Nightcap oak translocation

Under the Saving our Species (SoS) program, NPWS Threatened Species Officers carried out the translocation plantings within the Nightcap Range in north-eastern NSW.

The endangered Nightcap oak (Eidothea hardeniana) is an ancient species that dates back to Gondwanan origin. Its range has contracted over millions of years and it now occurs in just a single population of less than 150 mature individuals in the wild.

Threats to this single wild population include wildfire, weeds and lack of ecological knowledge. Under SoS, these threats have been carefully assessed and there are several management actions being implemented to protect this ancient species, one of which is establishing insurance populations.

Seeds and cuttings

An important step in establishing insurance populations was to collect seeds and cuttings. In 2020, a total of 416 seeds were collected from 54 trees, and an additional 103 seeds were collected from 29 trees in 2021.

These seeds have been propagated in a nursery specialising in rainforest species. Notoriously difficult and slow to propagate, efforts by the nursery specialists resulted in 50 seed-grown plants, with another 20 seeds expected to germinate in spring 2021.

In addition to propagation by seed, SoS has partnered with the Australian Botanic Gardens Mount Annan to propagate the species using vegetative cuttings. This work is based on the results of a genetic study undertaken by the Royal Botanic Gardens Sydney (RBGS).

Plants grown from cuttings will supplement those grown from seed to provide a genetically representative planting at each of the eight translocation sites.

Ensuring long-term conservation outcomes

The first translocation involved 20 seedlings propagated from seeds collected in 2020 and 2021, being planted at four different sites in Nightcap National Park. Over the next two years SoS aims to establish more than 200 translocated plants at eight sites in Nightcap and Mount Jerusalem National Parks.

The sites for the translocation were selected using scientific modelling and based on current and predicted habitat suitability, including under future climate scenarios.

At each of the translocation sites, the population of planted individuals is genetically diverse so that future populations are representative of the current known wild population.

Translocation sites will be visited biannually for the first two years and annually after that for maintenance and monitoring. Where rainfall is less than expected, additional visits will be made to provide supplementary watering and mulching.

The next planting is planned for late spring 2021 and will consist of 30 plants grown from seed being established at the remaining four translocation sites.

Establishment of these translocated Nightcap oak seedlings and cuttings will increase the wild population of this ancient species over time and ensure its long-term conservation.

In addition, the NSW National Parks and Wildlife Service in partnership with SoS is working with RBGS to determine if there is a need to replace individuals lost in the 2019 bushfires by supplementing the existing wild population with plants grown from cuttings.

Learn more about the Nightcap Oak.