Designing And Planting A Firebreak

In fire prone areas, to ensure maximum safety for your property you would need to remove all burnable material for a considerable distance away from whatever you are trying to protect. This could result in a barren, unattractive landscape that most property owners would not consider desirable. By careful selection and placement however, it is possible to have plants nearby while still maintaining an acceptable safety level.

How to arrange plants
Careful placement of plants can significantly reduce the impact of fire. The immediate area around buildings should be free of trees and other combustible materials. Lush, well watered lawns, paved areas, driveways, etc. in this area can provide an effective barrier to the passage of fire.

A fire retarding shelterbelt placed at right angles to prevailing winds will also protect buildings (do not place these to close to buildings though a minimum distance between shelterbelts and buildings should be the height of the shelterbelt, although ideally the distance should be 3 to 5 times the height of the shelterbelt). The shelterbelt will act to reduce the wind which fans the fire, will deflect heat and smoke and will catch burning airborne material.
The shelterbelt should be made up of fire tolerant or resistant species (see lists below).

Distances from buildings
Keep trees at least the same distance as the height of the mature tree from any buildings, for example if the height of a particular tree is 20 metres when fully grown, then it should be planted at least 20 metres away from any building (if the tree falls, then burning branches won't hit the building).

Consider prevailing winds
The prevailing winds will effect the way fires will travel and where ash and burning embers fall. It is important to note that prevailing winds may vary from season to season, although days of extreme fire danger are usually characterized by hot gusty winds with southerly wind shifts later in the day.

Consider vehicular access
Access routes to dams, pumps, roads etc. should be kept free of trees and flammable material. This includes all routes of escape.

Maintenance: Points to remember.
* Water trees in summer (keep moisture in the plant high)
* Fertilize your plants regularly in summer. A plant that has lush green growth is less likely to burn.
* Have a hose ready at all times, and ensure water is readily available.
* Only use mulches that will not burn readily. You should remove twigs, leaf litter, etc. from the ground. A compact mulch of stone or even woodshavings is not generally a problem, but leaves and twigs can be, in a bushfire. Leaf litter can be dug in or composted to prevent it burning.
* Remove flaky loose bark from trees. Smooth barked trees are less likely to catch fire.
* Prune lower branches so that burning debris under plants can't ignite foliage.
* Remove dead trees and fallen branches.
Fill hollows/cavities (hollow trunks, depressions where branches break & rot gets in) with concrete or remove the plant...fire can catch in such hollows and the tree may smoulder for some time without you knowing it.
Avoid large dense clumps of trees & shrubs particularly near buildings
Have succulent ground cover, lawn or gravel under large trees or regularly slash or cut any underlying scrub and grass to remove potential fuel for fires.

Fire Resistant Plants
The following types of plants are less likely to catch alight and burn in a bushfire:
Plants with high salt content (eg: Tamarix, Rhagodia, Atriplex, Eucalytpus occidentalis, E.sargentii).
Plants with fleshy or watery leaves (eg: cacti)
Plants with thick insulating bark.
Plants which have their lowest branches clear of the ground.
Plants with dense crowns.

Plants which are more likely to burn include:
Those with fibrous, loose bark (eg: Stringybark eucalypts).
Those with volatile oils in their leaves (eg: most eucalypts, callistemons, melaleucas).
Those with volatile, resinous foliage (eg: many conifers).
Those with dry foliage.
Those which retain or accumulate dead leaves and twigs.

Plants with some degree of fire resistance include:
Acacia dealbata, melanoxylon Acer campestre, negundo
Alnus jorulensis Atriplex sp.
Agapanthus Artichoke (Globe)
Brachychiton populneus Cacti
Carrina grandiflora Casuarina cristata, cunninghamiana
Ceratonia siliqua (Carob) Cinnamonum camphora
Coprosma repens Echium fastuosum
Ficus carica, macrophylla Hakea salicifolia, suaveolens
Lagunaria patersonii Laurus nobilis
Ligustrum sp. (Privet) Lippia canescens
Ilex aquilifolium Melia azaderach (White cedar)
Morus sp. (Mulberry) Myoporum sp.
Tropaeolum sp. Pelargonium sp. & cultivars.
Pittosporum undulatum Plantanus sp.
Populneus sp. (Poplar) Photinia robusta
Quercus sp (most thick barked oaks) Tilia vulgaris (Linden)
Rhagodia sp. Salix sp. & hybrids.
Schinus molle (Peppercorn tree) Succulents (eg: Sedum, Carpobrotus, Mesembryanthum, Agave)
Thymus serpophyllum Ulmus sp. (Elm)

 

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