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Very interesting, I'll take another look. However if we take the paper at face value circa 8200BP there was some widespread climate event which is likely what d

by R0b0t1 5y ago

Very interesting, I'll take another look. However if we take the paper at face value circa 8200BP there was some widespread climate event which is likely what drove the change, not people. Why I consider this paper suspect is that the mechanism that drives the modern preservation of the prarie and sometimes its encroachment into existing woodland is well understood. It doesn't require the involvement of people. It does not exist today because the grassland is gone. Lightning during the drier days of fall would lead to grass fires, burning the trees. There were microenvirons near streams that had trees but they were not common.

oska 5y ago
I don't think you can say the paper is 'suspect'. It's primarily factual findings of a pollen analysis. But a criticism you certainly can make is that it's just one study from one geographic location. And that's a very valid criticism and looking back, I am guilty of over-extrapolating from this one single study in one location. > Lightning during the drier days of fall would lead to grass fires, burning the trees. This is one dynamic. There are other dynamics that help (not hinder) the expansion of forests. So again, I don't think the story is so simple. > There were microenvirons near streams that had trees but they were not common. Australia also has microenvirons along water courses where tropical & temperate rainforest species are preserved. Rainforest species are much more resistant to fire as opposed to the very fire-prone (but also fire adaptive) Eucalypt species that are highly dominant across the Australian landscape. But this is a change since the arrival of man, when rainforest and other less fire-prone tree species were much more predominant. In other words, fire-prone but also fire-adaptive trees/forests were 'selected for' by humans in Australia. Trees along streams on the North American Great Plains could also just be remnants of earlier much more wide-spread forests. So you can see that I'm continuing to push the influence of humans in the diminution of forests. In many ways humans are 'the enemy' of forests (with the exception of some rainforest tribes that are highly adapted for forest living). Anyway, it's a very interesting topic and I've appreciated this exchange of views.

by R0b0t1 5y ago

oska 5y ago

I don't think you can say the paper is 'suspect'. It's primarily factual findings of a pollen analysis. But a criticism you certainly can make is that it's just one study from one geographic location. And that's a very valid criticism and looking back, I am guilty of over-extrapolating from this one single study in one location. > Lightning during the drier days of fall would lead to grass fires, burning the trees. This is one dynamic. There are other dynamics that help (not hinder) the expansion of forests. So again, I don't think the story is so simple. > There were microenvirons near streams that had trees but they were not common. Australia also has microenvirons along water courses where tropical & temperate rainforest species are preserved. Rainforest species are much more resistant to fire as opposed to the very fire-prone (but also fire adaptive) Eucalypt species that are highly dominant across the Australian landscape. But this is a change since the arrival of man, when rainforest and other less fire-prone tree species were much more predominant. In other words, fire-prone but also fire-adaptive trees/forests were 'selected for' by humans in Australia. Trees along streams on the North American Great Plains could also just be remnants of earlier much more wide-spread forests. So you can see that I'm continuing to push the influence of humans in the diminution of forests. In many ways humans are 'the enemy' of forests (with the exception of some rainforest tribes that are highly adapted for forest living). Anyway, it's a very interesting topic and I've appreciated this exchange of views.