Fire in a landscape is a subject that I want to treat very seriously. It is a common hazard[1].
Fire has a periodicity specific to the site. This fire periodicity depends on two factors: First, the rate that fuel accumulates on site. This is a critical factor. The second factor is the amount of moisture contained on site. Any ridge top is far more fire prone than its valley systems. Typically, the vegetation of ridge tops may even be fire-dependent, with species that germinate well after fire burns the ridges. In the valley, on the other hand, you may get species that may be killed by fire, but which burn very suddenly. While ridges are more fire-prone than their adjoining valleys, so are the sun-facing sites more fire prone than their shaded slopes.
It is possible to work out the fire periodicity on site by examining the cross-section cut of an old tree in the area, or even from historical records of fire in the area. With a rainfall of 30 to 40 inches, a catastrophic fire will occur about every 25 or 30 years. I am not talking about a local spot fire. I am talking about a fire that races through a large area. `A lot can be done to change that cycle.
Advantage is gained if it can be delayed even one period. The less a site burns, the less it is likely to burn, because there will be more humus and more moisture incorporated into the site. On the other hand, the more it burns, the more likely it is to burn again soon. This is because fire removes a lot of moisture-retaining humus and kills a lot more than it consumes, resulting in a fire prone litter build-up. So the periodicity can change to a very short term if an area continues to burn. Areas that naturally experience fire every thirtieth year will burn every eighth or tenth year, once they are being burned at shorter intervals. Fire is a very destructive influence[2].
In permaculture landscapes, there are sequences of defense that you must throw up. What you must do is reduce fuel. That must be the primary strategy. You can do this by creating non-fuel surfaces, such as roads and ponds, by constructing swales and doing pit mulching, and reducing fuel by means of browsing or grazing.
It is very simple to protect the house site. You only need a hundred feet of non-fuel systems between the house and the forest. That is not very far; it is a raking job. Select plant species for this area that have fire-resistant characteristics, such as very high ash content, a very high water content, very low total bulk, and which grow densely. The ice plants, the Coprosmas, some of the thick-leaf evergreen plants, whose littler decomposes very fast, have leaves that are highly nutritious and don't last very long on the ground. A list of plant species useful for fire control in any area varies with the climate. Fire departments in fire-prone areas are often able to make recommendations.
Some trees, particularly the pines, and many of the leaf species, are litter accumulators. They form a hard and volatile litter that simply builds up and carries very large ground fire. Do not use plants to the fire danger side -- the downhill side -- which have high volatile oil content. Eucalypts are a positive no-no, and so are pine trees. Both are to some extent fire weeds. Both carry cones and hard fruits that often don't open until fires. After fires, you will see a widespread covering of new growth from the seed of these trees. That is what they are waiting for, a fire to enable them to extend their range a little.
So you halt fires by working from the valleys upward with plantings of low fuel vegetation. Re-establish the rain forest that would be on the site if it did not burn. Bring in a lot of species that naturally occur in the valleys.
Now let us look at the fire itself. What does the fire do? It doesn't burn much. It burns a few leaves, and perhaps buildings in its path. The real danger of fire is radiation. Four hundred feet before a fire, your hair catches alight. Two hundred feet, your body starts to split and your fat catches alight. At 100 feet, you are a torch. Radiation kills birds hundreds of feet from the fire[3]. They just fall out of the air. Fire kills pigs very quickly. They don't stand radiation. Goats survive quite well. They just lean into it. And human beings are good at surviving a fire because they dodge about and hide behind shadows.
So we need to throw fire shadows over the central part of the system that contains our client. We do it with earth banks, and we do it with trees like willows and poplars that have high water content and that throw out a black cloud of steam. They don't let radiation through. So on many sites that you will design, where fire will be a future hazard, you pay a lot of attention to setting up fire-protection. In California, almost every plant depends on fire, and all have high oils, because they have been selected through a long history of fires. Greece was once a land of wet rain forests, with enormous oak and columnar beeches. It has become a skeleton of its former self, and its fire frequency is up and up[4]. Now you really can't burn Greece because the dirt is burned, the plants are burned, the hills are burned, the rocks slip down hill and you can't burn rocks. The whole of the Mediterranean and much of North Africa has reached this condition.
What we must do is start reversing the process. If your client is in that chaparral, then you must pay particular attention to fire protection. You will have to give him somewhere to go to when a fire comes. You really can't save him on the surface. So you dig a T-shaped or L-shaped pit and earth it all up. It can be a length of road conduit, earthed over. Then your clients can hop underground and wait it out. When they are out of the radiation, they are out of trouble. In Coventry and other areas that were burnt in war, there were fire storms[5]. Standing in a fire shelter, I have watched the glass pouring out of the windows in my car. It is hot out there, you think. It melts out the bearings in your car. You can't drive. Always duck behind things in a fire. Just get out of the radiation. And keep your mouth shut. Don't breathe. Otherwise, your lungs burn out. So if you don't breathe until you get behind things, you are all right. The main thing is not to be in direct radiation. Often you can dig a fire shelter into a bank with a backhoe. In some areas, this work of a few minutes may be the critical factor for survival.
Otherwise, give good advise to your clients: "Go behind the house and sit down 'til the front of the house is alright. Then walk around to the front of the house, because the fire will have gone past." Instruct clients about the need for litter reduction on the ground. Give them good instruction in pit mulching and swaleing[6]. If you have a very bad fire site, construct a few big swales, and cover the swales with old carpet so that you get a very fast rot down. Put in a whole lot of plants that are quite fire-proof. You can stand behind a Coprosma, and you don't even feel the fire, just a hot steam bath.
You can take advantage of the normal attributes of the raking animals, such as chickens. They break up that ground litter and mix it with oxygen so that it really breaks down. Short grazers, such as sheep and wallaby, on the fire side, will reduce the standing litter to one inch, and you will not need to worry about ground fire.
Just experimentally, I have lit around mulches, and they are not a risk. Sawdust, too, is good safe mulch. Actually, you may get a half inch fire across the top. It starts to smolder burn but it doesn't go anywhere. It can be quickly put out. You don't need to worry about mulches.
The primary protection in fire is to have good sprinklers down hill. If you can turn on a couple of those, you can sit on the front verandah and enjoy the sight of water pouring over the landscape before the fire gets there. I've seen water from the fireman's hose coming six feet from the nozzle and going up in the air as steam. If, before a fire gets there, you've turned your sprinklers on, and the ground is wet, the fire won't cross that ground. If the fire is already there when you put the sprinklers on, then the water doesn't get very far out of the sprinkler. So you must start your defenses before the fire.[7].
Sprinkler systems on roofs are very critical. A house is lost when ashes fall all over the roof, slide down it, prop against chimneys and fill gutters. The wind is blowing; the heat returns in under the roof and catches tar paper and insulation, and starts burning from the ceiling under the roofing. That is the way 99% of houses ignite.
The safest houses in fire are wooden. They have a 13 to 15 percent higher survival than stone or brick, which is a surprise, of course. In analysis of some houses of equal risk that didn't survive, the brick outnumbered wood. Almost without exception, stone houses are taken by fire. Stone transmits heat rapidly to the inner surfaces. Bricks are equally fast heat transmitters. You can burn a wood house with a blow torch if you go around catching it in a lot of places. But a wooden house is very resistant. Basically, wooden houses won't transmit heat through the fabric, and their drafting systems are better than in brick houses. White painted wooden houses, and paint generally, anything that will reflect radiation, is a protection.
When you are planning for fire, you must specify the use of screens and fire hardware mesh, so that large particles cannot enter the house system. The gutters should also be screened. Wherever you are experiencing snow, fire, or heavy leaf drop on the roof, it becomes necessary to put a rolled-under section on the bottom edge of the roof, and put the gutter back under, below that. Leaves will fall off. They can't get in the gutter. Snow will slide off. When snow melts, the melt will go into the gutter. Fire ash will slide down and fall off. It won't get caught in the gutter, either. That is a good device, and it can be fitted to existing roofs.
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| Rolled Roof Section. (T.F.: The original pamphlet edited by D.H. says: Illustration from Permaculture II by Bill Mollison (C) 1979, all rights reserved. Published by Tagari, 31 Rulla Rd., Sisters Creek TAS 73215 AUSTRALIA. Reproduced with permission. |
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You must say to your client, "Well, look, we will give you a few simple specifics in housing design, and you must watch how you lay out your roads and ponds. That will give you a much better chance of survival." Also, advise your client about how to proceed in case of fire.
Fire builds up to high intensity about 2:00 to 3:00 p.m. Inevitably, the people at home are people with young children. Mostly, they won't have a vehicle. They are a vulnerable group, and they must be told what to do. If the fire comes from this side, they have to stand here with their woolies on, woolen jackets, blankets over them, and a bucket of water so that wool won't burn. Then go into this little shelter that we have provided and have a drink of water. We should try to get water in there. It's worth it. Just walk in there and sit down, and leave your woolen blanket in the water. Dig that shelter into a little hill just at the back of the house, normally away from the fire, on the slope. Go maybe six feet deep. Open your back door, and hop down into your little root cellar, which is also a fire shelter. We must look after the people in ways like that.
Advise people never to jump into water in fire. That is another no-no. There is no oxygen left in the water and they will faint straight away[8]. It is like painting somebody's body. We breathe a lot through our skins. The fish already are dying from oxygen loss before fires ever get there. The people in the water will faint and drown. So jumping in the pond is a no-no.
In some areas, we will totally ignore this whole business, because for most of their history, those areas never burned. The prospects of a sweeping fire are remote.
Even in humid climates, high forested areas in the continental interior are not invulnerable to fire. When things dry up, and the wind whips about at 50 to 60 miles an hour, just a backfire from a car can set the whole area aflame. Fire travels about 400 miles an hour. There is no running away from it; no driving away from it. When fire starts, it spirals up, and increases in breadth at the base. You will be looking up at the sky, and there is half of somebody's house, way ahead of the fire -- an incredible sight. You will be looking up at a blue sky, an upstream of smoke, and there goes that burning house, a great fire in the sky. Then it drops. At that point another spiral starts up. These big spirals go up, taking everything that is burning with them, then drop it out, to start new spirals. A fire will cover a thousand square miles in an hour. So most people who are in it are in it. You can't go away from it. You have to just hold your place and sit it out. Don't start running. Don't try to run ahead of it. You have more chance of surviving a fire if you run straight at it. If you run away from it you are dead. You have to just hold your place and sit it out. Don't start running. You can't drive your car, because the petrol will evaporate. Unlike Hollywood, gas tanks never blow up; cars never catch alight; only the tires do[9].
The sensible thing to do with high explosives, like drums of fuel and the like, is to store them away from a living situation, have them in separate sheds, a bit dispersed. When one ignites, it doesn't ignite the others.
Don't put your poor client at the head of a converging valley in the saddle. Don't put your client where you would normally put an efficient windmill. Don't put him where the ridges converge. No, no!
I witnessed an example of landscape architecture in an Australian fire-prone site. I was driving by this place, and I looked at this house -- I couldn't believe it! There was an acre of fire-promoting vegetation just across the way, converging eucalyptus trees with pampas grass. It had been constructed by a landscape architect. While the aesthetics were reasonable; the function could be fatal.
So in my mind, function always comes first, then aesthetics. A good function is often a very pleasing aesthetic. He could have had a couple fire banks up the driveway. We could have had given him a pond and, just below it, a Coprosma hedge.
Construct the pond in front of the house, with your road beside it. The bank of the pond should rise toward the fire side. You will find that there isn't any conflict between good fire control and good placement of your elements. But if you don't have the initial planning, all sorts of things can go wrong.
[1] Fire as a Common Hazard
T.F.: Indeed, this is a far more common hazard than most of us realize if we do some long-term thinking. On the one hand, as many of us live in the city, our perception is shifted badly -- we just do not notice them much. Also, the amount of detail media cover events such as forest fires is very different from the level of attention received by e.g. terrorist attacks. According to official statistics, there have been 930 forest fires in Germany in 2006. As the climate gets hotter and precipitation therefore more unpredictable, we will encounter more forest fires.What one in particular has to realize here is that the present rate of human-made climate change is about 100 times as fast as natural processes. Nature actually was in a process of recovery from the changes induced by the end of the ice age before we set off climate change. The trees we plant today will grow up in a climate rather different from the one in which we make decisions what to grow. So, if we make the wrong decisions, they will fail, and if they fail, what will be the most likely occasions for their death (causes being, as Bill pointed out in the "phasmid conspiracy" section, multiple insult)? Bugs, mechanical failure in storms, and, of course, fire.
So, it is important to also pay close attention to this lesson. Furthermore, should you ever consider setting up systems in a forested region that is bound to become more arid, this is what you have to put a lot of emphasis on.
One further issue one should keep in mind when Bill Mollison talks about fire is that he and his family almost died in the severe Hobart fires of 1967. His autobiography contains fairly interesting additional material especially on processes that happen in the aftermath of such a fire and sensible strategies that can be employed to prevent major problems.
[2] Self Enforcement
T.F.: This means in particular that we can get self-enforced patterns from repeatedly burning down vegetation: where it burns well, it will burn even better in the future. The Australian aborigines must know a lot about these processes and actually use them constructively to establish systems. However, in the very long term (10000s of years), these methods also appear questionable.[3] Fire Radiation
T.F.: For large fires, a huge amount of heat transport is not mediated by the flow of hot matter (i.e.hot air), but just by radiation - basically, just very intense light and infrared that heats up things at a distance.One sad fact is that, in our culture, very few people have a sound commonsense idea about the behaviour of large scale fires, at least the size of a burning car or a burning tree - or even a burning house. As we are about to presumably enter a century of dire emergencies, we would do well -- as a society -- to generally step up our efforts in regular emergency training, which should include sessions where people can get first-hand experience of the effects of large fires.
[4] Greece
T.F.: Much of the Greek landscape was denuded as forests were felled in ancient times to produce wood for warships. Present vegetation is often dominated by small shrubs, thorny legumen, Nature's own "desaster repair" species such as gorse.[5] Firestorms during wartime
T.F.: During WW2, it was soon discovered that fire sticks thrown at cities for illumination and guidance purposes so that bombers knew where to drop their load often were more destructive than the bombs themselves. So, strategies soon shifted towards focusing on deliberately creating a firestorm by first bombing away roofs (and destroying enough of the infrastructure to make putting out fires difficult), then setting timber beams and furniture ablaze. The German city of Dresden was destroyed in an "engineered firestorm" during WW2. The same tactics, however, did not work with Berlin, due to its special architectural characteristics.[6] The Jean Pain System of Composting
T.F.: I included material on the Jean Pain system of composting from an Indian "appropriate technology" website, http://www.daenvis.org in this distribution. This is an integrated composting system which was originally designed to get rid of dangerous excessive fuel buildup in the woods, but, when done right (which admittedly is a bit tricky), will at the same time produce compost, winter heat, and biogas. So, we get four yields from one strategy, sound permaculture design.[7] Sprinklers
T.F.: Again, this is self-enforcement at work. Fierce fire creates the right conditions for more fierce fire, so we better see we control it right at the beginning when this is easiest.[8] Taking a bath
T.F.: While the idea of people fainting from entering oxygen-depleted water as their skins fail to breathe is wildly exaggerated, the advice is sound nevertheless: During a fire, there can be temporary phases of low oxygen which make people pass out, and passing out in water often means drowning. So, entering a body of water is not at all a good strategy.[9] Exploding Cars
T.F.: Experienced first aiders as well as paramedics claim in unison that bizarrely distorted TV reality, in particular cars exploding in fire, often make people hesitate when they should rescue somebody out of a burning car. It is quite true that only under highly unusual circumstances (read: pyrotechnical preparations), you would see a car explode hollywood-style.______________________________________________________________
Transcript of full Permaculture Design Course given by Bill Mollison in 1981:
1. Preface
2. Introduction to Permaculture
3. Permaculture in Humid Landscapes
4. Permaculture in Arid Landscapes
5. Permaculture on Low Islands
6. Permaculture on High Islands
7. Permaculture on Granitic Landscapes
8. Permaculture for Fire Control
9. Designing for Permaculture
10. Permaculture Techniques
11. Forests in Permaculture
12. Water in Permaculture
13. Permaculture for Urban Areas & Urban-Rural Linkages
14. The Permaculture Community
15. The Permaculture Alternative
16. Permaculture for Millionaires
1 Comments:
But if you prevent these fires, what will happen to the species that are fire dependent?
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