Level 2 invasive flora assessment at Bells Rapids
In March 2023 the City of Swan commissioned a Level 2 Invasive Flora Assessment at Bells Rapids, an area where public access needs to be balanced with protecting native flora and fauna. The aim was to identify, map and categorise invasive weed species.
Method
The work began with a desktop assessment that drew on past reports to build a botanical history of the Bells Rapids area.
The fieldwork was classified as a Supplementary Survey because it took place in winter rather than the optimal spring survey period. The method used:
- Transects: 150-metre transect lines branching off existing tracks, spaced approximately 100 metres apart
- Sampling: the presence and density of weed species recorded within a 10-metre radius on either side of each transect.
Mapping weed density
For larger weed populations, the team mapped polygons to capture the size and density of each infestation, using three categories:
- Low density: less than 5% cover
- Moderate density: between 5% and 75% cover
- High density: over 75% cover.
These data support cost-effective weed control strategies, helping the City direct resources to where they are needed, whether through chemical treatment or manual removal.
Outcome
The assessment gives the City of Swan evidence-based data on invasive species at Bells Rapids to inform targeted rehabilitation. Trace provides environmental assessments for government clients and land managers.
If you manage a reserve or public land that needs an ecological assessment, contact Trace Enterprises.
