Small, rock-dwelling vertebrates such as the nationally threatened pink-tailed worm-lizard (Aprasia parapulchella) have suffered from widespread habitat modification and will face further decline with new technology that is being used to crush vital rock habitat in agricultural landscapes. Photography by D. R. Michael.
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Removal of critical rock habitat threatens biodiversity

Thursday, 22 August 2019  | 

Australia has a rich biodiversity dependent on rock formations (e.g., rocky outcrops) and associated surface rocks. Rock formations are often minor features of landscapes—analogous to small islands—but can support a wealth of threatened and endemic species. Even small formations and scattered surface rock can provide important refuge for plant communities and wildlife adapted to life on rocks. Rocky outcrops may appear resilient, but they are fragile, underappreciated ecosystems, easily degraded by human activities. The impacts of illegal rock collection on threatened plants and reptiles, such as the broad-headed snake, are well established in conservation reserves. Yet the impacts of rock removal in agricultural landscapes are poorly recognised and require urgent investigation to prevent further declines in biodiversity.

Rock removal occurred at a massive scale during European colonialisation, but that threat has not gone away. Developments in broad-acre cropping technology have triggered a resurgence in large-scale removal of surface rock from agricultural landscapes. This new wave of habitat loss associated with rock-crushing machinery could spell disaster for threatened plants and reptiles, especially isolated and range-restricted species that depend on rock formations for their survival. Whilst not illegal, the removal of bush rock is listed as a key threatening process in NSW under the Threatened Species Conservation Act 1995. Broad-scale rock removal from grazing land is at odds with developments in sustainable farming practices, whereby agriculture and wildlife conservation can co-occur on the same land with mutual conservation and economic benefits. There is urgent need to develop guidelines to prevent the further degradation and removal of rock habitat in commodity production areas, and raise awareness of the ecological importance of preserving isolated rock formations across the broader landscape.

Supporting Research

Fitzsimons, J. A., & Michael, D. R. (2017) Rocky outcrops: a hard road in the conservation of critical habitats. Biological conservation, 211, 36-44.
A review of the literature on the ecological, cultural and economic values of rocky outcrops, threatening processes and conservation solutions.
McDougall, A., Milner, R. N., Driscoll, D. A., & Smith, A. L. (2016) Restoration rocks: integrating abiotic and biotic habitat restoration to conserve threatened species and reduce fire fuel load. Biodiversity and Conservation, 25(8), 1529-1542.
To examine the influence of rock habitat and native grass restoration and management scenarios (fire and herbicide application) on the use of the threatened Pink-tailed Worm Lizard (Aprasia parapulchella).
Michael, D. & Lindenmayer, D. (2018) Rocky Outcrops in Australia: Ecology, Conservation and Management. CSIRO Publishing, Collingwood, Australia.
To increase awareness of the biological, cultural and social values of rocky outcrops, the flora and fauna that depend on these systems and to provide management recommendations to improve their conservation values.
Michael, D. R., Cunningham, R. B., & Lindenmayer, D. B. (2008) A forgotten habitat? Granite inselbergs conserve reptile diversity in fragmented agricultural landscapes. Journal of Applied Ecology, 45(6), 1742-1752.
To examine the relationships of reptile diversity, rocky outcrop patch size and habitat condition.
Michael, D. R., Lindenmayer, D. B., & Cunningham, R. B. (2010) Managing rock outcrops to improve biodiversity conservation in Australian agricultural landscapes. Ecological Management & Restoration, 11(1), 43-50.
A review of the literature on granite outcrops in agricultural landscapes.
Pike, D. A., Croak, B. M., Webb, J. K., & Shine, R. (2010) Subtle–but easily reversible–anthropogenic disturbance seriously degrades habitat quality for rock‐dwelling reptiles. Animal Conservation, 13(4), 411-418.
To investigated the effects of human-induced rock disturbance on saxicolous reptiles.
Shine, R., Webb, J. K., Fitzgerald, M., & Sumner, J. (1998) The impact of bush-rock removal on an endangered snake species, Hoplocephalus bungaroides (Serpentes: Elapidae). Wildlife Research, 25(3), 285-295.
To examine the impact of rock removal on an endangered snake species (Hoplocephalus bungaroides).
Wong, D. T. (2013). Environmental factors affecting the occurrence and abundance of the Pink-tailed Worm-lizard (Aprasia parapulchella) in the Australian Capital Territory (Doctoral dissertation, University of Canberra).
To investigate the factors driving theoccurrence and abundance of the threatened Pink-tailed Worm Lizard (Aprasia parapulchella) in the ACT at regional and patch scales.