Living with Fire – Part 2 Regenerative Firescaping – Protecting Your Home With Good Design

This is a continuation of Living With Fire – Part 1: Basic Fire Science, Personal Responsibility And Site Selection. If you haven’t 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 won’t cover how to do zone and sector analysis in this post, as this has been written about extensively already (Gaia’s 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 (“sectors”) 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 – 30’ away from the house, and the second is from 30 – 100’ away from the house. Each zone comes with different recommendations for management to increase home survivability during a fire.

0 – 30’ Buffer Zone

The 0 – 30’ 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 home’s survivability. The aspects of this zone that can be designed for include:

• Removal of highly flammable landscaping (annual weeds, select perennial species).
• Installation of non-flammable landscaping – lawns and meadows, border plantings, flower gardens and structures such as pools, concrete decks and recreation areas help reduce fire hazards close to home.
• Installation of landscape plants with high fire resistance (in California, typically the native plants), along with proper design for assemblage and spacing. 
• All leaves removed from rain gutters, pipes, drainage devices and roof at beginning of fire season (this translates to nearly year round maintenance in California).
• Regular maintenance of landscaping plants.
  • Periodic overhead watering of native, drought-tolerant plants in drought-prone areas, or regular watering of non-native or non-drought tolerant plants.Regular pruning to reduce fuel loads and eliminate ladder fuels.
    • Specifically, identify and remove 1) dead plant material (branches, leaves) still retained in the canopy and 2) piles of dead, dry plant material at the base of the tree or shrub that would allow a ground fire to climb into the canopy.
• Particularly flammable trees not planted within 30’ of home (this can vary dependent upon crown size of the tree at maturity).
  • If trees are planted immediately adjacent to home (potentially advantageous in regards to home site temperature and wind speed moderation, but does increase fire risk to some degree) try to limit branches overhanging the home. Make doubly sure to eliminate any dead branches in the canopy. Be extra attentive to keeping gutters and roof valleys cleared of leaf and twig build up in these areas.
    • Can run an extension line from an outdoor WEEDS Fire Sprinkler System (more on this system below) to a broad, flat spray radius sprinkler anchored high in the canopy. Assuming you’ve maintained a clear understory and sub canopy, this sprinkler can wet the tree canopy from the inside out, which will create an excellent ember trap and radiation shield (more on those below, too) as well as saturating the drip line of the tree, part of which may overhang the house.

Fire-Resistant Landscaping Principles

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 “flash fuels”, in that they almost instantaneously ignite into 10’ flames, which allows them to spread at an unbelievable rate. This burning grass “feeds” the shrubs, which have 5′-30′ flames, and these “feed” 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 – 30’ Buffer Zone. Instructions from fire management agencies often look like this:

Our regenerative spidey senses should be tingling here…

…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 Using Fire-Resistant Trees and Shrubs

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 its’ surface) subjected to the cycle of relentless sun followed by the unabated pounding of rain drops. Having a vegetated “umbrella” 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 California’s 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:

• Plant shrub or tree species that are fire resistant (more on that below).
• Keep the understory of trees and shrubs clear of any ladder fuels (dead, dry plant material at the base of the trunk(s) that will allow ground fire to easily climb into the canopy). 
• Keep the ground surrounding the trunk(s) clear of dead, dry plant materials (limit fire’s ability to even approach the trunk in the first place.
• Plant trees and shrubs close, to maximize shade and coverage, but not so close that at mature size their crowns contact one another (should the fire get into the crown, you don’t want it to be able to spread easily to the next tree or shrub canopy).

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.

Filling in the Gaps with 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 don’t 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 (12-18” 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 – we’ve just created an ember trap.

Ember Traps

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 ¼”), can precede the fire front for several miles, and can:

• Catch under open eaves
• Lodge under loose or curved shingles
• Accumulate at the base of the structure
• Enter attic vents
• Enter window and door seams
• Catch in nooks and crannies
• Ignite materials near the structure (no woodpiles against the house!)

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”.

Fire Resistant Plant Selection

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:

• Have easily distinguished dead vs. living material.
• Require only minimal bending over or ladder work to maintain.
• Have an open, accessible growth habit to allow easy pruning without damaging the plant.
• Have a slow to moderate growth pattern to minimize the frequency of maintenance.
• Have a robust root system to prevent erosion (ideally 6’ or deeper).
• Be long lived.
• Have ample enough branching/leafing material to provide direct impedance barrier to rain, thus reducing rain’s impact on uncovered soil.
• Re-sprout / grow from the crown following a fire to help reduce re-vegetation costs.
• Have long leaf burn times

Fire-resistant plants SHOULD NOT:

• Have thorns (for ease of maintenance, by you or fire personnel).
• Retain dead leaves within the canopy.
• Have small leaves that stay on the plant once dessicated or dead (sages, buckwheat, chamise).
• Accumulate dead parts difficult to isolate (many ice plants, rabbit bush).
• Produce large amounts of hanging or dropping leaf litter (fan palms, pines, Eucalyptus).

Firebreaks

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

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 Designer’s 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 (“fedge”) 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.

30 – 100’ Buffer Zone

The 30’ – 100’ Buffer Zone requires less intensive management than the most critical 0’ – 30’ Buffer Zone, but still can play a huge part in the survivability of a home. In the 30 – 100’ Buffer Zone we look to…

• Perform annual fuels reduction and pruning to reduce vegetation volume. Pay special attention to ground fuels that will allow fire to advance towards a structure.
• Plant long-lived, slow-growing, fire-resistant perennials to cover exposed, bare soil or at minimum cover bare ground prior to rainy season (mulch, jute etc). This is especially important on hillsides.
• Eliminate weed fuels without creating conditions that favor their dominance (i.e. encourage deep rooted perennials that meet the Fire-Safe Criteria).
• Prune trees up 6 – 10’ from the ground. Thin accordingly to create breaks in the canopy. Underplant canopy breaks with low-growing fire-resistant perennial groundcovers.
  • Most mainstream fire prevention literature will insist upon 30’ breaks between clumps of trees. Depending on what type of tree, how flammable it is, how high the intra-canopy fuel load is, etc., this number can be reduced quite significantly to create a more contiguous forested landscape.

The 30 – 100’ 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.

Earthworks

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:

• Swales – can be flooded pre-fire, help saturate ground and increase moisture content of associated plantings, and can be used to establish planted fire shields of sappy trees and plants that will slow fire’s advance towards a structure.
• Earth berms – often installed to create wind protection or as effective sound barriers, also make excellent radiation shields. They can be planted with sappy, high-moisture content plants, groundcovers and evergreen trees to create additional ember traps and heat shielding.
• Ponds and pools (natural pools, ideally!)- large bodies of water surrounded by high-moisture content vegetation make excellent firebreaks and can be used as a reservoir to keep surrounding vegetation and structures wet.

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 “Do I stay or do I go?” decision. 

It’s 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 isn’t a whole lot of additional benefit we can add by remaining on-site with a hose, short of protecting landscaping and outbuildings.

Orchards

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 don’t 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.

After a Fire

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.

Immediate First Aid

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:

1. Drain Water – Drainage systems will be clogged with debris after a fire. Water skipping out of drains, such as culverts, is a leading cause of erosion, fire or not. Roof gutters, street gutters, culverts, swales, infiltration and detention basins, small streams, and concrete waterways will need cleaning. This is the very first thing to do.
2. Divert Sheeting Water – The chances of topsoil loss dramatically rise if a landscape receives sheeting water from nearby features. Driveways, roadways, sidewalks, and parking lots are often designed to sheet their runoff to the landscape. If this is the case on your property, divert that runoff away from your landscape and toward the storm-drain system. Sand bags, diversion ditches, staked boards, dry-stacked walls, and bales are the most common diversion devices. Plastic sheeting anchored with sandbags on ropes at top of hill can also be used to protect extremely sensitive areas.  Don’t anchor plastic with rocks (sharp edges will cut through plastic with wind whip) or stakes (wind whip will create larger and larger holes).
3. Minimize Traffic – Keep foot and equipment traffic off burnt landscapes. Activity on slopes will increase the likelihood of erosion by weakening a soil’s bonds, dislodging soil particles, and trampling newly sprouted plants. Activity on flat ground can compact the soil and lower its water-absorption rate, which increases runoff. Instead, plan on working on an injured landscape only after a plan of restoration has been developed and all the materials and tools are ready for use.
4. Watering – A recently burned landscape absolutely needs water, but there are two distinct types: The first watering is aimed at breaking the soil’s repellency layer. This watering is superlight—no more than 1 gallon per 10 square feet. The goal is to water only the top quarter-inch of soil. Once the repellency layer is broken, deeper waterings should begin. The goal is to get the water 4 inches deep and encourage seeds, roots, and surviving plants to sprout. Three to 5 gallons of water per 10 square feet is required. Water again only when the first 2 inches have dried.
5. Leave the Debris – Do not clean your landscape—the debris on your injured site provides much-needed protection. The charred remains of plants and garden features protect the landscape from wind and water erosion, slow sheeting water, and help prevent the surviving seeds and plants from drying out. Do not remove debris until a restoration plan has been developed.
6. Encourage Weeds – Any plant that sprouts after a fire should be encouraged. These plants are reducing the chances of topsoil loss. Weeds, or any unwanted plant, should not be removed until a restoration plan has been developed.  However, in order to prevent these plants from taking becoming a major headache to eventually eliminate, care should be taken to mow the weeds before they set seed.

Long Term Revegetation of the Area

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.

• Ryegrass can be seeded as temporary erosion control method. It must be watered in to be established prior to onset of rainy season, and MUST be killed prior to setting seed so that it does not persist in the landscape and complete with deeper rooted natives that will ultimately be more effective at protecting the soil. If the climate is cold enough, the grass will winter kill prior to setting seed. If not, light-occluding tarps may need to be used to cover the vegetation and starve it of sunlight.
• Barley Grass can be sown in 3’ separation between contour rows, more closely if soils are dense and have a low infiltration rate. Cut each year and leave the mulch in place to help protect soil and build moisture levels. Pre-germinate seeds 24 hours prior to application, water them in to establish.
• Vetiver Grass Planted On Contour is a relatively fast way to protect friable soils from sheet flow and erosion from direct impact or rain droplets. Plant plugs 4-6” aparts in a 6” deep trench following contour. Provide irrigation to establish. Requires full sun and loves heat (great for exposed southern and western slopes). Roots will ultimately grow between 9 – 15’ deep and create a dense, fibrous, interwoven biological retaining wall that will not only retain soil but also root into loose soil that might pile up on top of it. Vetiver grass is highly drought tolerant once established due to its deep root system. Plants do no set seed and have columnar root systems, so are not invasive, and can help create soil conditions (increased moisture, cover, stability) for deep-rooted canopied plants to establish. When vetiver is shaded it will grow less vigorously, and once completely shaded it will die. Can be burned to the ground / frozen and will regrow from the roots.
• Immigrant Forage Kochia – An evergreen, low-growing groundcover plant with succulent leaves, Kochia is salt and drought-tolerant, perennial, non-invasive and helps natives re-establish following cheat grass invasion. It can survive on as little as 6” of rain a year.

Generally speaking, non-woody groundcovers have an effective root depth of less than 3’ (“shallow-rooted”). 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 3-6’) and can be used amongst taller shrubs and trees. Plants with roots in the 6 – 15’ 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.

Evaluate and Adjust: What Lessons Did The Fire Bring?

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.