger scale, and therefore have a larger effect.

Had Opuntia arrived in Oz as chance seeds in pre-human times, they would
have established more slowly, other things would have evolved around
them. They would not have become the problem that they did.


Had Opuntia arrived in Oz as chance seeds in prehuman times, and
proliferated exponentially, you are right to say they would not have become
a problem, because there would not have been anyone on hand to perceive
their presence and their effect on that ecosystem as problems.

"Kay" wrote in message
...
In article , Tumbleweed
thisaccountneverr
writes

"Kay" wrote in message
...
In article , BAC
writes

"Kay" wrote in message
...
In article , Franz Heymann
notfranz.
writes


It would be unwise for a pragmatist like me to say yes or no
to such a
possible false generalisation.
There are circumstances where I would be prepared to
participate in
the eradication of some species in certain places for the
sake of
humans, or domesticated animals, for example

Prickly pears for the sake of grazing field
The common cold virus
Malaria-carrying mosquitoes
Bracken in the Lake District
Hedgehogs in N Uist and Benbecula
Cats on Marion Island

Well, out of that lot, nos 1, 5 and 6 could be regarded as
putting
things right after introduction of species to places where
they don't
belong,

What do you mean by 'places where they don't belong'?

They didn't get there without human intervention.

Whether it "didnt belong there' is a human value judgement. Had, in
pre-human times, a chance event carried prickly pear seed to Oz,
and it had
become established, presumably you'd now be saying it did 'belong
there'?


It wouldn't have arrived there as a result of human activity. OK,
you
can say that it's irrelevant which species brought it there -
whether it
came on a duck's foot or in a human's hand baggage, for example, but
what this discussion is leading me to believe is that there is a
quantitative difference between us and other species - we do things
more
purposefully and on a larger scale, and therefore have a larger
effect.

Had Opuntia arrived in Oz as chance seeds in pre-human times, they
would
have established more slowly, other things would have evolved around
them. They would not have become the problem that they did.

Oh yes? For all practical purposes every piece of Opuntia which lands
on the ground roots. My father once established an Opuntia hedge
(believe it or not!) by cutting the "leaves" into four pieces each and
inserting each into the bare ground. The bulk of them rooted. Within
a couple of years we had more prickly pears than we could eat or sell
at the village auction market.

Franz

"Kay" wrote in message
...
snip
Had Opuntia arrived in Oz as chance seeds in pre-human times, they would
have established more slowly, other things would have evolved around
them. They would not have become the problem that they did.


Not at all, it spread because it was a great environment for it and there
were no natural predators, not because of any specific human program to
deliberately spread it.

Whether they were a 'problem' or not is a human value judgement, the reason
they were regarded as a 'problem' is that it interfered with human
requirements for that land.

--
Tumbleweed

email replies not necessary but to contact use;
tumbleweednews at hotmail dot com

In article , Tumbleweed thisaccountneverr
writes

"Kay" wrote in message
...
snip
Had Opuntia arrived in Oz as chance seeds in pre-human times, they would
have established more slowly, other things would have evolved around
them. They would not have become the problem that they did.


Not at all, it spread because it was a great environment for it and there
were no natural predators, not because of any specific human program to
deliberately spread it.

It was introduced deliberately and therefore in a greater amount than
the odd chance seed. It was introduced as 'fencing', AIUI to control the
introduced rabbits.

I would imagine they introduced it by cuttings, which is the obvious
method of propagation (as Franz has described). An Opuntia seedling is a
delicate thing to begin with, and it would have been a lot slower to
establish ... as demonstrated by the fact that it hadn't managed to
establish itself out of its original continent until we started to help
it along.

--
Kay
"Do not insult the crocodile until you have crossed the river"

"Kay" wrote in message
...
In article , Tumbleweed thisaccountneverr
writes

"Kay" wrote in message
...
snip
Had Opuntia arrived in Oz as chance seeds in pre-human times, they
would
have established more slowly, other things would have evolved around
them. They would not have become the problem that they did.


Not at all, it spread because it was a great environment for it and there
were no natural predators, not because of any specific human program to
deliberately spread it.

It was introduced deliberately and therefore in a greater amount than
the odd chance seed. It was introduced as 'fencing', AIUI to control the
introduced rabbits.

I would imagine they introduced it by cuttings, which is the obvious
method of propagation (as Franz has described). An Opuntia seedling is a
delicate thing to begin with, and it would have been a lot slower to
establish ... as demonstrated by the fact that it hadn't managed to
establish itself out of its original continent until we started to help
it along.


"A lot slower " in the case of opuntia would have meant maybe 5 or 10 years
difference, nothing in the scheme of things.' exponential growth' is what
makes the difference, not people. One seedling or 1,000, give it a few
years and you'd see no effective difference.
hedgehogs in scotland,snakes in guam, snails & miconia in tahiti, all it
took in each case was a very few individuals and a little bit of time. The
latter was introduced as just a few plants about 60 years ago and now covers
something like 2/3 of the land area IIRC.


--
Tumbleweed

email replies not necessary but to contact use;
tumbleweednews at hotmail dot com