Hungry herbivores, fungal diseases and long hot summers are just a few of the challenges land managers face when attempting to re-introduce a threatened
plant species. But the biggest challenge of all may lie in calculating whether a reintroduction program has been successful.
“When we reintroduce a threatened plant species, we do so with the goal of creating a viable population that will be self-sustaining into the future,” says project leader Dr David Coates, from the Department of Parks and Wildlife, WA.
“The aim of our project [Project 4.3] is to examine the methods we use in our programs, in order to improve our success rates.”
Dr Coates and his team face a series of inter-related problems that begin with the challenges of propagation.
“Some of these species require unusual techniques to get them going, for example we need to use fire to extract the seeds from banksia cones.
“Sometimes seeds don’t propagate easily, either due to the specific soil mix or the difficulty of creating the right conditions. And other times we just don’t know why a particular species struggles to get going.
“We must always remain conscious that in the case of particularly rare species, we don’t have large amounts of seed to begin with, so we need to be very careful. Our margin for error is small.”
Even if the propagation is successful, the team must work to find a suitable habitat to reintroduce the young plants, and ensure there are no immediate threats.
“In Western Australia we are always on the lookout for dieback, which is an introduced pathogen and devastating soil-borne fungal disease. For the most part we can’t really combat it, other than by preventing access by people to affected areas to minimise its spread,” says Dr Coates.
“Both feral and native animal grazing are also threats, they are typically curious about our activities and have a taste for young seedlings. If we don’t fence them out, they will eat everything.
“We also need to keep an eye on the weather. Long hot summers can quickly undo all of our hard work and initial watering may be needed to assist establishment.”
In order to achieve the ultimate goal - a self-sustaining and viable population, a critical number of plants must survive to reproductive maturity.
“This will be a major focus of our research, looking at ways we can both measure and model levels of pollination, reproduction, recruitment and genetic variation. This will be challenging in some cases where the lifespan of a number of the shrubs and trees will usually outlast the lifespan of any given project.”
“We can then benchmark these results against natural populations.”
“It’s essentially a numbers game, where we need to discover how many plants need to be established in order to ensure a species’ survival. At the moment we aim for at least 250, but depending on the species, we may need many more.”
“Our research aims to provide the answers to these questions.”
Image: Lambertia orbifolia - Round-leaf Honeysuckle by Tatters/Flickr (CC BY-NC 2.0)
The Threatened Species Recovery Hub is receiving an additional $2 million to deliver research and scientific advice to help support wildlife and habitat recovery efforts following Australia’s bushfire crisis. The rapid rollout of meetings and expert workshops that were planned as part of this response now faces the added and acute challenge of COVID-19.
Predation by cats is a key threat to at least 123 threatened species in Australia. Better understanding and reducing the impact of feral cats on susceptible wildlife has been a major area of research for the Threatened Species Recovery Hub. Hub Deputy Directors Professors Sarah Legge and John Woinarski take a look at our research to address Australia’s cat problem.
The 2019–20 bushfires have been extensive and – in some areas – of very high severity. Many threatened species have had most of their distributions burnt, and fire is likely to have imperilled many species not previously considered threatened. One of the post-fire challenges to population recovery that many native species will face is increased risk of predation, including by introduced foxes and cats.
Australia has many unique small- to medium-sized mammals, which are vulnerable to predation by cats and foxes, two carnivores introduced to the continent with European arrival. For many of these species, effective conservation means heavy or total suppression of cats and/or foxes.
Oliver Tester from the Office of the Threatened Species Commissioner tells us about the Australian Government’s action on feral cats.