Nightcap oak conservation project
The endangered nightcap oak is an ancient species with less than 150 mature trees remaining in the wild. NSW National Parks is working with the Saving our Species program and partners to ensure this rare species' survival.
Once widespread across Australia’s Gondwana rainforests, it survives today in a single, endangered population in the Nightcap Range, north of Lismore.
As few as 150 mature trees remain in the wild, making this small, isolated population at very high risk of extinction.
Threats including wildfire and human disturbance have impacted habitat condition and species abundance, damaging exposed roots and fragile soils, and introducing invasive weeds and pathogens.
Under the Saving our Species (SoS) program, NSW National Parks and Wildlife Service (NPWS) are working with partners to manage risks and establish insurance populations.
A problem with dispersal
The nightcap oak belongs to a group of relict Gondwanan rainforest trees that have a common problem – they produce huge, nut-like seeds that no creature in their habitat today can swallow or move.
With the loss of animals like the pygmy cassowary, which is thought to have once dispersed the nightcap oak’s seeds, this species can’t expand its range. Even the largest rainforest seed couriers, like the wompoo fruit-dove and grey-headed flying-fox, are unable or uninterested in gobbling up and dispersing oak fruits.
Instead, seeds fall to the ground. While native rodent species are known to move the fruits short distances, they generally eat the seeds. So the trees are contained to their small site.
4 facts about the nightcap oak
1. An ancient species
The nightcap oak is just as old and rare as the well-known wollemi pine, with evidence of its existence dating back over 40 million years.
It can grow up to 40m tall, though most trees are smaller. The nightcap oak belongs to the proteaceae plant family, which includes banksia and grevillea.
While adult trees have dark green leaves with smooth edges, young trees are orange to red, their leaves have distinctive red veins and stalks and toothed leaves.
2. The missing link?
So how were nightcap oak seeds moved across the landscape in the distant past?
In 1891 a fossilised section of the lower leg of what palaeontologists believe was an ancient rainforest-dwelling pygmy cassowary, was discovered in regional NSW. It appears the pygmy possum lived in what’s now NSW, until it went extinct during the Pleistocene Age, 2.5 million to 11,700 years ago.
3. Stranded seeds
Creamy flowers bloom mid-October to mid-November, which are mostly pollinated by small nocturnal beetles.
The globular fruit of a nightcap oak takes over a year to develop to its full, 4cm long size. It changes colour from green to yellow as it matures, from mid-December.
Without the pygmy cassowary to move seeds around, by early March fruits fall to the ground, providing a feast for native bush rats, and an opportunity for scientists to collect seeds to propagate.
4. Out of harms way
As the Earth’s climate becomes increasingly warmer and unstable, more species will rely on human interventions to move them out of harm’s way.
Specially-grown new nightcap oak plants are being translocated to establish ‘insurance’ populations higher up from their current, vulnerable distribution at 400-800m above sea level, to suitable rainforest habitats at 800-1200m.
At higher elevations the air temperature remains cooler, rainfall is higher and climate more stable. This offers critical protection against devastating wildfires, like in 2019 when around 20% of the wild nightcap oak population was affected.
Propagation and translocation
It’s now up to scientists to take up the job of establishing new populations of nightcap oak, to increase the wild population and ensure its long-term survival.
SoS and NPWS are working with rainforest scientists to collect seeds to propagate nursery stock. Notoriously difficult and slow to propagate, the rainforest specialist nursery has successfully raised more than 50 seed-grown plants, with another 20 seeds expected to germinate in spring 2021.
SoS has also partnered with the Australian Botanic Gardens, Mount Annan to grow plants from cuttings. These will supplement seed-grown plants, and provide genetic diversity for the new ‘insurance’ populations planted at translocation sites in the species predicted habitat under climate change predictions.
Several areas within NSW national parks have been declared Assets of Intergenerational Significance (AIS), providing the strongest legal protections for the nightcap oak and its habitat, to ensure its survival for future generations.
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