What are Riparian Zones and Vegetation?
The edges of wetlands, creeks and drainage lines are commonly referred to as riparian zones. Riparian zones adjoin or directly influence a body of water and include land alongside small creeks and rivers, river banks, gullies and dips (which sometimes flow with water), as well as around lakes, wetlands and river floodplains that interact with the river in times of flood. The riparian zone can extend from several to hundreds of metres, depending on the water body. Riparian zones occur whether the water bodies are both permanent or temporary (for example many wetlands experience natural drying out periods). They also occur whether the water body is natural or artificial (a farm dam). Riparian areas contain specialised vegetation communities adapted to the moist conditions (eg. rainforest species, sedges, and species such as mangroves and saltmarsh that are adapted to flooding of freshwater or saline water). Many of these vegetation communities are sensitive to disturbance, vulnerable to weed invasion and are not well adapted to fire.
The Importance of Riparian Zones and Vegetation
Riparian zones are important habitat and breeding areas for native animals and plants. In a predominantly cleared landscape, riparian lands also provide wildlife corridors and refuge for animals in times of drought. Forming a link between land and water ecosystems, riparian lands are very important in slowing water velocity, stablising streambanks, and reducing erosion. Riparian vegetation acts as a water filter and is important in maintaining water quality, and nutrient and algal growth. Special attention should be given to the protection and management of riparian zones to prevent soil erosion and to protect and improve water quality.
Environmental Issues and Riparian Zones
Creeks, streams and rivers are dynamic entities that are continually changing in response to natural and human activities. Waterways are constantly shifting within their current channels and making adjustments across their floodplains. Use of riparian lands should recognise that it can be financially or physically impractical to stop these natural changes. The removal of native vegetation within catchments has caused major change to the way water moves through the landscape. Native vegetation once slowed the flow of water, allowing it to percolate through the soil and feed streams between rainfall events. The loss of native vegetation however has caused water to move quickly to drainage lines (including creeks and rivers) during rainfall. This increases the volume and velocity of flows during and shortly after rainfall events leading to higher rates of erosion including bank under-cutting and slumping, and stream bed erosion. These processes are particularly severe in areas where riparian vegetation has been degraded by clearing, stock grazing, and weed invasion.
The removal of large woody debris in many streams, undertaken in the belief that this would reduce flooding, has also contributed to unstable streambanks. Large woody debris include masses of vegetation such as full trees, shrubs, trunks, branches, tree heads or root masses, which have been washed into rivers, streams, or onto the floodplain. Large woody debris is very important in slowing the velocity of streams, reducing overall erosion and improving structural stability. The localised erosion that can occur around large woody debris is important for the ecology and structural diversity of streams and rivers, and forms essential habitat and breeding areas for aquatic animals such as fish and terrestrial animals such as birds.
Protecting Riparian Zones and Vegetation
There are a number of ways you can protect riparian lands and riparian vegetation, to benefit native wildlife and property productivity. They include:
- Revegetating banks and riparian areas, using a variety of native plant species (trees, shrubs, herbs and grasses)
- Fencing to restrict stock access to waterways and drainage lines using fencing. Stock watering can be provided through alternative off-stream watering points
- Controlling noxious and environmental weeds
- Seeking professional advice prior to attempting any works to prevent or repair erosion. This can be provided through the Hunter-Central Rivers Catchment Management Authority, Local Council, Landcare, or the Department of Environment and Climate Change
- Not removing sand or gravel (any such activity requires permission from the New South Wales Department of Environment and Climate Change)