Climate Change and Wildlife in Southwest WA

Professor Don Bradshaw and Cr. Peter Lane

March, 2016

At the recent Paris Climate Change Conference (December 2015), 196 nations agreed to limit global temperature rise to 1.50C above pre-industrial levels by signing up to 187 ‘plans’. Global temperatures have already risen, however, by 1oC and most scientists agree that this resolution will require stringent adherence if temperatures are not to rise by 2oC by the end of the century.

Although there is debate on the projected rise in sea levels [1], world ice caps and glaciers are melting faster than predicted [2] and the unanticipated escape of methane from the Arctic tundra will add to the problem [3].

The southwest corner of Western Australia is highly significant [4] in the world’s biota. It harbours an extremely rich flora and fauna that is already currently threatened by habitat degradation and loss [5], one of 34 such ‘hotspots’ in the world. [6] As part of this southwest corner, the Shire is faced with a serious challenge in being pro-active in maintaining this high level of biodiversity as climate changes. What are the challenges?

Water

There are many groundwater dependent ecosystems in the Shire. Wetlands include Kilcarnup swamps, Wilderness drive swamps, Margaret River swamps, Devils pool on Boodjidup Brook, Lake Davies wetlands and Turner Brook Wetlands. There is one small river, three creeks and eleven minor creeks that drain the coast in the Cape to Cape area. The Blackwood and Scott Rivers are two significant rivers that empty into the Hardy Inlet.

Increased groundwater extraction from the Leederville and Yarragadee aquifers (eg Nannup bore, drilled 2009) and declining rainfall and aquifer recharge have reduced availability of aquifers to discharge water into the Blackwood River and its tributaries, while the stress on this and other groundwater dependent ecosystems, already suffering by declining rainfall, will be even greater [7]. In most years Blackwood River summer flow is totally dependent on aquifer discharge as are the Margaret River pools east of Jackson Road [8, 9]. Hardy Inlet

Recent agricultural developments on the Scott Coastal Plain have led to a serious deterioration of water quality in the Scott River, with ten-fold increases in total nitrogen and phosphorus levels, due to dairy runoffs between 2000 and 2007.

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These have fuelled toxic algal blooms in the Hardy Inlet since 2005, the toxicity of which has been further exacerbated by reduced rainfall and the reduced discharge of groundwater into the Blackwood River and its tributaries.

Attempts to increase the flushing of the Inlet by management of the river mouth at Augusta will be an expensive and on-going problem for the Shire. Flora and fauna There have already been harbingers of the impact of extreme weather events on wildlife with reported deaths of Carnaby’s cockatoos in the summer of 2009/10 due to disease and heat stress [10] and predictions of the decline of Banksia species in the southwest [11] and the likely loss of pollinator species [12]. Western Australia has a large number of plant and animal species that are listed as Threatened or Endangered [13]. Where detailed research has been carried out on the reasons for their rareness, habitat loss stands out as the primary cause.

A study, drawing on the knowledge of fauna experts and covering a total of 26 species of native animals, concluded … “Habitat destruction was the factor most respondents implicated as the primary cause of range contraction of these species. These results suggest that the protection and retention of existing habitat areas is crucial for the long-term survival of most WA species, indeed 73% of species surveyed exist only in remnant areas of their former range.” [14] This poses an enormous challenge for biodiversity managers in such a diverse ecosystem as found in the southwest of WA and is just beginning to be acknowledged [15-17].

There have been efforts to re-introduce marsupials into former habitats disturbed by development, but few of these have met with success [18]. This failure has led to proposals for translocating species to areas where they did not exist in the past, but where the climate may be suitable [19]. If ‘assisted colonisation’ is to be used in an effort to relocate plants and animals that are likely to become extinct in traditional locations, new policies and legal frameworks will need to be developed [20]. To date, only the Western swamp tortoise Pseudemydura umbrina, the world’s most threatened chelonian and Australia’s rarest reptile, has been considered for assisted colonisation [21]. A recent study looking for possible translocation sites in the southwest identified areas of the d’Entrecasteaux National Park and the Scott Coastal Plain as wetland areas most likely to provide suitable habitat for Western swamp tortoises [22]. This highlights what will become a continuing problem for the Shire. There will be pressure on the existing natural habitats that will increasingly serve as refugia for plants and animals ‘escaping’ from drier areas to the immediate north of the Shire [23-25]. Recent studies, particularly with birds, have shown clearly what will happen as temperatures increase, habitats become drier and food becomes scarce. Wherever possible, birds move towards the southwest of the State, seeking refuge in cooler, wetter areas1 [26, 27]. Already, birds that we associate with the wheatbelt, such as pink and grey galahs, are now resident in Augusta. All three species of black cockatoos – Carnaby’s, Baudin’s and the Red-tailed are now all

1Climate change refugia for terrestrial biodiversity, Report of the National Climate Change Adaptation Research Facility (2013) http://www.nccarf.edu.au/content/biblio-1611, 216pp

2 found commonly in the Shire and all are listed as Endangered by the Commonwealth2. The Shire is also home to many rare and endangered species of plants; Lodge’s Spider orchid (Caladenia lodgeana), for example, is listed as Critically Endangered (CE) and now only found in one small area in the Donovan Street bushland. Other shallow soil endemics, such as Darwinia ferricola, Lambertia orbifolia 'Scott Plains' and the Scott River Boronia, Boronia exilis, all have very limited distributions and will come under threat with drying and any decline of the water table.

In summary, the predicted changes as a result of global warming that are likely to affect flora and fauna in the future are:

• Declining rainfall and river flows • Declining and eventual loss of aquifer support for groundwater-dependent ecosystems • Habitat loss • More frequent fires • Disease Most of these are interlinked: declining rainfall can lead to habitat loss through declining water tables; warming increases the chance of wildfire; too frequent fires lead to loss of fire-sensitive plant species [28]; habitat degradation can spread diseases such as dieback, insect infestations, etc (jarrah dieback and marri canker, neither of which may be directly linked to climate change but certainly to human activity, have the potential to forever change our forests). What can be done?

For the Shire to develop and implement policies that can in some way mitigate the impact of these changes on the biota, there are a number of options. Improvements in fire and water management and protection of habitat would appear to be the most effective in attempting to offset the impact of climate change on wildlife. In this the Shire is well placed with 167,265 ha, representing 67% of its land, still in a natural or relatively undisturbed state3. National parks account for 30,690 ha (12.3%), State forest and local reserves 98,210 ha (39.4%); land protected under the local planning scheme 1,475 ha (0.6%) and residual native cover (which may contain some eucalypt plantations) 36,890 ha (14.8%). These are the areas where most of the Shire’s biodiversity is concentrated and the largest of these areas is overwhelmingly comprised of state forests.

There have been calls for more targeted research on the impact of climate change on wildlife [29], but this will not necessarily provide answers and solutions to the immediate practical problem of what can be done to protect wildlife [30].

2 http://awsassets.wwf.org.au/downloads/sp018_fs_black_cockatoo_26feb08.pdf 3 Data courtesy Jared Drummond, Sustainability Planning Officer, SAMR

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Protection of and enhancement of habitat known to contain endangered species is a more proactive and effective response to the likely impact of climate change and needs to be embraced by the Shire [31].

The Shire has already introduced an innovative Conservation Incentive Scheme, whereby landowners are encouraged to preserve segments of native vegetation on their land, either through covenanting, or by concessions made to potential developers4. Initiatives such as this need to be expanded as part of an effort to both secure and increase the proportion of native vegetation and intact natural ecosystems in the Shire.

Recommendations

1. The Shire target habitat protection and creation as its primary goal in mitigating the effects of climate change on wildlife 2. Initiate an audit of remnant bushland within the Shire, both private and reserved, and identify other areas that could be further protected 3. Progress a planning initiative that would reward future developers for incorporating substantial areas of natural bushland into their planning scenarios 4. Encourage the planting of native gardens in the Shire and review the current policy of use of herbicides on road verges 5. Control the spread of weeds from adjacent farmlands onto road verges and reserves 6. Audit the current status of Shire ‘Flora Roads’ 7. Co-operate with the Department of Water to reduce nutrient runoff from dairies on the Scott River Plain into the Scott and Blackwood Rivers 8. Co-operate with Department of Water to establish baseline parameters of waterways (with some urgency, the Hardy Inlet) and GDE’s so that changes due to climate change and remedial work can be monitored 9. Encourage the prudent application of prescribed burning in protecting habitats of threatened and endangered species and ensure that threats to wildlife are assessed whenever applied 10. Establish contact with the Nannup and Busselton Shires in an effort to develop interlocking protocols for the protection of contiguous areas of natural bushland 11. Co-operate with Gondwana Link and other bodies working to increase the area of land under protection and establish linkages between currently fragmented ecosystems in the southwest5

4 Incentives Strategy for Conservation of Private Land within the Shire of Augusta-Margaret River February 2010 Land Insights: Planning Design Environment, 5 See Molloy, S., Wood, J. Hall, S. Wallrodt, S. and Whisson, G. (2009) South West Regional Ecological Linkages: Technical Report, WALGA.

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Proposed Motion

That the Sustainability Advisory Committee endorses proposals 1-11 in the Report and recommends these to Council for implementation by Shire Officers.

References

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