Re: MGS/ Ran Pauker lecture in Berkeley

In a message dated 11/12/100 11:06:01 PM EST, davidfeix@yahoo.com writes:

<< It is interesting
 to note that several evergreen trees here in Northern
 California tend to catch and increase precipitation
 below them. >>

I've also noticed that many native oaks, in particular the more-or-less 
deciduous Valley Oak (Quercus lobata) and Blue Oak (Q. Douglasii), in 
oak-savannah habitat, often have a patch of green underfoot that mirrors the 
drip-line, when all the grasses and forbs for miles around have assumed the 
gold of summer or gray of autumn.  Whether this is an effect of catching and 
increasing precipitation, or (as I suspect) a result of protection from the 
effects of the scorching sun, remains to be seen.  Providing some shade, 
particularly during the hottest months, can really make the difference for a 
lot of plants in our climate.  I've even noticed this "shade effect" on my 
own lawn.

<<Reading between the lines, if you are
using summer spray irrigation over thick mulches, and
allow them to dry out before the next irrigation, up
to the first inch of water may never reach the
plants...>>

This is particularly true if you are mulching with peat moss (often 
recommended for azaleas and other acid-lovers), which is very difficult to 
wet, once it has dried out.

<<It was amazing to me to hear that turf grasses could
be maintained in 40C temps in summer with only monthly
irrigation.>>

Amazing to me, too.  Here in the Central Valley of California, I would be 
willing to bet that there is virtually NO lawn, including one of Bermuda or 
St. Augustine grass, that could be maintained with only monthly irrigation.  
Kept alive, perhaps, but not attractive.  Lawns here are generally maintained 
in summer with a ONCE OR EVEN TWICE DAILY irrigation regime.  You can get by 
with every other day, or even skip two days every once in a while, but the 
appearance of your lawn will suffer as a result.  At the University of the 
Pacific here in Stockton, they get by with flood irrigating a large lawn area 
in the 'quad' once a week, but it is shaded by large trees, and they probably 
give it three inches of water a week in the hottest part of the summer.  I 
have tiny lawn areas in my front and back garden, but they really suffer if 
they are not watered every day during the hottest part of the summer.  There 
is a lot to be said for paving such areas in our climate...

<>

Many California natives, particularly those in the Central Valley, although 
they apparently survive on rainfall alone, are actually very dependent upon 
the snowmelt runoff from the Sierra Nevada, which once provided a sort of 
natural irrigation during the dry months of the year in the form of a high 
water table and seasonal flooding.  Now that most of this water is being 
siphoned off for human use, many once-widespread habitats and the plants they 
supported are in danger of extinction.  Valley Oak riparian forest, in 
particular, is down to about 1% of its former range.

<>

I think that's pretty close to San Diego, which gets around 11 inches per 
year.

Sorry I missed the lecture and meeting.  Sounds like it was interesting and 
informative.  As I get older, I find myself less and less inclined to spend 
my few remaining hours watering the garden...

Kurt Mize
Stockton, California
USDA Zone 9
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