[PCA] Reduce Western fires -- replant the native understory!

Craig Dremann craig at astreet.com
Tue Nov 13 10:12:04 CST 2007


Virgil Dupuis wrote:
> 
> Were not the grass and herbaceous areas maintained by more frequent,
> intentional fires.  Natives in this area likely played a significant role in maintaining the grasslands prior to introduced grazing pressures.

Dear Virgil and All,

The strip of arid shrublands near San Diego that recently burned, is
nearly unique in the world---the only other place that mimics those
environmental conditions,  is the vegetation in the mountains just north
of Salalah, Oman.  

Basically you have a very narrow strip, about 50-100 miles wide, of an
arid coastal plant community, trying to survive at the edge of the
hottest and driest desert in North America, that stretches 1,000 miles
eastward to about the 100th meridian.  

In Oman, the coastal vegetation strip is about 10-20 miles wide, and
then the famous "Empty Quarter" desert stretches 1,000 miles northward. 
You can get a good look at either of them on Google Earth, and they look
surprisingly similar from space.  That vegetation is a surprising
anomaly of the Arabian peninsula, that was protected from 5,500 years of
grazing, because that's where the frankincense groves grow.

Any burning in pre-European times, would have been a zero net effect on
the ecosystem, because you had a 100% mix of native species moving
around, some fire-followers getting a chance to grow in burn areas, etc.
and no groups like all of the bunchgrasses, going extinct on any large
scale.  

After European introduction of sheep, cows, goats and weeds, the whole
mixed has changed.  The native grasses are at a very low or nearly
extinct level, like the changes shown in the picture taken by Dr.
Humphrey at http://www.ecoseeds.com/desertgrass.html

The extermination of the bunchgrasses and native herbaceous perennials
left a lot of open spaces between the shrubs, that have been occupied by
exotic annual grasses and other flammable weeds.  

The conversion of the understory from natives to annual weeds in
low-elevation California has been 90-99% completed, and you can see 
maps of my Vegetation Megatransects at
http://www.ecoseeds.com/megatransect.html

The introduction of annual grasses, that possess five times the fire
biomass or "firepower" of the natives that they've replaced, greatly
increases the heat and spread of any fire that gets started in that
ecosystem. Let's call those the "5X Firepower Exotics" 

You can see the huge difference that the exotics make, by taking one
square foot of any of the annual grasses, and also take one sq. foot of
the native bunchgrasses in summer, and place a sensor of a recording
pyrometer  about 8" above the soil level, and then set the grasses on
fire, like I did about 20 years ago.

Once the extinction of the bunchgrass and herbaceous perennial native
understory has occurred, and the flammable weeds are added in their
place, no amount of fire will "manage" that ecosystem back to health,
and you must convert the weed areas back to the original local native
understory.

The "Back-to-Natives" conversion is done by sowing lots and lots of
seed, at least 100 pounds per acre, and it can't just be a monoculture,
because that's not what was there originally.  You need to resow at
least a dozen or two dozen local species to get it right, and sow them
back in the right proportions, like a cake mix.

An example of a local Open Space Districts in Central California, that
manages 20,000 acres of annual weeds, it is going to cost $5 million a
year for the next 10 years, to do the conversion.  You can read and see
pictures of how thick the "5X Firepower Exotics" like the wild oats are,
and how nice, low-growing (8") and green the bunchgrasses (Purple
Needlegrass) could be (photo taken July), at
http://www.ecoseeds.com/invent.html  

Once the bunchgrasses and perennial herbaceous native start replacing
all the exotic annual grasses and weeds in the San Diego ecosystem, THEN
fire might be one tool that could be used to manage the species
diversity in the future.  

Only until you get all the native species back in place, and get rid of
the "5X Firepower Exotics" species, and get the ecosystem will be back
in balance, then it will be able to bounce back better from fire, and
not cause such hot fires, and not cause so many mud slides after fires,
etc.

Sincerely,  Craig Dremann, Redwood City, CA (650) 325-7333




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