Native Species
Small stature plants suitable for planting adjacent to watercourses
Healthy and functional riparian areas provide several benefits. What to plant on a riparian margin depends on its intended benefit. Is it being retired to improve water quality in the stream, or to grow timber on an area of the farm that is difficult to graze, or to restore a habitat for native plants and wildlife?
Many native plants are ideal for riparian plantings. Native plants have evolved in New Zealand and so have adapted to the climate, soils and other growing conditions. Native plants are ideal for beautification as they have a wide range of foliage, colours and textures. Some native species are also fast growing.
The original riparian vegetation varied widely around Southland from mixed hardwood species to beech forest to red tussock to swamp vegetation. Most of the original riparian vegetation cover of Southland (especially in lowland areas) is now gone.
Riparian communities and particularly some specialised riparian plant species are now uncommon, or are nationally threatened. Some of these threatened plants include Olearia hectorii (nationally endangered), Olearia fragrantissima (nationally vulnerable), Hoheria angustifolia (locally uncommon). Even our cabbage tree is under threat by a disease-causing agent called Phytoplasma (which has devastated many northern regions). Therefore, utilising native species can help restore some of the natural character and species of the riparian area.
There is a scarcity of native birdlife in many of New Zealand’s populated and developed areas, both town and country. Although we cannot return New Zealand to its original state, the fact that native birds are seen in urban areas shows that some species can live in situations differing greatly from their original habitats. Plantings can be used to attract wildlife into an area. Those which produce fruit and seeds (wine berry, coprosma etc) or nectar (kowhai, flax etc) are the best species to try. Some birds also feed on foliage (kowhai, lacebark). Plants will provide nesting habitat for a range of birds including ducks.
Native trees suitable for riparian planting
- Black mapou Pittosporum tenuifolium
- Broadleaf Griselinia littoralis
- Glossy karamu Coprosma lucida
- Halls totara Podocarpus hallii
- Kahikatea Dacrycarpus dacrydioide
- Kowhai Sophora microphylla
- Lemonwood Pittosporum eugenoides
- Manuka Leptospermum scoperium
- Matai Prumnopitys taxifolia or Black Pine)
- Mingi Mingi Coprosma propinqua
- Ribbonwood Plagianthus regius
- Wineberry Aristotelia serrata
- Olearia species such as O.dartonii, O.traversi, O.arboreseas, O.avicenniaefolia, O.paniculata are especially good for exposed sites
Shelterbelts with native species
Natives may be planted in groups or randomly placed. The plants recommended for the exposed edge are those that are hardy to wind. However, the Olearia species are not as frost hardy as the other species. Pittosporum spp (black mapou "tenuifoliu" and lemon wood "eugenioides") are generally used more abundantly than other species.
When planning for mixed shelterbelt, place the hardiest species on the exposed side, the tallest growing species in the middle section and lower growing species towards the front. Besides providing good shelter this plan gives a wonderful visual pleasure:
- Edge exposed to wind (you can think of windbreak cloth also)
- Flax (2 m)/toe toe (2 m)/cabbage tree (12 m)
- Olearia traversii (6 m)/Olearia dartonii (4.6 m)/Olearia paniculata (6 m)
- Middle section – tall growing species
- Black mapou (10 m)/wineberry (8 m)/ lemonwood (12 m)/lowland
- Ribbonwood (15 m)/red mapou (7 m)/ tree fuchsia (12 m)/kaikomako (12 m)
- South island kowhai (10 m)/marble leaf (10 m)/broadleaf (15 m)
- Front – leeward side
- Koromiko (3 m)/lancewood (12 m)/ Olearia arborescens (4 m)/three finger (5 m)
There are a number of nurseries that produce stock for shelterbelt and riparian plantings. These often have a range of hardy native species that are suitable for Southland conditions. Plants grown from locally collected seed are the best.
Cost
The cost depends on the plant size/pot size and also the number of plants. Root trainer plants are generally cheaper.
Preparation/maintenance
Erect stock proof fence as early as possible. This allows grass to grow and become rank. This also affords some shelter to the newly planted seedling. For best results, it is worthwhile to spot spray individual planting sites. This reduces competition while the plant establishes. It also assists plants to release spray or grub around plants to remove competition until plants reach 70-80 cm tall. If release spraying, use a selective herbicide (such as Gallant which is grass selective) to avoid damaging plants. Use correct label rates and avoid any chemical entering the waterway.
Site variation
Near the coast, salt spray and wind exposure may affect plant selection. Inland sites may experience harder frosts; this may also affect plant selection. In exposed sites, hardy shelter plants may require to be planted initially with other species added later. Some native plants are restricted in their distribution e.g. beech tends to be found in western and northern Southland, not on Southland plains or eastern Southland.
Ensure the plants chosen are suitable and tolerant of the conditions they will experience. If unsure seek advice from Environment Southland’s Land Sustainability Officers or Department of Conservation. )
Environment Southland is the brand name of Southland Regional Council.