Grevillea iaspicula - critically endangered species listing

NSW Scientific Committee - final determination

The Scientific Committee, established by the Threatened Species Conservation Act, has made a Final Determination to list the shrub Grevillea iaspicula McGill. as a CRITICALLY ENDANGERED SPECIES in Part 1 of Schedule 1A of the Act, and as a consequence, to omit reference to Grevillea iaspicula McGillivray from Part 1 of Schedule 1 (Endangered species) of the Act. Listing of Critically Endangered species is provided for by Part 2 of the Act.

 

The Scientific Committee has found that:

 

  1. Grevillea iaspicula (family Proteaceae) is described by Makinson (2002) as a shrub, mostly 1.2–2.5 m high. Leaves light green, narrow-elliptic to -oblong, 1–3.5 cm long, 3–10 mm wide, margins entire and recurved, glabrous. Inflorescences often deflexed and pendant, in ovoid clusters, much branched, 2–3 cm long. Perianth green to cream, pinkish near curve, glabrous outside, bearded usually above the middle inside. Gynoecium 16–18 mm long; stipe inconspicuous, ventrally swollen, usually pilose; ovary glabrous or with isolated hairs; ovary densely hairy and ± sessile; style pink to red, glabrous. Follicle usually hairy, without dark stripes or blotches.

 

  1. Grevillea iaspicula has a very highly restricted distribution around the Wee Jasper-Burrinjuck area in south-eastern NSW. It is known from seven small populations; five around Wee Jasper and along the steep cliffs of the Goodradigbee River, and two on the shores of Lake Burrinjuck, near Burrinjuck village. This species was first collected in 1966 at another site, ‘Macphersons Swamp Creek’, north-west of Wee Jasper. The species has not been re-located at this site, despite survey effort (Briggs & Leigh 1990).

 

  1. Grevillea iaspicula grows only on skeletal grey-clay loam on rocky outcrops, sink-holes entrances and cliff bases in limestone country. It occurs in low woodland of Eucalyptus and Brachychiton, generally with an open understorey of shrubs and grasses (Briggs & Leigh 1990).

 

  1. Flowering occurs prolifically in July to August and birds are the most likely pollinators (Briggs and Leigh 1990). Honeyeaters have been recorded visiting the flowers (Hoebee & Young 2001), as have honeybees (R. O. Makinson pers comm. December 2008).

 

  1. The species apparently sets abundant seed and seedlings emerge episodically (J. Briggs, pers. comm. May 2008). However, levels of seedling recruitment are low and there is limited gene flow among populations, although genetic diversity within and between populations is high (Hoebee et al. 2008).

 

  1. The overall population of the species, and possibly its geographic range, is likely to have been reduced as a result of land clearing and heavy grazing. The remaining populations have become severely fragmented. The geographic distribution of G. iaspicula is very highly restricted (Bray 2008). The Extent of Occurrence for the species is less than 56 km2, and its Area of Occupancy is approximately 44 km2, based on a 2 x 2 km grid cell, the scale recommended by IUCN (2008) for assessing areas of occupancy.

 

  1. Based on surveys conducted in 2003, the total number of mature individuals of G. iaspicula in the wild was estimated to be at least 144 (J Briggs unpublished data), and is unlikely to exceed 250, as only part of one of the seven populations remains uncounted (Bray 2008). The total population of Grevillea iaspicula therefore includes a very low number of mature individuals.

 

  1. Five of the seven extant populations of Grevillea iaspicula occur on private land, one occurs on a crown reserve and one occurs within Burrinjuck Nature Reserve.

 

  1. Fire, drought and goat browsing have impacted on the largest subpopulation (Hoebee et al. 2008). Standing plants of Grevillea iaspicula are apparently killed by fire and, based on data for other Grevillea species in fire-prone habitats (Morris 2000; Auld & Denham 2006), the population depends on regeneration of seedlings from a persistent soil seed bank. The time taken for seedlings to reach maturity and produce seed is unknown, but likely to be at least several years based on other Grevillea species in fire-prone habitats (NSW NPWS fire response data base). Frequent fires may therefore interrupt the life cycle and result in population declines (Keith 1996). Seedlings in the post-fire environment may be exposed to grazing from native, domestic and feral herbivores, which may adversely affect their survival. ‘High frequency fire resulting in disruption of life cycle processes in plants and animals and loss of vegetation structure and composition’ is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.

 

  1. Grazing and trampling by domestic livestock and browsing by feral goats have resulted in declines of some populations of Grevillea iaspicula and degradation of its habitat. Some of the populations have been fenced to protect plants from herbivory and habitat degradation, but lack of maintenance of fences damaged by fires has allowed herbivores access to some locations. ‘Competition and habitat degradation by Feral Goats, Capra hircus Linnaeus 1758’ is listed as a Key Threatening Process under the Threatened Species Conservation Act 1995.

 

  1. Weed invasion, particularly by Rubus fruticosus spp. agg. (Blackberry), also poses a threat to the species. Limited control measures have been implemented in the past (Butler et al. 1991), but ongoing management of weeds is limited. If weed control measures, such as blackberry spraying, are carried out indiscriminately, plants of Grevillea iaspicula could be adversely affected.

 

  1. Drought is known to inhibit regeneration of Grevillea iaspicula. Desiccated seedlings have been observed during times of drought (J Briggs pers comm.).

 

  1. Hybridisation and genetic introgression from cultivated Grevillea taxa, particularly Grevillea rosmarinifolia, is a potential threat, and has been documented at one site (R. O. Makinson pers. comm. December 2008).

 

  1. The small range and population size of Grevillea iaspicula makes this species susceptible to environmental and demographic stochasticity.

 

  1. Grevillea iaspicula is currently listed as an Endangered species under the Environment Protection and Biodiversity Conservation Act 1999 (Threatened Species Scientific Committee 2008).

 

  1. Grevillea iaspicula McGill. is eligible to be listed as a Critically Endangered species as, in the opinion of the Scientific Committee, it is facing an extremely high risk of extinction in New South Wales in the immediate 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:

(a) very highly restricted

and:

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

(i) an index of abundance appropriate to the taxon, and

(ii) geographic distribution, habitat quality or diversity, or genetic diversity.

 

Clause 16

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

(a) very low

and:

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

(i) an index of abundance appropriate to the taxon, and

(ii) geographic distribution, habitat quality or diversity, or genetic diversity.

 

Dr Richard Major

Chairperson

Scientific Committee

Proposed Gazettal date: 11/12/09

Exhibition period: 11/12/09 – 05/02/10

 

References:

 

Auld TD, Denham AJ (2006) How much seed remains in the soil after fire? Plant Ecology 187, 15-24.

 

Briggs JD, Leigh JH (1990) ‘Delineation of important habitats of threatened plant species in south-eastern New South Wales’, Australian Heritage Commission, Canberra.

 

Bray C (2008) ‘Conservation status of Grevillea iaspicula McGillivray (Proteaceae) in New South Wales’. Report to the NSW Scientific Committee, Sydney.

 

Butler G, Richardson M, Ganter W (1991). ‘Recovery plan for Grevillea iaspicula McGillivray (Wee Jasper Grevillea) – 1991–2000’, Australian National Botanic Gardens, Canberra.

 

Hoebee SE, Thrall PH, Young AG (2008) Integrating population demography, genetics and self incompatibility in a viability assessment of the Wee Jasper Grevillea (Grevillea iaspicula McGill., Proteaceae). Conservation Genetics 9, 515-529.

 

Hoebee SE, Young AG (2001) Low neighbourhood size and high interpopulation differentiation in the endangered shrub Grevillea iaspicula McGill (Proteaceae). Heredity 86, 489–496.

 

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). (http://intranet.iucn.org/webfiles/doc/SSC/RedList/RedListGuidelines.pdf).

 

Keith, D. A. (1996). Fire-driven mechanisms of extinction in vascular plants: a review of empirical and theoretical evidence in Australian vegetation. Proceedings of the Linnean Society of New South Wales 116, 37-78.

 

Makinson RO (2002) Grevillea. In: ‘Flora of New South Wales’. Volume 2. Revised Edition. (Ed. GJ Harden) pp 32-66 (University of NSW Press: Kensington, NSW).

 

Morris EC (2000) Germination response of seven east Australian Grevillea species (Proteaceae) to smoke, heat exposure and scarification. Australian Journal of Botany 48, 179–189.

 

Threatened Species Scientific Committee (2008) ‘Commonwealth Conservation Advice on Grevillea iaspicula (Wee Jasper Grevillea).’ Department of the Environment, Water, Heritage and the Arts. (http://www.environment.gov.au/biodiversity/threatened/species/pubs/22024-conservation-advice.pdf)

Page last updated: 28 February 2011