National recovery plan for the Elaeocarpus sp. Rocky Creek (syn E. sp. 2 'Minyon')

NSW National Parks and Wildlife Service, January 2003
ISBN 0 731 36909 2

  1. Habitat
  2. Ecology
  3. Population structure

5. Habitat

5.1 Vegetation

The forest type in which E. sp. Rocky Creek is found corresponds with Floyd's (1990) warm temperate rainforest Ceratopetalum/SchizomeriaCaldcluvia (Suballiance No. 35) and Webb's (1978) simple notophyll vine forest (McKinley et al. 1996).

Species associated with E. sp. Rocky Creek include Ceratopetalum apetalum, Schizomeria ovata, Flagelleria indica, Cyathea leichhardtiana, Hicksbeachia pinnatifolia, Helicia ferruginea, Caldcluvia paniculosa, Sloanea australis, S. woollsii, Archontophoenix cunninghamiana, Calamus muelleri, Cordyline rubra, Linospadix monostachya, Synoum glandulosum and Ripogonum elseyanum. Most sites are in proximity to or include Lophostemon confertus or sclerophyll species such as Eucalyptus pilularis, Euc. microcorys, Euc. grandis and Corymbia intermedia (McKinley et al. 1998).

Pre-logging vegetation maps of Whian Whian State Forest (J. G. Tracey unpublished) show that many of the known E. sp. Rocky Creek individuals occur at the boundary between rainforest and Lophostemon confertus forest type. Much of Whian Whian State Forest has since been logged, with the degree of disturbance varying from light logging to clear felling. Historical vegetation data is not available for other areas (McKinley et al. 1998).

5.2 Soil

Almost all populations occur on rhyolite-derived soil or soils derived from rhyolite and basalt (McKinley et al. 1998). The main Whian Whian State Forest and Mt Jerusalem National Park populations are on rhyolite; the Snows Gully Nature Reserve population is on rhyolite with basalt influence.

The single tree and translocated specimens on the western edge of Rocky Creek are on krasnozem soil, which is probably not indicative of the usual habitat of E. sp. Rocky Creek.

5.3 Other variables

Annual precipitation between 1977-1994 at Rocky Creek Dam averaged 1729 mm with a range of 963 to 3076 mm (Rous Water, unpub.). There is a dominance of high summer/autumn rainfall. The altitude of known populations of E. sp. Rocky Creek ranges between 187 m and 430 m above sea level.

6. Ecology

6.1 Life history and ecology

Flowering and fruiting phenology

Little is known of the phenology of E. sp. Rocky Creek, although flowering and fruiting are said to be erratic (R. Kooyman pers. comm.). To date, only 32 trees have been observed in fruit (McKinley et al. 1996).

The tree near Rocky Creek Dam fruited in July 1993, May to July 1994, late April to mid-August 1995 and in April 1996. Fruiting has been observed from September to November 1995 and April to May 1996 in the populations in Whian Whian State Forest, Snows Gully Nature Reserve and Mt Jerusalem National Park. Six individuals from Site 2 in Whian Whian State Forest produced fruit in 2000/2001(R. Kooyman pers. comm.).

Pollination ecology

Nothing is known of the pollination vectors of E. sp. Rocky Creek. However, the flowers are similar to others of the genus and it is likely that pollinators would include the beetles, flies, wasps and other insects that visit E. grandis flowers (Coode 1984).

Seed dispersal

The dispersal vectors of E. sp. Rocky Creek are unknown. The fruit is blue as in other members of the genus and may be adapted for dispersal by birds (Coode 1984).

Regent Bowerbirds (Sericulus chrysocephalus) and Green Catbirds (Ailuroedus crassirostris) feed on the fruit of E. grandis (Floyd 1989). These two species have been observed in the canopy of the large trees of E. sp. Rocky Creek at Snows Gully Nature Reserve, however, they were not observed to be feeding on the fruit (McKinley et al. 1996). The fruit is likely to be palatable to species such as the Australian Brush-turkey (Alectura lathami) and to other birds known to feed on E. grandis and E. kirtonii, e.g. Wompoo Fruit-Dove (Ptilinopus magnificus), Pied Currawong (Strepera graculina), Rose-crowned Fruit-Dove (Ptilinopus regina), and Topknot Pigeon (Lopholaimus antarcticus). It is possible that the Satin Bowerbird (Ptilonorhynchus violaceus) collect the blue fruits and may assist in dispersal through males raiding each others bowers (B. Moffatt pers. comm.).

Mammals such as the Bush Rat (Rattus fuscipes), the Fawn-footed Melomys (Melomys cervinipes), Grey-headed Flying-fox (Pteropus poliocephalus) and Black Flying-fox (Pteropus alecto) may also be responsible for fruit dispersal (McKinley et al. 1996). Fallen fruit beneath the canopy of individuals trees have been observed with gnaw marks consistent with those of a small mammal (A. Rich pers. comm.).

The fruit may be adapted for water dispersal. Tests carried out by Rich (1995) indicated that fruits have the ability to float for several weeks. Although the known populations are not clustered along the edge of creek banks (like E. grandis), most locations are in close proximity to creek systems (McKinley et al. 1998).

Where there is no possibility of dispersal by water, dispersal of fruit by animals is most likely to account for the occurrence of single trees where no parent tree is located nearby. At Snows Gully Nature Reserve seedlings are found about 30 m from a parent tree in an area where gravity and/or runoff are unlikely to have dispersed the fruits (McKinley et al. 1996).

Seed germination and other propagation

Natural germination of seed is occurring most successfully in Whian Whian State Forest (Sites 1 and 2) and the Mt Jerusalem National Park populations. Nursery attempts to propagate the species from seed have been hindered by a high percentage of infertile fruit and difficulties in inducing germination. Rich (1995) noted that only three healthy embryos were found within 73 fruit inspected from the single tree at Rocky Creek Dam. No seed from this tree has been germinated in any trial, however one seed was germinated from the Whian Whian State Forest populations (Mark Dunphy pers. comm.).

Propagation by cuttings has been more successful and has produced plants that have been re-introduced to the wild as part of remedial action post logging in Whian Whian State Forest. The Queensland Herbarium has succeeded in multiplying tissue cultured cells aseptically (Rich 1995). Rous Water planted 70 E. sp. Rocky Creek trees at Rocky Creek Dam between 1995 and 1997. The introduced trees included stock grown from cuttings and wild seedlings sourced from within one kilometer of the planting site. There has been 100 per cent survival of the introduced trees with the oldest stem 3-4 m high and a growth rate equivalent to Gmelina leichhardtii in the plot (R. Woodford pers. comm.).

In May 1996 two seedlings were removed from an area which is now Nightcap National Park, as they were subject to high levels of disturbance and had been uprooted. The seedlings were taken for ex-situ planting and one has been successfully established at Heritage Park, Mullumbimby (R. Kooyman pers. comm.).

7. Population structure

7.1 Population structure

Five hundred and sixty nine naturally occurring E. sp. Rocky Creek individuals have been recorded and are distributed unevenly across seven sites (not including Site 5). Forty nine per cent of the entire population was seedlings in 1999. There is great variation in seedling numbers between sites, with all seedlings occurring at only four of seven sites (Table 1). At Snows Gully Nature Reserve there has been high seedling mortality with only a few surviving to sapling stage.

Coppicing occurs in 35 per cent of the post-seedling population with many coppicing individuals having more than two stems (McKinley et al. 1996). While E. sp. Rocky Creek is known to coppice in response to injury, multi-stemmed individuals also appear to occur in the absence of apparent injury. This may be a useful strategy for a species with poor seed viability and slow recolonisation ability (Johnson & Lacey 1983).

Site 1 (Whian Whian State Forest and Nightcap National Park) and Site 7 (Mt Jerusalem) support relatively large populations. The sites vary greatly in their seedling and coppicing structures, and both have a history of logging. Mt Jerusalem National Park was logged in the 1960s and again in 1995, resulting in extensive damage to the E. sp. Rocky Creek population. The site has a high rate of coppicing and low seedling recruitment compared to the Whian Whian/Nightcap population, which was selectively logged, has fewer coppicing stems and the highest rate of seedling recruitment of any site.

Trees with large diameter at breast height (dbh) are rare with only seven per cent of all individuals recorded having a dbh greater than 25 cm (McKinley et al. 1996, 1998)2. Further research is required to confirm the extent of seedling recruitment and survival and to establish the age of many of the coppicing individuals.

Table 1. Cohort structure of Elaeocarpus sp. Rocky Creek populations at seven sites*
Site Rocky Creek Dam Whian Whian SF
& Nightcap NP
Mt Jerusalem NP Snows Gully NR Whian Whian SF Whian Whian SF Whian Whian SF Class totals
Seedlings 0 174 78 14 0 0 10 276
Saplings cm dbh 0 19 87 19 6 15 5 151
Trees 10-25 cm dbh 1 29 65 1 0 0 6 102
Trees 25-50 cm dbh 0 24 7 3 0 0 4 38
Trees 50-75 cm dbh 0 0 1 1 0 0 0 2
Site totals 1 246 238 38 6 15 25 569

*Based on available size class data to February 1999 (not including Site 5). Multi-stem individuals continue to be classified by the dbh of the largest stem (revision of McKinley et al. 1996).

2Multi-stem individuals have been classified according to the dbh of the largest stem.