Indicator: Changed fire regimes

| Indicator description | Complete list of Indicators |

What the results tell us for Tumut

No information was obtained for this indicator for this 2000 State of the Environment Report.

Frequency over time, intensity and area/type of vegetation affected were not available for the 1997 State of the Environment Report, either. However, Council had reported that there were 16 fires in the Tumut Shire during 1996–97.

One-third of the Council's area is native grassland, land cleared for grazing and/or agriculture or dry forest. Grassfires pose a threat to native grassland communities and their species, as well as leaving the ground bare and susceptible to erosion.

About the data

Comments were extracted from the 1997 state of the Environment Report for Tumut Shire.

Description: What does 'changed fire regimes' measure?

Which data are collected?

• area and proportion of different vegetation communities and selected species affected by low and high intensity burns for medium and large fires, in relation to ecosystem requirements
• total number and area of "controlled burns" and wildfires each year

Why do we report this indicator?

A fire regime is a long-term pattern of fires, defined by their frequency and intensity and the season in which they occur. Many of Australia's native plants and animals show evolutionary adaptations to pre-European fire regimes (rather than to fire itself). Changes to these fire regimes impact on native ecosystems, indicating the pressure of European settlement on our biodiversity.

Fire frequency in native ecosystems can vary from ten or so years for some heathlands (and perhaps less for grasslands) to a few hundred years for wet eucalypt forests. Frequency affects intensity because biological litter accumulates between fires. For example, fires in the south-eastern forests are more frequent since European settlement than they were during sole Aboriginal occupancy. Plants species that are better-adapted to more frequent fires clearly are at an advantage in such situations, while species that do not set seed until they are several years old will be disadvantaged and possibly eliminated in the medium to long term.

Conversely, excluding fire from some areas (e.g. bushland fringing urban areas) may lead to the loss of species which require fire to germinate their seed: this may include short-lived species, like many heathland plants, and long-lived ones, like Alpine Ash (Eucalyptus delegatensis).

Current fire regimes, including the incidence of "wildfires", in relation to ecosystem requirements are of concern to State of the Environment reporting because they indicate the pressure on native ecosystems of human activities in the environment.