Flammability of Plant Species

Fire and Emergency New Zealand

Flammability of Plant Species

If you live in a rural area, or on the rural/urban interface, can face dangers from wildfires. You can reduce these dangers by managing the vegetation around your home.

  • Fuel is the only component of fire that can be altered to reduce the probability of damage from wildfires.
  • The replacement of high flammability species with lower flammability species can reduce fire hazard and help create a defensible space around your home that allows heat and embers to dissipate.
  • Low flammability species can also be positioned to break up flammable landscapes, provide a buffer zone bordering urban areas, or to reduce fire hazard in the immediate vicinity of individual properties. 

Planting less

  • The best way to protect your house is to reduce the intensity of the fire as it approaches; this can be achieved by creating an area around your house where all flammable material such as scrub vegetation, long, rank grass, leaves and twigs has been removed.
  • The flammability of vegetation affects fire intensity, which has a major influence on fire control and the chance of homes being damaged or destroyed by fire.
  • High flammability fuels have characteristics which greatly assist fire spread; for example, heavy fuel loads, continuous structure, volatile oils, or low moisture contents.

Flammability classes of plants

These flammability classes are intended as a guide only. Species flammability also varies as a result of genetic and environmental factors, so that the flammability of a particular species will depend on age and situation. For example, flammability may increase as a result of drought or other critical fire weather conditions, or mature vegetation could carry greater amounts of dead material, adding to the potential severity of any fire.

Low

Suitable for green breaks or defensible space, but when in the immediate vicinity or structures, there should be at least 3-4m break between the crowns to reduce fuel continuity.

Low/Moderate

Not recommended for planting in green breaks. If planted in defensible space, elevated dead material and litter should be removed regularly, greater than 4 m should be left between tree crowns, and trees or shrubs in this category should not be within 10 m of structures.

Moderate

Most of these species produce heavy accumulations of flammable litter and elevated dead material, and/or have flammable green foliage. Not recommended for green breaks or for planting in defensible space.

Moderate/High

Species may have flammable green foliage and/or produce high levels of litter and elevated fuel. Not recommended for green breaks or defensible space.

High

Burn readily at Low/Moderate forest fire danger conditions.

Low flammability species

Fuchsia excorticata  Kotukutuku
Pseudopanax crassiofolius

Horoekea/Lancewood

Pseudopanax arboreus Five finger
Coprosma robusta Karamu
Coprosma grandifolia Raurekau/Kanono
Geniostoma ligustrifolium Hangehange
Coprosma australis Raurekau
Coprosma repens Taupata
Carpodetus serratus Putaputaweta
Corynocarpus laevigatus Karaka
Griselinia littoralis Papauma/Broadleaf
Griselinia lucida Puka
Macropiper excelsum Kawakawa/Peppertree
Solanum aviculare Poroporo

Low/moderate flammability species

Hebe salicifolia and H. stricta Koromiko
Melicytus lanceolatus Mahoe/Whiteywood
Aristotelia serrata Mako-mako/Wineberry
Coriaria arborea Tutu
Myoporum laetum Ngaio
Pittosporum crassifolium Karo
Pittosporum eugenioides Tarata/Lemonwood
Hoheria spp Hoheria/Lacebark
Knightia excelsa Rewarewa
Nothofagus menziesii Tawhai/Silver beech
Phyllocladus glaucus Toatoa
Plagianthus regius Manatu/Ribbonwood
Weinmannia racemose Kamahi

Moderate flammability species

Beilschmiedia tawa Tawa
Cordyline australis Ti kouka/Cabbage tree
Pittosporum tenuifolium  Kohuhu
Dacrydium cupressinum  Rimu
Metrosideros umbellate Southern rata
Agathis australis Kauri
Phormium spp. Flax
Podocarpus dacrydioides Kahikatea/White pine
Weinmannia silvicola Tawhero/Towhai

Moderate/High flammability species

Podocarpus totara Totara
Dodonaea viscosa Ake-ake
Cyathea and Dicksonia spp.  Tree ferns
Cyathodes fasciculate Mingimingi

High flammability species

Kunzea ericoides Kanuka
Leptospermum scoparium Manuka

For further information