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    Climbers' CornerTree Academy

    Natural Wind Gusts, Branch Sway and the Effect of Pruning


    Further analysis of the 2011/2012 Tree Fund funded project “Effect of Pruning Type on Crown Motion” examines the relationships between natural wind gust frequency, branch sway, and pruning effect.  To date very few studies have focused on the natural wind gust frequency, this study will speak specifically to the interaction of limbs and natural wind gust frequency.

    The project investigated the effect of pruning on the dynamic motion of tree crowns. Recent studies of tree biomechanics have explored many of the theories surrounding the dissipation of wind energy within plant stems. However, much of this theoretical work had yet to be linked to current arboricultural practices, or examined in an in situ setting. Specifically, this project examined the change in crown motion resulting from two typically prescribed pruning treatments: crown thinning and crown reduction.

    Six mature Acer saccharinum were fitted with data logging accelerometers, matched to anemometers collecting proximal wind speed data for each subject limb. Acceleration and wind data was collected over the course of 9 days, following which the trees were pruned with one of two prescribed techniques, crown thinning and crown reduction. Following pruning, data collection continued for another 30 days.  Initial data from the project was presented at the 2013 ISA International Conference, Toronto; currently a journal article on that data is also in preparation.  

    The next phase of the project has been to examine the relationship between wind gust frequency and limb sway.  The proposed presentation will focus on this aspect of the project, and shed more light on the direct link between wind gusts, limb sway frequency and aerodynamic damping properties. The results will help to inform practitioners on the effects of the specific pruning regimes, and how they contrast in regards to energy absorption and dissipation.


    With nearly 20 years’ experience as a practicing arborist Matt Follett is a graduate of the Niagara Parks Commission School of Horticulture, and is currently pursuing a Master’s Degree in Urban Forestry at the Université du Québec à Montréal (UQAM). Matt has taught practical arboriculture and tree climbing since 2001, and has presented on arboricultural topics at regional and international ISA conferences, research symposia, private training courses and garden shows.

    Climbers' CornerTree Academy

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