Australasian Plant Conservation
Originally published in Australasian Plant Conservation 20(1) June - August 2011, p 5-6
Conserving the rare flora of the Granite Belt in Southern Queensland
National Parks Association of Queensland, Brisbane. Email: firstname.lastname@example.org
Increased frequency and hotter fires as a result of climate change may result in plant death and loss of soil seedbanks for obligate seeders that only regenerate from seed, such as the Granite Boronia (Boronia granitca).
Prickly Bottlebrush (Melaleuca williamsii), listed as vulnerable species, is threatened by inappropriate or altered fire regimes. A 5–15 year fire regime is considered to be a suitable fire frequency to prompt resprouting in this species.
The Granite Belt is an extensive complex stretching from Stanthorpe in Queensland south to Armidale in New South Wales. It has many diverse and unusual habitats resulting from its elevation, topographic variation, outcropping rock and rainfall gradients. Vegetation communities vary from tall open forest in moist eastern parts and shrubby open forest and woodland on rocky slopes, to grassy open forests on alluvial plains and heath on granite pavements. Only 45% of the native vegetation in the Queensland part of the Granite Belt remains as remnants and 12% (17 000 ha) is located within conservation reserves. The latter areas are complemented by several state forests and a growing number of nature refuges.
The Queensland component of the Granite Belt has high plant species diversity and a high level of endemism. Over 50 species are listed as endangered, vulnerable or near threatened under State legislation. Another 70 species, mostly occurring in the montane heaths and shrubby woodlands of rocky areas, montane swamps, riparian habitats and sheltered valleys, are defined as being of special conservation interest. Some plants are at the northern limits of their range, while others in unusual habitats (such as shallow peaty depressions near the top of granite tors) are restricted to fewer than 10 populations. Many species are clustered together in areas of suitable habitat, some of which have formal protection in national parks and nature refuges, but other areas are completely unprotected. The National Parks Association of Queensland (NPAQ) has been working with local landholders to identify and protect rare flora in the Queensland Granite Belt area, particularly in the face of the predicted impacts of climate change.
The threat of climate change
A suite of threatening processes affect plants in the Queensland Granite Belt, some of which appear to be exacerbated by subtle changes in climate. The area is getting warmer: the first frosts appear earlier than two generations ago, the number of frosts is decreasing, and the peak spring wildflower period is now early, rather than late, September. Projected climate scenarios predict that by 2050 the Granite Belt will experience warmer temperatures (winter maxima +1.5–2.0°C; summer maxima +1.0–1.5°C), a 5–10% decrease in winter rainfall and a 0–10% increase in rainfall in the other seasons (DECC NSW 2008).
The predicted climatic changes could affect the conservation the Granite Belt’s rare flora through:
- more frequent and hotter fires that cause tree and shrub death, including of species regenerating only from seed (i.e. obligate seeders, including rare Boronia species) and destruction of soil seed banks
- changed hydrological regimes resulting in the drying of habitats, such as elevated swamps and wetlands, making them more susceptible to fire and potential habitat destruction
- the arrival of a suite of new species, e.g. drought-adapted exotics, that dislocate native species and alter species’ interactions
- subtle shifts in vegetation types, for example towards more ironbark-dominated communities and more open woodlands.
Rare Flora Survey Group
In late 2008, the National Parks Association of Queensland established a Rare Flora Survey Group to train and coordinate volunteers in identifying rare plant species and their habitats on public and private lands that make up the protected area estate in Queensland. To date, 19 people have been trained in plant identification and 40 people have participated in surveys of four nature refuges on the Granite Belt. These surveys have identified more than 40 new populations of rare and threatened plants. This is valuable information that landowners can use to direct the management of their properties for conservation. The ecological application of fire, fencing off specific areas from stock, removing weeds and managing natural regeneration are just some examples of these actions used in the area.
Dealing with climate change
The role of climate refugia
Climate refugia allow species to persist in the face of climatic stress (Morton et al. 1995) and are characterised by diverse topography, shelter from extreme events such as severe wildfires, and the persistence of moisture and temperature regimes suited for species unable to survive in the surrounding environment. Evolutionary refuges, such as mountain tops, contain taxa with naturally fragmented and geographically restricted distributions.
Ecological refuges include sites that provide microhabitats that are moister and cooler than the surrounding environment, drought refuges such as permanent waterholes, and sites that offer some form of amelioration from prevailing environmental conditions and refuge from human impacts (Mackey et al. 2002). These areas support localised populations of species that are absent from or rare within the surrounding landscape, and which could become increasingly isolated and under pressure. Ecological refuges on the Granite Belt include elevated swamps, waterholes, mound springs, riparian areas, south-facing gorges and protected rainforest pockets (Donatiu 2009), while granite outcrops may also function as evolutionary refuges (Byrne 2007).
The role of landscape scale corridors
In Australia many conservation groups and governments are currently promoting the establishment of landscape scale corridors as mechanisms to conserve biodiversity and maintain ecosystem function. Such projects are valuable when they promote collective conservation effort amongst land managers, connect otherwise unconnected remnant vegetation, increase habitat area or provide, where this is possible, altitudinal pathways for plant and animal migration.
Many such projects understate the role of landscape scale corridors in sustaining habitat variation and overstate the migratory benefits of such linkages. Currently there is little evidence to show that corridors will enable most Australian plant and animal species to adapt to the changes in climate that are occurring now and have been forecast for the future. Some research shows that species appear to be responding to climate change in less predictive ways and will not be served by the creation of migratory pathways (e.g. see Byrne 2007). Such research challenges the science behind, and emphasis placed on, large scale corridor conservation projects in Australia.
There are other arguments against the widespread use of landscape scale corridors. For example, they can exacerbate edge effects, act as a conduit for the spread of invasive species, increase the spread of wildfire, and will not be able to protect species unable to move.
The National Parks Association of Queensland has undertaken site and wildlife surveys of iconic Queensland landscapes since 1930, and advocated for their inclusion in the reserve estate. This task is no less important today, as the Queensland Government pushes for 20 million hectares in protected areas by 2020. But resources are finite, and acquisition decisions must be made responsibly using the best scientific understanding of the impacts and complex interactions wrought by a changing climate. The current Caring for Our Country Business Plan rightly prioritises the protection of refugia areas. At a local level, regional bodies such as the Queensland Murray-Darling Basin Committee are investigating how they can identify and protect these areas in places such as the Granite Belt by working with local landholders and conservation groups. The National Parks Association will continue to contribute as much as it can to this process.
Byrne, M. (2007). Phlyogeography provides an evolutionary context for the conservation of a diverse and ancient flora. Australian Journal of Botany 55: 316–25.
DECC (2008). NSW Climate Change Action Plan. Summary of climate change impacts New England Tableland/North West Region. Department of Environment and Climate Change (DECC), New South Wales.
Donatiu, P. (2009). The Vanishing Wild: Rare flora surveys of current and proposed nature refuge properties on the Stanthorpe Plateau. National Parks Association of Queensland, Brisbane.
Mackey, B., Lindenmeyer, D., Gill, M., McCarthy, M. and Lindesay, J. (2002). Wildfire, Fire and Future Climate. A Forest Ecosystem Analysis. CSIRO Publishing, Melbourne.
Morton, S.R., Short, J. and Barker, R.D. (1995). Refugia for Biological Diversity in Arid and Semi-arid Australia. Biodiversity Series, Paper No 4, Biodiversity Unit, Environment Australia, Canberra.