Bolivia Wattle - profile

Indicative distribution

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Key:

known

predicted

The areas shown in pink and/purple are the sub-regions where the species or community is known or predicted to occur. They may not occur thoughout the sub-region but may be restricted to certain areas. ( click here to see geographic restrictions). The information presented in this map is only indicative and may contain errors and omissions.

Scientific name: Acacia pycnostachya

Conservation status in NSW: Vulnerable

Commonwealth status: Vulnerable

Profile last updated: 07 Nov 2022

Description

Bolivia Wattle is a shrub or small tree, between 1 and 10 m tall. The grey-green leaves are very firm and somewhat curved (almost sickle-shaped). They are 7 - 10 cm long by 1 - 2.5 cm wide. The species is characterised by the very coarse, sharply ridged but flattened branchlets. Bark is finely fissured and light brownish grey. Deep yellow flowers are borne on a 2 - 5 cm long spike and occur in spring. A brown, leathery pod, 8 - 12 cm long and 3 - 4 mm wide contains the seeds.

Distribution

Restricted to NSW. Three extensive populations exist in the vicinity of Bolivia Hills and Bluff River Nature Reserves south of Tenterfield, and on nearby Crown Land. Smaller populations have been found on private land in other areas and the species may be more widespread than is currently documented. The plant tends to occur in patches although sparsely distributed individuals are common across the Bolivia Hill ranges.

Habitat and ecology

Flowers in spring or from July to October. Fruits are borne October to November. The species may not tolerate too-frequent fire (more often than 15-20 years), which may kill adult plants before the soil seed bank is adequate to provide recruitment.
Acacia pycnostachya typically grows in dry sclerophyll forest amongst granite outcrops, on hillsides at altitudes of 700 to 900 m, but is flexible in its habitat. Soil types range from acid volanics to sandy and skeletal on exposed outcrops, to shallow sandy loams in less exposed sites. It often grows in stands in areas sheltered from fire.
Generally plants appear to dominate the understorey or tall shrub stratum below an open canopy of taller shrubs or trees. Dense stands are currently common.
Associated species include Eucalyptus prava, Eucalyptus andrewsii, Callitris endlicheri, Acacia adunca, Eucalyptus campanulata, Leptospermum brevipes, Acacia neriifolia, Stypandra glauca, Notelaea microcarpa and Callitris species.
Multiple sub-populations of Acacia pycnostachya located at Bolivia Hill currently comprise approximately 40,000 plants. The population in the Back Creek area north-west of Tenterfield was estimated as well over 200,000 individuals, and more than 200 plants were recently discovered at a distant site near Anketell. Together with the Bluff Rock population, the species currently numbers about 300,000 individuals spread over a wide area. The discontinuous nature of this metapopulation potentially protects it from single catastrophic events such as wildfire.
The population at Bolivia Hill, which is the most closely monitored, did not suffer significant declines during the recent severe drought. Less than 10% of mature individuals died, although mortality was patchy and in some areas there was no loss. Survivors currently have recovered to good health after ample rainfall. The site was not burned during the extensive bushfires of 2019-2020, yet subsequent seedling recruitment in response to rain has greatly increased the abundance. Neither goat nor macropod browsing is having a significant impact on seedlings or mature plants. Both herbivores have been consistently present among Acacia pycnostachya populations over the past decades at variable densities

Regional distribution and habitat

Click on a region below to view detailed distribution, habitat and vegetation information.

New England Tablelands

Threats

Clearing of habitat for agriculture.
Clearing associated with road, powerline and railway maintenance.
Climate change may increase drought and fire threats to the species, leading to population declines
Browsing by feral animals, particularly goats during drought conditions. The rocky habitats are also vulnerable to degradation and erosion from the feral goat populations.
Infrequent fire, longer than every 15-20 years, may lead to death of adults and depletion of the soil seed bank causing a lack of recruitment. The species responds to fire by seeding prolifically and doesnÆt necessarily lead to decline. Species occurs in rugged country which discourages widespread fire.

Recovery strategies

A Saving Our Species conservation project is currently being developed for this species and will be available soon. For information on how you can contribute to this species' recovery, see the Activities to assist this species section below.

Activities to assist this species

Assist with the control of feral animals.
Protect areas of known and potential habitat from frequent fire.
Protect populations and areas of habitat during road, railway or powerline maintenance.
Protect areas of open woodland on granite from clearing.
Report new records of Bolivia Wattle to the OEH.
Identify populations and areas of habitat and mark onto maps used for maintenance work.

Information sources

Bentham, G. (1863) Flora Australiensis. Volume 2 (1864). (Reeve, London)
Briggs, J.D. and Leigh, J.H. (1996) Rare or Threatened Australian Plants. Revised Edition. (CSIRO Publishing, Melbourne)
Clarke, P.J., Knox, K.J.E., Campbell, M.L. and Copeland, L.M. (2009) Post-fire recovery of woody plants in the New England Tableland Bioregion. Cunninghamia 11(2): 221–239
Hall, N. and Johnson, L.A.S. (1993) The names of acacias of New South Wales - with a guide to pronunciation of botanical names. (Royal Botanic Gardens, Sydney)
Hogbin, P. (2002) Review of the Threatened Species Conservation Act Flora Schedules: Recommendations to the Scientific Committee.
Hunter, J.T. and Clarke, P.J. (1998) The vegetation of granitic outcrop communities on the New England Batholith of eastern Australia. Cunninghamia 5(3): 547-618
Hunter, J.T. and Earl, J. (1999) Field Survey to Determine the Locations and Distribution of the Threatened Plant Pimelea venosa Threlfall. Report to the Northern Directorate, New South Wales, National Parks and Wildlife Service.
Kodela, P.G. and Harden, G.J. (2002) Acacia. Pp 381-476 in Harden, G.J. (ed.) Flora of New South Wales. Volume 2. Revised Edition (New South Wales University Press, Sydney)
Maslin, B.R. (2001) Mimosaceae 1. Acacia. 789. Acacia pycnostachya F. Muell. ex Benth. In Orchard, A.E. and Wilson, A.J.G. (Eds) Flora of Australia 11B: 271 (Fig. 55B-E).
Maslin, B.R. and Pedley, L. (1982) The distribution of Acacia (Leguminosae: Mimosoideae) in Australia. Part 1. Species distribution maps. Western Australian Herbarium Research Notes 6: 1-128.
NSW National Parks and Wildlife Service (2003) Threatened Species of the New England Tablelands and North West Slopes of NSW. (NSW NPWS, Coffs Harbour)
Quinn, F., Williams, J.B., Gross, C.L. and Bruhl, J. (1995) Report on Rare and Threatened Plants of north-eastern New South Wales. Report prepared for the New South Wales National Parks and Wildlife Service and the Australian Nature Conservation Agency.
Simmons, M.H. (1981) Acacias of Australia. (Nelson, Melbourne)