Our manuscript provides novel information about the sway response of large, open-grown trees, for which there are very few data. Our results contrast previous studies on conifers.

Open-grown trees in residential settings, which often assume a decurrent form, provide many benefits but also pose a risk to people and property if they fail. Reliable mechanistic models to predict failure of such trees are uncommon. Parameters to describe dynamic oscillations such as natural frequency (f _n) and damping ratio (ζ) are important components of mechanistic models, but few data exist for large, open-grown trees. Attributes of crown architecture and tree size as well as f _n and ζ were measured on eight large, open-grown sugar maples (Acer saccharum) growing in Belchertown, MA, USA. Although previous work has not demonstrated this correlation, f _n was directly proportional to the cumulative diameter of primary branches. Similarly, previous work has not established reliable predictive models for ζ, which was directly proportional to crown width of sugar maples. Predicting f _n from the cumulative diameter of primary branches is consistent with the multi-modal dynamic response of trees. Predicting ζ from crown width appeared to be due to aerodynamic damping, consistent with previous studies on broad-leaf trees.