Watercourses and their associated riparian areas — the vegetation corridors along streams and rivers — hold enormous value for farming operations and are important assets for production and biodiversity, not to mention the significant carbon storage capacity of riparian areas. Healthy riparian ecosystems improve water quality throughout the entire catchment area, benefiting the landholder and downstream users. Healthy and intact riparian habitats also provide shelter, reduce erosion, regulate flows, provide critical habitat for wildlife and are aesthetically desirable.
It is important that these sensitive areas are managed carefully to make the most of the services they provide. In agricultural landscapes, streams and riparian areas are often heavily degraded. However, restorative works in riparian areas and alteration of management practices can be highly effective and help to restore the crucial functions of these important landscape features.
Riparian ecosystems are complex, with many processes interacting simultaneously to maintain healthy watercourses and landscapes. A healthy riparian area on a farm provides a multitude of benefits to agricultural operations and farmers including: improved water quality; minimising land lost to erosion; nutrient deposition; limiting flood damage; improved water retention; and improved property values.
Healthy riparian areas are highly productive and provide high quality habitat for wildlife. Many terrestrial (land-dwelling) animals, including several threatened species, rely on riparian ecosystems to provide foraging and breeding habitat. Healthy riparian areas improve the condition of aquatic ecosystems, particularly for native fish, invertebrates and frogs. Good riparian area management will significantly reduce the main threats to many aquatic species.
With appropriate management, riparian areas can deliver a number of services for farm productivity and for wildlife.
|Productivity and profitability benefits||Biodiversity benefits|
Vegetation (especially native grass) filters nutrients and debris from adjacent paddocks and prevents contamination of water. Vegetation also slows runoff, causing water to flow in slow-moving sheets rather than fast-moving channels, thereby reducing erosion.
Planting vegetation to stabilise banks limits land lost to erosion and improves water quality.
Limiting stock access:
Functioning watercourses allow floodwaters to breach banks and deposit nutrients onto the floodplain. This dissipates flood energy and reduces the intensity of flooding downstream.
Facilitates the formation of chain-of-ponds watercourses. By slowing flows during wet times, sediment is deposited at many points along the watercourse, which causes gentle build-up of barriers that act as natural ‘leaky weirs’. When times are drier, these barriers form deep pools at intervals, so that the water is stored throughout the watercourse rather than all being deposited downstream, thus improving the water retention ability of properties during dry periods.
Improved property values due to amenity and visual appeal and by limiting the amount of land lost to erosion and allowing continued access to sections that might otherwise be cut off by deep erosion gullies.
Riparian areas often support large old trees, which are increasingly rare in the heavily cleared agricultural landscape of south-eastern Australia.
Large trees often have hollows, which are an extremely limited resource that provides critical habitat for a multitude birds, mammals and reptiles of conservation concern.
The threatened Squirrel Glider relies on drainage lines as feeding areas in periods when no trees are flowering (which is most of the time).
Several bird species, such as the Diamond Firetail, are attracted to riparian areas and build their nests near these landscape features.
Arboreal marsupials — such as possums, gliders — and antechinus species prefer to breed in riparian areas, but need these areas to be well vegetated in order to do so.
Where riparian areas have good grass and sedge and reed cover, sediments are filtered and erosion is controlled. These components are also a major source of organic matter supporting aquatic biota and are a crucial component of the aquatic food web.
The greater variety of available habitats generated by the formation of deep pools leads to greater diversity of native fish and frogs.
Healthy watercourses are essential to support some of our most attractive and interesting species, such as the Azure Kingfisher, Southern Myotis (or fishing bat), Rakali (or Water Rat) and one of Australia’s most iconic animals — the Platypus. Native animals such as these add immeasurable value to a farm, make riparian areas highly desirable places to spend time, and have positive benefits to mental health.
1. Restrict stock access
The most important step in restoring riparian areas is fencing to exclude or strictly control stock access. Given that squirrel gliders and other species, such as bats, occupy these areas, it is important that wildlife friendly fencing is used to avoid their entanglement.
The arrangement of fences will depend on the grazing history of the property and the goals of the land manager. The best practice for riparian restoration is to install fences to permanently exclude or limit stock grazing. It is important to ensure that these fences are installed above the high water mark to prevent damage during flood events, and well back from active erosion zones (generally the outside of bends).
Sedimentation can impact on biodiversity in a number of detrimental ways and should be controlled as much as possible. Waterways with cobblestones are biodiversity hotspots that attract invertebrates. Many species, such as the threatened Booroolong Frog, lay their eggs in between cobblestones. Sediment free cobblestones and other rock features are also important habitat for the Macquarie Perch. When allowed access to these areas, stock can quickly stir up enough sediment to fill the gaps between cobblestones and thus eliminate habitat.
Where it is not feasible to exclude grazing, fences can be installed beyond the immediate riparian area to create a riparian pasture, which can be carefully grazed as a part of a rotational grazing system. Temporarily resting riparian areas from grazing until there is sufficient recovery to recommence grazing according to sustainable management principles and practices can make a substantial difference in the function of these areas.
If none of these options are immediately possible, providing alternative shelter and water away from riparian areas, as well as moving any supplemental resources such as feed, salt and mineral stations away from sensitive riparian areas can encourage stock to spend less time there and may provide some benefit.
2. Plant native vegetation
Native trees, shrubs and grasses are essential layers in a healthy riparian ecosystem. When restoring a riparian area, it is important to replace any missing vegetation layers. It may be possible to achieve this through natural regeneration, but in many cases active planting will be required. Given that many watercourses are still fringed by remnant trees, enhancement plantings (plantings that complement existing vegetation) can be an effective and economical way of restoring structure to riparian vegetation.
Shrubs and understorey plants are the layer that is most commonly missing, as they are vulnerable to grazing at all stages of their lifecycle. This layer, combined with the ground layer, play important roles in filtering runoff and provide excellent habitat for a range of small birds and reptiles.
It is important not to underestimate the role of the ground layer in the services provided by functioning riparian areas. The ground layer — which includes grasses, sedges, reeds and rushes — does much of the heavy lifting in terms of nutrient and sediment capture from runoff. If trees and shrubs are too densely planted, they will shade out this ground layer and limit their ability to perform these functions. It is important when planting to account for this and not to plant too densely.
Generally speaking, the ground layer will regenerate naturally, when grazing is carefully managed.
3. Keep snags where they are
Healthy watercourses have many snags — tree branches, large limbs or whole trees that fall into or beside a watercourse. In the past, snags were removed from larger watercourses to make them navigable. However, today we know that snags are important features of watercourses and should not be removed as they facilitate the formation of pools by forming obstructions that trap sediment and fast-track the development of leaky natural weirs. They also provide excellent habitat for threatened native fish — such as Macquarie Perch and Murray Cod — and many frog species.
- Sources and further reading
Crane MJ, Lindenmayer DB & Cunningham RB. 2013. Use and characteristics of nocturnal habitats of the squirrel glider (Petaurus norfolcensis) in Australian temperate woodlands. Australian Journal of Zoology, 60: 320-329.
Mac Nally R & Soderquist TR & Tzaros C. 2000. The conservation value of mesic gullies in dry forest landscapes: Avian assemblages in the box-ironbark ecosystem of southern Australia. Biological Conservation, 93: 293-302.
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