Designing your garden for fire resilience

Fire has played a part in the Australian landscape for many thousands of years. Consequently, Permaculture design has a focus on designing to exclude wildfire from the home and garden. This involves multiple strategies, which include house design, water supply, firebreak areas surrounding both individual houses and also hamlets of houses, animal yards, and other important human infrastructure.

Windbreaks of fire retardant species can be a useful strategy to attempt to slow a cooler fire front as it approaches a house or settlement. A well-maintained windbreak would consist of species with a low volatile oil content, less flammable leaves or bark, and trees and shrubs which don’t lose a lot of leaves or dead branches over time. They would be placed outside of the fire-protection zone. To retain the fire- retarding qualities these plantings will need to be either kept moist through irrigation, or be part of a water retaining design e.g. planted on swales to have a permanent source of water available, once water has infiltrated over a number of years.

Fruit trees with fire-retarding ground cover of comfrey and mowed strips between tree rows. (Photo: Robyn Francis)

Other important strategies include the maintenance of separation between areas of fuel. Firstly, by pruning lower and dead branches, vertical separation is maintained. Having areas of ploughed land or scraped back firebreaks, can provide horizontal separation in a cool fire. Keeping trees hedged and managed, and the incorporation of compost in to the soil to maintain its water-holding capacity, and mowing, irrigated areas, roads, maintenance of forest trails, and clearing up and composting of dead leaves and branches, are all useful strategies. Wood-chippers are very useful for tree prunings, to be used for compost. These strategies have use in low to severe fire situations. Once a fire storm develops in either extreme or catastrophic conditions, the situation is extremely unpredictable and any plant that becomes dry enough will burn. The following is a list of useful plants which may be less likely to burn in the less extreme fire situations

Low firebreak    
Common name Botanical name Flammability
Agapanthus* Agapanthus africanus* and Low
  A. orientalis *  
Clivia Clivia miniata Low
Crinum Lily   Crinum pedunculatum Low
Day lily Hemerocallis aurantiaca   Low
Warrigal Greens Tetragonia tetragonioides Low
     
     
Medium firebreak shrubs  
Coprosma Coprosma repens Low
Rhododendron Rhododendron sp. Mod
Rhododendron Tropical Rhododendron Vireya Mod
Tagasaste* Chamaecytisus palmensis*  
     
     
Trees    
Low flammability Deciduous fruit trees  
               
Apples Malus domestica  
Carob Ceratonia siliqua  
Cherries Prunus avium Low
Feijoa Acca sellowianna  
Fig Ficus carrica  
Mulberries Morus rubra and M.alba Mod
Nashi Pear Pyrus pyrifolia  
Pears Pyrus calleryana  
Persimmon Diospyros kaki Mod
Plums European Prunus domestica Low
Plums Japanese Prunus salicina Low
Most nuts    
     
Deciduous European Trees    
Oak Quercus robur  
Willow* Salix babylonica* Mod
Box-Elder Maple Acer negundo  
Sycamore* Acer pseudoplatanus*  
Chinese Elm Ulmus parvifolia  
Box-Elder Maple Acer negundo  
Ash Fraxinus sp.*  

Note: Populus sp. Poplar tree, Platanus sp., Plane tree and Pittosporum undulatum Pittosporum are regarded as hard to burn by the authors of Fireguard 3 (an older publication), whereas Chladil and Sheridan 2006, regard them as having high flammability.

* These plants may become environmental weeds.

Flame tree in full bloom (photo: Robyn Francis)

Australian rainforest plants

http://anpsa.org.au/fire.html  accessed 04/12/2019  “*ANPSA knows of no plant that is completely non-flammable. ANPSA cannot guarantee that the species listed will not burn…they are simply more resistant than many other species*.”

Deep Yellowwood  Rhodosphaera rhodanthema ANACARDIACEAE  
  Elaeodendron australe CELASTRACEAE
Orange Boxwood Denhamia celastroides CELASTRACEAE
Black Wattle Callicoma serratifolia CUNONIACEAE
Black Plum Diospyros australis EBENACEAE
Silver Croton Croton insularis EUPHOPRBIACEAE
Silver Croton Croton insularis EUPHORBIACEAE
Red Kamala Mallotus philippensis EUPHORBIACEAE
Bolwarra Eupomatia laurina EUPOMATIACEAE
Kurrajong Brachychiton populneus MALVACEAE
Flame tree Brachychiton acerifolius MALVACEAE
White Cedar Melia azederach MELIACEAE
Whalebone tree Streblus brunonianus MORACEAE
Golden Penda Xanthostemon chrysanthus MYRTACEAE
Cheese tree Glochidion ferdinandi PHYLLANTHACEAE
Long leaved- quinine bark Petalostigma triloculare PICRODENDRACEAE
Native Frangipani Hymeonosporum flavum PITTOSPORACEAE
Native Frangipani Hymenosporum flavum PITTOSPORACEAE
Muttonwood Myrsine howittiana PRIMULACEAE
Firewheel tree Stenocarpus sinuatus PROTEACEAE
  Lomatia fraseri PROTEACEAE
Buckinghamia Buckinghamia celsissima PROTEACEAE
Native Hydrangea Cuttsia viburnea ROUSSEACEAE
Coast Canthium, Supple Jack Cyclophyllum coprosmoides RUBIACEAE
  Hodgkinsonia ovatiflora RUBIACEAE
Flintwood Mountain Cherry Scolopea braunii SALICACEAE  
Wild Quince Alectryon subcinereus SAPINDACEAE
Steelwood Sarcopteryx stipata SAPINDACEAE
Boobialla Myoporum sp. SCROPHULARIACEAE
White Hazelwood Symplocos stawellii SYMPLOCACEAE
Buff Hazelwood Symplocos thwaitesii SYMPLOCACEAE

Other Australian plants

Botanical name Common name Flammability
Acacia decurrens Green wattle mod
Acacia mearnsii Black wattle mod
Acacia melanoxylon Sally wattle/ Blackwood mod
Araucaria heterophylla Norfolk Island pine mod
Myoporum insulare Boobialla moderate

New Zealand Species

List compiled by Robina McCurdy of Earthcare Education Aotearoa  flammability rate from Wyse et al. 2016)

Indigenous Maori name (common name) Botanical name Flammability rating
Taupata (mirror bush) Coprosma repens  
Karamu* Coprosma robusta* low
Kotukutuka (tree fuschia) Fuschia excorticata low
Hange hange (NZ privet) Geniostama ligustrifolium low
Mahoe/ whiteywood Melicytus ramiflorus Low/med
Ngaio P   Myoporum laetum low/med
Puaou/ (five finger) Pseudopanax arboreum low
Red matipo Myrsine australis low
Papauma (broadleaf) Griselinea littoralis low/med
Akeake (hop bush) Dodonea viscosa med
Karaka (NZ laurel) Corynocarpus laevigatus low/med

P poisonous plant

* may become an environmental weed

References:

Chladhil, M. and Sheridan, J. Fire Retardant Plants, fire_retardent_plants_brochure.pdf Revision 3 2006. Tasmanian Fire Research Fund

Department of Bushfire Services, Fireguard Resource 3. Tree Selection for Fire-Prone Areas. Rosehill NSW

Mollison, B. Permaculture Design Course 1990, Byron Bay

Small Tree Farm www.smalltreefarm.com.au about-retarants.pdf Accessed 4/1/2017, Balingup WA

Wyse, S. V., Perry, G. L. W., O’Connell, D. M., Holland, P. S., Wright, M. J., Hosted, C. L., Whitelock, S. L., Geary, I. J., Maurin, K. J. L. & Curran, T. J. (2016). A quantitative assessment of shoot flammability for 60 tree and shrub species supports rankings based on expert opinion. International Journal of Wildland Fire 25: 466-477. 

Article prepared by Janelle Schafer

There is no guarantee that any of the species listed in this article will not burn. Any species will burn once it is dry enough. Please consult your local fire authority for recommendations for fire protection in your area.

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