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This is a continuation of Living With Fire – Part 1: Basic Fire Science, Personal Responsibility And Site Selection. If you havenโt read that post yet, while not absolutely necessary, it is a good primer for the material covered here.
Once a fire-resistant house site has been chosen and ample access planned for, we are ready to begin examining the various zones and sectors of the site and overlay them with best practice recommendations for increasing fire resistance – with a regenerative twist of course. We wonโt cover how to do zone and sector analysis in this post, as this has been written about extensively already (Gaiaโs Garden and The Permaculture City by Toby Hemenway, The Basics of Permaculture Design by Ross Mars, and the Zone and Sector Analysis Blog Post by Deep Green Permaculture are good places to begin if you are unfamiliar with the concept).
Once we have identified the most likely avenues (โsectorsโ) of fire approach, including any seasonally high fire danger areas (i.e. Santa Ana winds), we can overlay our zone maps to get an idea of how often we interact with different areas surrounding the house. The frequency with which we interact with the landscape in each zone surrounding the house and the likelihood of fire advancing through that zone will help guide our decision making when it comes to creating a Regenerative Firescape.
Most fire prevention literature refers to two different buffer zones around a home. The first buffer is from 0 – 30โ away from the house, and the second is from 30 – 100โ away from the house. Each zone comes with different recommendations for management to increase home survivability during a fire.
The 0 – 30โ Buffer Zone is the most critical area for fire and watershed safety. It is where we as individuals can have the greatest impact on our homeโs survivability. The aspects of this zone that can be designed for include:
The largest culprits in the rapid spread of fires are the annual grasses and weeds (like mustard, anise, broom, and thistle). These, when dead, are called โflash fuelsโ, in that they almost instantaneously ignite into 10โ flames, which allows them to spread at an unbelievable rate. This burning grass โfeedsโ the shrubs, which have 5′-30′ flames, and these โfeedโ the trees, which can put up a fire ball 75′ tall and 50’+ wide.
Once the annual weeds have been cleared, the remaining plants and their assemblage can be assessed for fire resistance. Most firescaping instructions give blanket recommendations regarding the spacing and assemblage of plants within the 0 – 30โ Buffer Zone. Instructions from fire management agencies often look like this:
Our regenerative spidey senses should be tingling hereโฆ
…what about all that BARE GROUND?! Especially on steep, erosion-prone slopes?!
While effective at slowing the advance of a fire and limiting convective and radiative heat gain, leaving this much bare ground will guarantee us three things: (1) that Nature will constantly be trying to fill those gaps between deeper rooted perennial plants with the fast-growing weedy annuals that you just removed- the kind that turn brown and crisp by the end of Spring and have a high propensity to ignite and carry a ground fire rapidly towards a home or neighborhood, (2) requiring you to be forever stuck on the weeding- or mowing-go-round, and that (3) year after year that fragile soil will be left unprotected from winter rains, leading to major erosion problems.
Simply keeping the buffer zone barren or mowed is highly energy intensive, not to mention not the aesthetics will suffer. Somehow we need to marry the dual imperatives of fire resistance and erosion/weed prevention. This is where creation of a closed canopy and use of groundcover, both utilizing fire-resistant plants that are regularly maintained and watered, and the use of mulch comes into play.
Creating a closed canopy simply means that we plant fire-resistant shrubs and trees in areas of barren soil, and prune and maintain existing shrubs and trees around the home to eventually nearly touch each other at mature size, creating a buffer for the soil from sun and rain. Think of a plant shaped like an umbrella (single trunk, large horizontally expanding canopy). We want to avoid whenever possible having bare soil (and all of those dormant weed seeds contained on itsโ surface) subjected to the cycle of relentless sun followed by the unabated pounding of rain drops. Having a vegetated โumbrellaโ overhead is very effective at shading out weedy annuals and reducing rain droplet energy prior to it reaching the soil. Additionally, most perennials capable of forming such a canopy will have much deeper root systems than annual grasses, enabling them to survive Californiaโs long dry season as well as helping to stabilize loose hillside soils. From a weed and erosion control perspective, this makes perfect sense.
So how do we go about maximizing closed canopy while simultaneously ensuring that we are maximizing fire resistance? It all comes down to how we interact with the environment.
To maximize fire resistance we want to:
We can improve the fire resistance of the landscape around our homes by shaping trees and bushes to decrease their susceptibility to fire, selectively removing them where they are too dense, and regularly removing dead plant material from the canopy and the base of the trunks. There will still be holes in the canopy, however, so we must bring in another ally; Fire Resistant Groundcover.
We should employ groundcover (either plants or mulch) to fill in the gaps between closed canopies, thereby ensuring we cover all bare ground with either a vegetative umbrella (canopy) or carpet (groundcover). Using groundcover plants or mulch (such as leaves and decomposed or shredded woody material) might at first seem to make it easy for fire to advance underneath the canopy towards a home, and, again, in the cases where the ground is covered with weedy annuals or low-growing, high oil content plants, this would be true. However, properly selected ground-cover plant species are highly resistant to fire, and mulch does burn, but creeps along with a smoldering fire that will rarely ignite plants that donโt have low-lying branches or leaves and can be easily kicked or raked out. This type of mulch burns with a lot of smoke and little flame- typically 1-2 inches in high winds. If there are no winds, they typically will not even have visible flames, just smoke. Mulch is an especially important component of California’s gardens/landscapes and ecology, as the moisture that mulch retains helps keep the plant material hydrated and a little less flammable.
When choosing groundcover plants, selecting appropriate species becomes especially important. Fire-resistant groundcover plants should be low growing (12-18โ high), remain green through the dry season, have relatively high moisture content and have relatively low water needs in addition to exhibiting the more general Fire-Safe Plant characteristics listed below.
By planting fire-resistant groundcover plants and/or spreading mulch underneath the canopy gaps, we get the soil-protective effect of a truly closed canopy while also mitigating the risk of fire crowning near the home. By employing this patchwork of varied canopy heights and fire-resistant groundcovers we also gain an additional fire-preventive element – weโve just created an ember trap.
Houses routinely catch fire far ahead of the main fire front due to embers that have been drawn up by hot updrafts, which are then scattered downwind.
Embers that have been drawn into the air by hot updrafts and are then scattered downwind are the main cause of home destruction during wildfires. These embers are often very small (can be less ยผโ), can precede the fire front for several miles, and can:
By creating impediments with intelligently selected and placed vegetation we can create barriers to embers advancing towards a home, and ideally prevent them from ever making contact with it in the first place. Ember traps halt the advance of embers (also known as firebrands) towards a home in two ways; by direct impedance and by creating small low pressure pockets on the leeward side of trees and bushes that allow airborne embers to drop to the ground. An excellent visual by a junior scientist illustrating how ember traps work is linked below.
And here is another excellent video detailing how embers are an even greater danger to homes than the more visually frightening “wall of fire”.
An incomplete list of fire-resistant trees, shrubs, and groundcovers for California climates is provided in Appendix A. Generally, in California at least, unwatered native plants are more fire resistant than watered non-native plants. Another great resource is the Leaf Burn Times article on the Las Pilitas Nursery website. In general, fire-resistant plants have the following characteristics:
Fire-resistant plants SHOULD NOT:
The oft-seen and mandated firebreak is largely ineffectual against airborne embers and cannot be depended upon to save a home. Denuding landscapes around dwellings in hopes of creating a fire break is not only ecologically damaging and unsightly, its less effective at actually reducing fire-risk than having well-designed firescaping with fire-resistant shrubs and trees, as explained in the video below. Large expanses of open ground turn into bowling alleys for wind driven embers that will keep moving until they hit something solid – and that is usually the house that accompanies the fire break. Firebreaks very close to the home in conjunction with ember traps, radiation shields (more on this below), and other fire-resistant landscaping elements can help to create areas of decreased fire intensity allowing for safe operation by fire personnel or homeowners.
Firebreaks are a way of decreasing fire intensity and will most likely not stop a fire and cannot be counted on to do so. They can, however, provide a safe evacuation avenues and space to operate around a home during a fire.
Firebreaks can be formed by roads, marshes, ponds, river areas, summer green vegetation, sappy plant crops in hedgerows (opuntia, for example). A horizontal firebreak (i.e. a bare strip of ground, roadway, line of sappy, green trees) reduces fire front energy, while a vertical firebreak (removal of lower branches, dead materials at base of tree, planting of sappy groundcover under canopies) prevents crowning in trees. If feasible, pairing a firebreak with a radiation shield, described below, makes the firebreak easier to operate in for firefighters.
It should be noted that no firebreak is effective in firestorms/fire tornadoes – firestorms can drop material up to 20 miles downwind.
Radiation shields are objects that reflect or harmlessly absorb the radiant heat from the fire front. Radiant heat is the type of heat that can quickly kills plant and animals. These are particularly helpful when used to protect machinery that needs to operate during the fire (water pumps, vehicles).
Radiant heat shielding can be performed by a variety of things, including houses, stone walls, thick tree trunks, hollows or caves, hedgerows and car bodies, brick walls, earth mounds, and densely-planted, sappy, high-moisture shrubs and trees (such as ceanothus). White paint on houses and walls further reduces radiation absorption. Fire-proof or slow to burn insulation in houses (such as mineral wool, seagrass, sawdust, feather, wool) all keep interiors cool and assist fire control.
Fire shadows taper to a point at 4-5 times the height and width of the radiation shield, as illustrated in an image taken from the Permaculture Designerโs Manual below – so make sure the shield extends well past the edges of the structure needing protection.
These radiation shields, like all of the other elements discussed thus far, can be selected and placed using permaculture design approaches to serve multiple functions. For example, a radiant shield formed using a ceanothus hedge can also double as a privacy screen, windbreak, and wildlife-attractant (birds, etc). A radiant shield formed from a densely planted edible food hedge (โfedgeโ) can provide an array of food to the homeowner. A series of rocks can form a thermal mass to moderate the nearby temperature for plantings.
The 30โ – 100โ Buffer Zone requires less intensive management than the most critical 0โ – 30โ Buffer Zone, but still can play a huge part in the survivability of a home. In the 30 – 100โ Buffer Zone we look to…
The 30 – 100โ Buffer Zone generally puts us into Zones 2 and 3, possibly even 4, using the permaculture zonation concept. As we move progressively further from the home, elements tend to require less attention and have the potential to be larger than those closer in to the home.
Larger earthwork systems can be very effective at increasing fire survivability, not just for the home but also for other more vulnerable elements (orchards, gardens etc). While earthworking can range greatly in size, and indeed can be applied in many forms in Zones 1 and 2, here we will consider some larger installations that are typically found at the outer edges of Zone 2 and beyond.
Earthworks for fire resistance can include:
If we wish to use a pool or other water body as a fire suppression reservoir and wish to do better than hauling out water by the bucket, it behooves us to have a gas or propane-powered water pump (needs to be grid independent), high-pressure fire hose, an adjustable fire suppression nozzle, and protection for the operator (eye protection, respirator, heat resistant clothing). Staying at home to suppress flare ups and preserve structures is a risky decision dependent upon entirely too many factors to make a blanket recommendation for. However, if this option is on the table, it pays to be prepared with the right equipment and a very clear plan – as well as a crystal clear way to make the โDo I stay or do I go?โ decision.
Itโs worth noting that if a WEEDS-style Fire Sprinkler system is installed (described further in Part 3), along with the other appropriate fire-resistant elements detailed in this post, there isnโt a whole lot of additional benefit we can add by remaining on-site with a hose, short of protecting landscaping and outbuildings.
Home orchards make excellent ember traps provided the tree spacings are offset from one row to the next (i.e. if you have an unobstructed view all the way to the other side of your orchard, you donโt have an ember trap, you have a wind tunnel!). They can be irrigated to increase moisture and decrease the intensity of an advancing fire front. Fruit and nut bearing trees are typically quite sappy and have high moisture content. Though they may be damaged or killed in the fire, orchards can provide a tremendous boost to home survivability.
Fires can eliminate the canopies of landscapes that were not designed and tended well, burn off leaf litter, and expose the soil. When there is nothing to slow or stop them, wind and water gain leverage – and soil gets shoved around as a consequence. According to Douglas Kent, author of Firescaping, the chances of erosion can grow to 200% after a fire in urban and suburban areas. With this erosion comes mass sedimentation and alteration of stream beds, as well as damage to property and infrastructure. In some cases, this leads even to injury and death.
In addition to the removal of protective cover, the soil in landscapes immediately after a fire exhibit water repellency. Fires cook the waxes that are natural to our soils which, once cooled, coat the first inch of soil with a repellency layer, stopping water from infiltrating.
The combined result of the lack of protective cover and water repellency following a fire can be incredible amounts of runoff and debris flow following a fire. This runoff and debris can overwhelm stormwater drainage systems, leading to extensive erosion elsewhere. Worse still, debris flowing downslopes can overrun homes, businesses, and small communities.
According to Kent, immediate first aid on the landscape is needed after a fire has passed in order to reduce the chances of severe and costly erosion. He recommends the following six steps:
After immediate first aid has been completed, we need to look to revegetate the landscape with desirable, fire-resistant plants and provide further protection of vulnerable hillsides from erosive processes during the coming rainy season. Planting deeper rooted woody plants to stabilize a hillside, while the preferred method, will take several years to become effective – a fast growing herbaceous groundcover is often needed to fill the gap until such plants are established or regrown.
Below is a list of some methods, common and uncommon, to help stabilize denuded soil quickly.
Generally speaking, non-woody groundcovers have an effective root depth of less than 3โ (โshallow-rootedโ). Shallow-rooted plants should not be used as permanent cover on steep slopes unless they are interplanted amongst taller shrubs and small trees. On fill slopes in particular, interplanting in this fashion is necessary to create stability.
Woody groundcover plants generally have slightly deeper root systems (between 3-6โ) and can be used amongst taller shrubs and trees. Plants with roots in the 6 – 15โ depth range include many of the woodland shrubs that make up the chaparral community. These plants are very drought-tolerant and ideal for stabilizing slopes over the long term. However, they will need to be regularly maintained to keep fuel volumes low and create a closed canopy effect without ladder fuel build up.
After the fire, once life and property are safe, it is valuable to reflect on the experience and the lessons learned from it.
Our society currently has an unhealthy relationship with fire and its place in the natural world. Much needs to change regarding how we live our lives, plan our dwellings and make land management decisions if we are to learn to live in relative harmony with this ever- present force of nature.
Should you experience fire up close and personal, take some time to sift through the experience once the adrenaline has settled. Write your insights down. This will not only be valuable information for you and your kin, but should you decide to share it with a larger audience you can help erode the dominant paradigm that pits human settlement in a never-ending struggle with fire, and hopefully build a regenerative fire paradigm in its place that accepts fire as a part of living in this landscape and harmonizes with its inevitable occurrence.
Continue on to Living with Fire – Part 3: Home Construction and Retrofitting for Fire Survivability.
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