Re: Eucalyptus Questions

Hello Cali,
I can partially answer this question regarding Itlaian
Cypress.  These trees are so efficient a capturing
rainfall that they tend to create rain shadows within
their drip line, funneling most light rainfall amounts
directly to their own roots.  It then becomes very
difficult to grow smaller shrubs/perennials at their
base, because they aren't even getting water from the
natural rains, as they would if planted further away. 
This effect can also be noticeable below many other
types of evergreen trees.

I'd suggest that a partial solution would be to locate
plants that require drier winter conditions to do well
in a mediterannean climate in these locations, and
kill two birds with one stone!




--- Cali Doxiadis <cali.doxiadis@verizon.net> wrote:
> I'd like to pose the same question in reference to
> cypresses.  Since they don't
> have a canopy the same answer probably doesn't
> apply.  What is it about them
> that discourages surrounding growth?
> Cali Doxiadis
> 
> Margaret Moir wrote:
> 
> > ----- Original Message -----
> > From: Glenn Breayley <valhalla@iafrica.com>
> > To: medit-plants <medit-plants@ucdavis.edu>
> > Sent: Wednesday, March 14, 2001 3:42 PM
> > Subject: Eucalyptus Questions
> >
> > > While on the subject, does anyone have the
> answers to the following
> > > questions.
> > >
> > > 1/ Are Eucalyptus leaves & compost truly
> poisonous to underfloor plants ?
> > > Might not their bare floor areas rather be due
> to their superior water
> > > robbing capabilities. ?
> > >
> > > 2/ Does anyone have any knowledge of the Jarrah
> ( E. marginata ) being
> > grown
> > > commercially outside of Australia ? Being one of
> the worlds greatest &
> > most
> > > durable of timbers I was wondering if it has
> commercial possibilities.
> > >
> > > Regards
> > >
> > > Glenn Breayley. Ragnarok & Valhalla Research.
> > > POBox 26158, Hout Bay, 7872, Capetown, South
> Africa
> > > Ph/Fax SA 021 7904253 E-mail
> valhalla@iafrica.com
> > > Wholesale nurseryman & Tillandsia specialist
> wholesale & retail grower.
> > >
> > Glenn, I don't believe the leaves themselves, once
> parted company with the
> > tree, have any toxic properties at all. In common
> with many other species
> > many of them are allelopathic, and the canopies
> may also have a "toxic
> > drip"........rain leaches a chemical from the
> canopy that is a growth
> > retardant to other plants. This is not universal
> with all eucalypts, mostly
> > just the ones that have to be super-competitive in
> their own environments.
> > Your surmise, that like a lot of trees they drink
> a lot of water and
> > out-compete other plants is frequently the case
> when no allelopathy is
> > present.
> > The WA Jarrah/ Marri/ Karri forests are the
> overstorey for thousands if not
> > millions of plants, growing densely underneath the
> trees, no toxins there.
> > But once a tree is mature, it is almost impossible
> to get things back in the
> > understorey if it has been lost thro' grazing or
> whatever. However a fire
> > will release nutrients trapped in the humus and
> leaves and provide an
> > ash-bed that the re-generating plants can
> germinate in.
> >
> > The reason the leaves are resistant to being
> composted is because they're
> > sclerophyllous and have a very hard waxy coating
> to make them resistant to
> > transpiration. If the leaves are chopped up, such
> as through mowing or a
> > mulching machine they break down much more
> quickly. In combination with a
> > high nitrogen plant matter such as lawn clippings,
> they can make a great
> > mulch/compost. Eventually, even if entire, they
> will crumble to a superb
> > leaf mould but in the natural environment this is
> much hastened by fungal
> > associations.
> >
> > Jarrah? It's never been attempted as forestry
> plantings......the tree is
> > much too slow growing to interest any foresters.
> Probably about [this is
> > just a rough guess] 200 years old before millable.
> > Margaret.
> > Margaret River
> > Western Australia.
> 


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