Geography and distribution
Before the bush fires of February 2009, shining nematolepis was believed to be confined to a single population within a few hectares in the upper catchment of the Yarra River, about 80 km east of Melbourne, Australia.
The habitat it resided in was a narrow transition area between tall eucalypt forest, dominated by the worlds tallest flowering plant, mountain ash (Eucalyptus regnans), and cool-temperate rainforest dominated by southern myrtle beech (Nothofagus cunninghamii).
Post-fire regeneration and water use
The only known population of shining nematolepis was in the upper catchment of the Yarra River. This area forms part of the protected water catchment that supplies Melbourne, the second largest city in Australia, with a population of around 3.8 million people. Melbourne’s water supply has been steadily dwindling through decreasing rainfall, at a time of increasing population, and currently capacity stands at only about 35% and decreases below 30% during summers.
Habitat of Nematolepis wilsonii (Photo: Neville Walsh, Royal Botanic Gardens, Melbourne)
One consequence of the 2009 fires that burnt about 30% of Melbourne’s catchment area is that the post-fire regenerating forests will consume up to 50% more water than did the mature mountain ash forests they are replacing. Many of the original forests included trees that were around 300 years old, and these are the sorts of timescales that are projected to be required for run-off rates to return to their pre-Black Saturday levels.
Overview: This member of the Rutaceae (citrus family) is an attractive shrub or small tree, to 10 m tall, with mottled bark. The branchlets are covered in small protuberances.
Leaves: The leaves are lance-shaped to narrowly elliptic, 30-80 mm long and 5-15 mm wide, with a smooth and glossy upper surface and a lower surface covered with silvery scales.
Flowers: The small, star-like white flowers are borne on inflorescences of 1-9 flowers.
Fruits: The fruit is capsule-like with up to 5 single-seeded segments.
Threats and conservation
Sambar deer (Cervis unicolor)
As well as the ever-present possibility of summer bush fires, one of the most serious threats to shining nematolepis is the sambar deer (Cervis unicolor). These deer are native to southern Asia (including India and Sri Lanka), and were introduced into south-eastern Australia in the 1860s by the Victorian Acclimatisation Society who sought to ‘improve’ the impoverished Victorian bush by adding species regarded as valuable for food, recreational hunting, or other resources such as timber.
The past few decades have seen an explosion in sambar numbers and expansion of their range into new sites. While Nematolepis is not a favoured food-plant for sambar, their stems appear to offer just the right texture and resistance for the stags to ‘de-velvet’ their new antlers each spring, and in doing so they effectively ring-bark saplings and mature Nematolepis plants. They are preferentially sought out by sambar for this activity, and up to 10% of previously monitored individual plants had been killed or severely damaged by them prior to the fire, whereas plants of similar stature of other associated species remained untouched.
Prior to the fires, about half of the population of Nematolepis had been fenced-in to protect them from deer.
Prior to the 2009 fires, shining nematolepis was the subject of a translocation programme that sought to establish several new populations in secure sites nearby, in a separate sub-catchment of the Yarra River. Due to the same drought that caused February 2009 to be such a severe fire season, plants were not planted into their new homes (which incidentally and fortuitously were not burnt), but were maintained at the Royal Botanic Gardens, Melbourne and Royal Botanic Gardens, Cranbourne.
Like many capsular-fruited Rutaceae (tribe Boronieae), N. wilsonii initially proved difficult to germinate, so much of the material for translocation was grown from cuttings from 31 parent plants, sampled across the population to provide some genetic diversity in the founder population.
Seedlings were not too uncommon in the wild – appearing at the edge of a small track that traversed the population, and on areas disturbed by mammals such as the native wombat (Vombatus ursinus), and the introduced sambar deer. Scientists found that the seeds needed time in the soil in nature, germinating after a suitable period following soil disturbance.
Consequently, the translocation programme was designed to include seed addition near the plots where the nursery-grown plants were to be installed. It was hoped that, in time, plants produced in situ, would establish to create self-sustaining populations. Laboratory tests have now shown that N. wilsonii will germinate readily if exposed to a prolonged chilling (5˚C) period for 2 months. In nature, this corresponds to a winter dormancy and germination the following spring – a good strategy as spring is the season of maximum rainfall in the plants’ natural habitat.
None known, but the closely related N. squamea has the common name of ‘Lancewood’ suggesting its use as a spear by aborigines.
Millennium Seed Bank: Seed storage
In February 2009, bush fires wiped-out all wild plants of shining nematolepis (Nematolepis wilsonii). Fortunately, Kew’s partners in Australia had already collected seed from this species.
Shining nematolepis was a target species for the Millennium Seed Bank Partnership (MSBP), supported by Victorian Conservation Seedbank, and good representative seed collections had been made from across the population of about 200 mature plants, before they were destroyed in the bush fires.
Kew's Millennium Seed Bank Partnership aims to save plant life world wide, focusing on plants under threat and those of most use in the future. Seeds are dried, packaged and stored at a sub-zero temperature in our seed bank vault.
Description of seeds: Average 1,000 seed weight = 1.52 g
Number of seed collections stored in the Millennium Seed Bank: One collection duplicated at the RBG Melbourne Victorian Conservation Seedbank, and RBG Kew Millennium Seed Bank. A total resource of some 16,000 seeds
Germination testing: Successful
Flower of Nematolepis wilsonii (Photo: Neville Walsh, Royal Botanic Gardens, Melbourne)
Grows readily from semi-hardwood cuttings. Plants used for translocation were grown in coconut fibre pots that avoided root-binding and could be planted entire. Seedlings have been successfully produced by chilling the seed at 5˚C for eight weeks prior to sowing.
Although there was still no seedling recruitment of N. wilsonii after three months from the fires, subsequent visits in spring detected thousands of healthy seedlings. Although this is not a surprising response for the hard, black-seeded Rutaceae that are common in temperate Australia (eg species of Boronia, Correa, Zieria) there were fears that, owing to the intensity of the fires and the deep-burning of the humus-rich soils at the known site, the soil-stored seed bank might have been destroyed. Most of the emerged seedlings have been fenced for protection against animals or accidental damage and are being monitored on a regular basis.
A bonus of the work surrounding the establishment of a ‘new’ population and monitoring of the emerged seedlings, has been an increased awareness of the plant by staff from Parks Victoria who manage the land where the plant occurs. This has resulted in the detection of a second population of N. wilsonii by Parks Victoria staff while checking on a site for a rare mammal, the broad-toothed rat (Mastacomys fuscus) within an area burnt on Black Saturday. This population was largely but not entirely burnt in the Black Saturday fires and numerous seedlings, as well as the handful of surviving adult trees, have been included in monitoring activities.
As plants mature, seed will be harvested from this population, providing a wider genetic representation of stored seed for the species.