"Larry Caldwell" wrote in message
...
In article ,
writes:

The "water thief" concept is a bizarre one for me. I understand
removing
invasive non-native species that can dominate riparian zones - tamarisk
for
example - but just whose water is being stolen? Cattle? Irrigators?
And
who had it before cattle and irrigators? Buffalo and jackrabbits? What
is
the water balance between what used to be available to streams and
basins
(i.e. fish) before settlement and now. Is juniper invasive in sage?
It
would seem they'd have very different water requirements.

It's all management, Mike. Fish and sage grouse are having a hard time,
while there is no shortage of juniper or the species that eat juniper
berries. In areas that get less than 15" of rainfall a year, juniper
will exterminate all competing vegetation, including sage.

It's interesting that you mention buffalo, because buffalo kill trees.
The Great Plains are a fossil artifact of the great buffalo herds that
used to kill off all the trees. Now that the buffalo are gone, trees are
encroaching on areas that are not farmed or disturbed. It takes a while
for a seed reservoir to build up, but 500 years from now the Great Plains
will be the Great Central Forest.


The old explanation for the Great American Desert that I recall was wind -
too much evapotranspiration to allow broadleaved trees except in valleys and
on streams but ideal for grass. I wouldn't discount long term effects of
fire, plowing or grazing either. Restoration experts have managed to bring
back small parcels of pre-settlement plant communities just by fencing OUT
the cattle. Pioneer graveyards usually held reservoirs of original plants
that stopped abruptly at the fenceline.
If juniper is advancing is it because of less grazing, less fire, less
management or a change in climate? Succession should follow the usual
rules.