Riparian planting and stream care
A riparian zone is an area that links the land with water eco-systems, most commonly a stream bank or a wetland. It is an important zone for preventing contamination of fresh water, and for increasing diversity of bird and fish life, as well as simply a nice place to be. The riparian margin also acts like a sponge to help protect the land from flood damage
What are the benefits of riparian planting?
- Improves habitat for fish by shading the water and keeping temperatures cool
- Improves habitat for birds and other wild life providing a corridor from the hills to the sea
- Improves amenity and aesthetic values for people
- Filters sediments and pollutants from entering waterways, and helps prevent flooding.
- Observe the stream through the year and how it changes seasonally – what plants grow in the stream dependant on water flow and temperature, how the flow behaves dependant on water levels.
- If you own the stream, consider planting a riparian margin – 10 metres either side of the stream is the recommended minimum width.
Planting and maintaining a riparian margin or zone
A stream has different zones that need different types of plants - for instance to cope with being water logged in winter but possibly quite dry in summer, or to not restrict water in the event of high water levels so that they contribute to flooding. Plants in the flood area must be able to bend with the flow of the water such as the Carex species.
Steps for planting a riparian margin:
- Prepare a planting plan that accounts for the different zones of your riparian area.
- Find out how many plants you need and of what species. To do this you need to know the size of your planting area. You will need approximately one plant per 1.5 metre square – smaller plants such as sedges and ferns can be planted up to 5 per square metre whereas larger trees such as Kahikatea, may need 5 metres apart and set in amongst smaller species.
- For appropriate species for your area see link to heritage planting guide
- Do not plant any pest plants link to pest plant guide
- To establish a planting, you will need suitable coloniser or nurse species. These are fast growing plants that can cope with drier more open situations, and provide the bulk of your planting. Once established, these plants provide shelter for your longer term plants such as titoki or kahikatea where space allows.
- For a successful planting, you need to prepare your site well. In rural areas, exclude stock from your planting site by fencing the waterway or wetland link to rural fencing info
- Clear the site of grass and weeds round each planting site so that new plants get enough light and nutrients without having to compete with weeds or grass.
- The best time to plant in the Nelson area is from around April to August, dependant on rain fall. This will allow plants to establish before the heat and dry of summer. Be aware of the tendency for frosts in each planting situation as some species will be sensitive to early spring frosts.
- Purchase your native plants from those nurseries that eco source plants, or try and eco source your own plants from local seeds. Read DOC's Eco-Sourcing Guidelines for Nelson City
- Take on small sections at a time so that you can provide each planting area with the maintenance that will be needed for success, especially weed management.
- Stake your plants or use plant protectors to make sure you can locate them later.
- Regularly check your plants for a few years after planting. Weed around them to avoid their having to compete with other plants.