[permaculture] Ecosystem Diversity & Bio-mass: Prairies vs. Forests
mpludwig at facstaff.wisc.edu
Mon Jul 8 17:09:11 EDT 2002
This was very interesting, I'll only comment on these bits...
>I believe the trees and woodlands were kept in check by the bison more
Doubtful. If the northern plains are any indication the natives relied on
fire to keep woody plants down and attract grazing animals. A hot fire
will totally top kill woody plants while grazers do very limited pruning by
comparison. Conversely many woody plants regenerate by seed germination
very aggressively after fire. One oak woods we burned years ago came up
thick in new oak trees the falling spring. very striking.
>Improper grazing, burning and mechanically clearing juniper and mesquite
>are probably what are provoking them out of their original habitats -
>which were considerable.
Disturbance = germination. That I can see.
> I would also conjecture that humus rich soils, several feet deep broke
> down plant litter rapidly and that even when lightning struck, fires were
> much harder to get going than today because the land is now so much more
> brittle and tender than it was 500 years ago.
Keep in mind that there were hardly any earth worms in NA at the time of
European settlement. The duff layer may have had more staying power rather
than less. My experience is that areas that do not get burned frequently
have very hot fires when they do burn as the years of accumulated fuel are
there to support strong fires. Grazing animals could limit this
considerably of course.
>It may be that there were vast treeless expanses in the Great Central
>Plains or Prairies but I believe that such treeless-ness ends at the line
>between the Texas High Plains and Rolling Plains. One of Texas largest
>contiguous forests is reported to have been in the Rolling Plains. Even
>supposed desert bioregions such as the Trans Pecos are famous for dwarf
I suspect it was much like the rest of the central plains, mostly in grass
with localized climates like the gulf coast or riparian areas providing the
moisture needed for trees. Around here you can read the soil type at
120kph by looking at the vegetation.
Mark P. Ludwig
Poultry Research Lab
University of Wisconsin -Madison
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