Ecological burning - Sunshine diuris (Diuris fragrantissima)

For more than 15 years, we have worked with volunteers from the Australasian Native Orchid Society to restore native basalt grassland habitat. In March 2018, we conducted an ecological burn in grasslands at Sunshine in Melbourne’s west to decrease the density of the kangaroo grass, which was smothering wildflowers. One of these flowers was the Sunshine Diuris (Diuris fragrantissima), a beautiful, white orchid, also known as the fragrant doubletail. It has a distinctive and attractive scent that people enjoy wafting across a sunny, native grassland plain.

The Sunshine Diuris is endangered, the only known wild population is limited to 40 individuals from a single site of native basalt-plains grassland at Sunshine. Our Port Phillip Natural Environment Program is responsible for this orchid’s survival by permanently reserving the Sunshine site and delivering fire management to restore its grassland habitat. This orchid, and the native grassland habitat it exists in, are fire adapted and without regular burning face extinction. For the orchids to thrive, they need regular fires that occur during their period of dormancy – January to early March. Ecological burns are being scheduled every three to five years during the dormancy period to encourage the Sunshine Diuris to emerge from their dormant, underground, potato-like tubers and help decrease the density of tussock grasses, which creates space for wildflowers to flourish.

We have has worked closely with volunteers from the Orchid Society to ensure that ecological burns benefit the grassland biodiversity. For the March 2018 burn, the area was searched for orchids in the weeks leading up to the burn. Two orchids – visible only as paired, tiny, grass-like leaves – were found and covered with wet ceramic pots to protect them from the burn. Other rare plants and two “bee hotels” (an artificial structure used to provide habitat for native bees and wasps that pollinate the grassland wildflowers) were protected by cutting and raking away the grass, wetting the ground and covering them with wet hessian sacks. After the fire we watered the orchid patch to alleviate the dry conditions.  

The two orchids that had emerged before the burn continued to grow, as did the other rare plants, and native bees and wasps continued to inhabit the bee hotels. By winter 2018, 32 orchids had emerged, and a further 125 were planted in the burn area. Additionally, rare plants spontaneously reappeared after the burn, likely sprouting from seed stored in soil. Wildflower species include plains yam daisy (Microseris scapigera s.s.), geranium species, basalt peppercress (Lepidium hyssopifolium), tough scurf-pea (Cullen tenax) and button wrinklewort (Rutidosis leptorrhynchoides) have also been re-established at the Sunshine site. All the orchids and grassland habitat are monitored as part of a research program for sunshine diuris recovery and the research findings are used to guide recovery actions.

Ecological burning is an important part of an integrated program of management actions that has seen the re-establishment and ongoing improvement of native grassland cover over what, only six years ago, was a weed-infested site. The collaboration between our Natural Environment Program and dedicated volunteers is ensuring that wild sunshine diuris populations will continue to exist into the future.Banner photo credit: Peter Lynch

Page last updated: 15/10/18