An extinction-risk assessment tool for flora threatened by Phytophthora cinnamomi
S. Barrett A C , B. L. Shearer B , C. E. Crane B and A. Cochrane BA South Coast Region, Department of Environment and Conservation, Albany, WA 6330, Australia.
B Science Division, Department of Environment and Conservation, Locked Bag 104, Bentley Delivery Centre, WA 6983, Australia.
C Corresponding author. Email: sarah.barrett@dec.wa.gov.au
Australian Journal of Botany 56(6) 477-486 https://doi.org/10.1071/BT07213
Submitted: 23 November 2007 Accepted: 22 July 2008 Published: 16 September 2008
Abstract
A risk-assessment tool was used to investigate the risk of extinction from disease caused by Phytophthora cinnamomi to 33 taxa from the Stirling Range National Park, Western Australia. Criteria used to score risk of extinction were the direct impact of P. cinnamomi on taxa, number of extant or extinct populations, percentage of populations infested by P. cinnamomi, proximity and topographical relationship of populations to P. cinnamomi, proximity of populations to tracks and the number of additional threatening processes. Direct impact scores were derived from mortality curves determined from the survival of taxa after soil inoculation with P. cinnamomi in a shade-house environment. On the basis of the total extinction risk score, nine taxa had a ‘very high’, five had a ‘high’, six a ‘moderate’, eight a ‘low’, four a ‘very low’ and one ‘no’ risk of extinction. Whereas the methodology confirmed the current threatened status of nine taxa, it also identified five taxa, not currently listed, to be at ‘high’ risk of extinction. Other threatening processes identified included fire, herbivory, aerial canker disease and climate change. These combine with P. cinnamomi to push taxa further towards extinction. Quantification of risk of extinction identifies taxa at risk and allows for prioritisation of management actions for currently threatened flora. This risk-assessment methodology combined glasshouse inoculation with habitat and ecological data, current in situ disease impact and proximity to disease and vectors, to enable a more comprehensive assessment of extinction risk and may be used in other areas with endemic flora threatened by P. cinnamomi.
Acknowledgements
The authors acknowledge the assistance of Malcom Grant and Greg Freebury (Department of Environment and Conservation, South Coast Region, WA), Andrew Crawford (Threatened Flora Seed Centre, Department of Environment and Conservation) for germinating seeds and the Botanic Gardens and Parks Authority for root cuttings. Thanks go to C. Dunne, J. McComb and E. O’Gara for comments on the manuscript. This research was supported by funding from South Coast Natural Resource Management Inc.
Aberton MJ,
Wilson BA, Cahill MJ
(1999) The use of potassium phosphonate to control Phytophthora cinnamomi in native vegetation at Anglesea, Victoria. Australasian Plant Pathology 28, 225–234.
| Crossref | GoogleScholarGoogle Scholar |
Barker PCJ, Wardlaw TJ
(1995) Susceptibility of selected Tasmanian rare plants to Phytophthora cinnamomi. Australian Journal of Botany 43, 379–386.
| Crossref | GoogleScholarGoogle Scholar |
Barrett S, Gillen K
(1997) Mountain protected areas of south Western Australia. Parks 7, 35–42.
Close DC,
Messina G,
Krauss SL,
Rokich DP,
Stritzke J, Dixon KW
(2006) Conservation biology of the rare species Conospermum undulatum and Macarthuria keigheryi in an urban bushland remnant. Australian Journal of Botany 54, 583–593.
| Crossref | GoogleScholarGoogle Scholar |
Cochrane A, Coates D
(1994) Western Australia’s Threatened Flora Seed Centre and its role in conservation of genetic diversity. Danthonia 3, 4–7.
Crane CE, Shearer BL
(2007) Hemispherical digital photographs offer advantages over conventional methods for quantifying pathogen-mediated changes caused by infestation of Phytophthora cinnamomi. Australasian Plant Pathology 36, 466–474.
| Crossref | GoogleScholarGoogle Scholar |
Gill AM, Bradstock RA
(1992) A national register for the fire response of plant species. Cunninghamia 2, 653–660.
Guest D, Grant BR
(1991) The complex mode of action of phosphonates as antifungal agents. Biological Reviews of the Cambridge Philosophical Society 66, 159–187.
| Crossref | GoogleScholarGoogle Scholar |
Hardy StGE,
Barrett S, Shearer BL
(2001) The future of phosphite as a fungicide to control the soil borne plant pathogen Phytophthora cinnamomi in natural ecosystems. Australasian Plant Pathology 30, 133–139.
| Crossref | GoogleScholarGoogle Scholar |
Hope PK,
Drodowsky W, Nicholls N
(2006) Shifts in the synoptic systems influencing southwest Western Australia. Climate Dynamics 26, 751–764.
| Crossref | GoogleScholarGoogle Scholar |
Keith D
(1996) Fire-driven extinction of plant populations: a synthesis of theory and review of evidence from Australian vegetation. Proceedings of the Linnean Society of New South Wales 116, 37–78.
Mast AR, Thiele K
(2007) The transfer of Banksia R.Br. to Banksia L.f. (Proteaceae). Australian Systematic Botany 20, 63–71.
| Crossref |
Peters D, Weste G
(1997) The impact of Phytophthora cinnamomi on six rare native tree and shrub species in the Brisbane Ranges, Victoria. Australian Journal of Botany 45(6), 975–995.
| Crossref | GoogleScholarGoogle Scholar |
Reiter N,
Weste G, Guest D
(2004) The risk of extinction resulting from disease caused by Phytophthora cinnamomi to endangered, vulnerable or rare plant species endemic to the Grampians, western Victoria. Australian Journal of Botany 52, 425–433.
| Crossref | GoogleScholarGoogle Scholar |
Shearer BL
(1994) The major plant pathogens occurring in native ecosystems of south-western Australia. Journal of the Royal Society of Western Australia 77, 113–122.
Shearer BL, Fairman RG
(2007) Stem injection of phosphite protects Banksia species and Eucalyptus marginata from Phytophthora cinnamomi for at least four years. Australasian Plant Pathology 36, 78–86.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Shearer BL,
Crane CE, Cochrane A
(2004a) Quantification of the susceptibility of the native flora of the South-West Botanical Province, Western Australia, to Phytophthora cinnamomi. Australian Journal of Botany 52, 435–443.
| Crossref | GoogleScholarGoogle Scholar |
Shearer BL,
Crane CE, Fairman RG
(2004b) Phosphite reduces disease extension of a Phytophthora cinnamomi front in Banskia woodland, even after fire. Australasian Journal of Plant Pathology 33, 249–254.
| Crossref | GoogleScholarGoogle Scholar |
CAS |
Shearer BL,
Fairman RG, Grant M
(2006) Effective concentration of phosphite in controlling Phytophthora cinnamomi following stem injection of Banksia species and Eucalyptus marginata. Forest Pathology 36, 119–135.
| Crossref | GoogleScholarGoogle Scholar |
Shearer BL,
Crane CE,
Barrett S, Cochrane A
(2007a) Phytophthora cinnamomi invasion, a major threatening process to conservation of flora diversity in the South-west Botanical Province of Western Australia. Australian Journal of Botany 55, 225–238.
| Crossref | GoogleScholarGoogle Scholar |
Shearer BL,
Crane CE,
Barrett S, Cochrane A
(2007b) Assessment of threatened flora susceptibility to Phytophthora cinnamomi by analysis of disease progress curves in shadehouse and natural environments. Australasian Journal of Plant Pathology 36, 609–620.
| Crossref | GoogleScholarGoogle Scholar |
Weste G,
Brown K,
Kennedy J, Walshe T
(2002) Phytophthora cinnamomi infestation—a 24-year study of vegetation change in forests and woodlands of the Grampians, Western Victoria. Australian Journal of Botany 50, 247–274.
| Crossref | GoogleScholarGoogle Scholar |
Weste G, Law C
(1973) The invasion of native forest by Phytophthora cinnamomi. 111. Threat to the National Park, Wilson’s Promontory, Victoria. Australian Journal of Ecology 21, 32–51.
Wills RT
(1993) The ecological impact of Phytophthora cinnamomi in the Stirling Range National Park, Western Australia. Australian Journal of Ecology 18, 145–159.
| Crossref | GoogleScholarGoogle Scholar |
Wills RT, Keighery GJ
(1994) Ecological impact of plant disease on plant communities. Journal of the Royal Society of Western Australia 77, 127–133.