In the 1970s Sydney former industrial chemist Joan Bradley and her sister Eileen developed an approach to regenerating the Australian bush in the reserve adjoining her home at Clifton Gardens on Sydney Harbour.
Later to become known as the Bradley Method of Bush Regeneration it involved:
- Careful preliminary survey work to identify the native and weed plant species on a site
- Commencing weed removal in areas of bushland where the weeds were sparse and then moving gradually into areas of denser infestation
- Following weed removal the leaf litter was carefully replaced and the soil disturbed as little as possible to discourage weed regrowth
- The weeding was not to be hurried. A worker would advance in stages into areas of denser weed infestation allowing native plants to germinate and regrow in the area just worked before proceeding further.
The Bradley Method also became known as the Minimal Disturbance Method.
After considerable investigation and consultation the Bradley Method was adopted for use at the National Trust’s Blackwood Sanctuary at Beecroft.
Mosman Council was the first council to fund the undertaking of a Bushland Survey by the Trust. The first of many such surveys this involved detailed mapping of the bushland and its condition.
In the early eighties Councils such as North Sydney, Manly, Kogarah, Hurstville and Ryde approached the Trust to carry out Bush Regeneration surveys of their local reserves and subsequently commissioning the Trust to undertake Bush Regeneration work on a contract (paid) basis.
A period of rapid expansion ensued with the workforce increasing in numbers dramatically. Most of the Councils in the Sydney area were surveyed and work spread to a number of regional locations such as Wingham Brush, Rotary Park (Lismore) and North Entrance Peninsula.
In the mid 1980s newly appointed Trust Conservation Director Chris Pratten arranged a seminar to investigate Bush Regeneration methods and arranged for the creation of a new National Trust Bush Management Advisory Committee to underpin the scientific basis of the Trust’s Bush Regeneration work.
It was finally determined a new approach would be adopted by the Trust. This incorporates some of the careful labour intensive techniques of the Bradley Method in areas of healthy bushland with few weeds but also adopts a more pro-active approach to the clearance of weeds in the heavily infested bushland.
This change in approach was predicated on a number of conclusions:
- If not treated, heavy weed infestations such as Lantana and Privet would continue to provide a weed propagule source for birds to re-infest adjoining bushland. Many of these infestations were upslope and weed seed and bulbs would be carried downslope into the bushland
- These weed infestations often surrounded bushland reserves and it became increasingly difficult to convince councils that progress was being achieved while the most visible weeds remained.
- The availability of newer herbicides such as Glyphosate allowed the development of “cut and paint” techniques for quicker and easier control of large weed trees such as Privet and Camphor Laurel. This herbicide was also used in a “cut and dip” technique to control the Wingham Brush vine infestations with spectacular results. It should be noted that this herbicide was not available when the Bradley’s developed their method.
- It was acknowledged that disturbance itself is a catalyst for regeneration. While densely covering weeded areas with leaf litter would suppress weed growth it also suppressed the growth of native plant seedlings. This effect can also be seen along bushland tracks where the number of species may increase in comparison with adjoining bushland due to the disturbance, bare soil and extra light.
At this time the Trust also consulted with the Fire authorities on the use of fire to promote regeneration of native plant species. Deliberate burning was problematic. Intense, infrequent fire would generally promote native plant regeneration. But frequent, cooler burns (those advocated by the fire authorities to reduce flammable loads and fire hazard) achieved less effective regeneration and could reduce species diversity and lead to local extinction of species.
The Trust pioneered the field of Bush Regeneration, is about to celebrate its twenty-fifth anniversary in Bushland Management and continues its work with numerous local government authorities.
The Trust is the key Australian community heritage conservation organisation and Bushland Management is one of its most visible and important programs employing a highly trained, talented and committed workforce and providing vital funding for the broader work of the National Trust.