Sunday, February 24. 2008
Greg Rubin, a San Diego area landscape designer and contractor, helps people to design their yards so as to be beautiful, use little water, and survive wildfires. Here is a letter that he sent to the California Native Plant Society's San Diego chapter last week. (Used here with his permission.)
What the fires have taught me.
Over the last few months I have experienced a number of epiphanies with regard to fire behavior that run counter to the conventional wisdom and which I would like to share in the hopes of starting a discussion that ultimately leads to a win-win situation for both the chaparral and our homes. There is always so much hysteria that surrounds these events, but I think pragmatic solutions are at hand.
We have landscaped close to 500 homes in San Diego county over the past 10 years, many of which have been in the paths of major wildfires, NONE of which have been lost. Since last October I have personally travelled to numerous developments touched by the Witch, Guejito, and Harris fires. I have taken hundreds of photos, interviewed my customers and other homeowners, and toured with FEMA, who were impressed enough to write an article about our experiences and include natives as part of their best practice recommendations. We have also been involved in the rehabilitation of these same damaged landscapes. Here are some observations:
- Clearing 200, 300 even 400 feet to bare ground around structures often did not save them.
- Many of our customers had scorched native landscapes completely surrounding their intact homes while the neighbors who had cleared were burnt to the ground. Often there was a huge green lawn and palm trees surrounding a pile of rubble.
- The fires had no trouble skipping over hundreds of feet of concrete aprons and highway.
- In one case, a large wooden deck came in contact with the smoldering natives, which did not develop enough heat to even singe the deck. Most of the scorched native landscapes are still alive and rapidly recovering.
- In every case, the native landscapes were receiving light summer overhead irrigation every 10 to 14 days - enough to wet leaves and mulch but not saturate warm soil. This practice appears to keep the plants nicely hydrated without compromising their ecology - more like a summer thunderstorm or fog drip.
- Often the exotics in these landscapes were burnt to ash, while adjacent natives (either planted or voluteer) such as BUCKWHEAT (!) still had green leaves.
- In two cases at the base of Lyons Peak, the Harris fire actually stopped at the edge of the native landscapes and did not encroach, not even into the mulch.
- The shredded redwood mulch has proven to be very fire resistant. The Encinitas fire department ran burn tests in November on the "Gorilla Hair" redwood mulch and wanted to know what kind of fire retardent we had been adding!
As a result of these observations, I have been playing with a number of hypotheses and conclusions:
- The first 100 feet around a structure are still critical; the first 30 feet should be mostly hardscape and watered, low-fuel plantings. DG, gravel, and concrete aprons also seemed very effective; the 30 - 70 foot zone should be lightly irrigated native/drought tolerant plants, mostly lower growing, or native chaparral thinned to 50% coverage with larger shrubs pruned to 6 feet. Paths through this area also help to break up the fuel.
- Beyond 100 feet, however, clearing to bare ground may actually be counterproductive. Removal of more distant vegetation may leave the house completely vunerable to high winds laden with embers (some from miles away), providing nothing to create turbulence that would disturb the flow. Additionally, there would be no cooling effect on the flows due to vegetative moisture. These are hypotheses that need testing. Also, these areas tend to be replaced with dry weeds and grasses that create flashy fuels that are ready to burn again in less than a year. Not to mention the horrific erosion that occurrs in these areas.
- It appears that the more drought tolerant the plants (upland natives being theoretically the most drought tolerant, especially when connected to a mycorrhizal supply of moisture), the more they "hang on" to the meager hydration provided by the occasional light irrigation, and as a result, the plants typically scorch, rather than burn with enough intensity to burn structures. Again, this needs to be tested.
- Houses must be built with the most fire resistant materials available.
- Houses should not be situated right above box canyons, especially at the end of cul-de-sacs. These are good places for open space!
- "Shelter in place" may really work. Many of the homes were saved by those who stayed behind (which I do not advocate for legal reasons). However, there may be something to creating neighborhood fire shelters and training volunteers to put out spot fires. You can never count on there being enough fire fighters to save your house.
So these are the thoughts I have come away with. I can't describe the pride I felt when a client called and said "Rubin, your landscape saved my house, now I want to make it 5 times bigger!". Hopefully we can curb this desire to destroy so much of our native heritage (for no good reason) and start to address the very real issue of fire safety with common sense and success.
California's Own Native Landscape Design, Inc.
And he sent along some photos to corroborate his statements. Click on any link to see a full-sized image. Again, his words:
Here are some of the fire photos. Note the buckwheat has green leaves right next to an incinerated rosemary. Note the wood deck unaffected by the scorched native vegetation. Note the two photos where the fire actually stopped at the edge of the landscape. I think I also added a photo of a burned house surrounded by green grass and palms.
Here is another photo he sent later:
...its a picture from the Witch fire in Ramona. The whole back slope scorched, but it didn't generate enough heat to burn the wood deck at the back of the house! Most of the landscape has come back already.