The effect of fire on the Australian environment
- Effect of fire on plant communities
- Effect of fire on wildlife populations
- Effect of fire on soil and water
The long term effect of fire on plants and animals varies according to sequences of fire events rather than to a single fire event. Sequences of fire events are known as 'fire regimes'. Fire regimes are determined by: intensity (how severe fires are), frequency (how often fires occur at a place), season (the time of year fires occur), extent (how large the fire is and the spatial pattern), and type (e.g. peat versus forest).
Ecologically appropriate fire regimes across the landscape are important for the protection of native biodiversity. Different plants and animals are adapted to different fire regimes. For example, Mountain Ash (Eucalyptus regnans) regenerates from seed, and therefore may not survive if fires are too frequent as the plants are unable to reach maturity and produce sufficient seed before the next fire episode.
Conversely, excluding fire from some landscapes for long periods and over large areas can threaten ecosystem health. For example, there can be negative consequences if a species is no longer able to reproduce (senescent) or if heavy fuel loads accumulate resulting in large, very intense and ecologically damaging bushfires.
| Effect of fire on plant communities The recurring recovery of native vegetation after fire, where flame temperatures can reach 900oC, is a natural wonder. Native vegetation uses a variety of methods to respond to fire, including resprouting from rootstocks and stems and growing from seed stored in the soil. Other species release seeds from woody fruit on the branches (e.g. banksias, eucalypts), or a combination of these. The period immediately following a fire provides an excellent opportunity for many plant seeds to germinate and grow due to the enhanced light, available nutrients and reduced competition. Fire can have negative consequences for biodiversity. While many plants in forest, woodland, healthland and grassland ecosystems have adaptations to enable them to regenerate naturally after fire, some ecosystems like rainforests, alpine moss beds and peat bogs have a very low tolerance to fire and need to be protected. Species of plants with low tolerance to fire, especially some threatened species also require special protection. Fire is a disturbance that can increase weed invasion and browsing of plants leading to increased pressure on survival of native plants and animals.  Information sheet: Effects of Fire on Victorian Bushland Environments (PDF - 397 Kb) Information sheet: Using Fire to Manage our Parks and Forests (PDF - 365 Kb) Fire and Biodiversity in Victoria (PDF - 290 Kb)page top |   |
| Effect of fire on wildlife populations Like plants, many of our native wildlife species have evolved to survive fire events and some have even developed specialised relationships with fire. Animals survive the fire by fleeing (e.g. birds) or by taking refuge underground (e.g. some mammals, reptiles) or in unburnt patches of vegetation in wet gullies and leeward slopes. Fire also plays an important role in maintaining populations of certain animal species. Fire affects the age, structure and composition of vegetation thus creating habitats which suit different animal species. For example, the Silky Mouse (Pseudomys apodemoides) only lives in diverse heathland vegetation that is between 3 and 10 years post-fire. Although many species of animals do suffer reductions in populations during or immediately after a fire, most populations will recover. After a fire many animals are vulnerable due to shortages of food and/or predation by other species. Therefore targeted predator (fox, cat) control is an important priority immediately following a fire. Of concern are some threatened species, such as the Mountain Pygmy Possum (Burramys parvus), for which disturbance by fire can be an additional pressure on their survival. Information sheet: Effects of Fire on Victorian Bushland Environments (PDF - 397 Kb) Fire & biodiversity - Responding to fire-affected wildlife (PDF - 139 KB)page top | small.JPG)  |
| Effect of fire on soil and water Bushfires can have biological, chemical and physical effects on soils. The occurrence and/or extent of these effects are dependent on the fire's intensity and the resulting temperature of the soil. Generally, only the top few centimetres of soil are affected as they are subjected to the highest temperatures. In high intensity fires, rocks can split and break down due to the extreme temperatures. Microbes and fungi that live in soil are affected to varying degrees depending on the fire intensity, however the functioning of both lifeforms returns rapidly. This process may be supported by the flush of some nutrients which occurs immediately after a fire. The removal of vegetation during a fire exposes the soil to wind and water. These two factors make soils very susceptible to erosion. Fire can affect stream water quality. Erosion may cause soil, ash and nutrients to be transported into streams. This increases the sediment load and the turbidity of the water. These changes have the potential to negatively affect aquatic biota. Fire may also influence the amount of water produced by a forest (that is, the levels of runoff). The quantity of water produced by an area that has been burnt may initially increase, as there is little vegetation, and subsequently little water usage or entrapment. Some time later, however, high water use by regenerating vegetation can reduce water yield from a catchment. Information sheet: Effects of Fire on Victorian Bushland Environments (PDF - 397 Kb)Please note: Document(s) on this page are presented in PDF format. If you do not have the Adobe Reader, you can download a copy free from the Adobe web site. |   |