Riparian zone planting
Riparian zones are the areas that border streams and rivers, and other bodies of water like ponds and lakes. Planting riparian zones benefits the environment by filtering sediment and nutrients before they enter waterways. The plants also help prevent bank erosion and improve the habitat for native wildlife.
Benefits of riparian planting
The benefits of riparian zone planting include:
- improved streambank stability
- shade to decrease water temperatures – this reduces weed and algae growth and provides stable temperatures for aquatic life
- slowing the rate at which some sediments, nutrients and bacteria enter waterways
- improved habitat quality for fish, insects, birds and aquatic plants
- increased biodiversity
- improved landscape aesthetics.
Research by Scion looked at the benefits of planting trees around waterways.
What are riparian zones?
Riparian planting can be divided into 3 zones:
Lower bank zone
This is the strip of land prone to flooding. Plants must be able to tolerate waterlogged roots and survive many days underwater.
Plant at 1 to 1.5m spacings.
Middle bank zone
This zone is on higher ground but may partially flood every couple of years. Use plant species that can tolerate having damp feet.
Plant at 2.5 to 3m spacings.
Upper bank zone
May partially flood every couple of years. Plant species that prefer dry conditions. If planting on farms, then leave a grass strip at least 1 metre wide.
Riparian planting guides
Dairy NZ has regional planting guides which have a planting list appropriate to each region.
Your regional council may also have riparian planting guides.
Sometimes you could look at planting fast growing willows to stabilise any highly eroding streambanks. If preferred, they can then be cut back and natives established to gradually replace them.
Case studies on YouTube
DairyNZ's video on how to make riparian planting a success talks about planting techniques and tools.
Waikato Regional Council's video shows how dairy farmers, Barry and Julie Burwell, successfully plant their riparian areas.