Re: Fire Safety

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Interesting.... After the 2003 and 2007 fires here in the San Diego area, I drove through burned areas looking to see patterns.  What I saw was no pattern.  We don't have redwoods here and our oak population is very small.  Where I did see large trees, they were mostly singed below and hanging on on top.  Any lower growing vegetation, succulent or not, was totally destroyed.  Ice plant, one of the plants that people swear is fire resistant, was dust alongside everything else.

This is why I am interested in seeing testing done.  I suspect that climactic conditions, soil hydrology, recent rainfall, irrigation  patterns, and many other factors play a very large role in plant flammability.  Telling people that plant x or plant y is fire resistant is risky.  Though observations like yours are critical starting points, There are no guarantees.  Correlation is not causation, we really need as a society, to make the investment and figure out which plants fare better though fire, which slow the fire path, and under what conditions.

As I understand it, University of California at Riverside (about 2 hrs east of Los Angeles and north of San Diego) has a fire lab capable of supporting this kind of work but no one has taken on such a project. 

Any researchers out there interested?

Nan

On Mar 12, 2011, at 12:33 PM, david feix wrote:

Nan,

Observation in the field doesn't lie...  The trees that survived the Oakland
Hills Fire were those that didn't immediately go up in flames when the wall of
fire rolled over them.  Driving all around the Oakland Hills fire zone, which
destroyed over 500 homes, it is a consistent fact that the few landscape trees
that survived the fire were almost always Coast Live Oaks and Coast Redwoods.  I
would in fact expect this to be the case, as both these tree species are adapted
to fires, and have developed the thicker bark and less flammable foliage(in the
case of oaks), as a response to fire.  The fact that the Coast Live Oaks and
Coast Redwoods were primarily only singed and may have had some bark killed on
the down slope sides of horizontal branches is immediate and obvious
confirmation that these tree's foliage and bark is slower to burn than many of
the other ornamentals in the landscape.  


As to the more general suggestion that plants with less woody mass and more
water retentive succulent foliage are slower to burn is also intuitive, but
these sorts of plants obviously do still burn and did not generally survive the
fire in the Oakland Hills conflagration.  What they did do, was to slow down
the  fire progress because they had less fuel load to spread the fire further,
essentially slowing down the spread of the fire.  Even if they in fact did not
burn any less slowly because of the intense heat, they didn't tend to spread the
fire further with fuel that would blow in the intense winds and carry it to
places further away such as larger woody trees and shrubs such as the Pines and
Eucalyptus and trees with volatile oils.

If you need scientific field tested data to make the sort of conclusions I made
here, I can't help you.  My thoughts on this have more to do with close
observation of actual circumstances in the field, and I stand by my conclusions
as they relate to how I promote more fire safe gardens for locations in the
hills at greater risk of urban forest fires.  Of course, the bigger issue is
people still fail to realize that any tree planted within 30 feet of a house on
a hill increases the fire risk, and that all trees should be regularly pruned
and thinned to reduce fuel loads.  As I drive through the Oakland Hills these
days almost 20 years after the fire, I can observe that very few people have
taken these concerns to heart.  Even the newer rebuilt homes landscaping often
has big trees left unpruned too close to structures, with no attempt to create
defensible space around buildings, especially on the downslope side.  I
generally advise any new client in the hills to more seriously consider fire
safety as more important than aesthetic issues, period.  When they are unwilling
or unable to remove/thin trees, at the very least I make damn sure the new
plantings don't increase the fire risk, but minimize it.



----- Original Message ----
From: Nan Sterman <T*@PlantSoup.Com>
To: david feix <d*@yahoo.com>
Cc: Medit-Plants listserv <m*@ucdavis.edu>
Sent: Sat, March 12, 2011 12:00:33 PM
Subject: Re: More garden photos:Medit plants for a California hillside garden

Wow David, another wonderful garden!

I am curious about your statement regarding slow burning plants.  From all the
research I've done, there have been  no studies nor documentation of
flammability of plants, native or otherwise, in California.  All the
organizations and individuals I spoke with said they'd gotten their lists of
"fire resistant" plants from someone else who, when I contacted them, said it
was from someone else, and so on.  Finally, one of the botanic gardens told me
that years ago, a volunteer took leaves home and put them in his oven - then
based their list on that.  Fire departments told me it was based on firemen's
observations in the field, but of course the conditions vary so much from fire
to fire and region to region, that those observations make a good starting point
but don't tell you anything about predicting flammability.

So  Im very curious to know what resources did you use to base your selections
in terms of fire resistance.

Nan