Wildfire is a fascinating and terrifying thing.
There's some attention to wildfire danger in the permaculture designer's manual; the Australians have a lot of relevant experience and intense bush fuels to manage.
I've been discussing this on another site, and thought we might want to kick more ideas around here.
How to integrate this advice with good permaculture design is the question.
(Our current house is not it.)
There's a potential conflict between flammable shrubs and debris in Zone 1 for fire protection, and biological resources for intensive gardening (mulch, perennials, etc) in Zone 1 for permaculture.
I might look at something like earth-shaping berms and swales, or short masonry walls in rings around the house to help define the garden. Something like that could catch flammable debris / mulch in pits, where you can use it for gardening, yet shield the house from the radiant heat it might release if it burns. And it might cut down wind speeds at ground level (or however high you build the walls). You could also conveniently remove any windblown debris or gutter-cleaning debris into nearby mulch pits for the permaculture garden.
For house finishes and integrated systems right up against the house, like chickens, water catchment, etc, consider using non-flammable materials like earthen building, lime plasters, and metal or ceramic roofs and water containers, rather than plastics. We've seen excellent fire protection effects from coating or embedding normally-flammable materials in clay, for example light clay-staw insulation tested in Ontario for timber-frame infill.
Fascinating and timely topic! The Australians also have a lot of good, relevant experience.
Zone and sector analysis:
Fire is most likely to approach in our area from downslope, upwind (west in summer, NW in winter), from lightning strikes (anywhere), and from human-caused fire sources (hot engines driven over dry grass, people using chainsaws or lighting fireworks during a burn ban, absentee cooking, absentee heating, and other ill-managed DIY infrastructure like electrical fires).
So we have specific directions we watch during fire season, including specific neighbors.
Chapter 12 of the designer manual has a wildfire section, we could expand on this if anyone wants to go in-depth:
https://permies.com/t/34465/pdm/Permaculture-Designers-Manual-Chapter-HUMID#269777 Ironically it's in the HUMID climates chapter, whereas I would think there's more concern in ARID climates (ch. 11).
But the humid / seasonally dry areas (mediterranean, monsoon) have lots of fuels, waxy and resinous species, and annual periods of high fire danger. So there it is.
We have that Western montane combination of wetter winters and spring, very dry summers.
So in winter, these forest textures are capturing cloud moisture, hoarfrost, and generally pulling down critical survival moisture for soils, plants, and animals. Lichens swell and look almost like seaweed, soaking up mist and dew; pine needles whiten and shed tinkling frost crystals to the forest floor even in months of almost 0 measurable precipitation.
In summer, they are oily, tinder-dry, dormant life that lights up almost like flash paper when we have dry lightning strikes. The fire chief calls roll by phone when we have a dry lightning system on the weather radar.
So I don't want to deforest, but I also want some gaps in there - "designated smoking areas" if you will, where a fire might not be able to torch into the trees because of horizontal or vertical gaps between them.
The permaculture notion of growing food at all levels - canopy down to groundcover - is modeled on rainforest biomes. Works lovely in them.
For permaculture in the arid West, we need to take our models from the best, thriving Western forests and brush-steppe and savannah and chapparal, and mimic them in both fire-resistance and climate mitigation. These are patchier landscapes, with bare soil crusts between trees and shrubs and bunch-grass. The wildlife is more sparse than in a tropical or temperate coastal rainforest, and often migratory, timing their visits for seasonal abundance of fruits or greens.
Not sure what that looks like - but for starters, swales look a lot better than raised beds.
This seems to be the year of wildfires here in Washington ... we're expecting more thunderstorms over the upcoming week and keeping our fingers crossed.
Permaculture is a gestalt ... a study of the whole. Not just how to produce more and better food, but how human life on the planet affects and is affected by the surrounding environment.
Bill Kearns http://columbiabasinpermaculture.com
A good friend of mine used to run fire crews for the forest service. His recommendations are pretty simple, keep any ground fuel around a structure cut short. Flame height is 3x the fuel height. So if you trim your tree branches to 6 feet up, 2 feet of grass can be fully ablaze below and won't ignite the tree. It will go right by. Also, he says that juniper and aspen are and were "safety areas" during a fire. Juniper is considered less so these days. Though aspen will smolder then suddenly fall on your head so it's not entirely safe. He has extremely heavy criticism for the American style of "run away" evacuate procedures for fire mitigation. He has pounded the point to me, that nearly any structure can be saved during a fire and the Aussies don't run for the hills during a fire. They defend their homes, and effectively.
During a fire event, he recommends covering soffit vents with foil and sealing other house penetrations where embers could get in. If fuel is managed effectively, all you'll have to deal with is a grass fire which can be successfully managed with a garden hose.
Incidentally, this is how the native tribes dealt with fire. They kept forest branches trimmed to 6 or 8 feet, then set it ablaze periodically. The fire will simply go right by trees that have been properly trimmed unless you're dealing with a canopy fire which means step 1 failed.
I worked forestry fire crews also. We often referred to the 'fire ladder', which is where the grasses will ignite the short bushes, which will ignite the taller bushes...all the way to the canopy trees.
In permaculture, we speak of the 7 vertical layers. This is the fire ladder. If you live in fire prone areas, you do not want these 7 layers anywhere near your structures. A good rule of thumb might be nothing taller than waist high within 10 paces from the structure. This keeps serious threats away from the structures.
We also want large roof overhangs - to keep our firewood dry, and to collect more rain water (places where rains are scarce are more likely to be fire prone areas). Overhangs are fire traps. Instead of 'swooshing' harmlessly up the side of the structure, the fire and heat are now trapped at the edge just below your roof...not a good scenario.
When autumn comes, and the leaves begin to fall, rake them away from structures, and by all means, do not let them accumulate in your rain gutters.
Solar Station Construction Plans by Ben Peterson -- ebook