How fire affects NSW plants and animals
Fire heats the soil, cracking seed coats and triggering germination; it triggers woody seed pods held in the canopy to open, releasing seed onto a fresh and fertile ash bed; it clears thick understorey reducing competition for seedlings; it encourages new growth that is food for many animals; and, it creates hollows in logs and trees that are used by animals for nesting and shelter. It can also burn vegetation communities such as rainforest that take hundreds of years to recover, kill threatened species, cause erosion and subsequent sedimentation of creeks and wetlands and open areas up to the impacts of weed and feral animal invasion as well as human access and vandalism.
Fire and plants
Many of the plants of NSW have evolved in the presence of fire for thousands of years and have developed adaptations to allow them to survive in a fiery environment. Large sections of wet sclerophyll, rainforest and wetlands however, also exist in NSW. These areas have evolved in the wetter or cooler areas that are not impacted as heavily by fire and they do not have adaptations to cope with successive fire events. It may take hundreds of years for some of these communities to fully recover from a fire.
The time between successive fire events is the fire regime. All plants in NSW are adapted to a specific fire regime and are able to recover from a fire (reach maturity and produce sufficient viable seed) within the time between fires of that fire regime. Where this fire regime is altered through successive prescribed burning or bushfire events (increasing the fire frequency) or by effective fire suppression and fire exclusion (reducing the fire frequency) then those plants that have adapted to the original fire regime may die out to be replaced by plants that are more adapted to the new fire regime. The ecological consequences of high frequency fires have been listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.
This has fundamental implications for prescribed burning for hazard reduction. Prescribed burning can change the fire regime by increasing fire frequency eliminating rainforest and wet sclerophyll species and promoting more fire tolerant species which in turn burn hotter and more readily thus increasing the hazard in the area and the requirement for more prescribe burning for hazard reduction.
Many plant species are able to re-shoot from protected buds called epicormic buds, on their stems or roots that enable them to recover rapidly after a fire event. Thick bark protects these buds from the damaging heat of fires.
Plants most vulnerable to altered fire regimes are those that can only regenerate from seed, called obligate seeders. Generally obligate seeders are killed by fire and rely on seeds that they store in the soil or in woody capsules on the plant to regenerate. If fires occur too frequently these species may not be able to reach maturity to produce seed and will not persist. Infrequent fires on the other hand will also affect these and other species that rely on fire to stimulate germination of seeds or regeneration. A lack of fire or too infrequent fire will result in senescence where these species grow old and die and their seeds rot in the soil before they have the opportunity to be germinated by fire.
Fire and animals
Fires can have an impact on native animals. In most cases populations will not be affected as native animals will recolonise a burnt area from surrounding areas after a fire. Where a species population distribution is limited or the species is listed as vulnerable or endangered on the Threatened Species Conservation Act 1995 however, a significant fire event can impact these populations.
Native animals can escape fire by fleeing to unburnt islands within the burn area or to surrounding unburnt vegetation. Insects, reptiles and small mammals may be able to hide underground and arboreal animals will move up into the treetops to escape low to moderate intensity fires. Birds are the least impacted as they have the ability to fly away however, chicks and eggs can be impacted depending upon the season of the fire.
The impact of prescribed burning on native wildlife is considered carefully during fire planning and detailed in environmental impact assessments. Detailed environmental impact assessments ensure that DECC plans prescribed burns so they have the minimal environmental impact to achieve the objectives.
Page last updated: 07 December 2015