Rocky outcrop degradation and the impacts on native wildlife A rocky outcrop from Mount Buffalo National Park, Victoria. This granite tor is located on the Buffalo plateau and rises high above the surrounding woodland and treeless plains. These types of rocky outcrops were once home of the Brush-tailed Rock Wallaby Petrogale penicillata, a species which has disappeared over much of its former range. Photo: Damian Michael What are rocky How do rocky outcrops Why are rocky outcrops outcrops? form? important? Rocky outcrops are visible Rocky outcrops form when bedrock Rocky outcrops provide plants and exposures of bedrock. They is exposed at the Earth’s surface animals with shelter, protection occur on all continents, many through erosion, a process which from predators and refuge from islands and on the ocean floor, may take millions of years. Heat, fire or extreme weather conditions. and are found in a wide range water and chemical reactions shape Rocky outcrops also provide animals of vegetation types and climate the exposed rock resulting in a wide with places to forage, lay their eggs zones. Rocky outcrops vary range of characteristic and complex or give birth to live young. Many considerably in size and shape, rock formations. Different rock rocky outcrops support rare and and often have an ‘island-like’ types produce rocky outcrops with endangered plants and animals and appearance of protruding distinctive shapes and features. For are places rich in biological diversity. from relatively flat landscapes. example, granite outcrops are often domed-shaped with flared sloping Large rocky outcrops can influence sides, ironstone formations are weather conditions and provide often irregularly shaped, sandstone geologically stable microclimates formation are often flat-topped and that are exploited by organisms layered in appearance and basaltic with ancient lineages. Some rocky formations are often block-shaped outcrops retain moisture through and have column-like features. moss beds and subsurface seepages which is then slowly released back into the environment. Many rocky outcrops are sacred and provide The Inland Carpet Python Morelia spilota metcalfei is a threatened species closely Indigenous people with a wide associated with rocky outcrops in parts of range of resources, including water, its geographical range. This species is often food, medicine and stone tools. illegally collected from the wild and sold in the pet industry. Photo: Damian Michael What threatened From an agricultural perspective, and animal communities are affected rocky outcrops are important by climate change, air pollution species are dependent because they provide livestock with and acid rain. Degradation of rocky on rocky outcrops? shelter, harbor species that prey on outcrops reduces habitat suitability Approximately 180 species are agricultural pests, and support insects for a wide range of plants and restricted to rocky outcrops in which contribute to crop pollination. animals and places many species Australia, of which, more than 50 Large expanses of exposed rock at risk of local extinction. are threatened with extinction. serve as natural fire breaks and These include various rock- buffer the effects of intensive fires. How should rocky outcrops be managed to dwelling lizards and snakes, bats What are the main threats and rock-wallabies, possums, improve biodiversity? rock rats, rock pigeons and to rocky outcrops? Rocky outcrops in good condition grass wrens, spiders and aquatic Rocky outcrops are quarried and invertebrates. Some of the most should be fenced off from livestock used for landscaping, constructing and grazing pressure, invasive weeds threatened species restricted buildings and roads. Some rock types to rocky outcrops include the and pest animals should be managed are used to make pavers, benchtops or controlled. Rocky outcrops in poor Black Mountain Boulder Frog and sculptures. In peri-urban areas, Cophixalis saxatilis, Gulburu condition should be revegetated rocky outcrops are destroyed or with local providence species Gecko Phyllurus gulbaru, removed to make way for urban Arnhem Land Skink Bellatorius taking into account plant species development. In rural areas, rocky composition and planting density. obiri, Barrier Range Dragon outcrop are often damaged by Ctenophorus mirrityana, Brush- Artificial rocks can be created and livestock and feral animals such used to restore missing microhabitats. tailed Rock Wallaby Petrogale as pigs, goats and deer. penicillata, Central Rock Rat Zyzomys pedunculatus Rocky outcrops can damaged by and Southern Bentwing Bat illegal reptile collectors, bush rock A rocky outcrop in an agricultural landscape Miniopterus schreibersii bassanii. removal and various recreational that has been degraded by land clearing, overgrazing by livestock and invasion by activities such as rock crawling and A large number of plants exotic weeds. Photo: Damian Michael and ecological vegetation rock climbing. The vegetation that communities associated grows on rocky outcrops is often with rocky outcrops are also degraded through land clearing, threatened. These include the inappropriate fire and livestock Arnhem Plateau Sandstone grazing regimes, and invasive weeds. Shrubland complex and species In some regions, rocky outcrop plant such as the Narrabarba Wattle Acacia constablei, Bega Wattle A. georgensis and Rhyolite Midge Orchid Genoplesium rhyoliticum. Further Information For more information contact Dr Damian Michael [email protected] Fenner School of Environment and Society, The Australian National University. For more information on Research Project 1.2.1.6 Enhancing critical habitat for the Pink-tailed Worm-lizard in agricultural landscapes see the TSR Hub website. This project is supported through funding from the Australian Government’s National Environmental Science Programme..