As mentioned the Nursery is on a cold, exposed site with frequent high winds. This means particular attention has been paid to encourage root establishment in Eucalypts for anchorage. Initially there were problems with windthrow and instability of the Eucalypts. Staking low down with a short sturdy stake, and using smaller plants will help to prevent basal sweep and help stability. Also, in the authors experience it is well worth removing at least half each seasons growth for the first two or three years in September before the worst of the winter storms to reduce the 'sail' area of the crown. Prune as described in the hedging section. Although this may seem drastic this short term sacrifice of growth makes a substantial contribution to the trees long term stability on exposed sites. In storms the evergreen 'sail' area of the tree's crown catching the wind, particularly in vigorous bushy trees, exerts considerable leverage on the lower stem and root system. If there is not a well balanced root/shoot ratio the tree will become unstable. Cutting back in this way will not affect the mature appearance of the wind tolerant species.
Some species e.g. E. nitens & E. urnigera not mentioned as being exposure tolerant will survive quite well on these hostile sites by allowing the wind to tear and remove a substantial part of the crown over winter. Consequently the remaining leaves of the crown present very little resistance to the severe winds and the tree remains windfirm. It does however look somewhat unattractive until the new spring growth replaces the damage.
|
