"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

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