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permaculture - Re: [permaculture] nitrogen fixing trees/shrubs that feed livestock

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Chronological Thread  
  • From: Marimike6@cs.com
  • To: permaculture@lists.ibiblio.org
  • Subject: Re: [permaculture] nitrogen fixing trees/shrubs that feed livestock
  • Date: Wed, 29 Dec 2004 14:16:54 EST

Toby says

>If someone can show me that the arrival of a new species has resulted in
rapid multiple extinctions in an ecosystem that was not already badly
degraded by
humans, I'm happy to change my tune. There are probably cases of this
somewhere, but so far, I'm not finding them.

The problem is that everywhere there has been an isolated island, humans have
gotten there first and themselves been the agent of extinction. Not just
Hawai'i or Madagascar, but North America. A good library on paleontology will
possibly have a book called Pleistocene Extinctions: the Search for a Cause,
edited by Martin and Wright. The thesis has been argued for many decades
since the
1960's, when this early volume came out, but it is apparent that the world
over, major land fauna have disappeared whenever the old paleo hunting
culture
entered the scene. Thus giant ground sloths, uintatherium, sabertooth cats
and
horses departed the American scene nine to eleven thousand years ago, when
Folsom Man came with his refined toolkit and pack-animal tactics for bringing
down
big game.

Interestingly, around 30-35,000 years BP, major ancient species of megafauna
disappeared from Europe the same way, after the spread of the Aurignacian (as
memory serves me) culture. The European hippo and rhino were examples.

So the major invasive species that changes the landscape is us. Was then, is
today.

Still, let's not belittle the contribution of an ordinary snake when
introduced to an island without natural predators, where dull witted birds
make nests
on the ground. Such a snake in the Galapagos or on many other remote Pacific
islands would wipe out a dozen species easily because they are just to dumb
to
get out of the way.

A tourist in the Galapagos today would be in the same position as the sailors
of the 19th century, who could just stoop down and scoop up a duck-sized
booby for the stew pot. They look to be good eating, too. But today,
fortunately
the guides will make you put the bird down again. :)




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