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"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 |
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"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 |
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