“Riparian” is derived from the Latin word ripa meaning river bank, so riparian zone refers to the land beside a stream but is also applied to any buffer area around other wet areas such as wetlands, swamps and ephemerals. Land in this buffer zone interacts with rainwater runoff from hill slopes and with stream water when it overflows its banks. A well-vegetated riparian zone affects the stream by-
- intercepting runoff;
- providing shade that keeps water temperatures cool;
- providing leaf matter and wood for habitat and food; and
- stabilising stream banks.
Riparian management aims to reverse some of the impacts of land-use change, by filtering contaminants before they reach the stream water, and restoring the functions provided by trees (shade, bank stability). Methods include-
- fencing, so stock can’t get into streams;
- leaving a buffer of long grasses (occasional grazing of which permissible); and
- replanting with ground hugging species, shrubs and trees.
Developing riparian strips around streams and establishing and protecting wetlands to trap sediment and nutrients can mitigate the effects of nutrient and sediment movements off the deer farm paddocks and create a quality habitat for aquatic life. Riparian plants will filter overland flow and protect the waterway. See Section in the Landcare Manual on on fencing, flood gates and culverts.
While permanent exclusion of deer from riparian ‘planted’ areas is essential, in some cases, where riparian zones are in grass rather than shrubs and trees, occasional grazing can be beneficial to maintain a healthy and thick grass sword with good filtering capability. Sheep should be used in preference to other stock, as they are less likely to enter the water and eat shrubs and trees. A filter of thick grass on the riparian strip will retain deer pellets, exposing them to the sun’s rays, so the natural UV light will kill bacteria associated with dung.
Where access to the water is required for stock drinking, it should be limited to areas where the bank can be protected from erosion, potential wallows and storm water flows.
A wetland is the wet margins of streams, rivers, ponds, lakes, lagoons, estuaries, bogs and swamps. Wetlands can also be constructed to treat runoff from farmed catchments. Wetlands are valuable because they filter nutrients, control sediments, assist with flood control, provide a habitat for wildlife and native plants and may also have cultural or recreational values.
Wetlands are particularly valuable for cleaning up diffuse nutrient losses within the farm – see advice on Constructed Wetland Treatment of Tile Drainage.
Contact your local regional council for advice on managing wetlands.
Environmentally focused deer famers are increasingly creating environmental protection areas and instituting fencing, riparian planting and careful stock management around their natural water resources. Environmental capital expenditure on riparian fencing, planting and sediment traps is regarded as ongoing investment to improve economic sustainability, assist with stock management and enhance environmental outcomes. However riparian fencing to exclude deer is several times more expensive than for cattle or sheep. Riparian protection works can be programmed in the farm's LEP and scheduled to take place in an affordable manner over time.
Your regional council may administer funding programes to fence and plant both riparian and wetland areas.