Syzygium paniculatum - endangered species listing

NSW Scientific Committee - final determination

The Scientific Committee has found that:

1. Syzygium paniculatum (family Myrtaceae) is described by Wilson (2002) as: 'Shrub or small tree with flaky bark. Leaves lanceolate to obovate, 4.5-10 cm long, 1.5-3 cm wide, apex acuminate, base cuneate, glabrous, upper surface green and glossy, lower surface paler; lateral veins numerous, intramarginal vein usually discernible; oil glands small, rather scattered, distinct; petiole 2-10 mm long. Inflorescences cymose or paniculate, terminal and in the upper axils; flowers white. Petals 4-5mm long, free and spreading. Stamens 6-15 mm long. Fruit globose to ovoid, 15-25 mm diam., magenta; seed solitary, polyembryonic, cotyledons smooth. Flowers Dec.-Mar.’

3. Syzygium paniculatum is endemic to New South Wales and occurrences of the species are often separated by considerable distances. Five broad metapopulations have been recognised, including: Jervis Bay, Coalcliff, Botany Bay, Central Coast and Seal Rocks (DECC 2007). These comprise a total of 43 known subpopulations, in addition to six unconfirmed records (DECC 2007) all from the Sydney Basin Bioregion, and the NSW North Coast Bioregion (sensu Thackway and Creswell 1995). The extent of occurrence is approximately 15,000 km2 and the area of occupancy (based on a 2 km grid, as recommended by IUCN 2008) is approximately 180-210 km2 (Mackenzie & Keith 2008).

4. Across its range, Syzygium paniculatum occupies restricted habitats that have been extensively cleared or modified (DECC 2007) including lowland and littoral rainforest. Littoral Rainforest in the NSW North Coast, Sydney Basin and South East Corner Bioregions and Lowland Rainforest in the NSW North Coast and Sydney Basin Bioregions are listed as Endangered Ecological Communities under the NSW Threatened Species Conservation Act 1995 (NSW Scientific Committee 2004). The clearing of valley floor vegetation, including lowland rainforest and riparian gallery forest for agriculture, and clearing of coastal sand flats for development of residential and recreational areas, has almost certainly led to a reduction in available habitat, and a reduction in the size of remaining populations (DECC 2007).

5. There is strong evidence to suggest that the abundance of Syzygium paniculatum across its natural range has been markedly reduced since European settlement, and that a number of populations may have been entirely eliminated (DECC 2007). The three largest subpopulations on the Central Coast account for nearly three-quarters of the total known extant population (DECC 2007). Estimates for the number of mature plants within 30 of the known populations suggest that these comprise a total of approximately 530-1,320 plants (DECC 2007, Mackenzie & Keith 2008). The total population of Syzygium paniculatum is unlikely to contain more than 1,200-2,600 mature plants, even assuming that each of the remaining unsurveyed subpopulations include as many as 50-100 mature plants. A more realistic assumption, that unsurveyed subpopulations contain, on average, as many mature individuals as surveyed populations, suggests that the actual number of mature individuals is likely to be 760-1,900 (Mackenzie & Keith 2008). These estimates indicate that there is a low number of mature individuals in the total population of S. paniculatum. Recent surveys of suitable habitat in the valleys of Ourimbah Creek, Wyong Creek and Jilliby Creek located only one additional tree (R. Payne, in litt. October 2008).

6. Fourteen (one-third) of the 43 known subpopulations are wholly or partially within conservation reserves. Several of these reserved subpopulations contain small numbers of plants, are close to reserve boundaries or in sites degraded by previous land uses. Nine subpopulations (21 %) occur entirely on private property, including two of the three largest subpopulations (DECC 2007). The remaining subpopulations occur either wholly on council-managed land or straddle the boundaries between council land, private property and conservation reserves (DECC 2007).

7. Potential habitat for Syzygium paniculatum continues to be cleared and fragmented for urban expansion and infrastructure development, particularly in the Central Coast and Jervis Bay metapopulations (DECC 2007). The relatively large population in Wyrrabalong National Park, is exposed to edge effects associated with an existing road and is likely to be further threatened by future highway expansion. Recent construction of a golf course on the boundary of this population may increase its susceptibility to hydrological changes, fertilizer and pesticide runoff, weed infestation and salt spray damage in future (DECC 2007), although initial mitigation measures have been implemented to reduce salt spray, minimise hydrological risk and control previous weed infestations with monitoring planned for 5 years after 2005 (A. Clements in litt. November 2008) . ‘Clearing of native vegetation’ is listed as a Key Threatening Process under the NSW Threatened Species Conservation Act 1995.

8. A number of populations of Syzygium paniculatum are threatened by weed species including (DECC 2007):

‘Invasion of native plant communities by Chrysanthemoides monilifera’, ‘Invasion, establishment and spread of Lantana (Lantana camara L. sens. lat)’, and ‘Invasion and establishment of exotic vines and scramblers’ (including Ipomoea indica and Lonicera japonica) are listed as Key Threatening Processes under the NSW Threatened Species Conservation Act 1995. Numerous weed species also threaten littoral rainforest in which Syzygium paniculatum frequently occurs (NSW Scientific Committee 2004).

9. Grazing and watering of livestock within riparian vegetation is contributing to the destruction of some of the largest populations at Ourimbah Creek and in the Martinsville area. There is little or no evidence of recruitment in these areas due to the effects of trampling of creek banks and root disturbance by livestock (Payne 1997, R. Payne pers. comm. 2008). Grazing, and associated physical damage to soils and understorey, is an identified threat to littoral rainforest which provides habitat for Syzygium paniculatum (NSW Scientific Committee 2004). Feral deer, which occur at least in parts of the species range to the south of Sydney, are known to cause severe defoliation and bark-stripping, resulting in reduced growth and mortality of sapling-stage plants (Keith and Pellow 2004). ‘Herbivory and environmental degradation caused by feral deer’ is listed as a Key Threatening Process under the NSW Threatened Species Conservation Act 1995.

10. Extraction of water from creeks that support populations of Syzygium paniculatum has uncertain impacts on the species and associated riparian vegetation. Water is currently extracted from Ourimbah Creek which supports one of the largest populations of Syzygium paniculatum and approval has recently been granted to increase rates of extraction when water shortages occur. Reductions in water flow have the potential to reduce the frequency and magnitude of flood events which facilitate seed dispersal, and to lower the water table which may inhibit recruitment of seedlings into the population. ‘Alteration to the natural flow regimes of rivers and streams and their floodplains and wetlands’ is listed as a Key Threatening Process under the NSW Threatened Species Conservation Act 1995.

11. Populations such as the one at Towra Point situated near extreme high water mark, may be at risk from future sea level rise (Hughes 2003). ‘Anthropogenic Climate Change’ is listed as a Key Threatening Process under the NSW Threatened Species Conservation Act 1995.

12. The threats to Syzygium paniculatum described above, together with demographic and environmental stochasticity resulting from the restricted area and small sizes of its subpopulations, indicate that the species is undergoing a continuing decline, or likely to undergo a future decline in abundance, and in habitat area and quality.

13. Syzygium paniculatum is not eligible to be listed as a Critically Endangered species.

14. Syzygium paniculatum Gaertn. is eligible to be listed as an Endangered species as, in the opinion of the Scientific Committee, it is facing a very high risk of extinction in New South Wales in the near future as determined in accordance with the following criteria as prescribed by the Threatened Species Conservation Regulation 2002:

Clause 15

The geographic distribution of the species is estimated or inferred to be:

(b) highly restricted,

and:

(d) a projected or continuing decline is observed, estimated or inferred in:

(ii) an index of abundance appropriate to the taxon
(ii) geographic distribution, habitat quality or diversity, or genetic diversity

Clause 16

The estimated total number of mature individuals of the species is:

(b) low,

and:

(d) a projected or continuing decline is observed, estimated or inferred in:

(i) an index of abundance appropriate to the taxon
(ii) geographic distribution, habitat quality or diversity, or genetic diversity

Dr Richard Major
Chairperson
Scientific Committee

Proposed Gazettal date: 31/07/09
Exhibition period: 31/07/09 - 25/09/09

References:

DECC (2007) Draft Recovery Plan for the Magenta Lilly Pilly, Department of Environment and Climate Change (NSW), Sydney.

Hughes L (2003) Climate change and Australia: trends, projections and research directions. Austral Ecology 28: 423-443.

IUCN (2008) ‘Guidelines for using the IUCN Red List Categories and Criteria. Version 7.0.’ (Standards and Petitions Working Group of the IUCN Species Survival Commission Biodiversity Assessments Sub-committee: Switzerland)

Keith D, Pellow B (2005) Effects of Javan Rusa deer (Cervus timorensis) on native plant species in the Jibbon-Bundeena area, Royal National Park, New South Wales. Proceedings of the Linnean Society of New South Wales 126, 99-110.

Mackenzie BDE, Keith DA (2008). Geographic range and population size of Syzygium paniculatum Gaertn.: a supplementary report to the NSW Scientific Committee. Unpublished report prepared for the NSW Scientific Committee.

NSW Scientific Committee (2004) ‘Littoral Rainforest in the NSW North Coast, Sydney Basin and South East Corner Bioregions’ – endangered ecological community listing.

Payne R (1997) The distribution and reproductive ecology of Syzygium paniculatum and Syzygium australe (Myrtaceae) in the Gosford-Wyong region. Unpublished thesis prepared for the award of Masters of Natural Resources, University of New England, Armidale.

Thackway R, Creswell ID (eds) (1995). An interim biogeographic regionalisation of Australia: a framework for establishing the national system of reserves. Australian Nature Conservation Agency, Canberra.

Wilson PG (2002) Syzygium. In ‘Flora of New South Wales’. (Ed. G. J. Harden) pp. 164-167. (University of New South Wales Press, University of New South Wales, Kensington).