BOTANICAL SCIENCE
RESCUING
GONDWANAN RAINFORESTS WORKING WITH INDIGENOUS COMMUNITIES AND LAND CARE GROUPS, SCIENTISTS ARE EXPLORING WAYS TO PRODUCE RESILIENT POPULATIONS OF RARE RAINFOREST PLANTS,
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he Gondwanan rainforests of northern New South Wales and southern Queensland are one of the most unique set of ecosystems in Australia. Sadly they are also one of the most threatened. It is estimated that just 1% of these rainforests remain – the rest largely lost to the logging and land clearing associated with the expansion of agriculture in these regions over the past 200 years. These rainforests, which are found between Newcastle and Brisbane, are termed Gondwanan because when Gondwana existed (from 500 million years ago until it started to break up between 180-100 million years ago) it was, according to fossil records, covered by rainforests containing similar kinds of species that are living in these locations today. As a result, these rainforests have been designated World Heritage areas, and much of the existing rainforest has been protected in national parks. These ecosystems have long been a focus of interest to the Gardens and its scientists. If you wander round the Royal Botanic Garden Sydney, you will notice that many of the mature trees come from these ecosystems and previous directors such as Charles Moore and Joseph Maiden were particularly fond of planting species from these regions.
22 THE GARDENS AUTUMN 2022
More recently our focus has turned to rescuing at-risk species and enhancing the restoration and rehabilitation of these forests in northern NSW. Apart from the long-term impact of logging and land-clearing, these forests now face a number of new threats. In the Black Summer fires in 2019/20 we saw quite extensive impacts on these ecosystems – rainforests, as the name implies, are not expected to burn, not adapted to bushfire, and when they do burn it takes years, even decades for many of the species to recover. Additionally, many of the rainforest species in the family Myrtaceae are very susceptible to the exotic fungal disease Myrtle Rust. The combination of warm, wet weather and very susceptible species has seen this disease proliferate to the point where there are an estimated 16 species of rainforest Myrtaceae at imminent threat of extinction from the disease. In order to address these issues sustainably we need to find answers
‘Many of the plant species are of great cultural significance to indigenous people’
to a number of complex challenges – including how to collect, store and generate seed and other germplasm and how best to produce resilient populations of plants that will not only survive but will produce the next generations of plants. Our current areas of focus with respect to Gondwanan rainforests are centred on understanding the genetic resilience of the species in these forests – a critical factor given the shrinkage of these populations as outlined above – and on determining better ways to collect and store the seed of rainforest species. This latter factor is important as it may provide an opportunity to preserve at-risk populations of species and to extend the life of seed, which for many rainforest species can only be used freshly picked. Many of the plant species in these forests are of great cultural significance to Indigenous people. Species like Black Bean (Castanospermum australe) and the Bunya Pine (Araucaria bidwillii) were important food sources and, where the trees were located at some density, sites of congregation and celebration. Given this, it is not surprising that efforts were made to cultivate these trees, and Professor Maurizio Rossetto from our team at the Research Centre for Ecosystem Resilience – working with PhD student
Photos: © Royal Botanic Gardens and Domain Trust
ENSURING THEY SURVIVE AND THRIVE. BRETT SUMMERELL REPORTS.
