Quote:
Originally Posted by sheepdog 44
Just on this point:
I would say that millennial long Climate change would be the major factor. Over the time span it can turn plains into desserts and back again. However there is a very valid point that animals can have a significant effect between transitions of grassy or scrub land into desserts. I saw a documentary years ago that i can't recall about an invasive mouse like species i believe in australia. They would eat the seeds of the plants and burrow into the ground disrupting the soil. Of course without natural predators things get out of hand. And year after year you get miles of the ecosystem collapsing into desert. Eradicating the animal saw a rebound of the grassy scrubland into its natural range.
Small things like that can have a big impact on emergent species in transition zones. And the difference between zones will dramatically affect water and temperature. Any foriegn thing that does something unatural to the environment can do this, be it livestock or agricultural practices. I doubt killing buffalo contributed to the dustbowl in any meaningful way over the way it was farmed. However even the buffalo had their place in the health of the plains and predators. Also the plains are not a transitional zone into you get far into the west.
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I agree, but especially in the case of the Sahara, animals could not be responsible for the reduction in rainfall over the last 10,000 years. Likewise, neither could fossil fuels. It was caused by a shift in the Earth's axis and exposure to the Sun.