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)
Conservation managers considering the implementation of nest boxes programs need to give careful consideration to design, colour, placement and shade profile of nest boxes.
The vast brigalow forest that extended from northern New South Wales to southern Queensland has been cleared in the space of 60 years and it seems that many species have become threatened as a result. Rod Fensham and co-workers have identified the plant species that are likely to have become threatened and many of these species were not previously recognised as imperilled.
Monitoring is fundamental to good policy and effective conservation management. Data derived from monitoring underpin the process for listing of species as threatened, which is a precursor to recognition in policy.
TSR Hub researcher David Lindenmayer and colleagues embarked on a four-year case study examining the impacts of a biodiversity offset which established nest boxes to compensate for the losses of natural tree hollows caused by the widening of sections of the Hume Highway (the road linking Sydney and Melbourne).
In recent months you may have noticed some energetic public debate about what is the biggest threat to threatened species in Australia. Is it feral cats and foxes or is it the clearing and degradation of native vegetation?