permaculture

[Heide Hermary <heidehermary@pacificcoast.net>]

Interesting.
I wonder, though, if this is due to the trees being cleared, or the 
large scale artificial irrigation and use of chemical fertilizers, or 
maybe a combination of both.  I always cringe at simplistic explations 
that "blame" just one out of many changed variables for the failure of a 
system.  Permaculture is all about understanding systems and 
relationships. It's all too easy to jump to conclusions...
Heide

permed@nor.com.au wrote:

> > I have been surprised to read references from Australia blaming the 
> > ABSENCE of trees for RAISED ground water levels, because all other 
> > references accredit the PRESENCE of trees with raising the water level. 
> > I can't pretend to understand the mechanics of either of these 
> > assumptions, at least that's what I believe they are.
>
> This  phenomena is associated with soil salting in inland areas of 
> Australia. Previous open forest maintained the groundwater levels and 
> more importantly maintained a freshwater layer in the upper ground water. 
> Many of these areas were once part of a large inland sea and the lower 
> groundwaters are quite saline.  The forest facilitated the infiltration 
> of fresh rainwater and through transpiration kept water levels down in 
> the flat areas. With the trees cleared groundwater levels under the low 
> rolling hills has dropped and on the flatlands the ground water levels 
> have risen bringing saline water to the surface. Difficult to explain in 
> a nutshell without diagrams but hope this short explanation has helped.
> Robyn
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