On the second Saturday of every month, at eight in the morning, a group of between eleven and twenty-three people meets at the Long Gully car park on the eastern edge of Belair National Park, ten kilometres south of central Adelaide.
They unload mattocks, brush hooks, hand saws, and several large plastic jugs of a 50 percent glyphosate solution mixed with a blue dye, and they walk for between twenty and forty minutes into the park to whichever block they are working that month.
The group is called the Belair Olive Removal Group. It was founded in March 2015 by a retired civil engineer named Geoff Whittle and a botanist from the South Australian Museum named Helen Wirra.
Eleven years on, Whittle is eighty-one and still attending most Saturdays. Wirra retired from the museum in 2022 but co-leads the group with a younger botanist, Devika Pillai, who works at the State Herbarium.
The target species is African olive, Olea europaea subsp. cuspidata, which was planted as a hedgerow and ornamental in the Adelaide Hills throughout the late nineteenth century and which has since formed a dense, shade-tolerant canopy across much of the region's remaining bushland.
Belair National Park, gazetted in 1891 and the second-oldest national park in Australia, contains some of the heaviest olive infestations in the state. A 2014 mapping exercise by the Department for Environment and Water estimated that olive was present at greater than 30 percent canopy cover across 612 hectares of the park's 838.
The removal protocol is the cut-and-paint method. A single olive is felled with a hand saw or brush hook at ground level, and within thirty seconds the cut stump is painted with the glyphosate solution. Done correctly, the kill rate is above 90 percent.
Done badly, the olive coppices from the stump within months and returns thicker than before. The group has had to retreat over several areas where 2016 and 2017 work was done without adequate herbicide coverage.
Whittle keeps a paper logbook of every Saturday morning. As of the May 2026 entry, the group had completed primary treatment on 184 hectares and secondary follow-up on 79.
The remaining olive in the park is in steep, gullied country accessible only on foot, which is why park staff have not been able to address it with mechanised methods. The volunteers, who are mostly retired and average sixty-seven years of age, are slow but persistent.
Pillai's contribution since 2022 has been to push the group toward more systematic monitoring. She has set up permanent vegetation transects in three treated blocks, recorded at twelve-month intervals.
The early results are mixed. In the first treated block, a south-facing gully at the western end of the park, the native understory has recovered noticeably, with kangaroo grass, native flax, and several wattles establishing in the gaps left by removed olive.
In the second block, a flatter site with shallower soils, the dominant recoverer has been bridal creeper, a separate invasive that the olive had been suppressing. The group has had to add bridal creeper management to its monthly rotation.
The third block, treated in 2018, has begun to show seedling recruitment from the surrounding eucalypt canopy, which Pillai considers the best sign in the dataset so far.
The work is not glamorous. A Saturday morning produces, typically, between forty and ninety cut stumps per volunteer, depending on the density of the infestation and the steepness of the ground.
There are no photographs in the Group's quarterly newsletter of before-and-after vistas, because the change at the scale of a Saturday is invisible. The change is visible only across years and only to people who have walked the same gullies repeatedly.
Funding is minimal. The Friends of Belair National Park, the umbrella organisation, provides about 1,800 Australian dollars a year for tools and herbicide. The park service provides indemnity insurance and occasional staff support.
Whittle was asked, in a 2024 interview with the Adelaide Hills Magazine, whether he expected the project to be finished in his lifetime. He answered that he did not, and that this was not the point.
The point, as Pillai phrased it on a recent morning while painting a freshly cut stump, is that the work has to be done by someone, and that on this particular Saturday, in this particular gully, the someone happened to be them.
The group will meet again on the second Saturday of June. New volunteers are welcome and are asked to bring their own gloves and water.
