Fire Retardant Trees

March 19, 2009

Trees and Bushfires

Apart from the potential human tragedy and loss, bushfires often result in a temporary loss of landscape amenity.  Following bushfires there is often apprehension by those directly affected about replanting trees adjacent to homes and other buildings.

The benefits of trees in our landscapes are significant and well documented.  The use of fire retardant trees in areas prone to bushfires can not only add beauty to our gardens, but when selected and placed appropriately they can assist in safeguarding homes in the advent of a bushfire.

Trees with the best fire-retardant properties are those which have soft leaves with a high moisture content, smooth and non-peeling barks, and low volatility oils in their foliage. In general this includes the majority of deciduous trees and some evergreens from the sub-tropics and rain forests. Trees that create or hold on to lots of dry dead branches and debris, have loose flaky bark, have dense, fine foliage with a low moisture content should be avoided.

All plants, whether they are exotic or Australian, will burn when subjected to sufficient heat. Different fire conditions have varying effects at different times on the same species The tree selections made here will not guarantee safety in a bush fire. Instead, the following selection of trees, if correctly sited, can compliment fire management plans for individual homes by serving as a wind break absorbing and deflecting radiant heat from the fire and acting as a barrier to flying sparks and embers.

Trees and landscapes must be part of a complete fire planning system and ongoing diligence in managing your site.  Site management includes maintaining trees in a healthy condition, for example keeping soil moist, pruning out dead wood and cleaning up debris and leaf litter.

The following list is not definitive.  Further information can be sought from the references listed below and from local authorities.  The following trees could be used for specimen plantings.  Planting of trees should take into consideration separation distances between buildings. 

  • Acacia melanoxylon (Blackwood).  Tree will vary in size dependent on climate and soil type.  8-15 m in height.
  • Acer campestre (Hedge Maple). Deciduous medium tree 8-10m.  Use varieties ‘Queen Elizabeth’ or ‘Elsrijk’
  • Acer negundo ‘Sensation’ (Variety of Box-elder Maple). Deciduous, broad domed, medium sized tree to 12-15m.
  • Banksia integrifolia (Coast Banksia). Variable tree up to 10 m in height.
  • Brachychiton acerifolius (Illawarra Flame Tree). Pyramidal tree 8-15 m in height.
  • Brachychiton populneus (Kurrajong) Domed evergreen tree, 12-20 m in height.
  • Cupaniopsis anacardioides (Tuckeroo). Broad-domed evergreen tree 8-12 m in height.
  • Lophostemon confertus (Queensland Brush Box). Broad-domed evergreen tree 10-15 m in height.
  • Melia azedarach (White Cedar). Broad-domed, deciduous tree.  8-15 m in height.
  • Quercus canariensis (Algerian Oak).  Large, broad domed tree.  20-25 m in height.
  • Stenocarpus sinuatus (Firewheel Tree). Upright tree 8-14 m in height.
  • Syzygium paniculatum (Magenta Brush Cherry).  Narrow to broad-domed evergreen tree 10-15 m in height.
  • Tristaniopsis laurina (Water Gum, Kanooka).  Small, broad-domed tree 6-8 m in height.

The following trees could form useful screens adjacent to buildings. 

  • Acmena smithii var. minor (Lilly Pilly). Small tree, bronzy new growth 3-6m
  • Acmena smithii ‘Hot Flush’ (Lilly Pilly var.) Up to 3m with moderate growth habit and reddish new growth.
  • Acmena smithii ‘Sublime’  (Lilly Pilly var.). Small tree large shrub with lime green new growth. Up to 3-5m
  • Eleaocarpus eumundii (Eumundi Quandong).  Moderate sized conical tree to 8-10m tall by 3m.
  • Elaeocarpus reticulatus (Blueberry Ash)
  • Hymenosporum flavum (Native Frangipani).  Narrow tree to 10 m in height.  Best used in clumps or groups.
  • Pyrus calleryana ‘Capital’ (Callery Pear var.) Deciduous, columnar tree to 12m.

The following are varieties of Scrub Cherry (Syzygium australe).

  • Syzygium australe ‘Aussie Southern’ 3-4m
  • Syzygium australe ‘Elite’ 3-5m
  • Syzygium australe ‘Pinnacle’ Very narrow habit 3-5m
  • Syzygium ‘Aussie Northern’ Compact to 4-5m

Trees damaged by bushfire that are close to buildings, driveways or other high target areas should be inspected by a qualified arborist to ascertain tree hazard and appropriate remedial works. 
Some trees, although looking irreparable from external appearance, may recover.

References:
Australian Plant Study Group (1990). ‘Fire-retarders’ in Grow what where : over 2,750 Australian native plants for every situation, special use and problem area. Viking O’Neil, South Yarra, Vic., pp. 42-43.
Webster, J. K. (2000). The complete bushfire safety book, 3 rd rev. edn., Random House, Milsons Point, NSW.
Australian National Botanic Gardens Library (2009) Fires, gardens and fire retardant plants – a bibliography (Updated 13th January 2006). Available at  http://www.anbg.gov.au/bibliography/fire-plants.html [Accessed 9 March 2009].

About Stephen Frank

Stephen is the Managing Director of Tree Logic

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One Response to “Fire Retardant Trees”

  1. Tad Golian Says:

    Dear Mr Frank,

    Thank you very much for putting this information on the web. Since Black Saturday (7 Feb 09) I’ve been discussing these very issues with the Shire of Yarra Ranges and the Silvan Progress Association with respect to planning for a future firestorm in the Dandenong Ranges, VIC. Over the last three decades the Shire Councils have become obsessed with Green wedge politics and the planting of indigenous (highly flamable) trees, almost to the exclusion of all other species. What do you believe is the likelihood their policies will change to incorporate your recommendations, especially in light of the potential for extensive devastation caused by climate change induced megafires?

    Cheers,

    Tad Golian
    11 June 09

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