Reminders of Windbreaks

A short summary of salient points regarding planted vegetational windbreaks.

  • The taller the windbreak the greater the length of reduced wind speed on the leeward side and a short windward speed reduction occurs.
  • Windbreaks should be at right-angles to the wind directions of greatest local threats.
  • Multiple-row (2-5) windbreaks are generally safer/more effective and windbreaks must not have any gaps particularly if using a single-row design.
  • The espacement of trees must be appropriate to their likely mature height and spread (successive rows should be at a staggered spacing) but can vary between complimentary rows of ANY shorter/smaller species.
  • Gaps in windbreaks can increase wind speed by at least 20%.
  • Early protection from grazing stock is essential to success.
  • Choice of suitable species with respect to site quality/moisture status, foliar structure and longevity is critical to success.
  • Windbreaks must be somewhat pervious to enable laminar flow over the leeward side and to avoid vertical eddying via the “brick wall” effect.
  • Over large areas the effect of the leading windbreak can be extended by successive plantings at suitable intervals.
  • Windbreaks should be at least a mature tree-height from dwellings in case of windfalls in storms and further in fire-prone situations.
  • Avoid using trees that have double-leaders or a steep branching habit.
  • Windbreaks near dwellings should not be flammable by nature (e.g. bamboo) or drop many branches or large cones (e.g. bunya pine).
  • Windbreaks need to be regularly maintained to maintain structure and reduce suspended fuel build-up underneath.
  • Choice of suitable species can be used for nature corridors/refuges &/or as emergency drought fodder for stock and some species may be more aesthetically pleasing on the eye especially when they flower.
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