Workshop Report: Poplar and willow planting for Land Overlay 3A, Gisborne, East Coast region
Principles
In developing a logical argument over which treatment is best suited to an individual locality, it is easy to lose sight of the purpose of the ECFP. Preceded by the Conservation Forestry Scheme (1989–1993) the ECFP is the latest of many attempts since the 1960s, to provide central government funding for erosion control. It was introduced in acknowledgement of this region’s heightened erosion problems following Cyclone Bola (1988) – a 1:100 year event which has now been upgraded to 1:70 year event – and to provide a structured long-term (20 years) opportunity for this region to ultimately deal with its erosion problems. As such the ECFP was designed to traverse changes in government.
We also need to remind ourselves that in selecting the most appropriate erosion control solution we are dealing with the “worst of the worst” Category 3A land. In accordance with Variation 176 of the Sustainable Hill Country Regulation, treatment, if implemented, will have to remain effective in the event of severe storms which are likely to be more frequent.
There is optimism amongst soil conservators across the nation that, with appropriate species selection (using currently available clones), planting spacing, installation and maintenance, the erosion control performance of poplar and willow plantings can be greatly improved. To achieve an effective erosion control outcome for each site does, however, rely on the following key principles:
- Understanding the type of erosion and the processes requiring control. Each erosion type requires a different approach.
- Appreciating the severity of the erosion in question. Space planted trees will not control severely eroding soil slip faces. More severe earthflow erosion will require closer tree spacing.
- Matching the tree type to the land type. Thorough inspection of site conditions and factors such as soil moisture levels and retention, wind, frost and threats from animal pests. Failure to select the most appropriate variety will result in tree losses.
- Planting all the relevant parts of the slope and not just the actively eroding parts.
- Recognising that to achieve effective erosion control other techniques such as dewatering, drainage, gully support, dams and contouring may be required in conjunction with the various tree planting options. Treatments additional to tree planting are, however, outside the mandate of ECFP and therefore may have to be funded by the landowner.
- Continued maintenance of plantings is essential.
Contact for Enquiries
East Coast Forestry Project
Ministry of Agriculture and Forestry
Cnr Grey St & Childers Rd
1st Floor ZGFM Building
PO Box 2122
Gisborne 4040
Tel: +64 6 986 8691
Fax: +64 6 986 8697
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