Key points for forest developers and landowners to be aware of are:
Wildings are very obvious before they reach cone-bearing age.
Wilding tree spread in the Mackenzie Basin.
Wilding tree spread depends on 3 factors: species, siting, and downwind land use.
Use the score sheet below to calculate the risk of spread before you plant.
Use the highest figure applying to your situation.
Some species spread much more readily than others. Spread-prone plantation species such as Corsican pine and Douglas fir should never be planted:
Species vary in palatability, which affects how easily they are controlled by stock (see (1b) in the score sheet table below).
Two or more rows of less spread-prone species, such as Ponderosa or Radiata pine, planted along plantation edges may reduce the spread of internal trees.
Wilding seedlings are vulnerable to grazing for the first 2 years. Mob stocking with sheep will significantly limit their spread, often to the extent that other control requirements are minimal. Cattle grazing is not as effective.
Spread can be limited by oversowing and topdressing within a 200 m zone of spread-prone trees. This promotes increased grazing pressure on young wildings and helps the tussock grasslands compete strongly with germinating tree seedlings.
Enter your score (the number associated with each option) for each category in the boxes provided and your total score will be shown at the bottom of this form.
Pinus nigra and Pinus contorta pines spreading near native bush in the Rakaia catchment.
Tree planting can contribute significantly to hill country development and prosperity if wilding safeguards are taken.
Reference: "Wilding Prevention" by Nick Ledgard & Lisa Langer is available free of charge from: Forest Research Institute, Box 29 237, Fendalton, Christchurch.
Acknowledgement: "Calculating Wilding Tree Spread Risk from New Plantings" was prepared by: N Ledgard, NZ Forest Research Institute Ltd.
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