Bushfires: Aftermath Suggestions for Clients

By Wayne Van Balen MAIH RH0027, 8 February 2020.

 

Topic 1: Assessing fire damaged plants to establish whether they are alive or should be scrapped

Burning is not considered authorised clearing. A useful reference is the NSW Government Local Land Services publication, “Managing Native Vegetation after a Bushfire Emergency“. There is some allowance for the removal of burnt vegetation if there is an imminent risk of serious personal injury or damage to property. It is reiterated that reference should be made to the legislation. A further reference, particularly for commercial horticulture crops, is Hort Innovation’s “List of Information for Those Affected by Bushfires“.

Natives

Many affected plants will look dead or badly damaged but have a strong ability to regenerate.

Adaptions include, for example:

  • bark thickness.
  • in relation to Eucalyptus, resprouting from epicormic shoots in the trunk or from underground organs.
  • Regrowth from underground lignotubers e.g. Banksia.
  • Leaf-sheaths e.g. Xanthorrhoea, Lomandra, Cycads and tree ferns.
  • Fire-stimulated seed release.
  • Improved seedling germination, stimulated by seed rupturing, smoke and ash.
  • Flowering stimulated in geophytes.

Rainforests are a different issue and normally retard the fire, however rainforest boundaries can be moved back by fire, particularly when there are highly flammable grasslands on their flanks.

Ornamental Species

  • Ensure that any dangerous material where there is imminent risk of serious personal injury or damage to the property is removed. It should be noted that many species have an ability to regenerate and some time should be given before final assessment is made.
  • During the restoration phase, less fire-hazardous species can be researched and utilised.

Topic 2: What Next – How Can We Assist in Garden Regrowth

  • Control erosion.
  • Control weeds.
  • Use well-rotted mulches, if available.
  • Water regenerating plants where possible.

Drier and hotter conditions are causing skepticism about the ability of the ecosystem to bounce back. This is where consideration of different species that handle hotter and drier conditions might be made. Macquarie University has been carrying out research in this area.

Topic 3: Soil Remediation

Issues include:

  • Microbiology:
    • There is short term destruction of microbiology.
    • Micro-organisms in the upper layer of soil also have a strong ability to regenerate. Some assistance can be given to the restoration of microbial communities by adding organic matter which will improve the soil’s water holding capacity. This will also feed and attract earthworms and essential soil microbes.
  • Ash:
    • Ash comprises very fine particles and can cause the soil to become hydrophobic. In some areas, it can lead to the soil becoming too highly alkaline, but on acid soils, some ash can be beneficial.
    • Heavy rain can cause too much ash to be deposited in the water catchment and cause water pollution.
  • Pollution:
    • Fire-fighting retardant residues can lead to a pollution problem. It is recommended that details be provided on which retardants were used and how the residue can be managed.
    • Some building materials, including paints and asbestos, can pose a health hazard and require specific management.

Topic 4: Planting Decisions

Firstly it should be emphasized that all plants will burn and fire intensity and circumstances will vary.

Planting decisions to minimise fire risk and damage should consider the following points:

  1. Trees that reduce and retard ember attack are favourable. ie those that act as a heat barrier and shield from embers.
  2. Trees that slow the passage of flames should be used.
  3. Moisture in the leaf tissues may be enough to stop the fire or reduce wind speed as the fire approaches.
  4. Trees and shrubs should be lush with high moisture content and be low in flammable oil content.

Some examples of useful deciduous trees include:

  • Liquidambar
  • Oak trees
  • Elms
  • Most of these will recover well after a fire.
  • Other deciduous small trees that could be used include Pyrus, Prunus, Malus and Mulberries.
  • The dense foliage provided by evergreen exotic plants like the evergreen Magnolia species would also be satisfactory.

Some other examples are native tree species such as:

  • Tristaniopsis laurina (Water Gum)
  • Lilly Pillies
  • Hymenosporum flavum (Native Frangipani)
  • Cupaniopsis anacardoides (Tuckaroo)
  • Brachychiton acerifolius (Illawarra Flame tree)
  • Glochidion ferdinandi (Cheese tree)
  • Elaeocarpus species
  • Ficus

Examples of shrubs to use:

  • Hydrangea
  • Viburnum
  • Escallonia
  • Photinia
  • Coprosma
  • Plectranthus
  • Oleander
  • Aloe
  • Acacia iteaphylla
  • Correa

In drier areas, the list of native low fire risk species should be considered as the use of many of the exotic species would have higher water requirements.

Examples of useful Groundcovers:

Succulents, Hibbertia scandens, Dichondra repens, Dianella, Lomandra, Ajuga, Dampiera,  Scaevola, Pigface, Myoporum and Catmint.

Some of these can slow down a fire and reduce spot fires and reduce fire energy before igniting a house.

Some early fire prevention and minimisation measures include:

  • Get rid of rubbish.
  • Clear weeds and debris.
  • Cut back overhanging branches and dead growth.
  • Remove dead grass and fallen leaves and bark.
  • Remove flammable wood-based mulches (replace with Gravel or pebble).
  • Use of lush groundcover plants such as lawns closer to the dwellings.

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