The two Acacia implexa were mulched with grass clippings by local residents. Local residents mow and slash grass along a strip in the nature reserve behind their back fence and spread the clippings in the nature reserve.
According to observations of Friends of Mt Majura (FoMM) the spread of grass clippings was and still is the main source of Chilean Needle Grass (CNG) infestations in the reserve east of Rivett Street which is threatening the conservation work of the volunteers. Members of FoMM reported both the spread of grass clippings and the spread of invasive grass to the land manager since 2004 ie for 19 years. The land manager is now helping to speed up the spread of CNG by slashing during peak seeding time. See also nearby sighting of CNG with comment https://canberra.naturemapr.org/sightings/4469055.
CNG is a Weed of National Significance, highly invasive, and able to transform ecological communities. It is a priority weed of the land manager.
I took this photograph for documentation of the problem. Unfortunately, land manager staff change frequently and volunteers are not believed.