Rocky outcrops are areas of exposed bedrock found in many different farming landscapes. Large rocky outcrops are important for conserving the specialised plants and animals that use this habitat, harnessing water, contributing to soil nutrients and providing livestock with shelter from the wind and sun.
Rocky outcrops come in all shapes and sizes, ranging from huge granite boulders strewn across hilltops, to small collections of scattered rocks in a paddock.
When protected from grazing and revegetated with groundcovers and low shrubs, rocky outcrops can help filter and slow runoff, leading to increased soil moisture and reducing erosion.
They are also valuable habitat for a rich variety of plants and animals, including threatened and specialised rock-dwelling species.
The cracks and crevices among rocky outcrops protect vulnerable plants from grazing by livestock and other herbivores, meaning that many plants that were formerly widespread now find refuge among the rocks.
The Thick-Tailed Gecko (Underwoodisaurus milii) is widespread across south-eastern Australia and is particularly common on large granite outcrops where it excavates a shallow burrow beneath laminated rock slabs. Bush rock removal and poachers are damaging critical habitat for this and other rock-dependant species.
Damian Michael.
Comparison between a degraded rocky outcrop, left, and a fenced rocky outcrop where vegetation has been able to regrow, right. Photos by Damian Michael.
Rocky outcrops subject to high grazing pressure can become bare of vegetation, leading to erosion and limiting water infiltration into the soil. Fencing a rocky outcrop and allowing vegetation to regrow can bring a whole host of benefits, both for farm productivity and for native wildlife and plants.
Well vegetated rocky outcrops (left) can provide great habitat for wildlife and plants, including the eastern stone gecko, native bees, rock isotomes and peregrine falcons. Photos by Suzannah Macbeth, Dave Smith, Meredith Cosgrove, Mason Crane and Sam Gordon (CC BY-NC-SA 2.0).
Rocky outcrops and scattered surface rocks can take many millions of years to form. They are crucial and truly irreplaceable habitats.
Management of rocky outcrops as a key natural asset can offer farmers unique stewardship opportunities and support key ecosystem services like erosion control, pollination and hydrological cycling, as well as creating habitat complexity and conserving biodiversity.
Improving the management of rocky outcrops often requires minimal effort and cost. Where rocky outcrops are located on areas of low productivity, such as on hillsides with shallow soils, fencing the outcrop to exclude stock often has limited impact on the farm business.
Controlling or excluding livestock grazing is the most effective method for protecting and preserving rocky outcrops.
Livestock damage rocky outcrops in various ways, these include overgrazing the ground vegetation, changing the composition of the plant community, causing the loss of sensitive plant species, suppressing the regeneration of trees and shrubs, destroying shrubs and other midstorey plants, physically trampling surface rock and burrows in the soft soils, and accumulation of excess nutrients on the site.
The impact of livestock will vary with type, the stocking rate, time stock were left in and excluded and the timing of grazing. How livestock are managed in these areas will largely depend on the desired outcomes, for example if you wish to manage the site for the conservation of sensitive native plant species, livestock exclusion or very strict periodic grazing would have to be implemented depending on the vegetation type and structure.
Rocky outcrops can also provide habitat for pests such as rabbits, goats, deer and foxes. These species can have negative impacts on production and the environment. Consideration should be given to the impact of non-target species (such as pythons and quolls) when implementing pest control measures such as applying poison baits and burrow ripping.
Many rocky outcrops are heavily disturbed and largely cleared. Such outcrops will benefit from careful revegetation of native trees and shrubs, enhancing the feature for biodiversity and production.
However, if planting trees near your outcrops, take caution – dense plantings, particularly of eucalypts, can crowd out desired shrubs and wild flowers, and reduce reptile populations.
Surface rocks are an important habitat around rocky outcrops for many species, such as Pink-tailed Worm-lizards. It is common practice to collect these rocks for gardens or in an attempt to improve access for farm machinery. These practices have negative impacts on biodiversity. Similarly, logs also contribute to the environmental values of an area. Where these have been removed, the addition of rocks and logs can have positive outcomes.
Improved environmental management and increases in woody vegetation around rocky outcrops benefit other species, such as kangaroos, wallabies and wombats, which all have important roles in the natural ecosystem. To ensure these species and your rocky outcrops coexist, installing kangaroo-proof fencing may be necessary to protect your outcrop.
Rocky outcrops support high native plant diversity. The variation in shade, shelter and moisture levels of the soils allow for this. While some rare and threatened plants still exist on some outcrops, enhanced rocky outcrops also provide an opportunity to re-establish some of those plant species. This will benefit native bees, birds and butterflies, and can create reservoirs and seed banks for rare and/or threatened species.
Key features of a protected rocky outcrop.
Prior to modern forms of pest control, landholders once relied on carpet pythons to control pests like rats and mice around sheds and grain silos. But like many Australian species, python numbers have declined since the 1800s in many parts of Australia, they are now listed as endangered and are rarely seen.
Rocky outcrops are great habitat for carpet pythons. By protecting rocky outcrops and, where possible, connecting them to vegetated areas along creeks or in valleys, farmers can help create the conditions for the species to thrive and once again play a role in pest control.
Photo by Damien Esquerre.
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