Nillumbik roadside conservation significance

A standardised Rapid Habitat Assessment methodology was applied to evaluate the habitat value provided by roadside vegetation. 

1,433km of roadsides were assessed in September and October 2025. The habitat factors considered included:

• the number of trees with a diameter at breast height (DBH) of >50cm (large trees)
• the percentage cover of canopy, understorey and weeds
• the proportion of indigenous woody plant species recruiting
• natural regeneration of native plants
• the cover of organic litter (e.g. leaf litter)
• the length of logs and other coarse woody debris present
• habitat patch size
• connectivity to nearby native vegetation and bushland.

It was undertaken by ecologists from the consultancy Trec Land Services. They majority of the assessment was undertaken from a slow-moving vehicle, with some supplementary inspections completed on foot.

Detail on the methodology and limitations is available to view here. Will be uploaded shortly.

The last Shire-wide roadside conservation assessment of Nillumbik was undertaken in 1997. Further partial assessments were completed in 2005 and 2010. Where available and appropriate, the data produced by the previous assessments was considered in this update.  

High Conservation Values - These roadsides have strong habitat values and important biodiversity features such as large trees, canopy cover, remnant vegetation and habitat connectivity.

Medium Conservation Values - These roadsides retain some important habitat features but also show signs of disturbance or habitat decline.

Low Conservation Values - These roadsides have fewer habitat features, often due to historical clearing, the presence of infrastructure, weed invasion and urban development pressures.  

The 2025 assessment of 1,433 km's of roadside vegetation found that:

• 52% of roadsides (748 km) have high conservation values
• 28% of roadsides (399 km) have medium conservation values
• 20% of roadsides (286 km) have low conservation values.

Having more than half of all assessed roadsides rated as having high conservation significance values is a strong result for a peri-urban location. These roadsides are generally the highest priority for protection and careful management. 

While medium and low roadsides have lower current habitat values, many still contribute to landscape habitat connectivity, particularly for bird and arboreal mammal species. They may provide opportunities for biodiversity enhancement, especially in locations where the road reserve is wide. 

Other findings include that:

• The presence of large trees is a key strength:
  • large trees are common on 60% of Nillumbik's rural, township and some urban roadsides
  • canopy cover is at or near benchmark levels along 79% of these roadsides
  • these features provide important habitat and movement corridors for wildlife, particularly birds, gliders, Phascogales and other arboreal species.
• Understory is a key challenge:
  • 54% of roadsides have absent (none) or greatly reduced roadside understory
  • only 15% (218 km) of roadsides have understorey that meets benchmark diversity levels.
• Intact, high-quality examples of non-endangered Ecological Vegetation Classes (EVCs) are present on Nillumbik roadsides.  They have the greatest roadside conservation values. There are no intact areas of endangered EVCs on our roadsides.

• The most intact roadside vegetation (key biodiversity hotspots) is generally located in the north and east of the Shire around Kinglake, Strathewen, St Andrews and Christmas Hills - usually adjacent to nature reserves.

• Where roadsides are in more urbanised areas, abut private rural property, or have infrastructure on them such as overhead powerlines, their conservation values tend to significantly decline. 

The 2025 roadside conservation maps(PDF, 4MB) depict the relative habitat values of roadside vegetation across the Shire. 

• roadsides with HIGH conservation values are green
• roadsides with MEDIUM conservation values are orange
• roadsides with LOW conservation values are red

In some instances, one side of a road may have a different conservation value to the other side of the same road.

These conservation value categories provide an indication of habitat value at the time of assessment and should be considered alongside other site-specific information when planning works or management activities along roadsides.

The roadside vegetation assessment results and maps are intended to:

• Provide the community with an insight into the various biodiversity values of roadsides across the Shire
• Support the application of Local Law Clause 63(1)(d) - firewood cannot be collected from high conservation roadsides
• Support the application of the Planning Scheme where development is proposed on a roadside - e.g. new crossover locations
• Support informed roadside works, management and maintenance by Council, contractors and utilities.

The information helps inform:

• long-term roadside and shire-wide conservation priorities
• roadside weed management priorities
• roadside maintenance and infrastructure planning
• road maintenance considerations