Innovation and research to inform restoration of threatened species habitat

Establishment of trial site at Oatlands to research constraints of direct seeding.

We strive to ensure that our restoration of threatened species habitat continues to be leading edge, effective and efficient. That is why we are engaged in new research trials as part of our Tasmania Island Ark program to understand and overcome the constraints on successful direct seeding of native species.

In the variable climate of Tasmania, direct seeding has met with mixed results. We are working with University of Tasmania (UTAS) researchers and students from the ARC Centre for Forest Value across five sites in the Tasmanian midlands to investigate the effects of five innovative direct seeding treatments.

One of these treatments is to cover the direct seeding line with polymer film, a fine plastic which has been successfully used for agriculture and horticulture to improve crop yields and overcome water scarcity.

Direct seeding machine

Greening Australia is also working with Integrated Packaging, the CRC for Polymers research group and CSIRO to test whether the use of polymers is suitable for restoration and revegetation work. The polymer selected for the study has been especially designed to degrade over a period of two to three months when exposed to oxygen and sunlight.

“Early trials near Cressy show that the use of polymer film improves germination by creating a hothouse environment for seedlings to grow in. We are investigating whether this translates to other sites and if it works in the longer term to improve establishment and persistence of seedlings,” says UTAS researcher Dr Tanya Bailey.

“Our direct seeding machine scalps the soil, sows the native seeds and lays down the polymer film in one go.”

“It’s a delicate balance. If the polymer is removed too quickly, the seedlings go into shock due to the temperature change and there is a crash in survival rates. Leave it too long and the seedlings can get cooked by the sun during the hotter months.”

The work builds on Greening Australia’s polymer innovation trials in South Australia and Victoria.

Honours student, Yolanda Hanusch, monitoring seed predation by insects.

In addition to polymer film, UTAS researchers are studying the benefits of four other treatment types: once monthly irrigation, caging of individual plots to exclude browsing animals, insecticide application to reduce seed predation, and the use of wetting agents.

PHD student Claire Ranyard and Honours student Yolanda Hanusch from UTAS, are conducting additional research projects.

“Claire is looking at the constraints on the success of direct seeding whilst Yolanda is looking at the predation story – the influence of insects on plant establishment, particularly seed harvesting and predation by ants.”

“Claire is also very interested in seeing how the species mix of our restoration sites can be improved. In Tasmania, most direct seeding ends up being dominated by Acacias. We want to develop a way of addressing this imbalance.”

“Australia presents a lot of challenges for restoration work. The climate is unpredictable. The soils are very variable. Each direct seeding site faces each own challenges and constraints. Our research is helping to uncover how best we can overcome these.”

Oatlands to research site

The five year research projects are funded through the Australian Research Council (ARC) Centre for Forest Value, of which Greening Australia is an industry partner.

“This is a great opportunity to leverage the long-term research partnership between Greening Australia and the University of Tasmania to understand the constraints of direct seeding and improve restoration success for the long term benefit of some of Australia’s most endangered mammal species,” says Tanya.

Tasmania Island Ark is a major Greening Australia initiative to reverse the decline of threatened mammals in Tasmania, through restoring native habitat.