Case study examples of trends in significant species and communities – western australia
Eastern Stirling Range Montane Heath and Thicket Community
Description
This threatened ecological community (TEC) is within the eastern Stirling Range of Stirling Range National Park (SRNP), Western Australia (WA). It is distinct from plant communities occurring in the central and western Stirling Range. This community is found at high altitudes (~750m above sea level (a.s.l.) to 1080m a.s.l.). Andersonia axilliflora, which is or was an abundant and dominant member of the community, can be used to identify this community’s distribution (Barrett 1996).
The community extends from Ellen Peak (1012m) at the eastern limit of the Stirling Range more or less continuously at these altitudes to Coyanarup Peak (1045m), with a separate occurrence on the summit area of Mt Success (750m) (Barrett 1996). The community is largely restricted to the summit areas of this ridge, which includes the following peaks: Pyungoorup (1060m), the Arrows, Isongerup (994m), Moongoongoonderup (750m) and Bluff Knoll (1080m). The community covers about 363 ha along this ridge line including the separate occurrence on the summit area of Mt Success (Barrett 2000, Barrett unpublished).
Key features affecting the community’s composition and structure are aspect/exposure, soil type and depth, temperature, time since fire, and the effects of Phytophthora cinnamomi. The community structure is or was typically that of dense heath or thicket with scrub vegetation on skeletal soils. Taller thicket vegetation is favoured by more sheltered sites on deeper soils. Long-unburnt sites have minimal understorey vegetation, and plant growth after fire is extremely slow in more exposed locations. Factors affecting plant growth include low temperatures and high wind speeds that prevail for much of the year (Barrett 1996). There has been no detailed study of these aspects of the community’s ecological needs (Barrett 2000).
Significance
The TEC is listed as Endangered under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). Under WA’s categories of threat criteria it is listed as Critically Endangered (CR). It is listed due to its current limited distribution and very few occurrences, each of which is small and/or isolated and extremely vulnerable to known threatening processes (Barrett 2000).
The community is characterised by Andersonia axilliflora, Kunzea montana, Beaufortia anisandra, Calothamnus crassus, Sphenotoma sp. Stirling Range, Andersonia echinocephala and Darwinia spp. A range of proteaceous species were or are structurally significant and include Banksia oreophila, B. solandri, B. brownii and Dryandra concinna. Eucalyptus species are notable for their absence from the community but occur at immediately lower altitudes (Barrett 2000). There are also a number of species that are endemic to this community, including Andersonia axilliflora, Dryandra montana, Persoonia micranthera, Darwinia collina, Hypocalymma myrtifolium and Stylidium keigheryi (Barrett 2000).
Ten flora species within this TEC are listed as Threatened under the EPBC Act, with eight listed as Endangered [Andersonia axilliflora, Banksia brownii, Darwinia collina, Deyeuxia drummondii, Dryandra montana, Leucopogon gnaphalioides, Persoonia micranthera and Sphenotoma drummondii] and two as Vulnerable [Darwinia squarrosa and Darwinia sp. Stirling Range]. In addition to these species, Latrobea obovata, is listed as Declared Rare under the WA Wildlife Conservation Act 1950, and ranked as Critically Endangered (Barrett 2000, Barrett unpublished).
Data and information
The threatened Ecological Community has been well surveyed and its composition and condition are well known. There are many sources of information listed in the attached reference list. However, more information is needed for i) controlling P. cinnamomi, ii) controlling herbivore control, iii) understanding the reproductive biology of key species, and iv) reducing the impact of climate change.
Management requirements and issues
Phytophthora cinnamomi is the most significant threat to the community. It has spread to all of the peaks through the transportation of infected soil either by human or animal vectoring. Once high in the landscape, P. cinnamomi spreads rapidly down slope in surface or sub-surface water flow. It has significantly reduced the number of proteaceous and other susceptible species in infested areas. The composition and structure of the community has been extensively modified as susceptible species are replaced by resistant species such as sedges (Cyperaceae and Restionaceae) (Barrett 1996, 2000). Plant members of the community that are significantly impacted by the disease include the Proteaceae – Persoonia micranthera, Banksia brownii, B. oreophila, B. solandri, Dryandra montana, D. concinna and Isopogon latifolius; Epacridaceae - Andersonia axilliflora, Leucopogon gnaphalioides, Andersonia echinocephala, Sphenotoma drummondii and Sphenotoma sp. Stirling Range; and the Papilionaceae – Gastrolobium leakeanum and Latrobea obovata (Barrett 2000, Barrett pers. comm.).
Fire also poses a threat and three major fires have occurred within the eastern Stirling Range in the last 25 years (February 1972, April 1991 and October 2000). Some areas of the community were only burnt in one fire but significant areas were burnt in two or all three fires with few long-unburnt pockets escaping (Barrett 2000, Barrett et al 2004). Fire can have a detrimental effect on the community as plant growth rates on the exposed summit and plateau areas are extremely slow, particularly for obligate seed regenerating species (Barrett 1996). The length of time (10 years for D. montana), required for many species in the community to reach maturity following fire suggests a long fire-free interval (>2
There is also a relationship between fire and P. cinnamomi, as increased disease impact has been noted in recently burnt areas (Moore 2006). Observations in this threatened Ecological Community suggest that fire may increase site susceptibility to P. cinnamomi. Poor recruitment has been observed in burnt areas of the TEC where proteaceous species were present pre-fire (Barrett 2000).
Recreational activities impact this threatened Ecological community, as there is a long history of recreation use within the Stirling Range area. The main issue with recreational activity has been the spread of P. cinnamomi. Recreational activity can also cause side path formation, path erosion, bare-ground occurrences, camp fire remains, litter and nutrient enrichment of soils (Barrett 2000). These all affect the quality of the ecological community.
There is widespread evidence of grazing by rabbits (diggings and scats) on Bluff Knoll Plateau, East Bluff, Pyungoorup and Ellen Peak. Grazing by rabbits and/or quokka (Setonix brachyurus) has had a significant impact on plant health after the 2000 fire, and has affected the regeneration of threatened species (D. montana, L. gnaphalioides, L. obovata and P. micranthera) as well as more common members of the TEC (Barrett 2000, Barrett pers. comm.). Anecdotal information suggests rabbit numbers have increased after fires in 1991 and 2000.
The overall health, diversity and composition of the Eastern Stirling Range Montane Heath and Thicket Community needs to be maintained. The level of threat to this community also needs to be reduced. One of the main reasons this community needs to be managed is to reduce the impact of P. cinnamomi on the community as measured by improved survival of P. cinnamomi susceptible taxa in infested areas. (Barrett 2000).
Management actions and responses
This community has an Interim Recovery Plan (IRP) 1999-2002, which evaluates threats to the community and details ongoing management actions addressed through the Department of Environment and Conservation (DEC). There are also Interim Recovery Plans for specific species within the community such as D. montana, A. axilliflora, L. gnaphalioides, P. micranthera and B. brownii.
The community’s recovery plan aims to maintain the overall health of selected remnants of this community and to reduce the level of threat to these areas. Phytophthora dieback is being managed through aerial phosphite spraying. Susceptible flora are monitored after phosphite treatment to evaluate effectiveness. Threatened flora species have been caged to reduce the impact from herbivores and monitoring assesses the effectiveness of this action. Volunteers assisted DEC with annual monitoring of the community from 1999 to 2007. The collection of seed and translocations of several species has occurred for ex-situ conservation of threatened species. Between 1997 and 2007 approximately $296 000 was invested to manage this ecological community. As the community is located within Stirling Range National Park, this community also benefits from other associated management actions undertaken within the park by DEC.
Outcomes
Since 1999, a major fire in 2000 had a significant impact on the threatened Ecological Community and its threatened species, resulting in reduced numbers and/or populations of key species and deterioration in the quality of habitat. Since 2000, there has been no further decline in the condition of the TEC but it remains Critically Endangered.
After the 2000 fire, a research project into the fire ecology of the TEC commenced with annual monitoring of vegetation. Demographic monitoring of threatened species (D. montana, P. micranthera, A. axilliflora and L. gnaphalioides) also commenced in 2000 and is ongoing.
Since 1997, and the commencement of the phosphite spray program, key species have been monitored to evaluate the success of spraying. Preliminary analysis of demographic and phosphite monitoring data has in general shown a reduction in the rate of decline of Phytophthora susceptible species (Barrett 2003, Barrett unpublished).
Future scenario
It is predicted that this threatened Ecological Community will remain as Critically Endangered. Grazing of regenerating vegetation since the 2000 fire has proven to be a problematic management issue. While phosphite has in general been effective in enhancing plant survival, grazing has significantly slowed plant growth and reproduction. There has been no effective herbivore control to date. Threatened species have been protected from grazing where possible by ‘caging’ individual plants.
Since the 2000 fire, a draft fire management strategy for the SRNP has been developed to protect fire sensitive TECs (Barrett et al 2004). Research into practical methods of herbivore control for remote areas, and ongoing research into more effective use of phosphite and other methods to control Phytophthora cinnamomi is required to improve the survival of this TEC.
Seven species in the threatened Ecological Community are at high risk of species extinction, including those species endemic to the TEC (D. montana, P. micranthera, A. axilliflora, D. collina, L. obovata) as well as B. brownii and L. gnaphalioides. Since 2003, translocations have been implemented for four members of the TEC (D. montana, P. micranthera, L. gnaphalioides and B. brownii). Ex-situ plants of D. montana are now being used as a source of material to develop tissue culture techniques. It is hoped that if sufficient numbers of these rare plants can be propagated, that breeding for resistant clones can be initiated with a view to restocking the TEC in the future. In turn, these techniques could be expanded to other key members of the TEC.
Figure 1: Location of the threatened Ecological Community
Andersonia axilliflora, Bluff Knoll
Dryandra montana
Phosphite spraying in TEC
References
Barrett S (1996). A Biological Survey of Mountains in Southern Western Australia, Department of Conservation and Land Management, unpublished report.
Barrett S (2000). Montane Heath and Thicket of the South West Botanical Province, above approximately 900m above sea level (Eastern Stirling Range Montane Heath and Thicket Community) Interim Recovery Plan 1999-2002, Department of Conservation & Land Management, WA Threatened Species and Communities Unit.
Barrett S (2003). Monitoring of Aerial Phosphite Applications for the Control of Phytophthora cinnamomi in the Albany District, Western Australia. in ‘Proceedings of Phytophthora in Forests and Natural Ecosystems, 2nd International IUFRO Working Party, Albany Western Australia, October 2001’.
Barrett S and Gillen K (1997). Mountain protected areas of south Western Australia. Parks 7:35-42.
Barrett S, Broomhall G, Comer S, Freebury G, and Grant M (2004). Draft Fire Management Strategy for the Stirling Range National Park. Department of Conservation and Land Management Unpublished Report.
Hartley R, Yates C, Barrett S, and Gilfillan S (2005). Stirling Range Dryandra, Dryandra montana. Interim Recovery Plan for Dryandra montana 2005-2110. Interim Recovery Plan No. 207. Department of Conservation and Land Management, WA.
Moore N (2006). Role of fire on Phytophthora cinnamomi in the Stirling Range National Park, Western Australia. BSc (Hons) Thesis, Murdoch University, Perth.
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Assessment of Australia’s Terrestrial Biodiversity 2008