Bushfire risk profile, Mallee and Murray Goulburn Bushfire Risk Landscape, 1980–2021
Bushfire risk in Mallee and Murray Goulburn
The figure above shows the modelled bushfire risk profile for the Mallee and Murray Goulburn BRL for the period 1980–2018, and projected changes in bushfire risk until 2021. It shows that:
- In 2017-18, bushfire risk in the landscape was 44%.
- Most of the risk is concentrated in a small number of localities, so the risk profile is very sensitive to small changes in fuel around these places. The influential burns around Inglewood, Wedderburn, Tarnagulla and Rushworth in 2017-2018 helped reduce risk.
- More planned burning in smaller, vegetated blocks around larger, higher-risk communities – such as Inglewood, Wedderburn, Tarnagulla and Rushworth – led to a 13% drop in bushfire risk.
- Most of the remaining risk arises from private farming land and small parcels of vegetation, where it is more difficult to manage fuel with planned burning.
- If we complete all the fuel management activities on the current Joint Fuel Management Program (JFMP) and there is little bushfire activity, modelling indicates that bushfire risk will be maintained at 57% by 2021. If we cannot carry out any of our planned fuel management activities, modelling indicates that bushfire risk will still increase to 57% within the next three years. This is due to fuels re-accumulating in those influential high risk areas which were treated in 2017-18, and which cannot be re-burnt within the 3-year JFMP timeframe.
- As fuels reaccumulate in these areas risk levels will rise, but priority burns in high risk areas will maintain community safety at the highest possible level. Areas where risk is returning will be re-burnt once sufficient time has passed for adequate fuel accumulation and/or maintenance of ecosystem health.
Valuing our environment
Tolerable fire interval across Mallee and Murray Goulburn
The figure below shows the tolerable fire interval (TFI) status of vegetation on public land in the Mallee and Murray Goulburn BRL for the period 2007–18.
Nearly 78% (or 1.62 million ha) of the landscape is comprised of the largely intact Mallee land systems, namely Murray–Sunset — Hattah–Kulkyne, Big Desert – Wyperfeld and the Little Desert. Natural fire regimes and strategic planned burning in these ecosystems drive the trends shown in these figures.
The figure below shows the amount of the vegetation below minimum TFI in 2018 was 27%, with a 2% increase in the amount of vegetation within TFI. In 2017–18, less than 1% of the vegetation was burnt by bushfire or planned burning while below minimum TFI. This shows our strategic bushfire management planning is resulting in carefully considered planned burning to reduce impacts on vegetation below minimum TFI. To enhance ecosystem resilience, the proportions within and above maximum TFI both need to be larger than the proportion below minimum TFI.
TFI status of public land vegetation, Mallee and Murray Goulburn BRL, 2007–18
Growth stage stricture across Mallee and Murray Goulburn
The figure below shows the growth stage structure (GSS) status of vegetation on public land in the Mallee and Murray Goulburn BRL for the period 2007–18.
The figure below shows the proportion of the landscape in the juvenile and adolescent growth stages has fallen over the last 10 years from about 19% to about 12%, while the proportion of mature and old vegetation has risen from about 33% to about 46%. Improvements in fire history mapping may further reduce the proportion of the vegetation with no recorded fire history. To achieve optimal ecosystem resilience in the Mallee land systems, the proportion of mature and old growth vegetation combined needs to be approaching 90%.
GSS status of public land vegetation, Mallee and Murray Goulburn BRL, 2007–18
A large proportion of this landscape has no recorded fire history. Nothing can be inferred about the TFI and GSS of public land with no recorded fire history.