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Background

Windthrow assessment provides information on the intrinsic windfirmness of portions of a site prior to harvest or access development. Depending on how the block is developed, the actual risk of windthrow occurring can be increased or decreased. The basic principles of designing prescriptions to reduce windthrow are to reduce the wind loading on edge or residual trees, and to increase the resistance of these trees to wind loads. At the landscape scale or development planning stage such elements as block location, size, shape and access, and timing of removal of adjacent areas should be considered. At the block scale or engineering/cruising/silviculture prescription field work stage such elements as boundary location and orientation, reserve size and location, and edge modification should be considered.

For partial cutting, removal levels and leave tree criteria, and re-entry timing are additional elements to be considered. The different silvicultural systems provide a range of residual canopy structures and re-entry schedules. The strip shelterwood and strip selection systems were designed for use in windy climates.

 
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