Planting for erosion control

Poplar varieties are available including:

• Veronese is wind and drought tolerant. It prefers open sites where it is less likely to get rust during a humid period. It is not as possum palatable as some other clones. 
• Tasman is a fast growing narrow crowned tree ideal for wind breaks. Tasman is the bigger grower, reaching 20-30 metres. It is palatable to possums. 
• Kawa has a narrow crown and is possum resistant. It grows well on moist sheltered valley sites. It does not stand very windy sites.
• Toa is a newer similar hybrid to Kawa. It requires moister more fertile sites than Kawa but will stand more wind. Toa is unpalatable to possums.
• Eridano is possum resistant and does well in inland valley systems with higher rainfall. Eridano grows into a spreading tree with large leaves. Many farmers regard them as the best "looker" of all the hybrids.
• Yeogi is a suckering hybrid that has a narrow crown and is best suited to drier sites. Suckering can be a problem on some sites but is readily controlled by grazing or mowing. It is a definite advantage on highly erodible sites.
• Kilmog performs well over a broad range of sites and especially on rolling hill country. Very good on river berm sites. Medium resistance to possum damage and high resistance to wind damage.
• Argyle is similar to Kilmog and also ranks well on drier sites.
• Pakai is a fast growing tree very suitable for gully and stream planting. Not recommended for exposed or very dry sites.

Willows

Willows variety include: 

• Tangoio (NZ1010). A tree willow selected for farm and horticultural shelter planting because of its high wind tolerance and good lower branch retention. Also tends to be a single leader tree and is the most drought tolerant tree willow present. Female.
• Kinuyanagi or Japanese fodder willow. Large shrub to small spreading tree (6 x 6 m) very vigorous on moist fertile sites once established. Male.
• Gigantea (PN220) vigorous growing osier willow, with a multi stemmed habit and maximum height of 7 to 8 m. Male.
• Musk willow or Salix aegyptiaca. Moderately vigorous growing shrub willow with a broad wavy leaf almost similar to an apple. Up to 5 m in height. 

Other Uses

Poplars can be grown for a number of uses, including shade and feed. The nutritional value of poplar and willow leaf is well recognised. Their feed value is reasonable and the presence of condensed tannins is thought to contribute to the increase in lambing percentage by helping the ewes use the protein in feed they receive more efficiently.

• Poplars and Willows as Fodder (pdf 380 KB)

Harvesting of poplars is carried out during the months of May, June, July. Once the poles are harvested they are stood in water for a minimum of 10 days to aid their establishment before being delivered to the planting site. Planting can be carried out until the end of August.

For planting where erosion control of streams and gullies is the major purpose the Council does provide financial assistance and expertise for approved works. This generally entails providing the planting material at no charge.

Many native plants can be used for erosion control. Their growth rate is slower than some of the exotics such as poplars but they can provide greater biodiversity and aesthetic values.

Landcare Research has currently completed studies on what native plants might be suitable for stream bank management. They looked at a number of colonizing plants such as kowhai, lemonwood and five finger I.e. plants that are easy to propagate, have fast growth rates and robust root systems. The study showed that the end of the trial, at age 5, cabbage tree was a top performer for a number of growth attributes. Tutu and ribbonwood weren’t far behind. Obviously there might be some other issues such as animal health that need to be taken into consideration when selecting species. More information can be found on the Motueka Integrated Catchment Management websites:

• ICM: Native Plants for Erosion Control
• Establishing Native Plants - from the Landcare Research website

It is also important to select plants that suit your site and locality to ensure sucessful establishment and to enhance the local biodiversity.