Byron Flora and Fauna Study 1999 - Byron Shire Council

A GREENPRINT FOR A SUSTAINABLE FUTURE
Smooth Davidsonia (Davidsonia sp. A FAMILY DAVIDSONIACEAE)
Introduction. Smooth Davidsonia is an ornamental rainforest tree that is of particular botanical interest because it sets no
fertile seed and reproduces only by suckers. Its plum-like fruit are in demand from the bush food industry. Smooth
Davidsonia is named after J.E. Davidson, a pioneer sugar grower at Rockingham Bay in Queensland where the first
specimen of this genus was collected (Floyd 1989). Most of the known populations are in Byron Shire so that long-term
survival of the species depends to a large extent on adequate conservation within our local area.
A Recovery Plan is in preparation. Detailed species outlines have been prepared (Quinn et al. 1995 (NSW) and Barry and
Thomas (1994) (Queensland)).
Conservation status. Smooth Davidsonia is listed on Schedule 1 (Endangered) of the TSC Act, 1995 and has a ROTAP
code of 2ECi (Briggs and Leigh 1996).
Habit. Bushy well-branched suckering tree 5-18 m high.
Flowers. Pink-red in panicles up to 15 cm long, towards the end of leafy shoots. Flowering October to November (Floyd
1989). Pollinators of Smooth Davidsonia are unknown. The size and form of the flower suggest that the vectors are likely
to be small insects. Bees, beetles and ants have been observed visiting the flowers (F. Eliott pers comm.)
Fruit. A purplish-black, obloid to globose, c. 3-4 cm long, 3-5.5 cm diameter. Fruit with 2 or 3 small endocarps, which
have never been found to contain seeds, endocarp surface very shortly fibrous. Fruiting between December and March
(Floyd 1989.
Habitat. Smooth Davidsonia grows in disturbed subtropical rainforest or rainforest margins from 15-260 m altitude. It
has been recorded on metasediments and on basaltic and rhyolitic soils.
Distribution. Richmond River NSW to Currumbin Creek, Queensland. Recorded in NSW from Tintenbar; Broken
Head; Terania Creek; Whian Whian SF; Minyon; Snows Gully NR, Huonbrook; Burringbar; Mooball SF; Bilambil;
North Tumbulgum (Floyd 1989). Details of 13 locations were compiled for the study area, including a previously unknown
record for Blindmouth Road, Main Arm, discovered by the authors during this study.
Regeneration and horticulture. As no fertile seed is known, propagation can only be from suckers (damaging to the
plants) or stem or root cuttings. Cuttings can be struck only with difficulty (Costin 1993).
Economic and cultural significance. The fruit of Smooth Davidsonia is sought after by the bush food industry for the
eating qualities of its plum-like fruit. Otherwise, no particular use or significance is known apart from the aesthetic and
ecological values of all native rainforest species.
Abundance and reservation. The populations known in Byron Shire range from large clumps with numerous mature
stems to single stems, and include some of the most important populations known. Smooth Davidsonia is inadequately
reserved (Briggs and Leigh 1996). Conservation measures for the plants that occur on private land are therefore of
particular significance. In Byron Shire, one population is reserved at Snows Gully NR. All other populations in the Shire
are on private land.
Threats and amelioration. Clearing, lack of seed production, weeds and fire (Quinn et al. 1995). In addition, some sites
are grazed. Collection of propagation material for bush food plantings is an additional threat. As Smooth Davidsonia does
not set seed it has no capacity to colonize new sites. If, as seems likely, all individual stems within each population are
vegetatively connected it follows that there is very low genetic diversity within each population. This poses a long-term
threat to the viability of the species (Quinn et al. 1996).
To improve the conservation status of Smooth Davidsonia, the health of the populations and their regeneration potential
should be enhanced by weed management, grazing exclusion, fire protection and replanting of surrounding habitat.
Controlled propagation of Smooth Davidsonia to make plants available for bush food plantings will reduce the likelihood
of illegal and damaging collection of suckers.
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