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Trunk bending at 120mph

split barkClose-up of the lower portion of trunks bending in 120mph wind showed that the three pruning treatments resulted in the same lower trunk bending, and all three bent less than non-pruned trees. The inclinometer that measured lower trunk angle is visible in each close-up photograph. However bending on the upper portion of the tree was least for thinned and reduced trees; raised trees faired no better than trees that were not pruned. Raised trees in this study could be expected to act like lions-tailed trees in the landscape. Reduced trees might act like trees that received structural pruning.

Average angle of trunk from the vertical on 5 trees in 120mph wind is listed under each photograph.
Pruning treatment Before testing During testing
No pruning unpruned tree

trunk angle

Lower trunk angle = 27
Upper trunk angle = 46


crown reduced in height

Crown was reduced in height using a reduction cut.

trunk angle

Lower trunk angle = 10
Upper trunk angle = 17


thinned tree crown

Crown was thinned by removing primary branches back to trunk.

trunk angle

Lower trunk angle = 12
Upper trunk angle = 23


raised crown on tree

Crown was raised be removing lowest branches.

tree trunk angle

Lower trunk angle = 10
Upper trunk angle = 31